TEST PAPER 7 Flashcards

Question

25. A 73-year-old woman with weight loss, previous history of endometriosis and a CA-125 of 983 μg/mL, attends for an magnetic resonance imaging (MRI) scan of the pelvis after a cystic mass with nodules was noted in the left adnexa on ultrasound. There is a 6 cm predominately unilocular cystic mass in the left adnexa, which is bright on T1W & T1W fat-saturated images with enhancing solid mural nodules along its wall. It remains high signal on fat-saturated imaging. Which of the following is the most likely diagnosis? A. Dysgerminoma B. Brenner tumour of the ovary C. Endometrioma D. Ovarian dermoid E. Clear cell carcinoma of the ovary

Answer 1

25. E. Clear cell carcinoma of the ovary Clear cell carcinoma and endometrioid carcinomas are commonly found in patients with previous endometriosis. Clear cell carcinoma is an aggressive carcinoma. It is frequently cystic with enhancing mural nodules. The cystic and solid components are high signal on both Tl- and T2-weighted images. Brenner tumour of the ovary is low signal on Tl- and T2-weighted imaging. Endometrioma may have a bright Tl signal but should not have enhancing mural nodules or be associated with weight loss. Dysgerminoma is a solid germ cell tumour of the ovary, typically solid with a fibrous capsule and fibrous septa. Ovarian dermoid should contain fat and would not be associated with weight loss.

Answer 2

26. E. Posterior inferior cerebellar artery With posterior inferior cerebellar artery (PICA) aneurysms, the rate of intraventricular haemorrhage is high due to reflux of blood. If there is an isolated intraventricular haemorrhage, a peripheral PICA aneurysm. King in or near the fourth ventricle, may be suspected.

Answer 3

27. B. Ventricular septal defect Congenital cardiac anomalies can be categorised according to whether or not the child is cyanosed. Thereafter, assessment of both heart size and pulmonary arterial flow allows considerable shortening of the differential diagnosis: In the case provided, the only conditions not associated with cyanosis are ventricular septal defect (VSD) and atrial septal defect (ASD). VSD is the most common congenital heart anomaly.

Answer 4

28. E. None of the above A cemented component in a total hip joint replacement (THR) will demonstrate increased uptake on a radionuclide bone scan for up to 1-2 years. Following this time, increased uptake is good evidence to support mechanical loosening or infection with a 50%-100% sensitivity. It is, however, not specific and therefore correlation with the patients clinical presentation and plain radiography is required. Aspiration under fluoroscopic guidance may be required to diagnose or exclude infection. An arthrogram can be performed at the same time, which may allow a confident diagnosis of mechanical loosening to be made; however, a negative arthrogram does not exclude this. Cementless THR components may have persistently increased radionuclide uptake. This is secondary to bone ingrowth into die prosthesis and needs to be differentiated from pathology.

Answer 5

29. C. Pancreatic adenocarcinoma Painless jaundice commonly occurs secondary to tumours in the head of pancreas. The most common pancreatic tumour, by far, is adenocarcinoma. All the other tumours described are rare by comparison. Pancreas divisum is an anatomical variant relating to pancreatic duct morphology where rather than having a single pancreatic duct, the patient has two (embryologically, there is a failure of fusion); it has an association with idiopathic, recurrent pancreatitis but not with bile duct obstruction. Pancreatic pseudocyst is an encapsulated collection of pancreatic fluid found either within the pancreas or in a peripancreatic position. It most commonly occurs secondary to acute pancreatitis.

Answer 6

30. A. Amyloidosis Amyloidosis is a rare condition, which can affect one specific organ, or present as a systemic illness. The disease is characterised by the deposition of proteinaceous material either in a focal, tumour like lesion or an infiltrative fashion. Within the chest, cardiac involvement is the most commonly seen, with patients presenting with variable symptoms ranging from arrhythmias to cardiac failure. Pulmonary involvement is typically in the setting of multiple previous chest infections. Computed tomography often demonstrates ‘tree-in-bud’ opacity, usually in a peripheral location, at sites of previous pneumonia. Within the tracheo bronchial tree, mass-like lesions arc seen arising from the internal wall, often significantly compromising the airway lumen. While the other conditions listed could result in scattered intrapulmonary nodules, the additional endobronchial abnormality makes amyloidosis more likely.

Answer 7

31. D. Tricuspid atresia Congenital cardiac anomalies can be categorised according to whether or not the child is cyanosed. Thereafter, assessment of both heart size and pulmonary arterial flow allows considerable shortening of the differential diagnosis: In the case provided, the child is cyanosed; this excludes patent ductus arteriosus and coarctation as the cause. Ebstein anomaly classically produces a grossly enlarged heart. While tetralogy of Fallot is the most common congenital cardiac anomaly to cause cyanosis, it has characteristic CXR features; upturned cardiac apex and deficient main pulmonary artery creates a ‘boot-shaped’ heart. In addition, there is usually decreased pulmonary vascularity associated with Fallot’s tetralogy. Tricuspid atresia is the third most common congenital cardiac cause of cyanosis after tetralogy of Fallot and transposition of the great vessels.

Answer 8

32. C. Temporo-frontal Pick’s disease is a neurodegenerative disease, and one of the tauopathies (group of neurodegenerative diseases characterised by abnormal metabolism of tau proteins leading to intracellular accumulation and formation of neurofibrillary tangles, similar to Alzheimer’s disease) characterised by the accumulation of the Pick bodies. It is sometimes used synonymously with fonto-temporal lobar degeneration (FTLD), although strictly it is incorrect since all causes of FTLD isn’t pathologically Pick’s disease. The primary imaging abnormality is that of cortical atrophy of the frontal and temporal lobes. These changes can be markedly asymmetric and affect one region much more than another. Volume of the head of the caudate nucleus may also be reduced. Differentials include Alzheimer’s disease and corticobasal degeneration where parietal lobe involvement is more pronounced.

Answer 9

33. C. Compressive lesions are common in the lumbar spine Vertebral haemangiomas are a hamartomatous lesion. Spinal haemangiomas arc common and frequently multiple. The prevalence of haemangiomas seems to increase with age and is greatest after middle age, with a slight female predilection. Most haemangiomas are seen in the thoracic and lumbar spine. They are usually confined to the vertebral body, although they may occasionally extend into the posterior elements. Most spinal haemangiomas are asymptomatic. Occasionally, vertebral haemangiomas may increase in size and compress the spinal cord and nerve roots. Compressive vertebral haemangiomas can occur in patients of any age, with a peak prevalence in young adults and preferentially occur in the thoracic spine. CT shows the pattern as multiple dots (polka-dot appearance). At scintigraphy, the appearance of osseous haemangiomas ranges from photopenia to a moderate increase in radiotracer uptake. The presence of high signal intensity on T1- and T2-weighted MR images is related to the amount of adipocytes or vessels and interstitial oedema, respectively. Fatty vertebral haemangiomas (high on T1-weighted MR) may represent inactive forms of this lesion, whereas low signal intensity at T1-weighted MR imaging may indicate a more active lesion with the potential to compress the spinal cord.

Answer 10

34. D. Decreased resistive index in hepatic artery There are many features of liver cirrhosis identifiable with ultrasound. Most commonly, these include an echo bright, irregular, shrunken liver (late stage) with a coarse echotexture and hypertrophy of the caudate lobe (earlier in the disease the entire liver can hypertrophy). Isoechoic regenerative nodules may be apparent. If measured, there should be an increase in the resistive index (RI) of the hepatic artery. Reversal of portal venous flow (hepatofugal), portalisation of the hepatic veins, ascites and splenomegaly are extrahepatic signs that are commonly identified. Hepatocellular carcinoma is a major complication of cirrhosis that should always be borne in mind when examining these patients.

Answer 11

35. D. In blunt chest trauma, the perforation usually occurs in the lower third of the oesophagus. Oesophageal perforation is a surgical emergency that carries a high mortality. Oesophageal instrumentation, biopsy, balloon dilatation and attempted intubation (iatrogenic) are the most common causes of rupture and typically result in lower oesophageal injury'. Spontaneous rupture, also known as Boerhaave syndrome, arises when intraluminal pressure is elevated during sudden and severe vomiting episodes. While oesophageal rupture in blunt chest trauma is rare, this typically results in upper oesophageal injury and resultant right-sided hydrothorax. Chest radiography signs include mediastinal and neck emphysema, mediastinal widening and hydrothorax. Barium can be used in the assessment of patients with possible oesophageal perforation, but only after water-soluble contrast swallow has not shown an abnormality.

Answer 12

36. D. Rheumatic fever The imaging features described are those of acute congestive heart failure. In the context of joint pain following a recent sore throat and with no previous cardiac history, rheumatic fever should be considered. Rheumatic fever commonly causes a pancarditis with valve insufficiency that can lead to acute congestive heart failure in severe cases. This follows a streptococcal pharyngitis. Chronically, rheumatic heart disease can cause valve stenosis with varying degrees of regurgitation, arrhythmias and ventricular dysfunction. Rheumatic fever as a child is the most common cause of valvular heart disease in adults in the western world. The mitral valve is the most commonly affected. Currently, the disease rarely affects children in the West, but the condition remains common in the developing world.

Answer 13

37. E. Wilson’s disease Basal ganglia calcification: Common causes: Hypoparathyroidism, pseudohypoparathyroidism, idiopathic, normal variant, physiologic with ageing. Uncommon causes: AIDS encephalopathy, atherosclerosis, birth anoxia, hypoxia, carbonic anhydrase II deficiency, carbon monoxide intoxication, Fahr disease (ferrocalcinosis), familial idiopathic symmetrical basal ganglia calcification and microcephaly, Hallervorden-Spatz disease, haemorrhage, hyperparathyroidism, hypothyroidism, cretinism, Kearns Sayre syndrome, lead encephalopathy, lipoid proteinosis, MELAS syndrome, methotrexate therapy for childhood leukaemia, oculodento-osseous dysplasia, parasitic disease (e.g., toxoplasmosis, cysticercosis), parkinsonism, phenylketonuria variants, pseudopseudohypoparathyroidism, radiation therapy, Down’s syndrome, tuberous sclerosis, viral encephalitis.

Answer 14

38. B. Granulosa cell tumour Many ovarian tumours produce oestrogen, the most common being granulosa cell tumour. This results in postmenopausal bleeding, irregular bleeding in premenopausal women and precocious puberty in prepubertal girls. Breast tenderness is another sign, particularly in postmenopausal women. The fluid levels are caused by haemorrhage into the tumour cysts. Endometriosis tends to improve in postmenopausal women as there is no longer oestrogen being produced; it should not cause a thickened endometrium. Endometrial hyperplasia and haemorrhagic corpus luteal cyst are related to ovulation, so do not occur in postmenopausal women. Serous cystadenocarcinomas may produce adnexal masses but do not produce oestrogen, so do not cause endometrial thickening. Fibrothecomas can produce oestrogen and cause endometrial thickening but tend to be solid hypoechoic lesions.

Answer 15

39. C. Septa show intense enhancement post-contrast injection. Giant cell tumour of the spine occurs in the 2nd-4th decades of life, more frequently in females. Sacrum is affected in 90% of such cases. It is usually located in the upper sacrum and sacral wing. Extension to the iliac wing through the sacroiliac joint is possible. Lumbar, thoracic and cervical spine may be affected. It usually predominates in the vertebral body, with frequent involvement of the posterior arch. Extraosseous involvement of the soft tissues is common. Intervertebral disk invasion and extension into an adjacent vertebra are possible. In radiography, they appear as lytic lesion with cortical expansion. CT demonstrates lack of a sclerotic rim. Bone scintigraphy shows increased radiotracer uptake. The tumour usually has low-to- intermediate signal intensity on T1-weighted MR images. Areas of high signal intensity suggest haemorrhage. More specifically, they have low to intermediate signal intensity on T2-weighted images, caused by haemosiderin and high collagen content. Enhancement reflects its vascular supply. Cystic areas, haemorrhage, fluid-fluid levels and a peripheral low-signal-intensity pseudocapsule may also be seen. ABC occurs between 5 and 20 years but can manifest at any age. There may be a slight female predilection. Thoracic spine is most commonly affected. Spinal involvement is typically in the posterior elements, although extension into the vertebral body is common. Spinal ABC may extend into the adjacent vertebrae or intervertebral disk, ribs and the paravertebral soft tissue. CT and MR imaging typically show a well-defined lesion with internal septation. Fluid-fluid level is better seen on MRI. The predominant bone scintigraphic pattern is moderate to intense radiotracer accumulation at the periphery with little activity at its centre (‘doughnut sign’). Post-contrast images show intense enhancement of the septa. Solid components suggest secondary ABC.

Answer 16

40. D. Adenomyosis Adenomyosis can be focal or diffuse, the latter being the more common. The aetiology is unclear, but prominent endometrial glands extend into the myometrium with adjacent smooth muscle hyperplasia. Leiomyoma tends to be sharply demarcated as opposed to ill defined and tends to have low-intensity Tl and T2 signals, although multiple signal characteristics arc seen. It would be unusual for leiomyomas to have linear bands extending from the endometrium; this is more commonly seen in adenomyosis. Leiomyoma and leiomyosarcomas cannot be differentiated accurately on imaging; secondary features of lymphadenopathy or metastasis can help raise the suspicion of leiomyosarcoma. Endometrial carcinoma usually presents in an older age group and tends to present with symptoms of irregular bleeding, which is why it is often diagnosed at an early stage. There would likely be endometrial thickening also. Hydatidiform moles would usually be identified clinically, particularly in a patient being investigated for infertility, as she would have raised beta-human chorionic gonadotrophin levels.

Answer 17

41. D. Most colon cancers start as an adenomatous polyp. The vast majority of colon cancers begin as an adenomatous polyp (>90%), although the vast majority of polyps are benign (>90%). With increasing size comes an increased risk of malignant change. In addition, of the three recognised pathological subtypes (tubular, tubulovillous and villous), villous adenomas carry the greatest risk of malignant transformation. There are a large number of other risk factors for developing colon cancer but among them are the hereditary' polyposis syndromes (Peutz-Jeghers syndrome is less commonly' related as the polyps are more likely in the small bowel) and the inflammatory bowel diseases ‘Crohn's disease and ulcerative colitis'.

Answer 18

42. A. 32 mL @ 8 mL/s The aim is to closely replicate the natural blood flow in the vessel. A hand-injected test run is essential before a pump run to highlight the anatomy and confirm that the catheter tip is not in a subintimal position. An 8/32 injection delivers 8 mL of contrast per second to a total of 32 mL and lasts 4 s. The patients are usually asked to keep as still as possible and hold their breath to minimise artefact caused by motion.

Answer 19

43. B. Ovarian Brenner tumour Brenner tumours are uncommon tumours that are almost always benign. These tumours have a large fibrous component and therefore have a similar appearance to an ovarian fibroma (low signal on Tl- and T2-weighted imaging) on both ultrasound and MRI. Brenner tumours are commonly found with an adjacent epithelial tumour of the same ovary (usually mucinous cystadenoma); hence, in this case, the diagnosis of Brenner tumour is more likely than ovarian fibroma. An ovarian dermoid would usually contain fat but would also be in the differential diagnosis. However, the patient is postmenopausal and so endometrioma and corpus luteal cyst are unlikely.

Answer 20

44. B. Looser zones Looser zones are a highly specific radiographic feature of osteomalacia. They are sometimes referred to as pseudofractures and are focal linear areas of undermineralised osteoid at sites of mechanical loading. They are often seen bilaterally as linear lucencies that run perpendicular to the bone cortex and do not involve the whole bone width. Common locations include the medial cortex of the femoral necks, the inferior scapula and the ribs. These need to be differentiated from bisphosphonate fractures, which start at the lateral cortex of the proximal femur, are often bilateral and are termed as atypical fractures in patients on bisphosphonate therapy. Brown tumours are lucent lesions seen in hyperparathyroidism. Cloacas are seen in established osteomyelitis. Wimberger’s sign refers to localised bilateral metaphyseal destruction of the medial proximal tibias. It is a pathognomonic sign for congenital syphilis. Wimberger’s ring sign (sometimes also called just Wimberger’s sign to create confusion) is a radiographic sign seen in scurvy, showing thin pencil-like sclerosis along the epiphyseal margins. The cyclops lesion is an intra-articular mass of fibrotic tissue that may be seen post-anterior cruciate ligament (ACL) graft repair.

Answer 21

45. B. Humerus Stress fractures of the lower extremities associated with the onset of ambulation are called toddler’s fractures. These fractures typically occur in children between 9 months and 3 years of age, manifest with a refusal to bear weight and arc not preceded by a recognised acute traumatic event. A similar injury can result from subtle torsional forces, such as those occurring in a toddler who stumbles and falls on a positioned foot. 'The typical toddler’s fracture is a non-displaced oblique fracture of the distal portion of the tibia. Although other locations are less common, weight-bearing can also account for toddler’s fractures of the fibula, posterior aspect of the calcaneus, the base of the cuboid and the talus

Answer 22

46. B. Progressive supranuclear palsy Conventional MRI is usually not helpful in the diagnosis of early Parkinson’s disease because it most often yields normal findings. In advanced disease, abnormalities of the substantia nigra, including volume loss, decreased T2 signal reflecting iron deposition and blurring of the margins, can be seen. However, the primary role of MRI is to exclude structural abnormalities that potentially mimic Parkinson’s disease (e.g., NPH - normal pressure hydrocephalous, intracranial mass and bilateral subdural haematomas). FDG PET images are most often normal and show preserved metabolism in the putamen and globus pallidus. This is a defining feature of Parkinson’s disease and allows differentiation from both PSP (progressive supranuclear palsy) and MSA (multisystem atrophy, Shy-Drager syndrome), which commonly demonstrate reduced basal ganglia FDG activity. In patients with MSA-Parkinson’s type, abnormalities are confined to the putamen and include atrophy, symmetric hypointensity on T2 and T2*-weighted images and ‘slitlike’ marginal T2 hyperintensity. Putaminal atrophy appears to help discriminate MSA from Parkinson’s disease, whereas T2 hypointensity is a non specific sign that can be seen in PSP, Wilson’s disease, neurodegeneration with brain iron accumulation and other acquired conditions. Patients with PSP exhibit atrophy of the midbrain and tegmentum, manifesting as third ventricular dilatation, reduced midbrain AP diameter or flattening of the superior midbrain. Reduced midbrain AP diameter at the level of the superior colliculi on axial images gives rise to the Mickey Mouse sign. Midbrain atrophy with relative preservation of pons produces the hummingbird sign or penguin sign. Additional findings include superior cerebellar peduncle atrophy and increased FLAIR signal, both of which have reasonably high sensitivity and specificity in distinguishing PSP from Parkinson’s disease and MSA.

Answer 23

47. C. Linitis plastica Helicobacter pylori infects the gastric mucosa. In most cases, it is asymptomatic but can be associated with epigastric pain and dyspepsia. Imaging can demonstrate the sequelae of gastritis (thickened folds, polypoidal changes and enlarged areae gastricae), but most commonly patients have either a gastric or duodenal ulcer (or both!). Helicobacter pylori is the most common cause of both gastric and duodenal ulcer diseases. Linitis plastica (also known as leather bottle stomach) is a form of gastric stenosis that leads to narrowing of the stomach and which occurs secondarily to a number of conditions but is most frequently seen secondary to malignancy.

Answer 24

48. C. You immediately page the vascular surgeon on call You have just heard the dreaded symptoms and signs of compartment syndrome. The patient needs urgent surgical fasciotomy to prevent muscle necrosis. Any salvage treatment can be planned after that. Muscle oedema will raise the intracompartmental pressure in the calf fascial compartments. If it is not released promptly, it will lead to muscle necrosis. The patient must have suffered an embolus during the angioplasty procedure. This is a medical emergency and needs urgent treatment. The team can consider revascularisation options after this is done.

Answer 25

49. C. Decreased signal intensity of bone marrow on STIR images Osteomyelitis is the infection of bone of which the primary modes of pathogenesis are through haematogenous spread, direct spread through trauma or iatrogenic source and extension from adjacent soft-tissue infection. MR is highly sensitive in the diagnosis of osteomyelitis of which the loss of the normal T1-weighted bone marrow fat signal is the most sensitive finding. Other additional findings include increased T2-weighted and STIR signals from the oedema and inflammation. Post-contrast studies may reveal a rim enhancing intraosseous abscess, which would warrant surgical intervention.

Answer 26

50. D. Rhombencephalosynapsis Dandy Walker malformation is characterised by hypoplasia or agenesis of cerebellar vermis and cystic dilatation of the 4th ventricle, which can result in enlargement of the posterior fossa. Blake's pouch cyst is a result of absence of communication between the 4th ventricle and the subarachnoid space leading to tetraventricular hydrocephalus. The cerebellum has a normal size and shape. Typical neuroimaging findings include the presence of a cyst in a retro/infracerebellar location, which is essentially a diverticulum of the enlarged 4th ventricle. Giant cisterna magna is an enlarged cisterna magna (>10 mm on mid-sagittal images) with an intact vermis, normal 4th ventricle and, in some patients, an enlarged posterior fossa. Consistent presence of hydrocephalus allows the differentiation of Blake’s pouch cyst from mega cisterna magna. Arachnoid cysts are well-defined CSF density extra-axial lesions in the posterior fossa, which do not communicate with the 4th ventricle or the subarachnoid space. They may enlarge during infancy and produce mass effect on the cerebellum and vermis, which may cause a secondary obstruction of the ventricular system, hydrocephalus and/or remodelling or thinning of the overlying occipital bone. Isolated hypoplasia of the inferior vermis with normal 4th ventricle has been described variably in literature as Dandy-Walker variant. Rhombencephalosynapsis is characterised by the absence of the vermis and continuity of the cerebellar hemispheres, dentate nuclei and superior cerebellar peduncles, which creates a horseshoe shaped arch across the midline, resulting in a keyhole-shaped fourth ventricle. It is a key feature of Gόmez-Lόpez-Hernandez syndrome (parietal alopecia, trigeminal anaesthesia and craniofacial dysmorphic signs) and may be seen with VACTERL. Posterior coronal T2-weighted images show the horizontal folial pattern.

Answer 27

51. C. High Low The typical appearance of a brain abscess at conventional MRI is that of a ring enhancing lesion, with high signal intensity on T2-weighted images and low or intermediate signal intensity on T1-weighted images. A mature abscess has a low signal-intensity capsule on T2 weighted images. However, the presence of a ring-enhancing lesion in the brain is not diagnostic of abscess and must be distinguished from a necrotic neoplasm and other cystic lesions. Data from recent studies suggest that DWI is more sensitive than conventional MRI in distinguishing brain abscesses and cystic tumours. Pus in brain abscesses is strongly hyperintense on trace DWI and has a reduced ADC. On the contrary, most necrotic or cystic brain tumours have intermediate signal intensity on DWI and elevated ADC values

Answer 28

52. A. Cervical carcinoma recurrence causing haematometra Cervical carcinoma tends to be of higher signal on T2 than the surrounding cervical stroma and, in the above case, there is also disruption of the cervical stromal fibrous ring, increasing the likelihood of microscopic parametrial invasion. In this case, the cervical tumour is causing a malignant cervical stenosis and haematometra (high Tl signal is consistent with haemorrhage; tumour is usually intermediate signal/hypointense, similar to myometrium on T1 imaging). After radiotherapy to the cervix, cervical stenosis with haematometra can occur; however, post radiotherapy, the cervix becomes low signal because of fibrosis. Ovaries usually lie to either side of the midline, and it would be unusual for a cervical carcinoma metastasis of the ovary to have a high T1 signal. Imperforate hymen is congenital and is normally picked up either neonatally or at the time of menarche, if the latter commonly presents with haematometrocolpos; it would be inconsistent with a cervical cancer history, as this tumour is not seen in patients who are virgo intacta.

Answer 29

53. A. It is superior to cross-sectional imaging for local staging of oesophageal cancer. Endoscopic ultrasound (EUS) involves the addition of an ultrasound probe in the endoscopy apparatus. This has a number of clinical uses, which are currently being developed. Evidence already exists that EUS is superior to cross-sectional imaging in the local staging (for assessment of both the primary tumour and local nodes) of oesophageal, pancreatic and rectal cancer. By visualising the wall layers of the gastrointestinal tract, it is the modality of choice for assessment of submucosal lesions. EUS can be combined with interventional techniques such as drainage or fine needle aspiration cytology. It is useful for differentiating inflammatory and neoplastic pancreatic masses. Cross-sectional imaging remains superior in the assessment of liver metastases.

Answer 30

54. B. Severed tibioperoneal trunk The most common anatomical configuration of the popliteal trifurcation is the anterior tibial (AT) artery branching off first and terminating as the dorsalis pedis artery. The tibioperoneal trunk arises distal to the AT origin and gives rise to the peroneal artery and posterior tibial (PT) arteries.

Answer 31

55. E. Haemorrhagic ovarian cyst Acute pelvic pain in adolescent girls is a common problem, but ultrasound scanning is very useful in differentiating the many possible causes. Haemorrhagic ovarian cysts are a common cause of pelvic pain in adolescent girls and appear as an echogenic mass in relation to the ovary. Acute appendicitis is likely to occur as a blind-ending tubular structure. This may appear like a ‘target lesion’ in cross section and there may be fluid/collection adjacent to it. An acute appendix should be clearly distinct from the right ovary. Ovarian dermoids arc usually predominantly fat filled and therefore echogenic on ultrasound, but these tend to be a painless, incidental finding. Ovarian torsion can certainly produce an echogenic mass within the right pelvis, but litis is less common than haemorrhagic cysts and would not appear distinct from the ovary. Ectopic pregnancy usually appears as a 'doughnut’-shaped complex mass in relation to one of the uterine tubes; a foetal heartbeat may be present.

Answer 32

56. C. Mesial temporal sclerosis Mesial temporal sclerosis typically demonstrates an atrophic, T2 hyperintense hippocampus on imaging. Other pathology afFecting the temporal lobe including infection and tumour would cause enlargement of the hippocampus. Alzheimer's dementia results in medial temporal atrophy, but T2-weighted hyperintensity is not a feature. Herpes encephalitis is caused by Herpes simplex virus (HSV) type I in adults and HSV type II in children. It involves the limbic lobe (hypothalamus, parahippocampal gyrus, cingulate gyrus); and typically appears bilateral but asymmetric. Gyriform enhancement and haemorrhage are late features. Choroidal fissure cyst is a benign incidental finding, similar to arachnoid cysts in the brain. These occur in the region of the hippocampal fissure.

Answer 33

57. B. Second Frieberg disease is essentially osteochondrosis of the metatarsal head, of which the 2nd metatarsal is most commonly affected, and less commonly in the 3rd and 4th metatarsal. Ten percent of cases are bilateral. MRI findings of subchondral fracture of the metatarsal head with severe marrow oedema-like pattern suggest early-stage changes. Metatarsal head collapse with subchondral sclerosis and mild or absent marrow oedema-like pattern suggests late-stage changes.

Answer 34

58. D. Ovarian hyperstimulation syndrome Human menopausal gonadotrophins are an infertility drug, which contains follicle-stimulating hormone and luteinizing hormone, derived from the urine of postmenopausal women and given as an injection. One of its main side effects is ovarian hyperstimulation syndrome, which can also occur because of high levels of beta-human chorionic gonadotrophin seen in multiple pregnancies and hydatidiform moles. Typical symptoms are those mentioned in the question, vomiting and nausea. Corpus luteal cysts are singular and usually unilateral. Ovarian torsion is more common in infertility treatment but is usually unilateral, with a very oedematous ovary containing small, subcentimetre cysts arranged around its periphery. Polycystic ovarian syndrome causes bilaterally increased ovarian volume, but cysts are usually small and subcentimetre. Endometriomas usually contain low-level echoes.

Answer 35

59. D. Hepatic adenoma Hepatic adenomas are benign encapsulated liver lesions, which are usually 8-15 cm in diameter but can grow up to 30 cm. They are associated with the oral contraceptive pill and can often increase in size during pregnancy. They appear as hyperechoic lesions on ultrasound and are usually of low density on plain computed tomography and enhance in the arterial phase with rapid washout. They have a risk of haemorrhage and, if rupture occurs, can develop into a subcapsular haematoma. Focal nodular hyperplasia, haemangiomas and metastases would not be expected to grow this fast. Hepatic abscesses can grow quickly but the patient would be unwell, especially with spread into a subcapsular collection.

Answer 36

60. C. Bilateral renal artery angioplasty and stenting The results of the ASTRAL trial have shown no benefit of endovascular treatment when compared with best medical management of hypertension. However, recurrent flash pulmonary oedema is a good indication for intervention. Surgical endarterectomy is a procedure that carries huge risks and has no role in this case. Radiofrequency (RF) denervation is a relatively new method. The renal arteries are catheterised via a common femoral artery approach. Using an RF generator, the artery is denervated, excluding the kidneys, from the sympathetic control. The long-term results are unknown.

Answer 37

61. B. Perthes disease There are a large number of potential causes for hip pain in children. However, many of the conditions have common presenting age ranges, which makes creation of a differential diagnosis difficult. Perthes disease is an idiopathic condition where avascular necrosis affects the femoral head leading to chronic destruction of one or both heads of femur. It tends to affect boys between the ages of 5 and 8 years. Septic arthritis occurs at any age but would not be expected to present as a chronic finding, especially as many children have associated septicaemia. Slipped upper femoral epiphysis affects adolescent children (12-15 years) and is usually associated with childhood obesity or in those who perform high impact activity. Juvenile rheumatoid arthritis is similar to the adult form of the disease in that it is idiopathic but tends to affect the large joints of which the hip is not the most common. In addition, there are often other systemic features of the disease as well as multiple joint involvement. Finally, this condition tends to present in younger children (1-3 years). Developmental dysplasia of the hip presents in infancy but if undetected will lead to chronic hip problems.

Answer 38

62. E. Meningioma Intramedullary Lesions of the spinal canal can be divided into three categories: Intramedullary lesions: Ependymoma, astrocytoma, ganglioglioma, haemangioblastoma, PNET, metastasis, lymphoma, lipoma, epidermoid, abscess, vascular malformation, MS plaques, infarction, myelomalacia, sarcoidosis Intradural extramedullary. Nerve sheath tumour, meningioma, lipoma, dermoid, metastasis from outside CNS, ependymoma of filum terminale, arachnoid cyst, neuroenteric cyst Extradural: Dermoid, epidermoid, lipoma, lymphoma, metastasis, drop metastasis, meningioma, disc material, arachnoid cyst, infection

Answer 39

63. D. Gaucher disease Although the Ashkenazi Jews are particularly predisposed to this hereditary condition, Gaucher disease is not confined to any particular ethnic group or sex. Splenic enlargement is detected in up to 95% of cases. There is abnormal modelling of the distal femur and proximal tibia secondary to marrow infiltration, leading to an 'Erlenmeyer flask’ deformity. This feature is, however, not diagnostic for Gaucher disease and may be seen in all the other answer options. Diffuse medullary osteoporosis, bone infarcts and sharply circumscribed endosteal lytic lesions (owing to marrow replacement) can also be seen. The combination of Jewish ancestry, the radiographic features described and splenomegaly, makes Gaucher disease the most likely diagnosis.

Answer 40

64. D. Bartholin’s cyst Bartholin’s glands secrete mucous to lubricate the vagina and are equivalent to the male Cowper glands (adjacent to urethra, producing pre-ejaculate). They lie within the posterolateral portion of the lower vagina. Bartholin's cysts occur when the small duct becomes obstructed; superadded infection can occur, leading to an abscess. Nabothian cysts are small mucous-filled cysts on the cervix and are very common. Gartner duct cysts are a Mullerian duct remnant and are uncommon; they have a typical location within the anterolateral proximal third of the vagina. Squamous cell carcinoma would usually appear as a thickened vaginal wall on ultrasound, if seen at all. Usually, the proximity of the probe to the lesion can make it difficult to assess, so this is better demonstrated with magnetic resonance imaging. A lipoma would have the appearance of other superficial lipomas and characteristically would be hyperechoic

Answer 41

65. D. Perform transjugular liver biopsy This is a commonly occurring scenario. Liver biopsy is contraindicated in the presence of ascites and coagulopathy. The transjugular approach is a good alternative where available. The right internal jugular vein is punctured and a catheter is advanced into a hepatic vein, usually the right. Through this, a long specially designed biopsy needle is introduced and a biopsy is taken. The method is used for generalised liver disease and not for a focal lesion. An alternative method is the plugged liver biopsy; here the biopsy is done over a sheath, and coils are dropped after the core is taken to plug the hole.

Answer 42

66. C. Right CFA, antegrade The ‘down the leg’, antegrade, approach via a right common femoral artery puncture is the easiest and most direct approach. Retrograde puncture is usually used for angiography and intervention at the iliac systems, aorta and aortic branches. Ultrasound scan is commonly used to visualise the vessels during puncture. The puncture can also be safely performed using anatomical landmarks and feeling for the femoral pulse. The CFA can be found in the mid point between the anterior superior iliac spine and the symphysis pubis. By using USS, the local anaesthetic can be accurately placed around the vessel, ensuring good analgesia. The profunda femoris artery can also be visualised and hence minimise the chance of accidental puncture. The popliteal artery can be punctured using ultrasound guidance at the popliteal fossa, but it would not be preferred in this case.

Answer 43

67. A. Angular dermoid The location of this lesion at the angle of the eye brow with ultrasound imaging features such as contiguous bone scalloping, fluctuance and presence of mobile debris within the lesion is reassuring and points to a diagnosis of an angular dermoid. T1 hyperintensity demonstrated on MRI consistent with a fat signal is diagnostic of this lesion. As the lesion may also contain debris, this may result in an inhomogeneous signal on MRI. A haemangioma would be expected to demonstrate flow voids and increased vascularity on ultrasound and MRI. The location is very unusual for a lymphangioma.

Answer 44

68. D. Infection Percutaneous cementoplasty (vertebroplasty) with acrylic cement, PMMA (polymethylmethacrylate), is a procedure aimed at preventing vertebral body collapse and pain in patients with pathologic vertebral bodies. Indications: * Symptomatic vertebral angioma. * Painful vertebral body tumours and acetabular tumours. * Severe painful osteoporosis with loss of height and/or with compression fractures of vertebral bodies. Contraindications: * Haemorrhagic diathesis. * Infection. * lesions with epidural extension. These require careful injection to prevent epidural overflow and spinal cord compression by the cement or displaced epidural tissue. The absolute contraindications are haemorrhagic diathesis and infection. Patients with more than five metastases or diffuse metastases are not candidates for vertebroplasty.

Answer 45

69. C. Lung cancer metastasis The most common sites for bone metastases arc bones that contain red bone marrow. Hence, hone metastases have a predilection for the axial skeleton. Peripheral metastases are rare, and 50% of these are caused by lung cancer. The other options are also known causes of lytic metastases, but would be less likely to affect the hands.

Answer 46

70. C. Red degeneration within a leiomyoma Fibroids (leiomyomas) are benign tumours made of smooth muscle. Afro-Caribbean women are more prone than Caucasian women to developing fibroids. Fibroids can outgrow their blood supply and undergo degeneration causing them to look very different on MRI depending on the type of degeneration that they undergo. Typically, a non-degenerated fibroid is a well-defined low-intensity lesion on T1 and T2-weighted images, and enhances post contrast injection. Hyaline degeneration is caused by necrotic central change and increasing collagen content; this causes variable signal on T1-weighted images but low signal on T2-weighted images. With calcific degeneration, the fibroid has similar signal characteristics on T1 and T2 to typical non- degenerative fibroids. Cystic degeneration can produce areas of fluid signal within the fibroid, which does not enhance. Myxoid degeneration results in a very high T2 signal with a little enhancement. Red degeneration is a very rare type of degeneration; it typically causes severe pain and can cause a fever. It is the result of thrombosis of the vessels surrounding the fibroid leading to the high T1 and low T2 signal rim, and it usually occurs in pregnancy.

Answer 47

71. E. Administer high-flow oxygen and put the patient in the left lateral position. This scenario describes an iatrogenic air embolism. This is an uncommon complication that has an incidence of aroimd 0.13%. Treatment includes high-flow oxygen and placing the patient in the left decubitus position. This would allow the air to rise in the right atrium where it can be aspirated using a transjugular approach. Needle decompression in the right mid-clavicular line is the treatment for a tension pneumothorax. A chest X-ray might show air in the right heart but will not help in the immediate management. Injecting 10 mL of contrast down the sheath is performed when you are suspecting extravasation and placing the patient head down and giving fast intravenous crystalloid is the treatment for hypotension.

Answer 48

72. A. A lead point is rarely the underlying cause in adult cases. Intussusception refers to the telescope-like invagination or prolapse of an intestinal segment mto the lumen of an adjacent loop. Approximately 95% of cases occur in children, usually affecting those under the age of 2 years. A lead point is an unusual finding in this age group, with mucosal oedema and lymphoid hyperplasia secondary to viral gastroenteritis often being the underlying issue. Conversely, while intussusception in adults is uncommon, a lead point is far more commonly present. Lesions such as polyps, small bowel tumours, post-surgical changes and foreign bodies are recognised precipitants. In children, reduction of intussusception using either water or air can be attempted, provided that there is no initial evidence of perforation. A rule of ‘3s’ is well known, whereby a maximum of three attempts at reduction with 3 minutes separating each attempt and a hydrostatic pressure equivalent to an infusion bag 3 feet (91.4 cm) above the patient is observed. Surgical intervention may be required if such techniques are unsuccessful.

Answer 49

73. A. Sickle cell anaemia Gallstones are an uncommon occurrence in childhood irrespective of the symptomatology and therefore should always raise the possibility of a background predisposing condition leading to their formation. In the African population, sickle cell anaemia is the most likely diagnosis. One must also consider other conditions such as malabsorption, Crohn disease, thalassemia major (in patients of Mediterranean origin), total parenteral nutrition (TPN), cystic fibrosis and short gut syndrome. The radiologist is often the first to raise the possibility of a predisposing condition. Children are at risk of the same gallstone-related complications as adults, including severe acute pancreatitis, which may be life threatening.

Answer 50

74. D. Prostate metastases Brain metastases may be solitary' or multiple. Some tumours including breast, renal cell, colon and thyroid cancers are more commonly solitary, while others such as lung cancer and melanoma tend to be multiple. Imaging characteristics of metastases may suggest an underlying pathologic diagnosis. Metastases that classically haemorrhage include melanoma, choriocarcinoma, renal cell carcinoma and thyroid cancer. Lung metastases are also known to haemorrhage. In the absence of haemorrhage, metastases may be hypodense, isodense or hyperdense compared with the brain. Acutely haemorrhagic metastases appear hyperdense to brain. Melanoma metastases tend to be hyperdense to brain on CT even in the absence of haemorrhage

Answer 51

75. A. Le Fort I facial fracture All Le Fort fractures involve the pterygoid plate. In addition, Le Fort I involves maxilla and nasal septum. Le Fort II involves nasal bones, frontal process of maxilla, maxillary sinus, medial and inferior orbital wail. Le Fort III, in addition to II, involves lateral orbital wall and zygomatico-frontal suture. Le Fort II fracture is also called pyramidal fracture.

Answer 52

76. D. Splenic vein The splanchnic circulation includes the superior mesenteric vein, inferior mesenteric vein and splenic and portal veins. Hepatic veins do not form part of the splanchnic circulation as they do not drain to the portal vein but drain directly to the inferior vena cava (IVC). Chronic thrombosis of portal or superior and inferior mesenteric veins is often associated with gastro-oesophageal varices, owing to collateral circulation to IVC from submucosal veins of the oesophagus. Isolated splenic vein thrombosis causes only gastric fundal varices, formed by short gastric vessels serving as collaterals. This is known as left-sided portal hypertension. Left-sided portal hypertension is often associated with pancreatitis or pancreatic cancer.

Answer 53

77. B. Infrarenal IVC In the presence of normal anatomy, IVC filters should be placed inferior to the renal veins. This is to avoid potential clot propagation and renal vein thrombosis. If the patient has aberrant anatomy such as double IVC, a single suprarenal filter or twin IVC filters can be placed. Access is via a right internal jugular puncture or a right femoral vein puncture. A cavogram is performed to visualise the renal veins and to look for aberrant anatomy as described above. Indications for IVC filter include deep vein thrombosis where anticoagulation is contraindicated, where the patient is non-compliant with medical treatment or when there is free floating thrombus in the IVC. Retrievable devices are available and should be removed within 14 days from insertion. Pulmonary embolism can still occur despite an IVC filter with an incidence of 2.7%-4%.

Answer 54

78. A. Posterior calyx, middle/lower pole When further intervention such as antegrade stent placement or percutaneous nephrolithotomy is anticipated, a posterior upper pole calyx may be appropriate, Effort should be made to puncture below the 12th rib to avoid traversing the pleura. However, this is not always possible and puncture between the 11th and 12th ribs can also be used with care. Direct puncture of the renal pelvis should be avoided as the adjacent vessels here are large. Anterior calyces should also be avoided, as puncturing these from a posterior approach increases the risk of renovascular injury because of the volume of renal parenchyma traversed.

Answer 55

79. C. Inguinal hernia The child in this scenario has acute bowel obstruction, which can sometimes be missed on initial assessment. When assessing plain films, the hernial orifices should be remembered as an important ‘review area’ as inguinal hernia are common and should not be missed, both in children and adults alike. In this case, an ultrasound was performed first but the same principles apply and bowel loops in the scrotum are diagnostic. The radiologist may be the first to raise this possibility. An incarcerated hernia associated with obstruction or strangulation is an acute surgical emergency and requires urgent surgical intervention. Femoral hernia is uncommon in children. Acute testicular torsion may have a similar presentation and should always be considered. At least some part of a testis should be identifiable in case of torsion, tumour or injury. Non-visualised testis strongly suggests hernia.

Answer 56

80. C. Arachnoiditis Infectious aetiologies for arachnoiditis include bacterial, viral, fungal and parasitic agents. Non-infectious aetiologies include surgery, intrathecal haemorrhage and the administration of intrathecal agents, such as myelographic contrast media, anaesthetics and steroids. Neoplastic causes include metastasis from breast and lung carcinoma, melanoma and non-Hodgkin lymphoma or direct seeding of the CSF from primary’ CNS tumours like glioblastoma multiforme (GBM), medulloblastoma, ependymoma and choroid plexus carcinoma. MRI is the most sensitive modality' for diagnosis of arachnoiditis. Although arachnoiditis can be present throughout the subarachnoid space, it is most easily seen in the lumbar region where the cauda equina usually floats in ample CSF. In arachnoiditis, the nerve roots are irregularly thickened and clumped together, often stuck to the dura, resulting in an empty thecal sac sign.

Answer 57

81. B. Pachydermoperiostosis Pachydermoperiostosis is a self-limiting condition with similar radiological findings to those of hypertrophic osteoarthropathy: symmetrical bilateral periosteal reaction. It is seen in adolescents and is of autosomal dominant inheritance pattern. Males tend to be affected more often than females. Differential diagnoses of these radiological findings include thyroid acropachy, hypervitaminosis A, hypertrophic osteoarthropathy, metastases and chronic venous insufficiency. All of the above require treatment before resolution of the periosteal reaction. Hypertrophic osteoarthropathy is caused by many pulmonary and non-pulmonary diseases such as benign and malignant thoracic tumours, chronic infection/inflammation (bronchiectasis and lung abscesses), cyanotic congenital heart disease, inflammatory bowel disease and liver cirrhosis. In HO A, resolution of the radiological findings is only really seen following treatment of the underlying condition.

Answer 58

82. C. Refer for laparoscopic division of the ligament The symptoms and radiological findings are consistent with median arcuate ligament syndrome, the compression of the coeliac axis by the median arcuate ligament of the diaphragm. The median arcuate ligament passes superior to the coeliac axis in 10%-24% of the population. It can cause haemodynamically significant compression in a small subgroup. Treatment is controversial but benefit can be seen in cases where there is weight loss, post-stenotic dilatation along with postprandial pain. Laparoscopic ligation is the preferred method.

Answer 59

83. C. High-pressure chronic retention High-pressure chronic retention is a cause of bilateral hydronephrosis. It is usually caused by prostatic hypertrophy. The patient typically has a non-compliant bladder with incomplete emptying, although its overall capacity is often normal or may even be below normal. The high pressure in the bladder causes functional obstruction of the upper tracts, and hence causes upper tract dilatation and impairment of renal function. Treatment is by catheterisation, thus decompressing the bladder and upper tracts, and interval transurethral resection of the prostate if there is any recoverable bladder function. The other answers are valid indications for upper tract de-obstruction.

Answer 60

84. B. Acute Budd-Chiari syndrome Acute hepatic venous obstruction (Budd-Chiari syndrome) can be associated with disseminated malignancies. In addition to ascites and hepatomegaly, characteristic CT features are geographic liver (mottled liver enhancement) and a flip-flop pattern of enhancement (early-phase hyperenhancement of the central area of the liver with peripheral hypoenhancement, which reverses on delayed imaging with central hypoenhancement and peripheral hyperenhancement). The caudate lobe is spared as it has direct venous drainage to the inferior vena cava, bypassing hepatic veins. In the acute phase, the liver remains normal in size, but with chronic disease there is hypertrophy of the caudate lobe, which takes over the majority of liver function, thereby helping differentiation between acute and chronic Budd-Chiari syndrome. Peliosis hepatis may also be associated with disseminated malignancy, but CT demonstrates multiple spherical lesions with centripetal or centrifugal enhancement because of the presence of blood filled cavities.

Answer 61

85. C. Irregular liver contour Non-alcoholic liver steatohepatitis is the second stage of non-alcoholic fatty liver disease (NAFLD), a very common liver disease that affects about 30% of the western population. The most common cause for this disease is obesity and hypertriglyceridemia. The first stage of NAFLD - hepatosteatosis is potentially reversible but when untreated, 60% progress to NASH, which also has features of fibrosis and inflammation. Hepatosteatosis and NASH are indistinguishable radiologically and NASH can only be diagnosed on biopsy, which is performed in high risk patients. Progression to cirrhosis is observed in 10% of patients with NASH, where a small shrunken liver with irregular contour and secondary features of cirrhosis are observed.

Answer 62

86. E. Conservative management and repeat scan in 6 months Splenic aneurysms have an incidence of around 0.1% at autopsy. Indications for treatment include portal hypertension, size >25 mm, female patient of child-bearing age and pseudo- aneurysm. There is an increased risk of rupture in pregnancy. Interventional treatment is usually by coil embolisation although stent grafting and even transabdominal thrombin injection have been described.

Answer 63

87. D. Tectal beaking Holoprosencephaly results from a lack of normal cleavage of the forebrain. The septum pellucidum is always absent in this condition. Holoprosencephaly may be divided into alobar, semilobar and lobar forms depending on the degree of abnormality. Tectal beaking is a feature of Chiari II. Single ventricle, fused thalami, absent corpus callosum and hypoplasia of the optic nerves are all features of the various forms of holoprosencephaly. In its mildest form, lobar holoprosencephaly, absence of the septum pellucidum may be the only abnormality. The lobar form may be associated with septo-optic dysplasia and the two conditions overlap. The degree of facial abnormality and mental retardation mirrors the severity of the intracranial abnormality

Answer 64

88. C. Slow flow mimics sinus thrombosis on contrast-enhanced MRV. The classic finding on unenhanced CT is a hyperattenuating thrombus in the occluded sinus (delta sign). However, this is seen in only 25% cases. Increased attenuation in the venous sinuses may also be seen in patients with dehydration, an elevated haematocrit level, or a subjacent subarachnoid or subdural haemorrhage. On contrast-enhanced CT/MRI, the empty delta sign is seen, a central intraluminal filling defect that represents a thrombus surrounded by contrast enhanced dural collateral venous channels and cavernous spaces within the dural envelope. Unenhanced MRI is more sensitive for the detection of venous thrombi than is unenhanced CT. The absence of a flow void and the presence of altered signal in the sinus is a primary finding. Slow or turbulent flow also may cause a signal intensity alteration in the sinus. The signal intensity of venous thrombi on Tl- and T2-weighted MR images varies according to the interval between thrombus formation and the time of imaging. Time-of-flight (TOF) MR venography is the method most commonly used for diagnosis. Contrast-enhanced MRV utilises the paramagnetic effect of intravenous gadolinium to shorten Tl relaxation time and provide positive intravascular contrast enhancement. Small-vessel visualisation is improved at contrast- enhanced MRV. Depiction of the dural sinuses is also superior with contrast enhanced MR venography because of a decrease in the effects of turbulent/slow flow on vessel contrast. An irregular appearance of the sinus with multiple intrasinus channels and dural collateral vessels on MRV is characteristic of incomplete recanalisation. Complete recanalisation occurs more often in superior sagittal and straight sinus thrombosis than transverse and sigmoid sinuses after anticoagulation therapy.

Answer 65

89. D. The distal portions of the seminal vesicles and vas deferens are intraperitoneal. The seminal vesicles arc paired, elongated septated structures that lie above the prostate and abut the posterior wall of the bladder. Their fluid accounts for around 50% 80% of ejaculate. The seminal vesicle joins the distal vas deferens, forming the ejaculatory duct, which drains into the prostatic urethra at the verumontanum. The proximal portion of the vas deferens lies within the spermatic cord. The seminal vesicles and vasa deferentia are extraperitoneal structures. Seminal vesicle abnormalities are invariably found as incidental findings on imaging studies, although patients may present with haematospermia or infertility. Primary tumours of the seminal vesicle arc very rare indeed, with the majority of neoplasia occurring from local spread of prostate, bladder or rectal malignancies.

Answer 66

90. D. Hypertrophic osteoarthropathy Hypertrophic osteoarthropathy, or HOA, is characterised by smooth periosteal new bone formation, usually in the diametaphysis of the long bones. The tibia, fibula, radius and ulna are most commonly involved in -80% of cases with patients usually describing painful, swollen joints. When present, caution must be given to look for an underlying thoracic cause of which the most common aetiology is bronchogenic carcinoma. In such instances, it is commonly referred to as hypertrophic pulmonary osteoarthropathy, or HPOA. Extrathoracic causes of HOA include inflammatory bowel disease and liver cirrhosis.

Answer 67

91. E. Conservative management Varicocele is a commonly identified correctable cause of male factor infertility. Surgical correction has a failure rate of less than 5%. An alternative to surgery is the selective catheterisation and embolisation of the gonadal vein. The gonadal vein is catheterised via a common femoral vein puncture and embolic material is introduced. Indications include symptomatic varicocele, recurrence of varicocele post treatment and varicocele with associated infertility. Complications include pain, recurrence and reaction to iodinated contrast. Rupture of the testicular vein is a known complication, but it needs no specific treatment. Unlike surgery, embolisation is not associated with postoperative hydrocele or testicular loss from inadvertent injury to testicular artery. However there are case reports of renal loss from coil migration.

Answer 68

92. 13. Intrapulmonary bronchogenic cyst Bronchogenic cysts (BCs) are congenital lesions. They are usually found in the mediastinum or pulmonary parenchyma and, less commonly, cysts may be found in the neck, pericardium, pleura, diaphragm or abdominal cavity. Intrapulmonary cysts are most common in the lower lobes. Intrapulmonary BCs are usually sharply defined, solitary, non-calcified, round or oval opacities confined to a single lobe. These can present as a homogeneous water density, an air-filled cyst, or with an air-fluid level. Signal on MRI depends on the content, and fluid-containing lesions are low on T1-weighted and high on T2 weighted images; however, proteinaceous content makes them high on T1-weighted imaging. The differential diagnosis of intraparenchymal BCs must include acquired cystic lesions, such as a lung abscess, a hydatid cyst, infection with nocardia, an infected bulla, congenital lobar emphysema, fungal diseases and tuberculosis, especially when the lesions manifest as air filled or have an air-fluid level.

Answer 69

93. E. Posterior communicating cerebral artery The third nerves exit the brain stem medial to the cerebral peduncles, and course forward and laterally in the interpeduncular cistern between the posterior cerebral arteries-posterior communicating arteries (PcomA) above and superior cerebellar arteries below. The pupillary fibres are located dorsomedially and peripherally at this segment. Common pathologies involving this segment include aneurysm at PcomA or basilar tip, dolichoectatic vessels, microvascular ischaemia, SAH, meningitis, neoplasms (leukaemia, lymphoma, neurogenic tumours and leptomeningeal carcinomatosis), inflammatory disease (neurosarcoidosis, Wegener’s granulomatosis), demyelinating disease, transtentorial herniation (from supratentorial tumour, haemorrhage or brain swelling) and head trauma with nerve avulsion (usually at the posterior petroclinoid ligament where the third nerve is stretched because of downward displacement of the brain stem at the time of impact).

Answer 70

94. B. Lead poisoning The differential list for dense metaphyseal bands is plenty but includes normal variant in neonates, growth acceleration lines (usually in patients with chronic illnesses like diabetes, asthma), treated rickets, chronic anaemia, scurvy and lead poisoning. Recurrent abdominal pain is associated with lead poisoning. None of the other conditions, except for leukaemia, is associated with abdominal pain, but the dense metaphyseal band sign is acknowledged only in treated leukaemia rather than active leukaemia. Although the blood profile is often normal, the patient may sometimes have a mild microcystic, microchromic anaemia

Answer 71

95. A. Less than three hepatic lesions Liver metastases from colorectal cancer are among the most common hepatic secondary tumours. This is also the only type of metastatic deposit for which resection has shown a survival benefit. If liver metastases from colorectal cancer are to be resected, several radiological criteria must be met. There is no strict limit to the number of lesions that can be resected, but it is unlikely that more than six lesions will be removed. Compare this with hepatocellular carcinoma where only a solitary lesion can be surgically explored. If at least three segments of the liver are spared, there are enough hepatocytes to provide liver function following surgery; preoperative selective portal vein embolisation can be used to increase the volume of the remaining liver through hypertrophy.

Answer 72

96. D. Decreased or absent bowel wall enhancement Abnormalities in bowel wall enhancement after administration of IV contrast are very common and important positive findings in the evaluation of abdominal CT in a trauma scenario and should always be assessed. Generalised increased enhancement is typical for bowel wall injury with vascular involvement but without ischaemia, and is thought to be caused by increased permeability of the hypoperfused wall. Localised, patchy and irregular hyperenhancement is suggestive but not diagnostic of a fullthickness tear. Areas of decreased or absent enhancement in a segment of a bowel are indicative of bowel ischaemia; lack of enhancement is considered to be highly specific.

Answer 73

97. C. Biliary atresia Failure of gallbladder emptying following a feed and failure of isotope (HIDA) excretion into the bowel is a typical finding of biliary atresia. The presence of tracer in the urinary bladder implies that there is no hepatic excretion of tracer, only urinary excretion; this only occurs with sustained systemic levels as HIDA is preferentially excreted hepatically. The gallbladder is not visualised in some cases of high biliary atresia and cystic fibrosis. Transient neonatal hyperbilirubinaemia should resolve spontaneously by 2 weeks of age. Ultrasound imaging may demonstrate a triangular cord or tubular echogenic structure in the porta hepatis owing to fibrous tissue. When identified, this is pathognomonic of biliary atresia.

Answer 74

98. E. Vessel dilatation The rest are angiographic signs of active bleeding; vessel dilatation is not.

Answer 75

99. B. Multilocular cystic nephroma Multilocular cystic nephroma is a benign renal tumour that occurs in children and, less commonly, adult women. There is no known association with Wilms’ tumour. It is usually a unilateral abnormality that replaces an entire renal pole and presents as a large mass, often around 8-10 cm in diameter. Radiological appearances, while not entirely specific, can help to differentiate this lesion from other renal mass lesions. A sharply well-circumscribed, multiseptated cystic mass is typical, with a thick surrounding capsule. The cysts may appear to herniate into the renal pelvis - an appearance that is relatively specific. Unsurprisingly, these lesions are excised as a definitive radiological differentiation from malignancy is often not possible. Multilocular cystic nephroma can be differentiated from multicystic dysplastic kidney by the presence of normal functioning renal parenchyma and symmetrical renal excretion. Polycystic kidney disease involves the entire kidney, unlike multilocular cystic nephroma, which tends to be localised around a renal pole.

Answer 76

100. D. Parenchymal abnormalities secondary to venous occlusion are irreversible. Parenchymal lesions are better depicted and more commonly identified at MR imaging than at CT. Focal oedema (without visible haemorrhage) is visible on CT images in approximately 8% of cases and on MR images in 25% of cases. Diffusion-weighted MR imaging techniques allow sub classification of parenchymal abnormalities as either primarily vasogenic oedema (with increased ADC values presumably related to venous congestion) or primarily cytotoxic oedema (with decreased ADC values related to cellular energy' disruption). Haemorrhage may occur with both types of oedema. In contrast with arterial ischaemic states, many parenchymal abnormalities secondary' to venous occlusion are reversible. Although parenchymal changes may occur in areas of the brain that are directly drained by the occluded venous sinus, in some patients, the parenchymal changes may not closely correlate with the location of venous occlusion. Parenchymal swelling without abnormalities in attenuation or signal intensity on images may occur in as many as 42% of patients with cerebral venous thrombosis. Sulcal effacement, diminished cistern visibility and a reduction in ventricular size may occur.

Answer 77

101. C. Fractures of the distal pole are less common than fractures of the proximal pole. Scaphoid fractures arc common injuries but can have long-standing implications if not treated in a timely manner because of the risk of avascular necrosis and early development of osteoarthritis in cases of mal- or non-union. Scaphoid fractures most commonly occur within the waist of the scaphoid (70%), with the remaining occurring in the proximal pole (20%) and distal pole (10%). Due to the nature of the scaphoid blood supply, it is the proximal fracture fragment that is at risk of avascular necrosis. A fall on the outstretched hand is the most common mechanism. Fracture displacement and scapholunate ligamentous disruption with widening of scapho-lunate distance, (‘Terry Thomas’ sign) are common associated findings.

Answer 78

102. D. Nodes in the perivescical fat The strength of MRI in evaluation of prostate cancer is in the diagnosis of extracapsular and seminal vascular invasion. The criteria used for the detection of extracapsular extension of tumour (on T2-weighted images) include: irregular capsular bulge, obliteration of rectoprostatic angle, asymmetry of the neurovascular bundle, angulation or step-off appearance of the prostate contour, focal capsular thickening or retraction, broad (>12 mm) capsular tumour contact and breech of capsule with evidence of direct tumour extension.

Answer 79

103. E. Foregut duplication cyst Foregut duplication cysts usually occur on the mesenteric aspect of the alimentary canal and may be associated with other gastrointestinal anomalies. The absence of any spinal involvement and the late presentation seen here rule out other differential diagnoses. Other more likely differentials would include bronchogenic cyst and pericardial cyst, and these are often very difficult to differentiate even on computed tomography (CT) and MRI. Duplication cysts occur most commonly in relation to the small bowel, in particular the ileum; the oesophagus is, however, the second most common location. When identified, the 'muscular rim sign’ on ultrasound is diagnostic. This results from an alternating echogenic inner mucosal lining and a hypoechoic outer rim signal from the mucosal lining.

Answer 80

104. B. Acute disseminated encephalomyelitis Acute disseminated encephalomyelitis (ADEM) is a monophasic autoimmune demyelinating disease of the central nervous system that typically follows a febrile infection or vaccination. The disorder is immunologically mediated because of an autoimmune reaction to myelin. Peak incidence is in children aged 3-10 years. Typically, ADEM manifests as multifocal lesions mimicking MS. However, clinical and radiologic criteria distinguish between ADEM and MS. ADEM typically meets at least two of the three following criteria: (a) They have clinical symptoms atypical of MS, e.g., altered consciousness, hypersomnia, seizures, cognitive impairment, hemiplegia, quadriparesis, aphasia or bilateral optic neuritis, (b) They have absence of oligoclonal bands in CSF. (c) They have grey matter involvement (basal ganglia or cortical lesions). Imaging features, such as the number of T2 hyperintense lesions and the presence of gadolinium enhancement, oedema and periventricular or brainstem lesions, cannot be used to reliably differentiate between ADEM and MS. Corpus callosal involvement is less frequent in patients with ADEM than in those with MS. Cerebrospinal fluid findings, especially the presence or absence of oligoclonal bands, remain important in the differentiation of patients with MS from those with ADEM. The best criterion is the course of the disease, with a good outcome in 57%-81% of patients with ADEM, with no new lesions and partial or complete recovery of existing lesions on follow up MR images.

Answer 81

105. C. Measure the pressure gradient There will be a degree of vessel dissection in all vessels after angioplasty. If there is no limitation to flow or significant pressure gradient across the lesion, then the procedure can be regarded as being successful and no further action is necessary. The pressures can be measured by connecting the end of a catheter to a transducer via a three way tab. The catheter is placed through stenosis and the pressures are measured on either side. The difference is the pressure gradient, and it should be less than 10 mmHg.

Answer 82

106. E. Atrophy of the spinal cord Spinal cord injury can have devastating impacts on patients. Acute causes generally relate to traumatic events and include cord haemorrhage, contusion and transaction. Oedema, swelling and haemorrhage (epi and intradural) are often seen in the context of an acute cord injury. Occasionally, there can be increased enhancement in the hyperacute status, usually of the haematoma. Examples of causes of chronic cord myelopathy include chronic spinal stenosis (e.g., from a disc prolapse), from the sequelae of an acute cord injury or from a demyelinating process such as multiple sclerosis. Atrophy of the spinal cord is a common finding in these scenarios.

Answer 83

107. C. Epidermoid cyst Epidermoid cysts are also known as keratocysts. They are non tender and usually palpable. The US appearance varies with the maturation, compactness and quantity of keratin present within the epidermoid cyst. A target appearance, a solid mass with an echogenic rim and a characteristic “onion ring” configuration with alternating layers of hyper and hypoechogenicity have been described. These cysts do not show blood flow at Doppler US examination. The constellation of an onion ring configuration, negative tumour marker status and avascularity help differentiate testicular epidermoids from other germ cell tumours. The US findings of intratesticular varicocele are similar to those of extratesticular varicocele and include multiple anechoic, serpiginous and tubular structures of varying sizes. Colour flow and duplex Doppler US show a venous flow pattern with a characteristic venous spectral waveform, which increases with the Valsalva manoeuvre. An intratesticular spermatocele is a cystic intraparenchymal lesion that is attached to the mediastinum in the area of the rete testis.

Answer 84

108. D. Boerhaave syndrome Non-accidental abdominal trauma is the second leading cause of death from child abuse after head trauma. Presentation is usually delayed with abdominal pain, vomiting, peritonism and signs of obstruction. Non accidental visceral trauma is more common in the age group presented here than is incidental blunt abdominal injury and should always be considered as a differential diagnosis, especially if there are other associated features of NAI. Visceral perforation/ laceration, intramural haematoma and shocked bowel syndrome are all within the spectrum of NAI. Boerhaave syndrome is a complete transmural oesophageal rupture caused by forceful vomiting or impacted food bolus and more commonly affects adults.

Answer 85

109. A. Endotracheal tube with the tip 2 cm above the carina Close evaluation of any tubes and lines should always be performed to avoid any unnecessary complications and embarrassment. The endotracheal tube should be at least 5 cm above the carina to allow movement of the patient’s body so that it never lies within the right or left main bronchus. If it does, it can cause collapse of the non-intubated lung. Central venous catheters, including peripherally inserted catheters, should have their tip within the superior vena cava or right atrium. Intra-aortic counter pulsation balloon pumps should lie within the descending thoracic aorta with the upper aspect distal to the arch vessels to avoid obstruction of blood flow.

Answer 86

110. C. Meckel's diverticulum The findings on this technetium pertechnetate scan are typical of a Meckel’s diverticulum containing ectopic gastric mucosa. The uptake in the left upper quadrant should not mislead the radiologist as it is the result of normal tracer uptake in the stomach mucosa. Secretions from ectopic gastric tissue in a Meckel's diverticulum can cause ulceration of the diverticulum or adjacent small bowel and can lead to bleeding, which, if profuse, can simulate an upper gastrointestinal bleed. Meckel’s diverticulum may simulate acute appendicitis on clinical examination; however, a pertechnetate scan is only performed if a Meckel’s diverticulum is suspected clinically.

Answer 87

111. A. Canavan disease characteristically demonstrates reduced NAA. MR spectroscopy (MRS) allows tissue to be interrogated for the presence and concentration of various metabolites. MRS can help increase our ability to grade gliomas. As the grade increases, NAA and creatine decrease and choline, lipids and lactate increase. In recurrent tumour, choline will be elevated, whereas in radiation change, NAA, choline and creatine will all be low. With regard to ischaemic and infraction, lactate wall increase as the brain switches to anaerobic metabolism. When infarction takes place, lipids are released and peaks appear. With regard to HIV, choline is low or absent in toxoplasmosis, whereas it is elevated in lymphoma, helping to distinguish the two. PML may demonstrate elevated myoinositol. Canavan disease characteristically demonstrates elevated NAA.

Answer 88

112. B. Calcaneus, patella and olecranon The description is characteristic of diffuse idiopathic skeletal hyperostosis, or commonly known as DISH. The predominant finding is the calcification/ossification of the ligament and tendon entheses, most often in the spine. Within the thoracic spine, the ossification tends to occur on the right anterolateral aspect with postulated theories that the pulsations from the adjacent left sided thoracic aorta inhibits the hypertrophic ossification. The most common diagnostic criteria employed is the involvement of at least four contiguous vertebrae (flowing ossification from calcification of the anterior longitudinal ligament) and the absence of sacroiliac inflammatory change and apophyseal joint degeneration. Recent changes have proposed reducing the contiguous vertebral segment involvement to 3 rather than 4. Extraspinal manifestations are again of calcification of the entheses and hypertrophic bone changes, with the most common sites involving the olecranon, patella and calcaneum

Answer 89

113. D. Granulomatous prostatitis Granulomatous prostatitis is an inflammatory entity that often presents with a firm nodule on digital rectal examination and elevated prostate-specific antigen, thus clinically mimicking prostate cancer. Possible causes include previous intravesical BCG therapy, TB prostatitis and previous intervention such as TURP, although most cases are idiopathic. On MRI, granulomatous prostatitis may appear as a discrete mass with markedly abnormal T2 signal, DWI and ADC map. Furthermore, there may be associated infiltration of the periprostatic fat by inflammation, thus mimicking extraprostatic tumour extension. Currently, histopathologic analysis is regarded as the only means of definitively establishing the diagnosis and thereby excluding the presence of tumour; however, a suggestive history, such as prior BCG therapy, may be useful in prompting consideration of the diagnosis. In addition, the presence on MRI of large areas of non- enhancement, indicative of necrosis within the lesion corresponding with caseous abscess on pathologic evaluation, may suggest the diagnosis. A short-term follow up MRI may he obtained after antimicrobial treatment to assess for therapeutic response.

Answer 90

114. E. Shocked bowel syndrome Isolated, localised small bowel wall thickening is non-specific but highly suggestive of underlying bowel wall or mesenteric injury in the trauma patient. In all of the above conditions, apart from shocked bowel syndrome, this finding may be present. Diffuse bowel wall thickening is atypical for bowel wall injury. Following trauma, in the presence of increased bowel wall enhancement, a flattened inferior vena cava, hyperenhancement of adrenal glands and pancreatic and/or retroperitoneal oedema, a shocked bowel syndrome (hypoperfusion complex) is the most likely explanation. This must not be omitted in the differential diagnosis as treatment of hypoperfusion complex is conservative and there is no need for diagnostic laparotomy

Answer 91

115. E,. They classically are intra-articular in location. Gout is the clinical condition of symptomatic arthritis due to the deposition of monosodium urate crystals within or around the joints due to excess serum urate levels. There is often accompanying renal disease with formation of uric acid urinary' calculi. Tophaceous gout presents with an eccentric, asymmetric soft tissue mass(es) around the joint(s) and it is this that gives rise to the typical juxta articular erosions. Intra-articular erosions can also occur, though this is less common. Large overhanging edges of bone often develop, separating the tophi from the erosions.

Answer 92

116. C. The patient should take a course of treatment dose trimethoprim, starting on the day of the procedure for 3 subsequent days. Ensure that the baby undergoing MCUG receives 4 mg/kg of trimethoprim on the day of the MCUG and for three subsequent days to prevent complication of infection. If a child is on prophylactic 2 mg/kg does of trimethoprim, full dose is required as described above to cover the MCUG.

Answer 93

117. D. Choroid plexus papilloma Poorly circumscribed and poorly enhancing tumours Predominant imaging patterns of astrocytoma are mass with a enhancing or non-enhancing cyst and an intensely enhancing mural nodule, necrotic mass with a central non-enhancing zone or predominantly solid mass. They are associated with NFL Craniopharyngiomas are relatively benign neoplasms arising in the sellar/suprasellar region, often presenting with endocrine abnormalities. Paediatric craniopharyngiomas typically appear multicystic the solid portions enhancing heterogeneously with characteristic calcifications in paediatric craniopharyngiomas may not be discernible without SWI. Occasionally, they are predominantly solid, typically without calcification. PNETs arise from primitive (undifferentiated) brain cells. They are typically heterogeneous and are usually iso- to hyperdense on CT, with calcifications in 70%. On MRI, they may appear iso- to hyperintense to grey matter on FLAIR and T2-weighted images. The solid component usually has avid heterogeneous enhancement with minimal oedema. Necrosis and haemorrhage are common and are seen as restriction on DWI. On MR images, choroid plexus papillomas appear as isointense to hypointense intraventricular masses compared with normal brain parenchyma. Flow voids, consistent with flowing blood, are common. CT show intense enhancement. Hydrocephalus is very common. Gangliogliomas develop in the temporal lobe and are commonly associated with refractory seizures, partial complex type. Calcification is seen in 30%. Peripherally located gangliogliomas may cause scalloped pressure erosion of the calvaria. At MRI, a well-defined cystic mass with a solid mural nodule is typically seen; however, a solid mass with non specific low to intermediate signal intensity on T1-weighted images and high signal on T2-weighted images is also not uncommon. Enhancement is variable, ranging from non-enhancing to ring like to intense homogeneity. There is usually little associated mass effect or oedema.

Answer 94

118. C. Tracheal shift to the right Tracheal shift to the contralateral side from the pneumonectomy is an abnormal finding and along with depression of the ipsilateral hemidiaphragm may represent a bronchopleural fistula, empyema or haemorrhage. The other findings can be normally seen postoperatively following pneumonectomy. They can start to develop within 24 hours following surgery with partial and then complete filling of the thorax. The other signs such as ipsilateral mediastinal shift and elevation of the hemidiaphragm are caused by volume loss. When presented with a chest X-ray with complete white-out and ipsilateral mediastinal shift, the key to identifying pneumonectomy versus complete collapse is the presence of a posterior surgical rib defect.

Answer 95

119. B. Papillary tumour with pure intraluminal growth Squamous cell carcinoma accounts for <5% of bladder neoplasms; however, in parts of the world where schistosomiasis (bilharziasis) is endemic, it is a major health problem, accounting for over 50% of bladder cancers. Risk factors in non-bilharzial regions include chronic irritation from indwelling catheters, bladder calculi or chronic infection. All of these risk factors may be present in paraplegic patients, putting them at increased risk. Cyclophosphamide, smoking and intravesical BCG has also been implicated in the pathogenesis of squamous carcinoma of the bladder. The imaging findings in squamous carcinoma are non-specific. Tumours may appear as a single enhancing bladder mass or as diffuse or focal wall thickening. Intradiverticular squamous tumours are soft-tissue masses, sometimes with surface calcification. In contrast to urothelial carcinoma, squamous carcinoma is sessile rather than papillary, and pure intraluminal growth is not seen. Bladder wall thickening and calcification, from chronic inflammation or infection with Bilharzia, may coexist and complicate the diagnosis.

Answer 96

120. B. Mesenteric fat infiltration Significant mesenteric injury requires urgent vascular surgical treatment and, if missed, can lead to life-threatening bowel ischaemia. The most specific CT feature of significant mesenteric injury is mesenteric contrast extravasation, which is almost 100% sensitive. Other highly specific features are vascular beading (irregularity of mesenteric vessels) and termination of mesenteric vessels, which, when seen, are an indication for vascular surgery. Lack of bowel wall enhancement is highly suggestive of segmental bowel ischaemia secondary to significant vascular injury. Mesenteric fat infiltration is a common but very non-specific feature of abdominal trauma. It may be present in bowel wall laceration, contusion or incomplete bowel wall tear as well as in significant bowel and mesenteric injuries

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