TEST PAPER 5 Flashcards

Question

25. Foetal MRI is most commonly organised to evaluate inconclusive but potentially significant findings detected on ultrasound or to characterise definite abnormality detected on anomaly scan. Which one of the following MR imaging sequences is the most popular for foetal imaging? A. Fast spin echo T1W images B. STIR C. Fat suppressed T1W images D. Single-shot, fast spin echo (SS FSE) T2W images E. FLAIR

Answer 1

25. D. Single-shot, fast spin-echo (SS-FSE) T2W images Because foetal MR imaging is performed without maternal or foetal sedation, image acquisition is susceptible to foetal motion; therefore, foetal MR imaging is performed primarily using ultrafast MR imaging techniques known as single-shot, fast spin-echo (SS-FSE) or half-Fourier acquired single-shot, turbo spin-echo (HASTE). Using these rapid pulse sequences, a single T2-weighted image can be acquired in less than 1 second, reducing the likelihood of foetal motion during image acquisition. Because each image is acquired separately, foetal motion typically affects only the particular image that was acquired while the foetus moved.

Answer 2

26. B. Carotid-cavernous fistula Caroticocavernous fistulas are abnormal communications between the carotid artery and the cavernous sinus, either directly or via intradural branches of the internal or external carotid arteries. The pattern of venous drainage, either anterior into the ophthalmic veins or posterior into the petrosal sinuses, often dictates the clinical findings and radiographic appearance. Anterior drainage typically leads to the most dramatic ocular findings and enlargement of the superior orbital vein, the latter often detectable with CT or MRI. However, superior orbital vein enlargement is not specific to CCF. Additional radiographic findings with variable prevalence include lateral bulging of the cavernous sinus wall and enlargement of extraocular muscles on CT or MRI, and abnormal cavernous sinus flow voids on MRI. Direct visualisation of flow-related hyperintensity on the source images of three-dimensional time-of-flight MRA can be extremely helpful in CCF detection, with 83% sensitivity and 100% specificity, far superior to standard MRI

Answer 3

27. D. Group B streptococcal pneumonia Group B streptococcal pneumonia is associated with premature rupture of the membranes during labour. The disease may have an early onset with septicaemia and fulminant progression to severe respiratory distress, shock and respiratory failure within 24 hours or a late onset 1-12 weeks after birth, which is frequently associated with meningitis. Neonatal pneumonia can closely mimic hyaline membrane disease clinically and is the most frequent cause of septicaemia in the neonate. Infection may resemble hyaline membrane disease very closely, especially in smaller infants. However, extensive granular confluent infiltrates whose distribution is often less uniform than those of hyaline membrane disease are more commonly seen. There is also less atelectasis than in hyaline membrane disease. Pleural effusions are not uncommon and the lung volume is normal. The differential diagnosis includes hyaline membrane disease, which usually has a uniform distribution of pulmonary opacities, never has pleural effusions and has a decreased lung volume; meconium aspiration, which usually has nodular nonhomogeneous densities, may have pleural effusions and usually has an increased lung volume; and finally, transient tachypnoea of the newborn, which usually has non-homogeneous densities and may have pleural fluid.

Answer 4

28. C. There is no correlation between carmustine dose and toxicity. Cyclophosphamide and busulfan are the most common drugs that cause lung injury. Diffuse alveolar damage (DAD) is the most common manifestation of cyclophosphamide-induced lung disease, with NSIP and COP being less common. There is no relationship between development of lung injury and dose and duration of therapy. Carmustine is one of the few drugs for which there is a clear relationship between cumulative dose and lung injury. Lung injury can occur at low doses if the patient has undergone thoracic radiation therapy. DAD is the most common manifestation, with NSIP being less common. DAD is the most common manifestation of bleomycin-induced lung disease, with NSIP and COP being less common. The risk of developing lung injury is increased in the elderly, in patients on oxygen therapy, with a history of prior thoracic irradiation, or in whom therapy is restarted in 6 months of discontinuation. The prognosis is poor, with most patients dying of respiratory failure within 3 months. Paclitaxel may commonly cause pulmonary toxicity.

Answer 5

29. C. The fat ring sign Omental infarction demonstrates a variety of imaging appearances on CT. Classically; it appears as a fatty, large (>5 cm) encapsulated mass, with soft-tissue stranding adjacent to the ascending colon. Early or mild infarction may manifest as mild haziness in the fat anterior to the colon. Omental torsion is a rare cause of omental infarction and occurs when a portion of the omentum twists upon itself, leading to vascular compromise. In omental torsion, swirling of the vessels is often visible within the omentum. Although most cases of omental infarction are on the right side, left-sided infarction also may spontaneously occur. Unusual locations of infarction are more commonly seen in the setting of surgical trauma or post-operative changes that result in altered omental vascular supply and subsequent infarction. Similar to epiploic appendagitis, the adjacent colon is usually spared, although rarely the colonic wall may be thickened, a result of direct extension of omental inflammation. The fat-ring sign is seen in epiploic appendagitis, not omental infarction.

Answer 6

30. C. Morquio syndrome The mucopolysaccharidoses are a group of inherited diseases characterised by abnormal storage and excretion in the urine of various mucopolysaccharides. These patients have short stature and characteristic plain film findings. A characteristic finding in the hands is a pointed proximal fifth metacarpal base that has a notched appearance to the ulnar aspect. There is generalised flattening of the vertebral bodies (platyspondyly) (cf. not a feature of Hurler syndrome). Hunter and Hurler syndromes demonstrate an anterior vertebral beak that is inferiorly positioned, whereas Morquio syndrome demonstrates an anterior vertebral beak that is centrally positioned. Although achondroplasia can cause rounded anterior beaking in the vertebra of the upper lumbar spine, the findings described within the hands are more typical of die mucopolysaccharidoses

Answer 7

31. C. COP is a recognised pattern on HRCT in rheumatoid lungs. Thoracic involvement develops in patients with disease progression. Pleural disease is the most common thoracic manifestation and pleural thickening is the most common finding, more than pleural effusion. Pleural effusions are usually unilateral and may be loculated. They usually occur late in the disease and are commonly associated with pericarditis and subcutaneous nodules. HRCT shows basal and peripheral predominant fibrosis. Rarely upper lobe fibrosis, mimicking tuberculosis (TB), can occur. There is increased prevalence of lung cancer in fibrotic rheumatoid lung disease. Nodules are multiple and well circumscribed, often forming thick-walled cavities. Obliterative bronchiolitis results in air trapping and mosaic pattern. COP is also seen on HRCT.

Answer 8

32. E. Follow-up MRI is required in patients with high-grade liver injuries to identify potential complications that require early intervention. Non-surgical treatment has become the standard of care in haemodynamically stable patients with blunt liver trauma. The use of helical CT in the diagnosis and management of blunt liver trauma is mainly responsible for the notable shift during the past decade from routine surgical to non-surgical management of blunt liver injuries. CT is the diagnostic modality of choice for the evaluation of blunt liver trauma in haemodynamically stable patients and can accurately help identify hepatic parenchymal injuries, help quantify the degree of haemoperitoneum and reveal associated injuries in other abdominal organs, retroperitoneal structures and the gastrointestinal tract The CT features of blunt liver trauma include lacerations, subcapsular or parenchymal hematomas, active haemorrhage, juxtahepatic venous injuries, periportal low attenuation and a flat inferior vena cava. It is important that radiologists be familiar with the liver injury grading system based on these CT features that was established by the American Association for the Surgery of Trauma. CT is also useful in the assessment of delayed complications in blunt liver trauma, including delayed haemorrhage, hepatic or perihepatic abscess, post-traumatic pseudoaneurysm and haemophilia, and biliary complications such as biloma and bile peritonitis. Follow-up CT is needed in patients with high-grade liver injuries to identify potential complications that require early intervention.

Answer 9

33. C. Haemangioma Although not true neoplasms, cavernous malformations are the most common benign orbital mass in adults. Although these masses are commonly referred to as cavernous haemangiomas, many pathologists prefer the term cavernous malformation. On CT images, cavernous malformations are typically well circumscribed, homogeneous and ovoid. The majority occur at the lateral aspect of the intraconal space. Conal and extraconal cavernous malformations are rare. Phleboliths are virtually never seen. Cavernous malformations tend to displace and surround adjacent structures, such as extraconal muscles and the optic nerve, rather than cause direct invasion. Osseous remodelling may be present, although bone erosion is rare. At MRI performed with T1-weighted sequences, cavernous malformations are isointense relative to muscle; the lesions appear uniformly hyperintense on T2-weighted images, with no flow voids. Internal septations may be identified on T2-weighted images. At multiphase CT, enhancement of cavernous malformations is poor on early arterial phase images, owing to the scant arterial supply. Delayed venous phase images demonstrate progressive filling of the mass from periphery to centre, with complete filling within 30 minutes. This enhancement pattern may permit differentiation of cavernous malformations from other vascular lesions with rich arterial supply, such as capillary' haemangioma (a paediatric diagnosis), haemangiopericytoma and arteriovenous malformations. Rhabdomyosarcoma is the most common soft-tissue malignancy of childhood and most common primary orbital malignancy. CT shows moderately well-defined to ill-defined margins, irregular shape and mild-moderate contrast enhancement. Adjacent bony destruction occurs in 40%. Globe distortion and extension to the paranasal sinuses may also be seen. Calcification is rare unless posttreatment. MR typically shows bright T2 signal, distinguishing rhabdomyosarcoma from other tumours such as chloroma (granulocytic sarcoma), lymphoma and metastatic neuroblastoma.

Answer 10

34. E. High signal in inflammatory stranding in peritubal fat on T1 fat-suppressed images Pelvic inflammatory disease (PID) affects women of reproductive age and can lead to infertility, ectopic pregnancy and chronic pelvic pain. In acute cases when dilated fallopian tubes are detected, it is extremely important to be able to differentiate tubal torsion from a pyosalpinx. A tubal torsion and a hematosalpinx may have a similar appearance to that of a fluid-filled tube on T2-weighted and STIR images; on T1-weighted images, however, a fluid filled tube has low signal intensity. Layering is common with haemorrhagic lesions, and tubal torsion may have a comma-shaped appearance. A pyosalpinx may have a similar appearance to that of a hydrosalpinx, but a hydrosalpinx usually has thinner walls. An abscess usually has low T1-weighted and high T2-weighted signal, but there can be a large variation in the signal intensity on T1-weighted and heterogeneity' on T2-weighted images. Thick, irregular walls are typical of abscesses. The Tl signal of pyosalpinx/TO abscess varies according to haemorrhagic/proteinaceous content On post-contrast T1-weighted images, pyosalpinx shows wall enhancement. Enhancement of the surrounding inflamed fat can also be evident. Inflammatory fat stranding is also seen on fat-suppressed T2-weighted sequences.

Answer 11

35. B. Osteogenesis imperfecta Osteogenesis imperfecta is an inherited disorder that results from mutations in either the COL1A1 or COL1A2 gene of Type I collagen. The disease is usually apparent at birth or in childhood, but more mild forms of the disease may not be apparent until adulthood. The disease is classified into Types I-IV, with Type I, the mildest form, being described in the question. The presenile hearing loss is caused by otosclerosis. The differential diagnosis can be resolved by the extraskeletal manifestations (blue sclerae and dentinogenesis imperfecta). The other types are Type II, lethal perinatal; Type III, severe progressive; and Type IV, moderately severe

Answer 12

36. E. Transient tachypnoea of the newborn Although RDS is seen in association with maternal diabetes and caesarean section, hyperexpansion is not a feature of RDS. Transient tachypnoea of the newborn appears soon after birth (<4 hours) and has been identified as occurring with caesarean birth and infant sedation. Longer labour intervals, macrosomia of the foetus, and maternal asthma have also been associated. It may be accompanied by chest retractions, by expiratory grunting, or by cyanosis (which can be relieved with minimal oxygen). Recovery is usually complete within 3 days. The lungs are usually affected diffusely and symmetrically, and the condition is commonly accompanied by small pleural effusions. The clinical course of transient tachypnoea is relatively benign when compared with the severity suggested by chest films. Radiographic resolution by the second or third day characterises this entity and differentiates it from other possible disorders; if radiographic resolution is not complete by the third day or if respiratory symptoms persist longer than 5 days, an alternative diagnosis should be sought. Findings of transient tachypnoea of the newborn on chest radiographs may include mild, symmetrical lung overaeration, prominent perihilar interstitial markings and small pleural effusions. The radiographic appearance at times can mimic the diffuse, granular appearance of hyaline membrane disease but without pulmonary under aeration. Neonates with transient tachypnoea are usually delivered at term. Radiographic lung changes may also resemble the coarse, interstitial pattern seen with other causes of pulmonary oedema or the irregular pattern of lung opacification seen in meconium aspiration syndrome.

Answer 13

37. C. Multifocal hepatic lesions Henoch-Schönlein purpura is the most common vasculitis of childhood affecting small blood vessels. Clinical manifestations may include non thrombocytopenic purpura, arthritis, abdominal pain, gastrointestinal haemorrhage and glomerulonephritis. Imaging is useful to depict end-organ damage. Ultrasound findings may include bowel wall oedema, submucosal and intramural haemorrhage, intussusception, hypoperistalsis, bowel dilatation, ascites, normal or enlarged echogenic kidneys, and also possible intramural haematomas within the urinary bladder and ureters. Non-specific findings on scrotal ultrasound may be identified such as hydroceles, scrotal wall thickening and inflammation of the spermatic cord and epididymis.

Answer 14

38. D. Erosion of the medial aspect of the clavicle Bone changes of rheumatoid arthritis seen on chest X-ray include resorption of the lateral end of the clavicles, erosive arthritis of the shoulders (most commonly superolateral aspect of humeral head), global loss of shoulder joint space, superior rib notching, atrophy and rotator cuff tear.

Answer 15

39. D. Dual-phase CT pancreas Insulinomas are the most common functioning pancreatic endocrine tumours (PET), accounting for just over 40% of all functioning PETs. They have an incidence of two to four per million people each year. They tend to manifest earlier and have a smaller size than other functioning and non-functioning endocrine tumours, Insulinomas usually are sporadic, but they account for 10% 30% of functioning PETs in patients with Multiple endocrine neoplasia (MEN1) and they have been reported in patients with neurofibromatosis Type 1. In 1935, Whipple and Frantz described the classic clinical triad of insulinomas: symptoms of hypoglycaemia, low blood glucose and relief of symptoms with administration of glucose. Hypoglycaemia typically manifests during fasting or after exercise, and patients often self-medicate by eating frequent small meals. On CT and MR imaging, insulinomas arc typically homogeneous and hyperenhancing. The use of coronal images may help differentiate these small hyperenhancing lesions from nearby.

Answer 16

40. A. Hypointense cysts on T1W images Findings of an adnexal mass with high T1-weighted signal and high T2 weighted signal (although slightly lower T2 signal than simple or functional cyst) is highly specific for an endometrioma. The main differential for high T1 -weighted cysts are haemorrhagic functional cysts and mature cystic teratoma. Cystic teratoma is differentiated by means of T1-weighted fat suppressed images. Endometriomas tend to have higher Tl and lower T2 signal than haemorrhagic cysts, due to higher protein content and viscosity (described as T2 shading). Multifocal lesions and bilateral lesions also favour endometriosis. Hemosiderin laden macrophages combined with the fibrous nature of the cyst wall give it a low signal-intensity appearance on both Tl - and T2 weighted images. Wall thickening, septae and nodularity are also recognised.

Answer 17

41. E. Eosinophilic granuloma The vast majority of ‘vertebra plana’ lesions in relatively healthy children are caused by an eosinophilic granuloma. The other available options are all possible, but less common, differential diagnoses. There is usually preservation of the disc space and no kyphosis. The posterior elements are rarely involved.

Answer 18

42. D. Dermoid cyst Dermoid cysts represent the most common congenital lesion of the orbit and account for one-third of all childhood orbital tumours. CT shows an ovoid, well demarcated cystic lesion; there may be fat (50%) or calcification (15%) present. Bone remodelling and thin rim enhancement is described. The majority occur in the extraconal location, occupying the superolateral aspect of the anterior orbit (related to the frontozygomatic suture). MRI shows high signal on T1-weighted images, if containing fat or proteinaceous material with low to iso intense signal on T2-weighted images. Thin rim enhancement is seen on Tl FS images post administration of gadolinium, unless the lesion has ruptured.

Answer 19

43. B. Anterior ethmoid mucocoele Paranasal sinus mucocoeles are benign, expansile cystic masses covered by respiratory epithelium, resulting from accumulation and retention of mucus secretion in cases where the sinus drainage is obstructed. They primarily occur in the frontal sinuses (60%-65%) but may also be found in ethmoid sinuses (20%-25%). Usually, mucocoeles are seen as an isodense or mildly hyperdense sinus opacity in relation to the cerebral tissue, but in cases of acute infection it may appear as a more dense and peripherally enhanced image. The neighbouring bone structure is remodelled with areas of thickening, expansion and erosion. Additionally, in the areas of greater fragility, one may observe herniation into adjacent structures, displacing structures rather than invading them. Invasion would suggest malignancy. The radiological appearance at MRI varies with the time of evolution of the disease. Initially, the contents will be predominantly aqueous, so the corresponding image will be hypointense on T1-weighted sequences and hyperintense on T2-weighted sequences. Over time, the protein contents may increase, resulting in hyperintense images both on T1-weighted and T2-weighted sequences.

Answer 20

44. E. Central bronchiectasis Angioinvasive pulmonary aspergillosis occurs almost exclusively in immunocompromised patients with severe neutropenia. Characteristic CT findings include nodules surrounded by a halo of ground-glass attenuation (halo sign) or pleura-based, wedge-shaped areas of consolidation. In neutropenia patients, the halo sign is highly suggestive of angioinvasive aspergillosis. However, a similar appearance has been described in infection by Mucorales, Candida, herpes simplex virus (HSV), cytomegalovirus (CMV), Wegener’s granulomatosis, Kaposi’s sarcoma and haemorrhagic metastases. Separation of fragments of necrotic lung (pulmonary sequestra) from adjacent parenchyma results in air crescents similar to those seen in mycetomas. The air crescent sign is usually seen after initiation of treatment and with resolution of the neutropenia. Airway invasive aspergillosis shows multiple centrilobular nodules and the tree-in-bud pattern.

Answer 21

45. C. Smaller aneurysms have a higher likelihood of thrombosis Kawasaki’s disease is a common paediatric vasculitis of medium-sized vessels, with coronary vasculitis being the hallmark manifestation. It is the leading cause of acquired heart disease in children in developed countries. Coronary arterial aneurysms typically occur within the subacute phase of the disease and may be associated with sudden cardiac death. The aneurysms typically develop in the proximal segments of major coronary arteries and affect the left anterior descending artery followed by the proximal right coronary arteries in frequency of location. Smaller aneurysms, (<5 mm in diameter) are more likely to regress than larger aneurysms (>8 mm in diameter), which have a higher likelihood of thrombosis and infarction.

Answer 22

46. E. Leiomyoma Leiomyomas are neoplasms of mature smooth muscle cells and are the most common benign oesophageal neoplasm, although they are about 50 times less common than oesophageal carcinoma. They are also the most common mesenchymal tumours of the oesophagus, unlike in the remainder of the gastrointestinal tract, where GISTs predominate. Oesophageal leiomyomas are nearly twice as common in men as m women and have been reported in patients between 4 and 81 years of age, although they rarely occur in the paediatric population. Most patients are asymptomatic, but dysphagia and pain may develop, depending on the size of the lesion and amount of encroachment on the oesophageal lumen, in contrast to patients with malignant oesophageal tumours. Affected individuals usually have long-standing symptoms, with a duration of more than 2 years in most cases. Treatment options include endoscopic resection, surgical enucleation and observation. Oesophageal leiomyomas have a benign clinical course and typically do not recur after surgery.

Answer 23

47. D. Ureteric endometriosis is mostly intrinsic. Deep pelvic endometriosis is defined as subperitoneal invasion by endometriotic lesions that exceeds 5 mm in depth. Involvement of anatomic structures such as the uterosacral ligaments or the vaginal or rectal wall should be suspected when these structures have a hypointense thickened or nodular appearance on T2-weighted images. Intermingled high T2 signal would be secondary to ectopic endometrial glands. On T1-weighted or fat-suppressed T1 -weighted MR images, these foci may have either high or low signal intensity, depending on the presence or absence of bloody content. Some endometriomas may show restricted diffusion on DWI, probably due to intracystic blood clots. Enhancement may or may not occur post-contrast, depending on the proportions of inflammatory reaction, glandular tissue and fibrosis. Bladder endometriosis should be considered in anyone who presents with urinary tract symptoms after having undergone hysterectomy or other gynaecologic surgical procedure. Because vesical endometriosis seldom invades the mucosa, MR imaging may show abnormalities although cystoscopy is normal. As with bladder involvement, extrinsic endometriosis is the most common form of ureteral involvement. On MR imaging, ureteral endometriosis usually appears as irregular hypointense nodules on T2-weighted images. Deep retroperitoneal endometriotic lesions of the posterior compartment involve the rectovaginal pouch, retrocervical area, uterosacral ligaments, posterior vaginal fornix, rectovaginal septum and rectum. Obliteration of the pouch of Douglas occurs when retrocervical lesions extend to the anterior rectal wall.

Answer 24

48. D. 4 Physeal Salter-Harris fractures are divided into two categories on the basis of the involved physeal regions: (1) horizontal fractures without involvement of the germinal or proliferative zone of the physis and (2) longitudinal fractures that extend through all zones of the physis into the epiphysis. Horizontal fractures (Salter Harris Types I and II) result in bridge formation in 25% of cases, whereas longitudinal fractures (Salter-Harris Types III and IV) result in bridge formation in 75% of cases.

Answer 25

49. B. Involvement of endothoracic fascia Malignant mesothelioma occurs mainly in the pleura and peritoneum but can arise in the pericardium or tunica vaginalis testis. It is the most common primary neoplasm of the pleura and has a strong association with asbestos exposure, particularly crocidolite. Mesothelioma is not known to arise from plaques. There is a new TNM staging system for diffuse malignant pleural mesothelioma that emphasises the criteria for determinate local tumour extension and regional lymph node status, to identify patients with potentially curable early disease (T1a and b); potentially resectable but not necessarily curable (T2 and T3); and unresectable local tumour spread (T4). Signs of unresectability include multifocal extension into chest wall with or without rib or spine destruction, extension through diaphragm into peritoneum, extension into contralateral pleura, extension into mediastinal organs, extension through pericardium and direct extension into heart. Localised tumour extension into the endothoracic fascia (T3) is potentially resectable.

Answer 26

50. E. Ileum Enteric duplication cysts are an uncommon congenital abnormality. They can occur anywhere along the digestive tract on the mesenteric side. The small intestine is most commonly involved, with the order from most to least common being the ileum, jejunum and duodenum. Most duplication cysts manifest during the first year of life, although some occasionally manifest in older patients. Children can present with a variety of symptoms including abdominal distention, vomiting, bleeding, a palpable abdominal mass and rarely urinary frequency and hesitancy. Complications include perforation, intussusception, bowel obstruction from adjacent pressure or mass effect, volvulus and associated malignancy. Malignant lesions arising from duplication cysts arc rare, particularly in children.

Answer 27

51. E. Cervical factor infertility is the most common cause of infertility. Intrauterine filling defects seen at HSG may be caused by air hubbies in the contrast material injection, intrauterine adhesions, submucosal leiomyomas, endometrial polyps or blood clots. Intrauterine adhesions, or synechiae, may be the result of previous pregnancy, dilation and curettage, surgery or infection. They appear as irregular linear filling defects at HSG; the endometrial cavity may appear distorted or may not expand as expected with contrast, liven subcentimetric endometrial polyps and submucosal leiomyomas may interfere with embryo transfer and implantation. Submucosal leiomyomas distort the normal-appearing endometrium. Uterine contour irregularities observed at HSG can be due to adenomyosis, uterine leiomyomas and Mullerian duct anomalies. Submucosal leiomyoma located near the uterine cornua may obstruct the ipsilateral fallopian tube. Cervical abnormalities include cervical factor infertilityt an inadequate quality or volume of cervical mucus, a condition that accounts for approximately 10% of cases of female infertility, and cervical stenosis.

Answer 28

52. D. Granulomatosis with polyangitis CT scanning is likely to reveal a common mucosal thickening similar to that encountered in chronic sinusitis. However, the presence of bony erosions of the sinonasal wall is very suspect of the diagnosis of a granulomatous disease. Bone erosion commonly affects the lamina papyracea (orbital wall), inter sino-nasal wall and nasal septum. Bone destruction usually involves the nasal septum and then extends to the sinonasal wall, destroying the turbinates. Differential diagnoses including traumatic lesions (accidental, iatrogenic) or toxic lesions (cocaine abuse, chromium salts) should be considered. Isolated septal perforation should suggest the diagnosis of GP. There are no specific imaging findings to distinguish GP from ‘lethal midline granuloma’, but the destructive lesions seem to be more extensive in lethal midline granuloma. Pulmonary nodules and masses are the most common radiologic findings of Wegeners granulomatosis.

Answer 29

53. A. ACL The pivot shift injury is a non-contact injury commonly seen in skiers or US football players. The resulting bone contusion (pivot shift oedema) pattern involves the posterior aspect of the lateral tibial plateau and the midportion of the lateral femoral condyle. The exact location of the lateral femoral condyle injury depends on the degree of flexion of the knee at injury. Another recently described bone contusion pattern associated with the pivot shift injury is oedema within the posterior lip of the medial tibial plateau. Pivot shift oedema is typically associated with ACL tear, most commonly mid substance. Dashboard oedema is seen at the anterior aspect of the tibia and, occasionally, at the posterior surface of the patella. The associated soft-tissue injuries include disruption of the PCL (most commonly mid-substance) posterior joint capsule. Hyperextension of the knee can result in kissing contusion involving the anterior aspect of the tibial plateau and the anterior aspect of the femoral condyle. ACL, PCL and meniscal injury can be associated depending on the force. The classic bone contusion pattern seen after lateral patellar dislocation includes involvement of the anterolateral aspect of the lateral femoral condyle and the inferomedial aspect of the patella. This is associated with tear of MPFL. With clip injury (pure valgus stress), bone marrow oedema is usually most prominent in the lateral femoral condyle secondary to the direct blow, whereas a second smaller area of oedema may be present in the medial femoral condyle secondary to avulsive stress to the MCL (mostly at the femoral attachment).

Answer 30

54. D. Granulomatosis with polyangiitis Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis, affects small to medium sized vessels and most commonly involves the upper and lower respiratory tracts and kidneys. In comparison to adults, children are more likely to have multi-organ involvement with renal disease, subglottic stenosis, nasal deformity and pulmonary findings. Differential diagnosis of GPA may include those that present with pulmonary-renal features such as mixed connective tissue diseases, Goodpasture syndrome or systemic lupus erythematosus. Takayasu arteritis is a large vessel vasculitis with characteristic abnormalities of the aorta and its main branches. Kawasaki’s disease and polyarteritis nodosa (PAN) are medium vessel vasculitides. The hallmark imaging feature in Kawasaki’s disease includes coronary artery aneurysms. In PAN, angiographic findings of aneurysms, stenoses or occlusions of medium-sized vessels is a key diagnostic criterion. This is predominantly seen in renal and mesenteric arteries, although not pathognomonic. Cogan’s syndrome is an autoimmune disorder characterised by interstitial keratitis and bilateral audiovestibular deficits. It may be associated with a systemic vasculitis and typically presents in young adulthood.

Answer 31

55. E. High density consolidation Pleural disease is the most commonly encountered manifestation of asbestos-related disease. Benign pleural effusions are thought to be the earliest pleural-based phenomenon. The most common manifestation of asbestos exposure is pleural plaques that usually arise from the parietal pleura but may arise from visceral pleura. Calcification is reported in 10%—15%. The classic distribution of plaques is the posterolateral chest wall, lateral chest wall, the dome of the diaphragm (virtually pathognomonic) and the mediastinal pleura. The apices and costophrenic angles are typically spared. Diffuse pleural thickening is less specific for asbestos exposure. Asbestos related round atelectasis is also known as asbestos pseudotumour and is related to fibrosis in the superficial layers of the pleura. Asbestosis is the term given to lung fibrosis caused by asbestos. The changes are more pronounced in the lower lobes and subpleurally but often extend to involve the middle lobe and lingula. Malignant mesothelioma and bronchogenic carcinoma are known associations. High-density consolidation is typical of amiodarone lung changes.

Answer 32

56. C. Pneumobilia Of all the hollow viscera, the stomach is the least commonly affected by gas forming infections. Of the 30 reported cases in the literature, caustic ingestion (37%) and alcohol abuse (22%) were found to be the most common causes. Other predisposing conditions include recent gastroduodenal surgery, trauma and gastric infarction. Caustic ingestion of acid is thought to promote coagulative necrosis of the gastric lumen, whereas ingestion of an alkaline substance leads to liquefactive necrosis; in either case, the end result is mucosal damage and super infection with gas-forming bacteria. There are no predilections with regard to age, sex or diabetic status. Clinical manifestation may be dramatic, ranging from acute sepsis to gastric haemorrhage and, rarely, vomiting of the necrotic stomach cast. CT is considered the modality of choice for detection of intramural gas and evaluation for the presence of pneumoperitoneum or portal venous gas. CT may also demonstrate irregular mucosal fold thickening and may be used to monitor response to treatment or disease progression. An important differential diagnosis to consider is benign gastric emphysema. Gas collections form within the gastric wall without associated infection by gas-forming organisms. Gas may enter the wall from the lumen, peritoneal surface or oesophageal or duodenal connection and is usually associated with violent coughing, vomiting or severe obstructive pulmonary disease. Gastric fold inflammation and thickening are not present, and the patient is usually asymptomatic with spontaneous resolution expected.

Answer 33

57. D. Peritubal adhesions The differential diagnosis of tubal occlusion typically includes tubal spasm, infection and prior surgery. Rare causes include granulomatous salpingitis due to tuberculosis, intraluminal endometriosis, parasitic infection and congenital atresia of the fallopian tubes. When tubal occlusion in the proximal or interstitial portion of the fallopian tube is seen at hysterosalpingography, a tubal spasm should be considered as the possible cause. Delayed radiography may be performed to help differentiate tubal spasm from true tubal occlusion. A spasmolytic agent such as glucagon also may be administered to relax the uterine muscle and relieve a tubal spasm. Peritubal adhesions show' peritubal pooling of contrast material rather than occlusion of fallopian tubes.

Answer 34

58. B. Acquired attic cholesteatoma Cholesteatomas are composed of densely packed desquamated keratinizing squamous cells, arising from a peripheral shell of inward-facing epithelium. The role of CT is to assess the extent of disease and exclude complications. Key findings on HRCT include soft-tissue opacification in the attic, aditus (non-dependent location) and/or mastoid air cells, erosion of the scutum, disruption of ossicular chain (long process of incus erosion is common), presence of disease in sinus tympani and erosions of the tegmen tympani, semicircular canal, facial nerve canal and inner ear. In cases of clinical suspicion of intracranial extension, perform contrast CT/MRI to rule out intracranial complications. Congenital cholesteatoma is difficult to differentiate from acquired type, but clinical features help; it is commonly seen in children with intact tympanic membrane and absence of previous otologic disease.

Answer 35

59. B. Transient synovitis Acute transient synovitis is the most common non-traumatic cause of hip pain in young children. It tends to affect children between 2 and 9 years of age and boys are affected two to four times more often. Where history is typical no imaging may be required; ultrasound can be used to identify the effusion. Initial bone scan uptake can be reduced, mimicking SUFE, but can increase later on. Juvenile arthritis affects children above 4-5 years of age. Radiographs may show erosions and loss of joint space. MRI and ultrasound are more sensitive for soft-tissue changes, allowing demonstration of synovitis, distinguishing pannus from simple effusion and identifying cartilage destruction and cortical erosions. Septic arthritis is an emergency. The majority of patients are less than 2 years old and are usually unwell with pain on passive movement of the hip. Avascular necrosis (AVN) of the femoral head is a condition induced by compromised blood supply, resulting in progressive destruction of bone. It is most commonly idiopathic (Perthes) but may be seen following trauma, infection, steroid treatment and in association with haematological diseases, such as sickle cell anaemia. Perthes disease usually affects children between 4 and 10 years of age and is more common in boys. Plain radiography is insensitive at early changes. The epiphysis may appear small, sclerotic or flattened with subchondral lucency or more marked fragmentation. Where symmetrical changes are seen, hypothyroidism or epiphyseal dysplasia should be considered. Meyer’s dysplasia mimics Perthes disease unilaterally by appearance but is asymptomatic.

Answer 36

60. C. Abnormally large kidneys There are several causes of chronic liver failure in children: chronic hepatitis (hepatitis B and C), biliary atresia, drug induced (e.g., paracetamol), alpha-1-antitrypsin deficiency, Wilson’s disease, cystic fibrosis, IBD (inflammatory bowel disease), Budd-Chiari syndrome, TPN (total parenteral nutrition) induced and so on. Abnormal sweat test (>60 mmol/L of sodium chloride) suggests CF, while reduced serum copper and caeruloplasmin and raised 24-hour urinary copper suggests Wilson’s disease. US shows hepatomegaly, echogenic liver, splenomegaly, ascites and varices. Kayser Fleischer rings from copper deposition in the eye are pathognomonic but may require slit lamp examination to visualise. Adolescent patients can present with neurological symptoms. Enlarged kidneys are not a feature of Wilson’s disease and may be seen in the acute phase of glomerulonephritis, ATN, renal vein thrombosis, amyloidosis, lymphoma, diabetes, glycogen storage disease, polycystic kidney disease and so on.

Answer 37

61. D. Renal rhabdoid tumour Rhabdoid tumour is a rare, highly aggressive malignancy of early childhood. It is not related to Wilms tumour or rhabdomyosarcoma and was recently recognised as a distinct pathologic entity. Its name is derived from its histologic appearance, which resembles that of a tumour of skeletal muscle origin, although a myogenic origin has not been proved. Rhabdoid tumour occurs exclusively in children, comprising 2% of paediatric renal malignancies. Approximately 80% occur in patients less than 2 years of age and 60% in patients less than 1 year of age, with the majority (25%) diagnosed between 6 and 12 months of age. The median age at diagnosis is 11 months, with the lesion reported at up to 9 years of age.

Answer 38

62. E. Pulmonary embolism Extra-intestinal manifestations of inflammatory bowel disease: Musculoskeletal System Arthritis Colitic type, ankylosing spondylitis, isolated joint involvement, hypertrophic osteoarthropathy: dubbing, periostitis Miscellaneous Manifestations Osteoporosis, aseptic necrosis, polymyositis Dermatologic and Oral Systems Reactive Lesions Erythema nodosum, pyoderma gangrenosum, aphthous ulcers, necrotising vasculitis Specific Lesions Fissures, fistulas, oral Crohn’s disease, drug rashes Nutritional Deficiencies Acrodermatitis enteropathica, purpura, glossitis, hair loss, brittle nails Associated Diseases Vitiligo, psoriasis, amyloidosis Hepatopancreatobiliary System Primary sclerosing cholangitis, bile-duct carcinoma Associated Inflammation Autoimmune chronic active hepatitis, pericholangitis, portal fibrosis, cirrhosis, granulomatous disease Metabolic manifestations Fatty liver, gallstones associated with ileal Crohn’s disease Ocular System Uveitis/iritis, episcleritis, scleromalacia, corneal ulcers, retinal vascular disease Metabolic System Growth retardation in children and adolescents, delayed sexual maturation Renal System Calcium oxalate stones

Answer 39

63. C. They occur early in atherosclerotic disease. In a penetrating aortic ulcer (PAU), an atheromatous plaque ulcerates and burrows through the ultima into the aortic media. This leads to haemorrhage into the wall (intramural hematoma). The mural haematoma may break through into the adventitia to form a pseudoaneurysm, or it may rupture. Ulceration of an aortic atheroma occurs in patients with advanced atherosclerosis. On imaging, a penetrating aortic ulcer can be distinguished from an atheromatous plaque by presence of a focal, contrast-filled outpouching surrounded by an intramural hematoma, which confirms the aggressive behaviour of the lesion. The atheromatous plaque with ulceration but without penetration through the intima shows irregular margins, but no contrast material extends beyond the level of intima, which is frequently calcified, and no intramural hematoma is present. PAU can present with chest or back pain.

Answer 40

64. B. Continued increase in size of follicle Ovulation is sonographically determined by the follicle suddenly disappearing or regressing in size, irregular margins, intrafollicular echoes, follicles becoming more echogenic, free fluid in the pouch of Douglas and increased perifollicular blood flow velocities on Doppler.

Answer 41

65. A. Cholesterol granuloma Cholesterol granulomas of the temporal bone can occur in the mastoid segment, the middle ear and the petrous apex. They are the most common primary' petrous apex lesions. Temporal bone CT reveals an expansile, sharply defined and often rounded mass of the petrous apex with cortical thinning and trabecular breakdown. The general appearance is that of a slowly progressive benign process. There is central soft-tissue density without an internal matrix, a calcification or residual septations. If the lesion is sufficiently enlarged, frank bony dehiscence is observed. On MRI, cholesterol granulomas are typically hyperintense on both T1 and T2-weighted sequences because of the accumulation of blood breakdown products and proteinaceous debris. Small lesions may be relatively homogeneous, whereas large lesions show more heterogeneity. Often cholesterol granulomas have a distinct hypointense peripheral rim on T2-weighted images due to hemosiderin deposition. After contrast administration, there may be subtle peripheral enhancement secondary' to inflammatory response but no central enhancement that would indicate solid tissue.

Answer 42

66. E. Chondroblastoma Chondroblastomas are rare, benign, cartilaginous tumours that affect the epiphysis of children. On MR images, chondroblastomas are seen as epiphyseal lesions with high T2 signal intensity surrounded by a halo of oedema in the adjacent marrow and soft tissues. A characteristic thin (<1 mm) low-signal-intensity ring that corresponds to peripheral sclerosis is seen in more than 90%. Fluid fluid levels similar to Aneurysmal bone cyst (ABCs) are seen in 20%-30% of cases. Differential considerations include epiphyseal osteomyelitis and osteoid osteoma. Neuroblastoma metastasis and Langerhans cell hystiocytosis can also affect the epiphytes. Simple bone cyst (SBC), fibrous cortical defects and ABC affect the metaphysis.

Answer 43

67. D. Erythema nodosum Pyoderma gangrenosum (PG) has been reported in 1%—10% of ulcerative colitis (UC) patients and 0.5%-20% of Crohn’s disease (CD) patients. There is no significant difference between genders. There have been conflicting data regarding the distribution of PG among CD and UC; however there is no statistically significant difference between the two groups. Erythema nodosum is more common in CD than in UC. The occurrence of lesions parallels intestinal disease activity, and lesions frequently resolve when bowel disease subsides; thus, treatment is usually aimed at the underlying bowel disease. At times, erythema nodosum can precede bowel exacerbations and can require treatment with oral steroids. Based on these findings, patients with idiopathic EN should be evaluated for IBD.

Answer 44

68. D. Glomus jugulare About 80% of all paragangliomas are either carotid body tumours or glomus jugulare tumours. The typical CT appearance ot a carotid body tumour is a well-defined soft-tissue mass within the carotid space of the infrahyoid neck. The underlying hypervascularity of the tumour results in homogeneous and intense enhancement following intravenous administration of contrast material. Splaying of the common carotid bifurcation is very suggestive of a carotid body tumour. On high-resolution CT scans of the temporal bones, expansion and erosion of the jugular foramen characterise the glomus jugulare tumour. The tumour spreads along the paths of least resistance and is initially directed superiorly owing to the intrinsic weakness of this part of the jugular fossa. Subsequently, the hypotympanum, mesotympanum and the sinus tympani are invaded. Ossicular chain destruction is common. Inferior spread of the tumour produces infiltration of the IJV (internal jugular vein) and infratemporal fossa. Paragangliomas typically exhibit a low signal intensity on T1-weighted images and high signal intensity on T2-weighted sequences. As with CT, homogeneous and intense enhancement is noted following the intravenous administration of contrast material. Multiple serpentine and punctate areas of signal void characterise the typical paraganglioma with all MR sequences; these areas are variably distributed throughout the mass and are believed to represent flow voids in the larger intratumoural vessels (salt and pepper appearance).

Answer 45

69. D. The aortic wall appears thinned out. Aortic intramural hematoma may occur as a primary event in hypertensive patients from spontaneous bleeding from the vasa vasorum into the media or may be caused by a penetrating atherosclerotic ulcer. Intramural hematoma can also develop in blunt chest trauma with aortic wall injury. The hematoma propagates along the media layer of the aorta. Consequently, intramural hematoma weakens the aorta and may progress either to outward rupture of the aortic wall or to inward disruption of the intima, the latter leading to communicating aortic dissection. Intramural hematoma can be distinguished from mural thrombus by identification of the intima: mural thrombus lies on top of the intima, which is frequently calcified, whereas intramural hematoma is subintimal. On unenhanced CT, intramural hematoma is hyperdense. MR imaging aids in the distinction of slow flow in the false lumen of a dissection from no flow in an intramural hematoma. Dynamic post-contrast MR imaging is more sensitive for excluding slow flow in the thickened aortic wall, which would indicate aortic dissection rather than intramural hematoma.

Answer 46

70. C. Hysterosalpingography Hysterosalpingography provides optimal depiction of the fallopian tubes, allowing detection of tubal patency, tubal occlusion, tubal irregularity and peritubal disease. An imaging evaluation for female infertility typically begins with an assessment of tubal patency at hysterosalpingography, which may be followed by pelvic US, pelvic MRI or both to further characterise any additional findings.

Answer 47

71. A. Osteoid osteoma Osteoid osteoma is a benign bone tumour that occurs most frequently in men and boys between 7 and 25 years old. Most patients experience pain that worsens at night and is promptly relieved by the administration of salicylates. Typical radiographic findings of osteoid osteoma include an intracortical nidus, which may display a variable amount of mineralisation, accompanied by cortical thickening and reactive sclerosis in a long bone shaft. The nidus is round or oval and usually smaller than 2 cm. At CT, the nidus is well defined and round or oval with low attenuation. The nidus has low to intermediate signal intensity on T1-weighted images and variable signal intensity on T2-weighted images, depending on the amount of mineralisation present in the centre of the nidus. Oedema in adjacent bone marrow and soft tissue and joint effusion may also be seen. Enhancement of a hypervascular nidus may be seen at dynamic CT.

Answer 48

72. A. No further management is required. Typical indications for spinal US in newborns and infants are skin covered masses and midline cutaneous malformations of the back (e.g., dimple, haemangiomatous or hairy lesion), which are suggestive of associated dysraphic anomalies of the spinal cord. Spinal dysraphism is often associated with tethering of the spinal cord. The US appearance of tethering is a low-lying or blunt-ended conus medullaris due to abnormal fixation of the spinal cord. Moreover, movement of the spinal cord and cauda equina can be evaluated with real-time US with M mode scanning. Typically, the tethered cord is positioned eccentrically and demonstrates reduced or absent movement. Dorsal dermal sinus manifests as a small dimple or pinpoint ostium, which is often associated with an area of hyperpigmented, angiomatous skin or hypertrichosis and occurs in a midline location or rarely in a paramedian location. Soft tissue asymmetry and bone anomalies are common findings. Typical complications are infections such as recurrent meningitis, epidural or subdural abscess, and intramedullary spinal cord abscess. In particular, dorsal dermal sinus occurring in a paramedian location is often associated with an intraspinal dermoid or epidermoid cyst, which causes compression of neural structures with neurologic symptoms. For these reasons, dorsal dermal sinus has to be differentiated from simple sacral dimple or pilonidal sinus. The latter two anomalies do not extend to neural structures.

Answer 49

73. B. Supracondylar fracture The value of the fat pad sign is greatest as a predictor of an intra-articular disease process at the elbow in the absence of any radiographically visible bone abnormality. Fat pad displacement is independent of fracture displacement and comminution. This applies in particular to elbow examination in children, who often have very slight structural changes at presentation. Supracondylar fractures account for 60% of all elbow fractures in children, followed by fracture of the lateral epicondyle (15%) and separation of the medial epicondylar ossification centre (10%). In adults, fracture of the radial head or neck accounts for just under 50% of all fractures at the elbow, followed by fracture of the olecranon (20%) and dislocations and fracture dislocations.

Answer 50

74. C. Pulmonary vein The secondary pulmonary lobule, as defined by Miller, refers to the smallest unit of lung structure marginated by connective tissue septa. Secondary pulmonary lobules are irregularly polyhedral in shape and vary in size, measuring from 1 to 2.5 cm in diameter. Airways, pulmonary arteries and veins, lymphatics and the various components of the pulmonary interstitium are all represented at the level of the secondary lobule. Each secondary lobule is supplied by a small bronchiole, pulmonary artery and lymphatic branches centrally and is marginated by connective tissue, the interlobular septa, that contain pulmonary veins and lymphatics.

Answer 51

75. E. Hepatic haemangioma There is no association between PSC and hepatic haemangiomas. PSC is an idiopathic, chronic, fibrosing inflammatory disease of the bile ducts that eventually leads to bile-duct obliteration, cholestasis and biliary cirrhosis. A strong association with inflammatory bowel disease, especially ulcerative colitis, is noted (70% of cases). Although the cause of PSC is unknown, most experts believe it to be an autoimmune process because PSC may be associated with other autoimmune diseases such as retroperitoneal fibrosis, mediastinal fibrosis and Sjögren syndrome. The rate of progression is unpredictable, with up to 49% of symptomatic patients eventually developing biliary cirrhosis and liver failure. Treatment is usually palliative and includes medical therapy with orally administered agents such as ursodiol (ursodeoxycholic acid) or endoscopic or percutaneous mechanical dilation of dominant strictures. Currently, orthotropic liver transplantation is the only curative therapy for PSC.

Answer 52

76. E. MR contrast agent is routinely used in pregnancy. The present data have not conclusively documented any deleterious effects of MR imaging exposure on the developing foetus. Therefore no special consideration is recommended for the first, versus any other, trimester in pregnancy. Nevertheless, as with all interventions during pregnancy, it is prudent to screen women of reproductive age for pregnancy before permitting them access to MR imaging environments. If pregnancy is established, consideration should be given to reassessing the potential risks versus benefits of the pending study in determining whether the requested MR examination could safely wait to the end of the pregnancy before being performed. Pregnant patients can be accepted to undergo MR scans at any stage of pregnancy if the information requested from the MR study cannot be acquired by means of non-ionising means (e.g., ultrasonography), the data are needed to potentially affect the care of the patient or foetus during the pregnancy, or the referring physician believes that it is not prudent to wait until the patient is no longer pregnant to obtain these data. MR contrast agents should not be routinely provided to pregnant patients. The decision to administer a gadolinium-based MR contrast agent to pregnant patients should be accompanied by a well-documented risk-benefit analysis. There should be overwhelming potential benefit to the patient or foetus outweighing the theoretical but potentially real risks of long-term exposure of the foetus to free gadolinium ions. Studies have demonstrated that at least some of the gadolinium-based MR contrast agents readily pass through the placental barrier and enter the foetal circulation. From here, they are filtered in the foetal kidneys and then excreted into the amniotic fluid. In this location, the gadolinium-chelate molecules are in a relatively protected space and may remain for an indeterminate amount of time before finally being reabsorbed and eliminated. The longer the chelated molecule remains in the amniotic cavity, the greater the potential for dissociation of the potentially toxic gadolinium ion from its ligand. It is unclear what impact such free gadolinium ions might have if they were to be released in any quantity in the amniotic fluid. Certainly, deposition into the developing foetus would raise concerns of possible secondary adverse effects. The risk to the foetus of gadolinium-based MR contrast agent administration remains unknown; it may be harmful.

Answer 53

77. B. Use FSE imaging rather than GE imaging Several strategies help in reduction of susceptibility artefact from hip prosthesis. Some of these are as follows: * Reduced magnetic field strength * Increasing bandwidth during slice selection and readout * Increasing matrix size: 512 pixels * Maintain good SNR (signal to noise ratio) by increasing number of excitations NEX (number of excitation) * Use spin echo (FSE) instead of gradient echo (GRE) where possible * STIR for fat suppression (spectral frequency selective fat suppression performs better in a homogeneous field) * Use of shorter echo spacing * Use smaller water-fat shift * Use thinner slices * Align prosthesis parallel to the magnetic field * Use view-angle tilting (VAT)

Answer 54

78. C. Juvenile angiofibroma Juvenile angiofibroma presents characteristic imaging signs. The diagnosis by CT is based upon the site of origin of the lesion in the pterygopalatine fossa. There are two constant features: (1) a mass in the posterior nasal cavity and pterygopalatine fossa; (2) erosion of bone behind the sphenopalatine foramen with extension to the upper medial pterygoid plate. The characteristic features on MRI are due to the high vascularity of the tumour, causing signal voids and strong post contrast enhancement.

Answer 55

79. A. Mucinous cystadenoma The solid fibrous component of fibroma, fibrothecoma and cystadenofibroma characteristically demonstrates very low T2 signal intensity. With T1-weighted sequences, fibrothecomas demonstrate non-specific hypo to isointensity with mild enhancement following the intravenous administration of a gadolinium chelate. Brenner tumour is an uncommon epithelial-stromal tumour. The fibrous components, as well as calcifications (when present), are markedly hypointense on T2-weighted MR images. Exophytic subserosal leiomyoma have low T2 signal with low to intermediate Tl signal on MRI. The ‘bridging vessel’ sign represents tortuous vascular structures passing between the uterus and the lesion and may be seen at US; however, this sign is most clearly depicted at gadolinium-based contrast material-enhanced T1-weighted imaging or T2-weighted imaging, which nicely demonstrate vascular flow voids. The bridging vessel sign confirms that the lesion originates from the uterus and excludes an ovarian origin. Mucinous cystadenomas show a complex cystic structure with high signal on T2-weighted images.

Answer 56

80. B. The umbilical arterial catheter (UAC) tip at the L1 vertebral level The umbilical venous catheter (UVC) tip should lie within the inferior vena cava, just below or at the level of the right atrium. The tip of a UAC should be optimally positioned between the T6 and T9 levels so that it does not interfere with major upper abdominal arterial branches. The endotracheal tube (ETT) tip should he at the T2 vertebral level. The nasogastric tube (NGT) tip should be located below the diaphragm within a gastric air shadow'. The central venous catheter tip should be located at the cavo-atrial junction.

Answer 57

81. C. Scleroderma There are three possible HRCT distributions of nodules: perilymphatic, random and centrilobular. The causes of perilymphatic nodules include sarcoidosis, lymphangitis carcinomatosa, silicosis, amyloidosis (rare) and lymphoid interstitial pneumonia (rare). The causes of random nodules include miliary TB, miliary spread of fungal infection, metastasis and sarcoidosis (rare). The causes of centrilobular nodules include endobronchial infection, endobronchial tumour, aspiration, respiratory bronchiolitis interstitial lung disease (RB-ILD), hypersensitivity pneumonitis (HP), histiocytosis, vascular causes (oedema and haemorrhage) and talcosis.

Answer 58

82. A. Neuropathic osteoarthropathy Extra intestinal manifestations of inflammatory bowel disease: Musculoskeletal System Arthritis Colitic type, ankylosing spondylitis, isolated joint involvement, hypertrophic osteoarthropathy: clubbing, periostitis Miscellaneous Manifestations Osteoporosis, aseptic necrosis, polymyositis Dermatologic and Oral Systems Reactive Lesions Erythema nodosum, pyoderma gangrenosum, aphthous ulcers, necrotising vasculitis Specific Lesions Fissures, fistulas, oral Crohn’s disease, drug rashes Nutritional Deficiencies Acrodermatitis enteropathica, purpura, glossitis, hair loss, brittle nails Associated Diseases Vitiligo, psoriasis, amyloidosis Hepatopancreatobiliary System Primary sclerosing cholangitis, bile duct carcinoma Associated Inflammation Autoimmune chronic active hepatitis, pericholangitis, portal fibrosis, cirrhosis, granulomatous disease Metabolic Manifestations Fatty liver, gallstones associated with ileal Crohn’s disease Ocular System Uveitis/iritis, episcleritis, scleromalacia, corneal ulcers, retinal vascular disease Metabolic System Growth retardation in children and adolescents, delayed sexual maturation Renal System Calcium oxalate stones

Answer 59

83. B. Ochronosis Causes of intervertebral disc calcification include the following: * Degenerative disc disease is a relative common cause for disc calcification. * Alkaptonuria, or ochronosis, results in dense central calcification affecting the nucleus pulposus and is associated with generalised osteopaenia. Changes often start at the lumbar spine. * Ankylosing spondylitis is a recognised cause; associated findings helping in narrowing the diagnosis. * Calcium pyrophosphate dehydrate deposition disease (CPPD), haemochromatosis and hypervitaminosis D can result in calcification of the annulus fibrosus. * Transient intervertebral disc calcification is seen in children, typically in the cervical spine and spontaneously regresses. * Other recognised causes of disc calcification include juvenile chronic arthritis, amyloidosis, poliomyelitis, acromegaly, hyperparathyroidism, trauma and post-operative discs.

Answer 60

84. B. Nasopharyngeal carcinoma Imaging is crucial in delineating the extent of local tumour extension, as well as detecting nodal metastases, which are present in the vast majority of patients at the time of diagnosis (75% 90%). Nasopharyngeal carcinoma (NPC) usually presents with intermediate signal intensity, higher than the muscle signal, on T2- weighted images, low signal intensity on T1-weighted images and enhance to a lesser degree than does normal mucosa. Eighty-two percent of NPCs arise in the posterolateral recess of the pharyngeal wall (Rosenmüller fossa). Larger/more aggressive tumours may extend into any direction, eroding the base of skull and passing via the Eustachian tube, foramen lacerum, foramen ovale or directly through bone into the clivus, cavernous sinus and temporal bone. Invasion of the parapharyngeal space is associated with an increased risk of distant metastases and tumour recurrence. Following administration of contrast, the tumour mass and nodal metastases usually demonstrate heterogeneous enhancement. Careful assessment of cervical lymph nodes is essential due to the high rate of nodal involvement at the time of diagnosis. Cranial nerve involvement and venous occlusion is best demonstrated on post-contrast MRI.

Answer 61

85. E. Coal worker’s pneumoconiosis Many diffuse lung diseases may manifest cysts as the primary abnormality, although lymphangioleiomyomatosis and Langerhans cell histiocytosis (LCH) are the most common to present with diffuse lung cysts. Others include lymphocytic interstitial pneumonia, follicular bronchiolitis, amyloidosis, light-chain deposition disease, Birt-Hogg-Dube syndrome, end-stage fibrosis (honeycombing) and cystic metastasis (leiomyosarcoma, synovial cell sarcoma, epithelioid cell sarcoma and endometrial stromal sarcoma).

Answer 62

86. B. Chronic hepatitis There are a number of recognised risk factors for cholangiocarcinoma that all share the common feature of chronic biliary inflammation. Among these risk factors, infection with liver flukes (e.g., Opisthorchis viverrini and Clonorchis sinensis) and hepatolithiasis arc common causes of cholangiocarcinoma in endemic areas. Dietary or endogenous nitrosamine compounds associated with parasitic infections also play an important role as cofactors in carcinogenesis, probably due to the carcinogenic effect of nitrosamine compounds on the proliferation of epithelial cells of the bile duct Cholangiocarcinoma arising from a cirrhotic liver may be surrounded by a fibrotic pseudocapsule, which is an unusual finding in cholangiocarcinoma arising from a non-cirrhotic liver. In such cases, capsular retraction is noted along the tumour surface. This capsular retraction may be seen in some hepatocellular carcinomas (HCCs) with cirrhotic stroma but is more suggestive of cholangiocarcinoma. Cholangiocarcinoma can develop in a congenital choledochal cyst, with a lifetime risk of 10%-15%. In addition, a European study showed that a history of alcohol-related liver disease, cirrhosis, various bile-duct diseases, chronic inflammatory bowel disease or diabetes may increase the risk of development of cholangiocarcinoma.

Answer 63

87. B. Struma ovarii Struma ovarii is a rare ovarian lesion that accounts for 2% of ovarian teratomas. Struma ovarii is a highly specialised form of ovarian teratoma and is composed entirely or predominantly of thyroid tissue. About 5% of patients develop clinical evidence of hyperthyroidism. At US, struma ovarii has a non-specific solid, cystic appearance. MRI demonstrates a loculated cystic mass with variable signal characteristics. Cystic spaces may show marked T2 hypointensity and intermediate Tl signal intensity due to the thick, gelatinous colloid of the struma. Some locules may contain microscopic fat, as indicated by signal drop- off and chemical shift artefact on opposed-phase T1-weighted MRI. Struma ovarii typically demonstrates strong enhancement of the solid components on post-contrast T1-weighted MRI. Struma ovarii are benign in 95% of cases and usually occur in premenopausal women; therefore, preoperative diagnosis is essential to avoid unnecessary radical surgery.

Answer 64

88. A. Semimembranosus tendon and posterior oblique ligament The PMC contains the structures lying between the posterior margin of the longitudinal fibres of the superficial medial collateral ligament and the medial border of the posterior cruciate ligament. The PMC has five major components: the semimembranosus tendon and its expansions, the oblique popliteal ligament (OPL), the posterior oblique ligament (POL), the posteromedial joint capsule (or simply the posteromedial capsule) and the posterior horn of the medial meniscus.

Answer 65

89. D. Carotid body tumour A carotid body paraganglioma arises within the carotid body and characteristically splays the bifurcation of the CCA. As the tumour enlarges, it encases but docs not narrow the calibre of the EGA and ICA. With disease progression, the lesion may involve the lower cranial nerves and adjacent pharynx. Superior extension to the skull base and invasion into the intracranial cavity has also been reported. The typical CT appearance of a carotid body tumour is a well-defined soft-tissue mass within the carotid space of the infrahyoid neck. The underlying hypervascularity of the tumour results in homogeneous and intense enhancement following intravenous administration of contrast material. Splaying of the common carotid bifurcation is very suggestive of a carotid body tumour. The characteristic CT appearance is that of a uniloculated or multiloculated, hypoattenuated cystic mass adjacent to the carotid space. The mass may extend into the mediastinum. The signal intensity of thymic cysts on MR images is low on T1-weighted and high on T2-weighted images. The glomus tympanicum tumour manifests as a small discrete mass arising from the cochlear promontory' and confined to the tympanic cavity. Ossicular destruction is not typical, although encasement is frequent in larger lesions. The vagal paraganglioma appears similar to the carotid body tumour with some exceptions. These masses displace both the ECA and ICA anteromedially, separating these vessels from the IJV. In addition, extension into the suprahyoid carotid space is seen in approximately two-thirds of vagal paragangliomas, whereas it is uncommon with carotid body tumours (up to 8%).

Answer 66

90. E. Hyperparathyroidism Physeal fracture is the most common cause of bone bridging across the growth plate, but growth arrest may also be due to other insults: infection, therapeutic irradiation, metabolic or haematologic abnormality, tumour, bum, frostbite, electrical injury', sensory neuropathy, microvascular ischaemia or insertion of metal. Premature fusion of the growth plate has also been reported in patients with hypervitaminosis A.

Answer 67

91. B. External laryngocele Simply stated, a laryngocele is a dilated laryngeal saccule, and there are three types: internal, external and mixed. Approximately 40% of laryngoceles are internal; these laryngoceles are confined to the larynx and do not pierce the thyrohyoid membrane. External laryngoceles (26% of cases) extend through the thyrohyoid membrane at the point of insertion of the superior laryngeal nerve and vessels (neurovascular bundle). The component superficial to the thyrohyoid membrane is dilated, and the saccular portion inside the membrane is normal in size. Finally, mixed laryngoceles (44% of cases) have abnormal dilatation of the saccule on both sides of the thyrohyoid membrane. The association of laryngocele with laryngeal carcinoma is well documented: Investigators worldwide have reported an increased frequency of laryngoceles in patients with laryngeal carcinoma. On CT scans, a laryngocele appears as a well defined, smooth mass in the lateral aspect of the superior paralaryngeal space. Internal laryngoceles will be limited by the thyrohyoid membrane. External and mixed laryngoceles lie superficial to the thyrohyoid membrane at the point of insertion of the superior laryngeal nerve and vessels (neurovascular bundle). The attenuation of these lesions may vary, depending on the amount of secretions, air and soft tissue from an associated laryngeal neoplasm.

Answer 68

92. B. Lymphangitis The most common malignancy associated with lymphangitis carcinomatosa is bronchogenic carcinoma, most commonly adenocarcinoma, followed by breast, GI malignancies (stomach and colon) and prostate cancer. Chest CT is more specific and sensitive than CXR for the diagnosis of lymphatic metastasis. On HRCT, there is variable, smooth, irregular or nodular thickening of the interlobular septae and bronchovascular bundles, which often have a beaded appearance. Another characteristic feature is either smooth or nodular thickening of the peribronchovascular interstitium. Similar changes can be seen along the fissures. In many patients, the abnormality is unilateral or patchy. Pleural effusion and hilar adenopathy are associated.

Answer 69

93. D. Barium studies can detect gastric varices in approximately 75% of cases evidenced by lobulated folds and polypoidal fundal masses Gastrointestinal varices occur as a result of hepatofugal flow from the left gastric vein and splenic vein to the superior mesenteric vein. This usually occurs secondary to liver cirrhosis but isolated splenic vein occlusion (with pancreatic disease) can also be the cause. Gastric varices bleed less frequently but more severely than oesophageal varices.

Answer 70

94. B. Solid component suggesting malignancy Serous tumours are more common in both the benign and malignant categories. They are usually unilocular, whereas malignancies may demonstrate solid components and multilocularity. The signal is usually low to intermediate on T1 and high on T2-weighted images. At CT, diffuse psammomatous calcifications may cause these tumours or their implants to have very high attenuation. Mucinous ovarian tumours are less common. Mucinous ovarian tumours are generally cystic but unlike serous tumours may be very large and tend to be multiloculated. They often have variable signal intensity in the loculi owing to proteinaceous or mucinous contents and haemorrhage. The signal intensity of mucin on T1-weighted images varies depending on the degree of mucin concentration (watery mucin has a lower T1 signal than thicker mucin). On T2-weighted images, corresponding signal intensities are flipped, so watery mucin has a higher signal and thicker mucin appears hypointense.

Answer 71

95. E. Os naviculare - pain behind the heel The os acromiale has been implicated as a risk factor for the development of impingement syndrome. Hypertrophic osteophytes may arise at the synchondrosis of an os acromiale, and the os acromiale is thought to increase the incidence of osteoarthritis at the AC joint. Medial side foot pain (os naviculare syndrome) is the most common presenting feature of accessory navicular bone; the pain is aggravated by walking, running and weight-bearing activities. Positive ulnar variance is associated with ulnar impaction syndrome or ulnocarpal abutment with TFC degeneration and ulnar-sided wrist pain. Discoid meniscus is an uncommon anatomical variant, more commonly affecting the lateral meniscus. Although frequently asymptomatic, it is prone to cystic degeneration with subsequent tears. Clinical presentation may be with pain, locking or clicking. All lands of neurological deficits and clinical symptoms may occur with conjoined nerve roots. Besides the different phenotypes of low back or sciatic pain, the most common complaints are numbness and muscular weakness.

Answer 72

96. C. Arrowhead terminal phalanx Mucopolysaccharidoses (MPS) represent a heterogeneous group of inheritable lysosomal storage diseases in which the accumulation of undegraded glycosaminoglycans (GAGs) leads to progressive damage of affected tissues. The typical symptoms include organomegaly, dysostosis multiplex, mental retardation and developmental delay. Dysostosis multiplex is represented by several bone malformations found in the skull, hands, legs, arms and column. Some of the other common skeletal manifestations include macrocephaly with dolichocephaly, facial anomalies, obtuse angle of mandible with prognathism, paddle- or oar-shaped ribs, atlanto-axial instability, malformed vertebral bodies, hip dysplasia, coxa valga, proximal humeral notching, inferior tapering of ileum, rounded iliac wings, bullet shaped phalanges and hypoplastic and irregular carpal and tarsal bones. The abnormal storage of GAGs leads to liver and spleen enlargement; it also damages cartilage layers and synovial recesses in the joints.

Answer 73

97. D. Desquamative interstitial pneumonia Opportunistic Infections * Pneumocystis pneumonia (PCP) * CMV pneumonia * HSV pneumonia * Respiratory syncytial virus bronchiolitis Chronic Interstitial Diseases * HP * Desquamative interstitial pneumonia (DIP) * RB-ILD * NSIP * Acute interstitial pneumonia (AIP) * Lymphocytic interstitial pneumonia (LIP) * Sarcoidosis Acute Alveolar Disease * Pulmonary oedema * ARDS * Diffuse alveolar haemorrhage Others * Drug toxicity * Pulmonary alveolar proteinosis * COP * Bronchoalveolar carcinoma DTP is associated with smoking but not in immunocompromised host.

Answer 74

98. C. Organo-axial volvulus is more common than mesentero-axial volvulus and creates a ‘mirror-image’ stomach The aetiology of gastric volvulus is related to unusually long gastrohepatic and gastrocolic mesenteries. Organo axial volvulus rotates around a line from the cardia to the pylorus, whereas the axis of rotation in mesentero-axial volvulus runs from the lesser to the greater curve of stomach. Mesentero-axial volvulus is associated with ‘upside-down’ stomach appearance, whereas organo-axial volvulus is associated with a ‘mirror-image’ stomach.

Answer 75

99. C. Immature teratoma is mainly cystic. Ovarian tumours associated with endometrial hyperplasia or carcinoma includes endometrioid carcinoma, granulosa cell tumour and, occasionally, thecoma or fibrothecoma. Although rare, endometrioid carcinoma is the most common malignant neoplasm that arises from endometriosis. The presence of fat opacity or fat signal intensity in an ovarian lesion is highly specific for a teratoma. Mature cystic teratomas are predominantly cystic with dense calcifications, whereas immature teratomas are predominantly solid with small foci of lipid material and scattered calcifications. Ovarian tumours that are frequently associated with calcifications include serous epithelial tumour, fibrothecoma, mature or immature teratoma and Brenner tumour. Malignant germ cell tumours include dysgerminoma (raised HCG level) and endodermal sinus tumours (α-fetoprotein level) and are found in younger patients

Answer 76

100. B. Homocystinuria Homocystinuria is an AR disorder secondary to deficiency of cystathionine synthase. Arachnodactyly (metacarpal index >8.4 or >9.4; depending reference standard used) is seen in one in three patients (cf. 100% in Marfan syndrome). Lens dislocation is downwards and inwards (cf. upwards and outwards in Marfan syndrome). Homocystinuria is also associated with osteoporosis, bowing/factures, pectus deformities and biconcave vertebra. There is increased propensity of thromboembolic phenomena due to increased stickiness of platelets. Death is often from occlusive vascular disease. Sotos syndrome is an autosomal dominant syndrome considered a form of cerebral gigantism.

Answer 77

101. E. Osteogenic sarcoma Fewer than 10% of osteosarcomas arise in the craniofacial bones, with most such tumours developing in the mandible and maxilla. The most common sites of involvement are the body of the mandible and the alveolar ridge or the antral area of the maxilla. It may be secondary to radiation, fibrous dysplasia, Paget disease, trauma, osteomyelitis, ossifying fibroma and giant cell tumour. On CT, the tumour displays a spectrum of bone changes from well-demarcated borders, notably the low-grade osteosarcoma (uncommon), to lytic bone destruction with indefinite margin and variable cortical bone erosion, to the osteoblastic form, where the bone is sclerotic. The majority of osteosarcomas have matrix mineralisation, calcifications of the osteoid or osteoid like substance within the tumour and some tumours show a sunburst effect caused by radiating mineralised tumour spiculae. Ewing’s sarcoma can also occur in this area, although the expected age would be younger. On CT, it often shows the characteristic onion-skin appearance of periosteal reaction and less often a sunburst type of periosteal reaction.

Answer 78

102. A. Staphylococcus aureus Pneumatocoeles are thin-walled, air filled intraparenchymal cysts that develop secondary to localised bronchiolar and alveolar necrosis, which allow one way passage of air into the interstitial space. They commonly occur in immunocompetent patients and are most commonly associated with 5. aureus, followed by Staphylococcus pneumoniae infections. Although there is no dear correlation between the development of pneumatocoeles and mechanical ventilation, patients receiving mechanical ventilation have an increased risk for developing complications related to pneumatocoeles, including an increase in their size. Other than in hyperimmunoglobulin E syndrome, there is no known genetic or familial tendency for pneumatocoeles. The majority of pneumatocoeles (more than 85%) resolve spontaneously, partially or completely over weeks to months without dinical or radiographic sequelae

Answer 79

103. B. Lissencephaly Lissencephaly (smooth brain) is a severe malformation of the cerebral cortex that results from impaired neuronal migration during the third and fourth months of gestation. The affected brain shows either an absence or a paucity of gyri (agyria or pachygyria, respectively). The most common clinical manifestations include severe psychomotor retardation, developmental delay, seizures and failure to thrive. The prognosis depends on the degree of failure of cortical development. In severe cases, death occurs in infancy or early childhood. Prenatal diagnosis of an affected foetus allows appropriate counselling and optimisation of obstetric management. Abnormal cortical development is the main manifestation of lissencephaly, although other associated cranial and extracranial abnormalities may be present.

Answer 80

104. B. Respirator}' bronchiolitis interstitial lung disease RB-ILD is a smoking-related interstitial lung disease. The distribution at HRCT is mostly diffuse. The key HRCT features of RB-ILD are centrilobular nodules in combination with ground-glass opacities and bronchial wall thickening. Coexisting moderate centrilobular emphysema is common, given that most patients have a smoking history.

Answer 81

105. D. Typhlitis Typhlitis, also known as neutropenic colitis, is a recognised acute colitis affecting the caecum ± the terminal ileum and ascending colon with a predisposition for children with leukaemia, lymphoma and patients on immunosuppressive treatment (i.e., neutropenia). The CT findings include circumferential wall thickening of the caecum, which may extend to the terminal ileum and ascending colon, pericaecal fluid and localised fat stranding. Intestinal TB may be primary or secondary to haematogenous spread from pulmonary TB, and predominantly affects the colon and ileum. Appendicitis may also produce caecal wall thickening, but it is usually asymmetric in nature and rarely extends into the terminal ileum. Backwash ileitis is a chronic complication of ulcerative colitis in which the terminal ileum is affected with a patulous ileocaecal valve, absent peristalsis and granularity of the mucosa. Pseudomembranous colitis usually has a predisposition for the distal colon but may affect the colon in its entirety.

Answer 82

106. D. Assessment of polyhydramnios The most common indications for foetal MRI are neurological. MRI is commonly used to investigate underlying aetiologies of ventriculomegaly and morphologic brain abnormalities that are not as readily depicted with US such as dysgenesis of corpus callosum, malformations of cortical development and posterior fossa anomalies. Foetal MR] may detect subtle neural tube defects not shown by US and determine the level of the defect in myelomeningocele for potential foetal surgery. The next common indication for foetal MRI is evaluation of suspicious thoracic masses. MRI has the advantage over US in differentiating the liver and bowel loops from lung tissue or masses; this aids in differentiating a congenital diaphragmatic hernia from a pulmonary mass. MRI could be helpful in providing tissue characterisation of foetal abdominal masses when US study is non-specific. MRI is particularly useful in the assessment of pregnancies complicated by oligohydramnios, which can limit the diagnostic sensitivity of US.

Answer 83

107. D. Cartilage cap thickness of more than 2.5 cm Pain and increase in the size of osteochondroma raises suspicion of peripheral chondrosarcomatous transformation. MRI, in particular T2-weighted images, evaluate thickness of cartilage cap. A cap thickness of more than 2.5 cm is suspicious and warrants tissue diagnosis. Osteochondromas can be solitary or multiple. Multiple osteochondromas are known as diaphyseal aclasis. Multiplicity is not necessarily a feature/predictor of malignancy. Osteochondromas can sometimes turn malignant and become peripheral chondrosarcomas. Sudden pain and increase in size of an osteochondroma raises suspicion of peripheral chondrosarcoma. Neurovascular compromise can be secondary to compression by osteochondroma and does not indicate malignancy. Fracture and bursae formation are related to symptomatic osteochondromas and may be present in benign osteochondromas.

Answer 84

108. A. Extradural arachnoid cyst Spinal extradural arachnoid cyst (SEAC) is a rare disease and uncommon cause of compressive myelopathy. SEACs can be found in any location, although they are mostly reported to be located at the mid-thoracic to the thoracolumbar junction, commonly in a posterior position. The underlying cause is thought to be a dural defect. The cause of dural defect can be congenital or acquired. Trauma, arachnoiditis or iatrogenic cause can result in a small dural tear and subsequent CSF accumulation to develop SEACs. MRI shows an elongated cystic mass, low on T1-weighted and high on T2-weighted images. CT myelography shows communication between the subarachnoid space and die cyst, confirming a dural tear.

Answer 85

109. B. RB-ILD The crazy-paving’ pattern at thin-section CT of the lungs is characterised by scattered or diffuse ground glass attenuation with superimposed interlobular septal thickening and intralobular lines. Although originally described in cases of alveolar proteinosis, this pattern has subsequently been reported in a variety of conditions including Pneumocystis carinii pneumonia, bronchioloalveolar carcinoma, sarcoidosis, NSIP, COP, lipoid pneumonia, ARDS and pulmonary haemorrhage syndromes including idiopathic pulmonary haemosiderosis, Wegener granulomatosis, Churg-Strauss syndrome, Goodpasture syndrome, collagen-vascular diseases, drug-induced coagulopathy and haemorrhage associated with malignancy.

Answer 86

110. D. T2 N2 M0 Staging Tl = Limited to mucosa or submucosa T2 = Tumour involves muscle/serosa T3 = Tumour penetrates through serosa T4a = Tumour involves adjacent contagious tissues T4b = Invasion of adjacent structures, diaphragm, abdominal wall and so on N1 = Involvement of perigastric nodes within 3 cm of primary along greater or lesser curvature N2 = Involvement of regional nodes >3 cm from primary along branches of coeliac axis N3 = Para-aortic, hepatoduodenal, retropancreatic, mesenteric nodes Ml = Distant metastases

Answer 87

111. D. Congenital adrenal hyperplasia Classic congenital adrenal hyperplasia (CAH) is due to deficiency of enzymes in the steroidogenesis pathway and can present as a severe salt-wasting form that usually appears with acute adrenal insufficiency in early infancy (men in 7-10 days of birth) and a simple virilising form in which patients demonstrate masculinisation of external genitalia (women) or signs of virilisation in early life in men. Non-classic (late onset) CAH presents in pubertal girls with symptoms of mild androgen excess. Most lesions are asymptomatic and may be discovered incidentally. Larger lesions (typically over 4 cm in size) can present with retroperitoneal haemorrhage or related symptoms. They are associated with Cushing syndrome, congenital adrenal hyperplasia (21-hydroxylase deficiency) and Conn syndrome (primary hyperaldosteronism)

Answer 88

112. D. Menorrhagia Polycystic ovarian syndrome (PCOS) is the most common endocrine abnormality in women of reproductive age and carries with it significant health risks, including infertility, endometrial hyperplasia, diabetes (insulin resistance), obesity and cardiovascular disease (hypertension, hyperlipidaemia, coronary artery and cerebrovascular events). Patients with PCOS have hyperandrogenism, hirsutism and ovarian dysfunction (oligo- or anovulation) and present with oligo-amenorrhea.

Answer 89

113. A. A partial return to normal fatty marrow. The signal intensity of the fractured vertebral body would appear low on T1-weighted images in the acute phase and would gradually be restored to normal intensity from the periphery to the centre of the body, as healing progresses. On T2-weighted images, the signal intensity of the fractured vertebral body would appear high, with or without some strongly lowered area in it, in the acute phase, and would be gradually restored to normal intensity with time. Acute fracture and metastatic compression fracture can both show' enhancement post-contrast injection. However, contrast enhancement decreases with time in benign vertebral fractures as normal marrow signal is restored.

Answer 90

114. B. Synovial cyst Intraspinal synovial cysts are extradural lesions that arise from the synovial lining of the facet joints. Most cysts arc found at the L4-L5 facet joint, as this is the level where the most biomechanical spinal motion occurs. The differential diagnosis for synovial cysts includes arachnoid cysts, perineural (Tarlov) cysts, schwannomas and migrated herniated disk fragments. The MR imaging characteristics and the neuroanatomic location of the cyst help distinguish synovial cysts from these other lesions. Extradural arachnoid cysts are cerebrospinal fluid-filled outpouchings of the arachnoid membranes that extend through a defect in the dura mater. Two-thirds of these lesions occur in the thoracic spine; this helps to differentiate these masses from synovial cysts, which occur most frequently in the lumbar spine. Perineural cysts can be distinguished from synovial cysts because perineural cysts are separate from the facet and are intimately associated with the nerve root. Likewise, schwannomas can be distinguished from synovial cysts on MR images by their intimate association with the nerve root. Furthermore, the propensity for schwannomas to enhance homogeneously after administration of a gadolinium containing contrast agent helps one distinguish this entity from synovial cysts, which typically demonstrate only rim enhancement. Migrated disk fragments are sometimes found dorsal to the thecal sac, which complicates their differentiation from synovial cysts. They can, however, be distinguished reliably by their relationship to the ligamentum flavum, their signal intensity characteristics and their lack of degenerative changes in the facet joint. Migrated disk fragments are typically located anterior to the ligamentum flavum, whereas synovial cysts are located dorsal to or inseparable from the ligamentum flavum. Furthermore, migrated disk fragments are usually lobulated and have lower signal intensity on T2 weighted MR images than do the spherically shaped synovial cysts.

Answer 91

115. E. Diffuse alveolar haemorrhage Anti-glomerular basement membrane antibody disease (Goodpasture syndrome) is defined by a triad of diffuse pulmonary haemorrhage, glomerulonephritis and circulating anti glomerular basement membrane antibodies. Findings at chest radiography may occasionally be normal despite the presence of diffuse pulmonary haemorrhage. Diffuse pulmonary haemorrhage can also occur in patients with systemic lupus erythematosus, typically in the context of established disease associated with extrapulmonary manifestations such as glomerulonephritis

Answer 92

116. E. Clostridium difficile colitis Given the clinical history of recent antibiotic therapy and the introduction to a nosocomial environment, one must always consider Clostridium difficile colitis in the presence of multiple episodes of watery diarrhoea. CT, the most sensitive examination for C. difficile colitis, may demonstrate circumferential colon wall thickening with a predisposition for the rectum (but may affect the entire colon), a ‘target’ sign (due to submucosal oedema and mucosal hyperaemia), pericolonic fat stranding and ascites. The accordion sign is typical in severe cases of C. difficile colitis and appears as intraluminal contrast media trapped between multiple thickened oedematous folds of bowel wall the appearance mimics an accordion. There is no history to suggest radiation enteritis and the involvement of the rectum and distal colon excludes amoebiasis as a likely cause. Ischaemic colitis may have a similar appearance but is usually segmental in nature, dependent on the arterial distribution.

Answer 93

117. D. Serous cystadenoma Ovarian tumours with highly enhancing solid portions, although uncommon, include sclerosing stromal tumour, Sertoli-Leydig cell tumour, struma ovarii and cystadenofibroma.

Answer 94

118. C. Metacarpophalangeal joint (MCPJ) Primary OA describes degenerative joint disease with no local aetiological factor. It is age related and caused by high mechanical forces of a repetitive nature on a normal joint Secondary OA describes degenerative changes within a joint with an underlying aetiological factor. These may include trauma, CPPD, inflammatory arthritis, haemochromatosis, developmental dysplasia of the hip (DDH), AVN or loose bodies. The joints most commonly involved in primary OA are distal interphalangeal, proximal interphalangeal, first carpometacarpal joint, hips, knees, spine and first metatarsophalangeal. The joints commonly spared include metacarpophalangeal, wrist, elbow, shoulder and ankles

Answer 95

119. E. Meningioma Meningiomas are well circumscribed and show avid enhancement on contrast-enhanced imaging. On CT, they are iso/hyperattenuating. The hyperattenuation reflects the cellular nature of these lesions, but the presence of calcification also contributes. Hyperostosis may be seen but is not as common as in the intracranial forms. This is due, in part, to the more prominent epidural fat within the spine. They are most commonly isointense on both T1-weighted and T2 -weighted imaging. Some may be hyperintense on T2 weighted imaging, and flow voids may be seen. If they are densely calcified, they will show low signal on both T1 -weighted and T2-weighted imaging. Meningiomas prominently enhance on contrast-enhanced imaging, and a dural tail may be observed. On MRI, paragangliomas are well circumscribed and hyperintense on T2-weighted imaging and avidly enhance on contrast-enhanced imaging. The classic salt and pepper appearance associated with head and neck paragangliomas may be seen. The entire spine should be imaged because of the possibility of intradural metastasis. Because of the highly vascular nature, prominent flow voids in and around the tumour commonly occur. A low-signal hemosiderin rim may be seen on T2-weighted images. Neurofibromas and schwannomas can be difficult to differentiate by imaging. Both tumours may widen the neuroforamina, erode bone and cause vertebral body scalloping on CT. On MRI, both neoplasms are isointense on T1 -weighted imaging and hyperintense on T2-weighted imaging; however, schwannomas may have mixed signal intensity on T2-weighted imaging because of the mixture of cells. A central area of lower T2 signal may be seen in neurofibromas and is referred to as the ‘target sign’.

Answer 96

120. D. Superior mesenteric artery located to the right of the superior mesenteric vein The upper GI series remains the imaging reference standard for the diagnosis of malrotation with or without volvulus. The normal position of the DJ junction is to the left of the left-sided pedicles of the vertebral body at the level of the duodenal bulb on frontal views and posterior (retroperitoneal) on lateral views. In children with acute duodenal obstruction, the upper GI series may depict a Z-shaped configuration of the duodenum in the presence of obstructing peritoneal bands or a corkscrew shaped duodenum in the presence of volvulus. In children who have bowel malrotation without volvulus, the upper GI series shows an abnormal position of the DJ junction. The detection of the double bubble sign suggests duodenal obstruction. In infants in whom the radiograph demonstrates a double bubble, one should consider both intrinsic and extrinsic causes of obstruction. The intrinsic causes are duodenal atresia, duodenal stenosis and duodenal webs; the extrinsic causes include annular pancreas, malrotation of the gut with obstruction produced by mid gut volvulus or by Ladd bands and preduodenal position of the portal vein. The proximal left-sided bubble is the air- and fluid-filled stomach. The duodenum represents the second bubble to the right of the midline. The third part of the duodenum is a retroperitoneal structure. Normally SMV is to the right of the SMA. Distended bowel loops throughout the abdomen would exclude any significant mid-gut obstruction.

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