EXAM 1 Flashcards

Question

# **GIT** A middle-aged woman presents with cough and hemoptysis. Her chest X-ray reveals a large ovoid mass in the right lower lobe. She has a known history of Osler–Weber–Rendu syndrome. What is the most appropriate next imaging investigation that you will organize? A. MRA of the pulmonary artery B. CTPA C. CTPA with portal phase images covering the liver D. Chest HRCT E. Conventional pulmonary angiography

Answer 1

**C. CTPA with portal phase images covering the liver** Hereditary hemorrhagic telangiectasia, also called Osler–Weber–Rendu syndrome, is an uncommon genetic disorder characterized by arteriovenous malformations in the skin, mucous membranes and visceral organs. The brain, gastrointestinal tract, skin, lung and nose are the primary sites affected. It is associated with the classic triad of epistaxis, telangiectasias and a family history. Pulmonary AVMs are often discovered initially as a solitary pulmonary nodule or mass on plain chest films. If a pulmonary AVM is suspected, further imaging evaluation should be CT or conventional pulmonary angiography. Although conventional angiography is the gold standard, considering its invasive nature CT is considered a better method of diagnosis. This is more important when screening for AVM. Portal venous-phase liver images are often obtained at the same time, in case the lesion does turnout to be a solid nodule.

Answer 2

**B. Duodenal diverticulum** Duodenal diverticulosis is a common entity first described by Chomel in 1710. Its prevalence varies depending on the mode of diagnosis. Diverticula are found in 6% of upper gastrointestinal series, 9%-23% of ERCP procedures and 22% of autopsies. Its occurrence has no sex predilection, and the age range for detection varies from 26 to 69 years. Duodenal diverticula may be congenital or acquired, with the latter being more common. Congenital or true diverticula are rare, contain all layers of the duodenal wall, and may be subdivided into intraluminal and extraluminal forms. The CT appearance of a duodenal diverticulum includes a saccular outpouching, which may resemble a mass-like structure interposed between the duodenum and the pancreas that contains air, an air-fluid level, fluid, contrast material, or debris. A periampullary diverticulum may simulate a pseudocyst or tumour.

Answer 3

**C. Gartner’s duct cyst Posterolateral aspect of the upper vagina** Multiple paraurethral Skene’s glands are related to the female urethra. There are paraurethral ducts that drain into the distal urethral lumen. Nabothian cysts are retention cysts in the cervix related to chronic cervicitis. Gartner’s duct cysts are found at the anterolateral aspect of the proximal third of the vaginal wall. Bartholin’s gland cysts affect the posterolateral aspect of the lower vaginal wall. Urethral diverticulum occurs at the posterolateral aspect of the mid-urethra.

Answer 4

**C. Ankylosing spondylitis (AS)** AS is characterised by the hallmark of bilateral and symmetrical sacroiliac joint involvement, though there may be unilateral involvement in the early stages of disease. Other common findings include periostitis with whiskering of the pelvic bones and the typical ‘bamboo’ spine appearance from syndesmophyte formation. Up to 10% of AS cases are associated with inflammatory bowel disease, and iritis is common in up to 40% of patients. Ninety-six percent of patients are HLA-B 27 positive, the antigen associated with the other seronegative spondyloarthropathies of psoriasis, Reiter’s syndrome and inflammatory bowel disease-associated spondyloarthritis. Behcet’s syndrome affects the chest and gastrointestinal tracts and doesn’t involve the skeleton primarily.

Answer 5

**C. The pattern of brain atrophy can mimic Alzheimer’s disease** The T1 lesion load including enhancing lesions or black holes is correlated more closely than T2 lesion load with clinical outcome. Another imaging hallmark of MS is brain atrophy. Brain atrophy in MS usually appears as enlarged ventricles and reduced size of the corpus callosum. The rate of brain atrophy is higher in MS than in the normal ageing process. Significant loss of white matter rather than grey matter is seen in the early stage of MS, suggesting a different mechanism of atrophy compared to neurodegenerative diseases such as Alzheimer’s disease. MS lesions show reduced Magnetization transfer ratio (MTR), reflecting decreased myelin content. MTR is also reduced in normal-looking white matter, representing occult tissue damage. MS lesions usually have a more reduced MTR as compared with ischemic lesions in small vessel diseases. Such occult tissue damage is also detected by diffusion tensor imaging, showing reduced fractional anisotropy (representing microstructural damage).

Answer 6

**B. Kawasaki arteritis** Kawasaki disease is a systemic vasculitis that is more severe in small and medium arteries, and veins to a lesser extent, with inflammatory' lesions in virtually all organs. It is a leading cause of acquired heart disease in childhood. The aetiology of KD remains unknown, although the clinical presentation - self-limiting illness manifested by an abrupt onset of fever, rash, exanthema, conjunctival injection and cervical adenopathy - and the epidemiological features - a seasonal peak in winter and spring, age distribution and a geographic wave-like spread of illness during epidemics - strongly suggest an infectious cause. Fever is usually the first sign of KD. Rash is non-specific and mostly maculopapular. Cervical lymphadenopathy is the last common of the main manifestations. Cardiovascular complications include coronary artery aneurysms, myocarditis, pericarditis with pericardial effusion, systemic arterial aneurysms, valvular disease, mild aortic root dilatation and myocardial infarct. Takayasu arteritis (TA), also known as pulseless disease, is a granulomatous large vessel vasculitis that predominantly affects the aorta and its major branches, with increased prevalence in Asian women <50 years of age. Churg Strauss syndrome is a small-to-medium vessel necrotizing pulmonary vasculitis, affecting patients in the third and fourth decades with asthma, eosinophilia and systemic symptoms like purpura and arthralgia. Moyamoya disease is an idiopathic, non-inflammatory, non-atherosclerotic, progressive vasculo- occlusive disease involving the circle of Willis, typically the supra-clinoid internal carotid arteries. It has a bimodal age distribution, affecting children and adults. In children, ischaemic strokes are most pronounced, whereas in adults haemorrhage from the abnormal vessels is more common.

Answer 7

**C. Systolic dysfunction** In cardiac amyloidosis, the amyloid protein is deposited in the myocardium, which leads to diastolic dysfunction that progresses to restrictive cardiomyopathy. Because amyloidosis is a systemic process, involvement of all four chambers is common; thus, an increase in the thickness of the interatrial septum and right atrial free wall by more than 6 mm has been shown to be a specific finding for cardiac amyloidosis. Through the use of dynamic enhanced cardiac MRI, a distinct pattern of late enhancement, which was distributed over the entire subendocardial circumference, has been shown to have high specificity and sensitivity for cardiac amyloidosis Echocardiogram shows concentric LV hypertrophy, with hyperechoic granular sparkling of the ventricular wall.

Answer 8

**C. Main duct IPMN (Intraductal Papillary Mucinous Neoplasm)** IPMNs are a group of neoplasms in the biliary duct or pancreatic duct that causes cystic dilatation from excessive mucin production and accumulation. The true incidence of IPMNs is unknown because many are small and asymptomatic. However, in a series of 2,832 consecutive CT scans of adults with no history of pancreatic lesions, 73 cases of pancreatic cysts (2.6%) were identified. Many of these cases likely were IPMNs, given that IPMNs account for 20%-50% of cystic pancreatic neoplasms. There are three main types of pancreatic IPMNs: main duct, branch duct and combined. A main duct IPMN commonly causes dilatation of the papilla, with bulging of the papilla into the duodenal lumen. Filling defects caused by mural nodules or mucin may be seen at MRCP or ERCP. At CT and MRI, filling defects caused by mural nodules enhance, while filling defects caused by mucin do not enhance.

Answer 9

**E. Cystic transformation of rete testis** Cystic transformation of rete testis is a benign condition, also known as tubular ectasia, resulting from partial or complete obliteration of the efferent ductules that causes ectasia and, eventually, cystic transformation. The location of the lesion in or adjacent to the mediastinum testis and the presence of epididymal cysts are characteristic. Cystic dysplasia of the rete testis is a rare benign testicular tumour that is found mainly in the paediatric population. Abscesses are usually secondary to epididymo-orchitis; however, they appear cystic with shaggy, irregular walls; intratesticular location; low-level internal echoes; and occasionally hypervascular margins. Teratomas are the most frequent to manifest as cystic masses; however, cystic tumours are rare and, when present, usually have an abnormal rind of parenchyma with increased echogenicity surrounding the cystic lesion.

Answer 10

**D. Spontaneous osteonecrosis of the knee** Spontaneous osteonecrosis of the knee (SONK) is a rapid and painful condition in elderly patients that ultimately results in subchondral collapse of the weight-bearing portion of the medial femoral condyle. It is often idiopathic but can be associated with minor trauma. It is now also increasingly recognized as a subchondral insufficiency fracture resulting in rapid secondary' subchondral collapse. Perthes disease is a childhood disease with avascular necrosis of the femoral head. Sinding-Larsen disease is essentially tendinosis of the proximal origin of the patella tendon. Blount’s disease is a growth disorder of the tibia resulting in a ‘bow leg’ deformity from disturbance to the medial proximal tibial epiphysis. An osteochondral defect is a traumatic injury involving the articular cartilage and adjacent subchondral bone.

Answer 11

**C. Pyloric canal length of 14 mm** Ultrasound is the modality of choice because of its advantages of directly visualising the pyloric muscle and no ionising radiation. The hypertrophied muscle is hypoechoic, and the central mucosa is hyperechoic. Normal measurements of the pylorus are as follows: Pyloric muscle thickness (i.e., the diameter of a single muscular wall on a transverse image): <3 mm (most accurate) Length (i.e., longitudinal measurement): <15-17 mm Pyloric volume: <1.5 cc Pyloric transverse diameter: <13 mm Abnormal features on US includes target sign (hypoechoic ring of hypertrophied pyloric muscle around echogenic mucosa centrally on cross section), cervix sign (indentation of muscle mass on fluid-filled antrum on longitudinal section) and antral nipple sign (redundant pyloric channel mucosa protruding into gastric antrum). Other features include increased antral peristalsis and delayed gastric emptying. Infantile pyloric spasm also shows increased peristalsis and delayed gastric emptying with pyloric muscle thickness between 1.5 and 3 mm.

Answer 12

**A. Cervical segment** MS can show multiple lesions in the spinal cord. Typical spinal cord lesions in MS are relatively small and peripherally located. They are most often found in the cervical cord and are usually less than two vertebral segments in length.

Answer 13

**C. Urachal adenocarcinoma** Urachal adenocarcinoma is characteristically located at the dome of the bladder in the midline or slightly off midline. Ninety percent of masses occur close to the bladder, with the remainder along the course of the urachus or at the umbilical end. A midline, infra-umbilical, soft-tissue mass with calcification is characteristic and is considered to be urachal adenocarcinoma until proved otherwise. Eighty percent of urachal cancers are adenocarcinoma. At CT, the tumour is mixed solid and cystic in 84% of cases and solid in the remainder. CT is the most sensitive modality for calcification, which is present in 72% of cases and is more commonly peripheral than stippled. On T2-weighted MRI, focal areas of high signal intensity from mucin are highly suggestive of urachal adenocarcinoma. The solid portions of the tumour are isointense to soft tissue on T1-weighted images and enhance with intravenous contrast material.

Answer 14

**C. MRI shows good sensitivity for the differential diagnosis of focal chronic pancreatitis from pancreatic carcinoma.** The diagnosis of chronic pancreatitis on MRI is based on signal intensity and enhancement changes as well as on morphologic abnormalities in the pancreatic parenchyma, pancreatic duct and biliary tract. The imaging features of chronic pancreatitis can be divided into early and late findings. Early findings include low-signal-intensity pancreas on T1 -weighted fat-suppressed images, decreased and delayed enhancement after IV contrast administration, and dilated side branches. Late findings include parenchymal atrophy or enlargement, pseudocysts, and dilatation and beading of the pancreatic duct often with intraductal calcifications. Differentiating between an inflammatory mass due to chronic pancreatitis and pancreatic carcinoma on the basis of imaging criteria remains difficult. Decreased Tl signal intensity with delayed enhancement after gadolinium administration as well as dilatation and obstruction of the pancreaticobiliary ducts can be seen in both diseases. Irregularity of the pancreatic duct, intraductal or parenchymal calcifications, diffuse pancreatic involvement, and normal or smoothly stenotic pancreatic duct penetrating through the mass (‘duct penetrating sign’) favour the diagnosis of chronic pancreatitis over cancer. In distinction, a smoothly dilated pancreatic duct with an abrupt interruption, dilatation of both biliary' and pancreatic ducts (‘double-duct sign’) and obliteration of the perivascular fat planes favour the diagnosis of cancer.

Answer 15

**C. Infundibular stenosis** Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease. This disease accounts for approximately 10% of all congenital heart defects, affecting men and women equally. In addition, TOF is the most common cyanotic heart disease that survives to adulthood. The four components of TOF, first described in 1888 by French physician Etienne-Louis Arthur Fallot, are interventricular communication (ventricular septal defect), right-ventricular outflow tract (RVOT) obstruction, concentric right-ventricular hypertrophy (RVH) and deviation of the origin of the aorta to the right. Combined infundibular and pulmonary valvular stenosis is the second most common cause.

Answer 16

**C. Most lesions are centrally located.** Occurrence of spinal cord abnormalities is largely independent of brain lesions in MS. Both focal and disuse lesions affecting the cord arc described, though multiple focal lesion (median 3) is the most common finding. Patients with focally involved spinal cords mostly show multiple small lesions. Focal lesions have an elongated configuration along the axis of the spinal cord and affect the peripheral part of the cord. Cervical cord is the most commonly affected segment and the lesions usually extend over fewer than two vertebral segments in length.

Answer 17

**E. Giant bone islands can be locally aggressive** Bone islands arc benign entities and represent compact bone within the medullary space. They do not exhibit aggressive features regardless of size. Classically they are sharply defined with thorny radiations (brush border). Then can occasionally show increase or decrease in size (about a third of them) (cf. osteoblastic metastasis, which shows aggressive features, cortical break/destruction, periosteal reaction or soft-tissue component; osteoid osteoma is associated with typical pain and a nidus).

Answer 18

**C. Hirschsprung's disease** Hirschsprung's disease, also called aganglionosis of the colon (absence of parasympathetic ganglia in muscle and submucosal layers secondary to an arrest of craniocaudal migration of neuroblasts), results in relaxation failure of the aganglionic segment. It affects full-term infants during the first weeks of life, mainly boys. It is extremely rare in premature infants. It usually affects the rectosigmoid junction and results in short-segment disease (80%). Long-segment disease (20%) and total colonic aganglionosis (5%) are less common. Barium enema shows a ‘transition zone’ (aganglionic segment), which appears normal in size with dilatation of large and small bowel proximally with marked retention of barium on delayed films after 24 hours. Normal children show a rectosigmoid ratio of >1, as the rectum is larger in diameter than the sigmoid; in the case of Hirschsprung's disease, the ratio is reversed (rectosigmoid ratio <1).

Answer 19

**A. Transposition of great vessels (TGA)** A number of associated features can occur in patients with Tetralogy of Falot (TOF). Right sided aortic arch is the most common variant, known as Corvisart syndrome. Coronary artery anomalies, such as the left anterior descending artery arising from the right coronary artery (whose course may run directly across the right ventricular outflow tract) can occur. Other associations include patent ductus arteriosus, multiple ventricular septal defects and complete atrioventricular septal defect. Approximately 15% of patients have extracardiac anomalies, including chromosomal abnormalities such as Down’s syndrome, DiGeorge syndrome and Alagille syndrome.

Answer 20

**D. Gallbladder adenomyomatosis** Adenomyomatosis is a benign hyperplastic cholecystosis. Tt is a relatively common condition, identified in at least 5% of cholecystectomy specimens. There is no definite racial or sex predilection. Most diagnoses are made in patients in their fifties, but the age range is wide and case reports exist of paediatric adenomyomatosis. Adenomyomatosis is most often an incidental finding, has no intrinsic malignant potential, and usually requires no specific treatment. It frequently coexists with cholelithiasis, but no causative relationship has been proved. Adenomyomatosis occasionally produces abdominal pain, and in some cases cholecystectomy may be indicated for relief of symptoms. Cholesterol accumulation in adenomyomatosis is intraluminal, as cholesterol crystals precipitate in the bile trapped in Rokitansky-Aschoff sinuses, intramural diverticula lined by mucosal epithelium. Gallbladder wall thickening and intramural diverticula containing bile with cholesterol crystals, sludge, or calculi are the radiologic correlates of the distinctive multimodality imaging features of adenomyomatosis. US is a primary modality for biliary imaging, and adenomyomatosis of the gallbladder is frequently identified at sonography. The non-specific finding of gallbladder wall thickening is well demonstrated with US, as are sludge and calculi, when present. Echogenic intramural foci from which emanate V-shaped comet tail reverberation artefacts are highly specific for adenomyomatosis, representing the unique acoustic signature of cholesterol crystals within the lumina of Rokitansky-Aschoff sinuses.

Answer 21

**D. Bicornuate uterus** While the presence of a divided rather than triangular uterine cavity at Hysterosalpingogram (HSG) may suggest the presence of an Mullerian duct anomaly (MDA), it is not possible to differentiate between subtypes. MRI and US provide greater anatomic detail; both of these imaging methods provide information on the external uterine contour, which is an important diagnostic feature of MDAs. Furthermore, both MRI and US may be used to assess for concomitant renal anomalies; renal anomalies occur at a higher rate among MDA patients. Unicornuate uterus appears as a small, oblong, off-midline structure on US and MRI. Uterus didelphys results from complete failure of Mullerian duct fusion. Each duct develops fully with duplication of the uterine horns, cervix and proximal vagina. A fundal cleft greater than 1 cm has been reported to be 100% sensitive and specific in differentiation of fusion anomalies (didelphys and bicornuate) from reabsorption anomalies (septate and arcuate). Bicornuate uterus involves duplication of the uterus with possible duplication of the cervix (bicornuate unicollis or bicornuate bicollis). HSG demonstrates opacification of two symmetric fusiform uterine cavities (horns) and fallopian tubes. Historically, an intercornual angle of greater than 105° was used for diagnosis of bicornuate uterus. Septate uterus is the most common form of MDA, accounting for approximately 55% of cases. Historically, an angle of less than 75° between the uterine horns has been reported to be suggestive of a septate rather than bicornuate uterus. However, considerable overlap occurs between septate and bicornuate uteri; as such, the angle measurement is not a reliable diagnostic feature. Arcuate uterus at HSG shows a single uterine cavity with a broad saddle-shaped indentation at the uterine fundus.

Answer 22

**A. Calcium pyrophosphate deposition disease (CPPD)** This is a typical description of CPPD, which can be idiopathic or associated with endocrinological problems such as hyperparathyroidism and hypothyroidism. The joints of the knee, wrist and second/third MCP joints of the hand are most frequently involved. Differentials would also include gout, but the distribution of erosions are different, with gouty erosions tending to be juxta-articular and punched out (‘rat-bitten’) rather than subchondral. Joint space is also typically preserved in gout until the late stages. Psoriasis produces enthesitis and periostitis with new bone formation. Ochronosis, or alkaptonuria, is a metabolic disorder whereby there is abnormal build-up of homogentisic acid in connective tissue with pigmentation of the sclera and urine appearing dark in colour. Diffuse multilevel vertebral disc calcification and early OA changes in multiple joints are associated with this condition.

Answer 23

**B. Cystic components** Metastatic malignant melanoma is a commonly encountered neoplasm in the head. Typical appearance of a lesion is high signal intensity on T1-weighted images and low signal on T2-weighted images (melanotic pattern). The other described pattern is the amelanotic pattern. In this pattern, the lesion is hypointense or isointense to the cortex on T1-weighted images and hyperintense or isointense to the cortex on T2-weighted images. Metastatic melanoma presents as multiple brain metastasis, which are located predominantly in the cortex and at the grey matter- white matter junction. They can also present in miliary form or as subependymal nodules. The lesions often appear hyperdense on unenhanced CT. The lesions show moderate to intense contrast enhancement, although larger lesions can show non-enhancing or hypoenhancing necrotic areas. Prominent perilesional oedema is seen.

Answer 24

**B. CT shows soft-tissue mass displacing the aorta anteriorly** Intravenous urography usually demonstrates the classic triad of medial deviation of the middle third of the ureters, tapering of the lumen of one or both ureters in the lower lumbar spine or upper sacral region, and proximal unilateral or bilateral hydroureteronephrosis with delayed excretion of contrast material. CT and MRI is the mainstay of non-invasive diagnosis of Retroperitoneal fibrosis (RPF). CT allows comprehensive evaluation of the morphology, location and extent of RPF and involvement of adjacent organs and vascular structures. Moreover, abdominal CT allows detection of diseases often associated with idiopathic RPF (e.g., autoimmune pancreatitis) or demonstrating an underlying cause in cases of secondary RPF (e.g., malignancy). CT shows a well-defined mass, usually anterior and lateral to the aorta, sparing the posterior aspect and not causing aortic displacement. Idiopathic RPF typically has low signal intensity on T1 weighted images. The signal intensity on T2 weighted images is variable and reflects the degree of associated active inflammation (hypercellularity and oedema). After administration of contrast material, early soft-tissue enhancement mirrors the degree of inflammatory activity observed at T2-weighted imaging. The sensitivity of 18F-FDG PET is very high, which allows detection and quantification of the metabolic activity of retroperitoneal lesions. Although sensitivity is high, specificity is low and aortic wall in the elderly can show FDG uptake.

Answer 25

**B. Maximum of two attempts can be made.** Intussusception is one of the most common causes of acute abdomen in infancy. Perforation may already have occurred before enema therapy or may occur during the reduction process. There is no agreement on the number and duration of reduction attempts, the efficacy of premedication or sedation, the use of rectal tubes with inflatable retention balloons, or the use of transabdominal manipulation. The classic ‘rule of threes’ is that the number of reduction attempts is capped at three, lasting 3 min each. This rule has been discarded at some institutions, and some authors use a nearly unlimited number of attempts. Use of sedation, rectal tube with balloons and the Valsalva maneuver are said to improve the reduction rate achieved. Absolute contraindications to enema therapy are shock not readily corrected with IV hydration and perforation with peritonitis. Criteria that are linked to a lower reduction rate and a higher perforation rate are age less than 3 months or greater than 5 years, long duration of symptoms, especially if greater than 48 hours, passage of blood via the rectum, significant dehydration, small bowel obstruction and visualization of the dissection sign during enema therapy. Air enema produces excellent results but is also associated with maximum perforation rates.

Answer 26

**E. Aortic stenosis** Chronic histoplasmosis may lead to two well-described complications: fibrosing mediastinitis and broncholithiasis. Fibrosing mediastinitis is a fibrotic immune response to histoplasma antigens. The abnormal fibrosing process encases and narrows vital mediastinal structures, which can lead to superior vena cava syndrome, precapillary pulmonary arterial hypertension from pulmonary arterial stenosis, post-capillary pulmonary arterial hypertension owing to pulmonary vein stenosis, atelectasis from bronchial obstruction, tracheal stenosis, or dysphagia from oesophageal obstruction. The imaging appearance can mimic infiltrating metastatic disease or lymphoma; however, the presence of mediastinal calcifications often provides a clue to the diagnosis. Broncholithiasis results from erosion of a calcified hilar lymph node into an adjacent bronchus. Affected patients present with chronic cough and haemoptysis and even occasionally with lithoptysis. Typical imaging features include endobronchial calcification with atelectasis of the associated pulmonary segment or lobe.

Answer 27

**C. Type C** Different types of oesophageal atresia are identified on the basis of the presence (and location) or absence of a tracheo oesophageal fistula. Type A is pure oesophageal atresia without fistula, and Type B is oesophageal atresia with a fistula between the proximal pouch and the trachea. Type C is oesophageal atresia with a fistula from the trachea or the main bronchus to the distal oesophageal segment. Type D is oesophageal atresia with both proximal and distal fistulas, and Type E is an H-shaped tracheo-oesophageal fistula without atresia. Of these five types, Type C is by far the most common. Oesophageal atresia is generally suspected on the basis of polyhydramnios, inability to swallow saliva or milk, aspiration during early feedings, or failure to successfully pass a catheter into the stomach. Feeding difficulties with choking occur in infants with Type E (fistula without atresia), but the diagnosis may not be made until several years later when the patient presents with a cough while swallowing, recurrent pneumonia and a distended abdomen. In Types A and B, there is a complete absence of gas in the stomach and intestinal tract, whereas in Types C and I) the gastrointestinal tract commonly appears distended with air.

Answer 28

**E. Alport's syndrome** Causes of medullary nephrocalcinosis include hyperparathyroidism, sarcoidosis, myelomatosis, primary or secondary hyperoxaluria (Crohn’s disease), hyperthyroidism, osteoporosis, idiopathic hypercalciuria, renal tubular acidosis, medullary sponge kidney and drug-induced (hypervitaminosis D, milk-alkali syndrome). Alport’s syndrome is an autosomal dominant condition also called chronic hereditary nephritis, associated with ocular abnormalities, deafness, small kidneys, cortical calcification and progressive renal failure without hypertension.

Answer 29

**E. Capillary haemangioma** The classic haemangioma is an asymptomatic lesion that is discovered at routine examination or autopsy. At US, the typical appearance is a homogeneous, hyperechoic mass with well-defined margins and posterior acoustic enhancement. The CT findings consist of a hypoattenuating lesion on non-enhanced images. After intravenous administration of contrast material, arterial-phase CT shows early, peripheral, globular enhancement of the lesion. The attenuation of the peripheral nodules is equal to that of the adjacent aorta. Venous-phase CT shows centripetal enhancement that progresses to uniform filling. This enhancement persists on delayed-phase images. At MRI, haemangiomas are characterised by well-defined margins and high signal intensity on T2-weighted images, which is identical to that of cerebrospinal fluid. Specificity is improved by using serial gadolinium-enhanced gradient-echo imaging. The gadolinium intake is similar to the intake of iodinated contrast material during enhanced CT. With T2-weighted spin-echo and dynamic gadolinium enhanced T1-weighted gradient-echo sequences, the sensitivity and specificity of MRI are 98% and the accuracy is 99%. The imaging features of a haemangioma depend on its size; typical haemangiomas are mostly less than 3 cm in diameter.

Answer 30

**B. Wooden FB is hyperattenuating.** CT is a very sensitive imaging modality that can demonstrate metal fragments less than 1 mm in size. Non-metallic foreign bodies are more problematic; not only the size of the glass fragment but also the type of glass and its location affect detection rates. Wooden foreign bodies usually appear hypoattenuating on CT images. Because of their low attenuation, they can be mistaken for air. If the low-attenuation collection on CT displays a geometric margin, wood or organic FB should be suspected. The attenuation of wood changes

Answer 31

**C. Carpal tunnel syndrome** Imaging of carpal tunnel syndrome is controversial and diagnosis is primarily made on clinical grounds and nerve conduction studies. However, there are some imaging findings that can be associated with the syndrome. These include the pseudo-neuroma’ appearance of the median nerve (swelling of the median nerve just before the carpal tunnel entrance), increased T2 signal changes and increased post-contrast enhancement. It is associated with acromegaly. Neurofibroma of the median nerve can account for the symptoms but would tend to be more distinct as a lesion and sometimes associated with a low-signal central region.

Answer 32

**E. Suspected haemangioma** Contraindications for liver biopsy include the following: 1. Uncooperative patient 2. Extrahepatic biliary duct dilatation (except if benefit outweighs the risk) 3. Bacterial cholangitis (relative contraindication due to risk of septic shock) 4. Abnormal coagulation indices (having a normal INR or PT is not a reassurance that the patient will not bleed; however, there is increased incidence of bleeding with INR above 1.5) 5. Thrombocytopenia (platelet count below 60,000/mm3) 6. Presence of ascites 7. Cystic lesion

Answer 33

**C. Hyperthyroidism** Inflammation of the pericardium (pericarditis) occurs in response to a variety of stimuli. It results in cellular proliferation or the production of fluid (pericardial effusion), either alone or in combination. Causes include myocardial infarction (acute or post-myocardial infarction Dressier syndrome), pericardiotomy, mediastinal irradiation, infection (viral or bacterial), connective-tissue disease (rheumatoid arthritis, SLE), metabolic disorders (uraemia, hypothyroidism rather than hyperthyroidism), pericardial neoplasia, trauma and AIDS. Chest X-ray shows increased cardiac size, ‘flask' or ‘water bottle' configuration, filling of retrosternal space, effacement of cardiac borders and thickening of anterior pericardial stripe. Echocardiography is the investigation of choice for diagnosis.

Answer 34

**B. MRI** A main differential for a symptomatic lesion in the epiphysis of a long bone in an unfused skeleton is a chondroblastoma. MRI will reveal the presence of marked reactive surrounding marrow' oedema. In a fused skeleton, the differentials would include clear cell chondrosarcoma, giant cell tumours and other benign causes like subarticular cyst and intraosseous ganglion. Chondroblastomas are very well defined with sclerotic margin on plain X-ray and low-signal rim on MRI (cf. Langerhans cell histiocytosis, which appears less well defined with variable margins). Often definitive diagnosis requires surgical biopsy.

Answer 35

**D. Mesothelioma** Malignant mesothelioma is the most common primary pericardial malignancy. A causal relationship with asbestosis is uncertain because of low prevalence of this neoplasm. Mesothelioma may present as a well-defined single mass, multiple nodules, or diffuse plaques involving the visceral and parietal pericardium and wrapping around the cardiac chambers and great vessels. Other malignant primary tumours include lymphoma, sarcoma, pheochromocytoma and liposarcoma. Teratomas of the pericardium may also be malignant and arc most commonly seen in children. Pericardial metastases are much more common than primary pericardial tumours. Breast and lung cancers are the most common sources of metastases in the pericardium, followed by lymphomas and melanomas.

Answer 36

**D. Corneal abrasion** Vitreous haemorrhage is common, with varied clinical manifestations and causes. The most common causes include proliferative diabetic retinopathy, vitreous detachment with or without retinal breaks, and trauma. Less common causes include vascular occlusive disease, retinal arterial macroaneurysm, haemoglobinopathies, age-related macular degeneration, intra ocular tumours and others. Terson syndrome is the occurrence of a vitreous haemorrhage of the human eye in association with subarachnoid haemorrhage.

Answer 37

**C. Haemangioma** The classic haemangioma is an asymptomatic lesion that is discovered at routine examination or autopsy. At US, the typical appearance is a homogeneous, hyperechoic mass with well-defined margins and posterior acoustic enhancement. The CT findings consist of a hypoattenuating lesion on non-enhanced images. After intravenous administration of contrast material, arterial-phase CT shows early, peripheral, globular enhancement of the lesion. The attenuation of the peripheral nodules is equal to that of the adjacent aorta. Venous-phase CT shows centripetal enhancement that progresses to uniform filling. This enhancement persists on delayed-phase images. At MRI, haemangioma are characterised by well-defined margins and high signal intensity on T2-weighted images, which is identical to that of cerebrospinal fluid. Specificity is improved by using serial gadolinium-enhanced gradient-echo imaging (6). The gadolinium intake is similar to the intake of iodinated contrast material during enhanced CT. With T2-weighted spin-echo and dynamic gadolinium-enhanced T1-weighted gradient-echo sequences, the sensitivity and specificity of MRI are 98% and the accuracy is 99%. The imaging features of a haemangioma depend on its size; typical haemangiomas are mostly less than 3 cm in diameter.

Answer 38

**D. Vein of Galen aneurysm** Vein of Galen aneurysmal malformations (VGAMs) are rare congenital vascular malformations characterized by shunting of arterial flow into an enlarged cerebral vein dorsal to the tectum. Most of these malformations present in early childhood, often causing congestive heart failure in the neonate. Antenatal ultrasound scans demonstrate the venous sac as a sonolucent mass located posterior to the third ventricle. Ultrasonic demonstration of pulsatile flow within it helps in differentiating VOGMs from other midline cystic lesions. Associated venous anomalies can often be visualized. Evidence of hydrocephalus and cardiac dysfunction can also be obtained on antenatal ultrasonography. Contrast enhanced axial CT scan of the brain usually demonstrates a well-defined, multilobulated, intensely enhancing lesion located within the cistern of velum interpositum. Dilatation of the ventricular system and periventricular white matter hypodensities, as well as diffuse cerebral atrophy, are the commonly associated findings.

Answer 39

**B. High on T2 Intermediate on T2 Low on T2** On T1-weighted images, normal pelvic musculature and viscera demonstrate homogenous low-to-intermediate signal intensity. Zonal architecture is best demonstrated on T2-weighted MRI. T2 signal reflects the water content, which is highest in the endometrium, intermediate in the myometrium and least in the junctional zone.

Answer 40

**E. Hypothyroidism** A common cause of localised posterior vertebral scalloping is increased intraspinal pressure secondary to an expanding mass. Widening of the interpediculate distance and alteration of the configuration of the pedicles are associated signs. Relatively large, slow-growing lesions that originate during a period of active skeletal growth (such as ependymomas) are most likely to give rise to posterior vertebral scalloping. Dural ectasia is thought to cause posterior vertebral scalloping due to loss of the normal protection provided to the vertebral body by a strong, intact dura. Dural ectasia classically occurs in association with inherited connective-tissue disorders such as Marfan syndrome (classical) and Ehlers-Danlos syndrome. Posterior vertebral scalloping is also commonly seen in patients with neurofibromatosis, most likely due to dural ectasia but also secondary to neurofibromas or a thoracic meningocoele. It has also been reported in patients with AS; in these cases, the development of associated arachnoid cysts may give rise to cauda equina syndrome. Acromegaly has been described as a further cause of diffuse posterior vertebral scalloping, probably because of a combination of soft-tissue hypertrophy in the spinal canal and increased bone resorption.

Answer 41

**B. They are most commonly left-sided.** The most common congenital pericardial anomaly is a pericardial cyst. Chest pain is the most common presenting symptom, but most patients with pericardial cysts are asymptomatic. On plain chest radiographs, pericardial cysts present as well-defined, round, homogeneous soft-tissue densities and are most commonly found at the right pericardiophrenic angle. Pericardial cysts are visualised most easily using CT or MRI. With MRI, simple pericardial cysts are characterised by low signal intensity on T1-weighted images or high signal intensity on T2 -weighted images. With CT, pericardial cysts are usually of water density, but when they contain sufficient proteinaceous material the attenuation may be greater than that of water. Occasionally, pericardial cysts may calcify and simulate thymic cysts.

Answer 42

**C. Retinoblastoma** Retinoblastoma, a small round-cell tumour arising from neuroepithelial cells, is the most common childhood intra ocular malignancy. Diagnosis is typically by ophthalmologic examination, prompted by leukocoria or ‘white reflex’. Retinoblastoma appears as an echogenic soft-tissue mass with various degrees of calcification. The vascularity indicates tumour activity; that is, lesions are hypervascular at diagnosis and when active. Vascularity regresses with treatment. CT detects intra-ocular, extra-ocular and intracranial disease extension; excels at delineation of bony abnormalities; and readily depicts tumoural calcifications. On CT, retinoblastoma is characterised by an intermediate-density enhancing soft-tissue mass or masses, with varying degrees of calcification; calcification increases with therapeutic response. The vitreous may be abnormally dense from debris, haemorrhage, or increased globulin content. Retinoblastoma is a heterogeneously enhancing soft-tissue mass with various degrees of calcification on MRI. Lesions are typically hyperintense to vitreous on T1 -weighted sequences and hypointense to vitreous on T2-weighted sequences. The vitreous may be abnormally bright on T1-weighted sequences because of increased globulin content and a decreased ratio of albumin to globulin that occurs with malignancy. The other choices are all differentials for white reflex, but do not show a solid mass with calcification.

Answer 43

**B. Lens dislocation** In blunt traumas, ruptures are most common at the insertions of the intra-ocular muscles where the sclera is thinnest. CT findings suggestive of an open globe injury include a change in globe contour, an obvious loss of volume, the ‘flat tire sign, scleral discontinuity, intra-ocular air and intra-ocular foreign bodies. A deep anterior chamber has been described as a clinical finding in patients with a ruptured globe and can also be a clue on CT.

Answer 44

**A. Severe bleeding episodes, such as those manifesting with haemodynamic instability, decrease the pretest probability of a positive result for active bleeding at CT angiography.** Severe bleeding episodes, such as those manifesting with haemodynamic instability, increase the pretest probability of a positive result for active bleeding at CT angiography.

Answer 45

**D. Tracheo-oesophageal fistula** Horseshoe kidney is the most common fusion anomaly of the kidneys. There is recognised association with cardiovascular, skeletal, CNS, genitourinary anomalies (undescended testes, bicornuate uterus, duplication of ureter, hypospadias, etc.), anorectal malformations, trisomy 18 and Turner syndrome. Vesico ureteric reflux, hydronephrosis secondary' to PUJ obstruction and increased frequency of complications like renal stones and infection are recognised.

Answer 46

**C. Osteopoikilosis** Patients with co-morbidities like diabetes, anaemia and malnutrition can suffer from impaired bone fracture healing. Drug therapy like corticosteroids and NSAlDs can also produce similar problems. Osteogenesis imperfecta is a connective-tissue disorder with resultant abnormal bone density and structure, resulting in poor mineralisation and fragile, brittle bones. Osteopoikilosis is a benign condition and usually found incidentally. It is a form of sclerosing bone dysplasia with multiple enostoses. It is not associated with impaired fracture healing.

Answer 47

**B. Matched CBV (Cerebral blood volume) and CBF (Cerebral blood flow) represent salvageable brain.** An important advance in stroke imaging is the development of CT perfusion imaging. CT angiography source images (CTA-SI) represent cerebral blood volume that is reduced in the core infarct and correlates with infarct volume as seen on DWI (Diffusion Weighted Imaging). CBF (cerebral blood flow), CBV (cerebral blood volume), and MTT (mean transit time) are three parameters that can distinguish infarcted tissue from potentially salvageable penumbra. Ischemic but non infarcted tissue will have decreased CBF, elevated MTT, and normal or high CBV (mismatch). Once infarcted, there will also be a persistent decrease in CBV (matched defect). Sensitivity and specificity of DWI for stroke detection is very high. DWI bright signals do not necessarily represent irreversibly infarcted tissue but reflect redistribution of water from the extracellular to the intracellular space in ischaemic tissue. It is necessary to analyse maps of ADC (apparent diffusion coefficient) to distinguish the effects of reduced water diffusibility (dark on ADC) from T2 ‘shine-through' (bright on ADC). Both features lead to the DWI bright signals seen in ischaemia. The volumetric mismatch between the FWI and DWI volumes is a marker of potentially salvageable tissue at risk. Overall DWI provides the best estimate of infarcted core.

Answer 48

**B. Failure to identify pericardium on CT or MR is diagnostic.** Congenital pericardial defects are uncommon. They range from small defects to complete absence of the pericardium. Both small pericardial defects and complete absence of the pericardium most often are left-sided. They can be recognised on plain chest radiographs because there is abnormal cardiac contour due to protrusion of all or part of the cardiac chamber, for example, the left atrial appendage, through the defect. Shift of the cardiac axis to the left and posteriorly is seen with complete absence or large pericardial defects. With CT or MRI, failure to visualise a portion of the pericardium does not necessarily indicate a pericardial defect, however, because the pericardium over the left atrium and ventricle may not always be visualised in normal subjects. Patients with pericardial defects also may have one or more associated congenital abnormalities, including atrial septal defect, patent ductus arteriosus, mitral valve stenosis, or TOF, which also are detectable on CT or MRI.

Answer 49

**D. Lymphangioma** A cystic hygroma is the most common form of lymphangioma and constitutes about 5% of all benign tumours of infancy and childhood. On US scans, most cystic hygromas manifest as a multilocular predominantly cystic mass with septa of variable thickness. The echogenic portions of the lesion correlate with clusters of small, abnormal lymphatic channels. Fluid-fluid levels can be observed with a characteristic echogenic, haemorrhagic component layering in the dependent portion of the lesion. Prenatal US may demonstrate a cystic hygroma in the posterior neck soft tissues. On CT images, cystic hygromas tend to appear as poorly circumscribed, multiloculated, hypoattenuated masses. They typically have characteristic homogeneous fluid attenuation. Usually, the mass is centred in the posterior triangle or in the submandibular space. A third branchial cleft cyst most commonly appears as a unilocular cystic mass centred in the posterior cervical space on CT and MRI. At US, a second branchial cleft cyst is seen as a sharply marginated, round to ovoid, centrally anechoic mass with a thin peripheral wall that displaces the surrounding soft tissues. The 'classic' location of these cysts is at the anteromedial border of the sternocleidomastoid muscle. The first branchial cleft cyst appears as a cystic mass either within, superficial to, or deep to the parotid gland

Answer 50

**E. SMV to the left of the SMA** SMV positioned to the left of SMA is the most specific sign of malrotation on CT (80%). Other signs on CT include the ‘whirl sign’ around the SMA and large intestine on the left with small intestine on the right. Abnormal position of the caecum and duodenum with duodeno jejunal junction over the right pedicle is the most specific sign of malrotation on barium meal studies.

Answer 51

**E. Dilatation of ventricle** Non-contrast CT is usually the first neuroimaging examination performed in acute stroke assessment. In addition to detecting haemorrhage, modern non-contrast CT can reveal early ischaemic change, such as hypo-attenuation of the parenchyma and grey matter with loss of grey-white differentiation (insular ribbon sign, obscuration of the lentiform nucleus, brain swelling with sulcal effacement) and compression of the ventricular system and basal cisterns, the dense artery (MCA) sign and the MCA dot sign.

Answer 52

**D. Tuberous sclerosis** Tuberous sclerosis (TS) is an autosomal, dominant, inherited neurocutaneous syndrome characterised by a variety of hamartomatous lesions in various organs. Classically, TS demonstrates a triad of clinical features (Vogt triad): mental retardation, epilepsy and adenoma sebaceum. Recently advocated criteria for diagnosis of TS consist of both major and minor diagnostic features. Major features include facial angiofibromas, hypomelanotic macules, cortical tubers and subependymal nodules (frequent); retinal hamartoma, LAM (lymphangioleiomyomatosis), renal AML (angiomyolipoma), and cardiac rhabdomyomas (common); and shagreen patches, ungual fibroma and subependymal giant cell tumours (uncommon). Minor features include dental enamel pits and hamartomatous rectal polyps (frequent); bone cysts, renal cysts, gingival fibromas and cerebral white matter radial migration lines (common); and confetti skin lesions and retinal achromatic patches (uncommon). Definite diagnosis requires two major or one major and two minor criteria.

Answer 53

**C. MR is better at demonstrating pericardial calcification.** Patients with constrictive pericarditis present with symptoms of heart failure. The most frequent causes are cardiac surgery and radiation therapy. Other causes include infection (viral or tuberculous), connective-tissue disease, uraemia, neoplasm, or idiopathic condition. Transthoracic echocardiography is not very accurate in the depiction of pericardial thickening. Transoesophageal imaging allows better visualisation of the pericardium, and Doppler techniques are particularly useful in the diagnosis; however, the transoesophageal approach has a narrow field of view and is invasive. Both CT and MRI demonstrate the pericardium very well. Normal pericardial thickness is less than 2 mm. Pericardial thickness of 4 mm or more indicates thickening and, when accompanied by features of heart failure, is suggestive of constrictive pericarditis. Constrictive pericarditis and restrictive cardiomyopathy are differentiated on the basis of thickened pericardium. Pericardial thickening may be limited to the right side of the heart or an even smaller area, such as the right atrioventricular groove. An additional advantage of CT is its high sensitivity in depicting pericardial calcification. It is important to remember, however, that neither pericardial thickening nor calcification is diagnostic of constrictive pericarditis unless the patient also has symptoms of physiologic constriction or restriction. At both CT and MRI, the right ventricle tends to have a reduced volume and a narrow tubular configuration. In some patients, a sigmoid-shaped ventricular septum or prominent leftward convexity in the septum can be observed. Systemic venous dilatation particularly inferior vena cava (IVC), hepatomegaly and ascites also are frequently seen.

Answer 54

**B. Turner syndrome** Turner syndrome is a female, sex chromosome abnormality from the deletion of one X chromosome (45 XO). It is characterised by a webbed neck and short stature. Skeletal manifestations include short fourth metacarpals and Madelung’s deformity. 5-20% of patients with Turner syndrome have coarctation of the aorta, which would account for the additional finding of rib notching. Pseudohypoparathyroidism and pseudopseudohypoparathyroidism can exhibit a short fourth metacarpal, but they are not associated with coarctation of the aorta. Noonans syndrome is associated with short stature and characteristic facies, along with other congenital cardiopulmonary anomalies, but shortening of the fourth metacarpal is not a feature of this entity. Marfan syndrome is associated with pectus excavatum and aortic root dilatation with the increased risk of aortic dissection.

Answer 55

**B. LUL, RML, RUL** Congenital lobar emphysema represents a condition of progressive over-distension of one or multiple pulmonary lobes secondary to deficiency/immaturity of bronchial cartilage, endobronchial obstruction, or extrinsic compression. It is more common in boys. Preferential involvement is LUL (left upper lobe) > RML (right middle lobe) > RUL (right upper lobe) > two lobes. Initial chest X ray shows opacification of lobe secondary to delayed clearing of pulmonary fluid; this is followed by progressive features of air trapping, hypertranslucent lung and mediastinal shift.

Answer 56

**D. Acute infarcts show hyperintense signal on ADC.** Sensitivity and specificity of DWI for stroke detection is very high. DWI bright signals do not necessarily represent irreversibly infarcted tissue but reflect redistribution of water from the extracellular to the intracellular space in ischaemic tissue. It is necessary to analyse maps of ADC to distinguish the effects of reduced water diffusibility (dark on ADC) from T2 ‘shine-through' (bright on ADC). Both features lead to the DWI bright signals seen in ischaemia. DWI is already positive in the acute phase (as early as 30 minutes) and then becomes brighter with a maximum at 7 days. DWI in brain infarction will be positive for approximately for 3 weeks after onset. ADC is of low signal intensity with a maximum at 24 hours and then increases in signal intensity and finally becomes bright in the chronic stage.

Answer 57

**A. Carcinoid syndrome has higher morbidity and mortality than the tumour itself.** Carcinoid is the most common tumour of the small bowel and appendix. Seven percent of small bowel carcinoids are associated with carcinoid syndrome. There is no association with NF2. Carcinoid tumours most commonly occur in the appendix (30%-45%) and small bowel (25%—35%). Carcinoid syndrome has higher morbidity and mortality than the tumour itself. Common sites of metastasis are liver, lungs, lymph nodes and bone (osteoblastic).

Answer 58

**D. Thoracic outlet syndrome** Thoracic outlet syndrome involves the brachial plexus and the subclavian artery or vein at three anatomic levels where they are vulnerable to entrapment; the interscalene space, the costoclavicular space and the retropectoralis minor space. Thoracic outlet syndrome may result from post- traumatic fibrosis of the scalene muscles, compression secondary to activities like backpacking, and clavicular fractures with callus formation and exercise-related muscle hypertrophy affecting weightlifters, swimmers, tennis players and so on. Other causes include mass lesions such as lipomas, neurogenic tumours, accessory muscles and fibrous bands. MRI can help identify specific muscle denervation patterns. Muscle oedema may occur within 24-48 hours. In contrast, fatty atrophy reflects chronic denervation and manifests several months later. In this setting, MRI has an advantage over electromyography, which does not demonstrate signs of muscle denervation until 2-3 weeks after nerve impairment. Radiographs may reveal a cervical rib or a prominent C7 transverse process. Narrowing has been reported in the costoclavicular and retropectoralis minor spaces during imaging with postural manoeuvres during dynamic MRI. Sagittal T1-weighted MRI sequences are particularly useful in demonstrating the presence of denervation-related fatty atrophy of muscles, effacement of fat planes around the compressed plexus and an abnormal intramuscular course of the components of the brachial plexus. The retropectoralis minor space is not frequently affected by entrapment and is more often involved by mass lesions.

Answer 59

**E. Embryo seen with a mean sac diameter of 10 mm.** The gestational sac is first identifiable on transvaginal ultrasound at 4.5 weeks. It appears as a round 2-3 mm fluid collection. It is located in the central echogenic part of the endometrium (decidua). In some cases, it is surrounded by two echogenic rings corresponding to the two layers of decidua, described as the double decidual sac sign of intrauterine pregnancy. Sometimes the gestational sac is eccentrically located on one side of a thin white line corresponding to the collapsed uterine cavity, called the intradecidual sign. The yolk sac is the first structure visualised on TVS (trans vaginal scan) within the sac at 5.5 weeks. Yolk sac is evident when sac diameter is 10 mm. Heartbeat is evident when crown-rump length (CRL) is 5 mm. On TVS, an embryo is seen when the mean sac diameter is 18 mm. Mean sac diameter increases by approximately 1 mm per day. Lack of foetal pole in a gestational sac with diameter more than 20 mm is suggestive of an anembryonic or nonviable pregnancy.

Answer 60

**C. Omentum** Bochdalek hernia represents the commonest type of congenital diaphragmatic hernia. It is more common on the left. The most common structure to herniate on the left is omental fat; on the right is the liver.

Answer 61

**E. On frontal chest X-ray, it is visualized as a 2-mm stripe outlined by fat.** The pericardium is composed of an outer layer of fibrous tissue and two inner layers of serous tissue. The normal pericardium is not usually seen on plain film chest radiography on the frontal projection, but it may be identified on a lateral projection as an opaque line bordered by mediastinal and subepicardial fat termed the fat pad sign. With high resolution CT, the pericardium may be visualized as a 1- to 2-mm band of soft-tissue attenuation. With T1 -weighted MRI, the pericardium is a dark band bordered by high-intensity fat. The pericardial sac normally contains 15-30 mL of fluid lying between the parietal and visceral layers of the serous pericardium. The fibrous pericardium is anchored to the diaphragm by the pericardiophrenic ligament and the central tendons; the sternopericardial ligaments provide anterior attachment. The outer layer of the pericardium extends to and fuses with the root of the aorta, the right and left pulmonary arteries, the superior vena cava and the pulmonary veins. The visceral pericardium reflects from the heart along the great vessels onto the parietal pericardium. Pericardial extensions, recesses, or sinuses are formed at these reflections.

Answer 62

**C. Sclerosing mesenteritis** Sclerosing mesenteritis is a rare condition of unknown cause that is characterised by chronic mesenteric inflammation. The process usually involves the mesentery of the small bowel, especially at its root, but can occasionally involve the mesocolon. On rare occasions, it may involve the peripancreatic region, omentum, retroperitoneum, or pelvis. Although the cause of sclerosing mesenteritis is unknown, the disorder is often associated with other idiopathic inflammatory disorders such as retroperitoneal fibrosis, sclerosing cholangitis, Riedel thyroiditis and orbital pseudotumour. The CT appearance of sclerosing mesenteritis can vary from subtle increased attenuation in the mesentery to a solid soft-tissue mass. Sclerosing mesenteritis most commonly appears as a soft-tissue mass in the small bowel mesentery, although infiltration of the region of the pancreas or porta hepatis is also possible. The mass may envelop the mesenteric vessels, and over time collateral vessels may develop. There may be preservation of fat around the mesenteric vessels, a phenomenon that is referred to as the fat ring sign. This finding may help distinguish sclerosing mesenteritis from other mesenteric processes such as lymphoma, carcinoid tumour, or carcinomatosis.

Answer 63

**C. HU value of more than 37 on delayed contrast enhanced CT** Features suggestive of adrenal carcinoma on imaging include large size (>5 cm); invasion of other organs like liver, kidney, IVC, or diaphragm; calcification; central heterogeneous area of low density (tumour necrosis); peripheral nodular enhancement on contrast-enhanced images; and delayed washout. A HU of more than 37 on contrast-enhanced CT at 5-15 minutes after contrast injection is diagnostic of a benign adrenal lesion.

Answer 64

**D. Superior labral anterior-posterior tear (SLAP)** The anteroinferior glenoid labrum is typically injured in an anterior shoulder dislocation. All of the aforementioned injuries except for the superior labral anterior-posterior (SLAP) tear involve the anteroinferior labrum. The glenolabral articular disruption (GLAD) lesion is a partial tear of the anteroinferior labrum with an associated glenoid cartilage injury. Perthes lesion is a complete tear of the labrum, which is still attached to the glenoid periosteum. An anterior labroligamentous periosteal sleeve avulsion (ALPSA) injury is similar to the Perthes lesion but with medial displacement of the tom labrum, which is still attached to the glenoid scapula periosteal sleeve.

Answer 65

**A. Pacchionian granulations** Hyperintensity on FLAIR in subarachnoid spaces has been well described in a wide range of pathologic conditions, such as subarachnoid haemorrhage (SAH), infectious or malignant meningitis, leptomeningeal spread of malignant disease, Leptomeningeal melanosis (part of the neurocutaneous melanosis congenital phakomatosis), vascular hyperintensity in the subarachnoid space produced by severe (>90%) vascular stenosis or occlusion of major cerebral vessels with resulting slow flow and fat-containing tumours like lipoma of subarachnoid space. Retrograde slow flow of engorged pial arteries through leptomeningeal anastomoses is also seen as high signal intensity in the subarachnoid space on FLAIR in patients with Moyamoya disease, called ivy sign. Other, less common, causes of subarachnoid FLAIR hyperintensity are artefacts.

Answer 66

**D. Symptomatic First 6 months Adulthood ** **Bronchopulmonary sequestration** *Intralobar* - - - - *Extralobar* Prevalence: 75% - - - - 25% Pleural involvement: Visceral pleura - - - - Own pleura Venous drainage: Pulmonary veins - - - - Systemic veins Associated anomalies: Less common (15%) - - - - More common (50%) Symptomatic: Adulthood - - - - First 6 months Arterial supply: Thoracic aorta - - - -Thoracic aorta Aetiology: Acquired - - - - Developmental

Answer 67

**E. Enhances avidly post-contrast** Lipomatous hypertrophy of the interatrial septum is defined as wedge shaped expansion of the interatrial septum by adipose tissue exceeding 2 cm in transverse diameter. The incidence increases with age and body mass and is also associated with chronic corticosteroid therapy. Patients are usually asymptomatic, but they may have arrhythmias or superior vena cava syndrome when the superior vena cava is encased. Lipomatous hypertrophy of the interatrial septum, in contrast to cardiac lipoma, does not have a capsule. Because lipomatous hypertrophy of the interatrial septum spares the fossa ovalis, it often has a dumbbell-shaped appearance. Lipomatous hypertrophy of the interatrial septum has the same density and signal intensity as fat on CT and MR, respectively. Lipomatous hypertrophy of the interatrial septum is hypointense on fat saturation sequences and does not enhance post-contrast.

Answer 68

**D. To look for a Stener lesion** Skier’s thumb, otherwise known as gamekeeper's thumb, is an injury to the ulnar collateral ligament (UCL) of the first MCP joint. Most of the injuries to the UCL are managed conservatively. However, in complete tears, the UCL may retract and slip to lie superficial to the adductor pollicis aponeurosis or muscle. This prevents healing of the UCL as the adductor pollicis aponeurosis/muscle is now interposed between the torn ends of the UCL, which is known as a Stener lesion. Ultrasound is primarily performed to identify this abnormality, as this requires surgical correction. Andersson lesion refers to the vertebral end plate changes seen in rheumatic spondylodiscitis.

Answer 69

**D.It is never seen beyond 2 weeks.** Cortical laminar and pseudolaminar necrosis cause serpiginous cortical Tl shortening, which is not caused by calcium or haemoglobin products; rather, it presumably results from some other unknown substance or paramagnetic material, possibly lipid-laden macrophages. High cortical signal intensity may be seen on T1-weighted images 3-5 days after stroke, and in many cases it is seen about 2 weeks after stroke. Thereafter, it increases in intensity and fades after about 3 months, but in some cases it may persist for more than a year. In patients with suspected cortical laminar necrosis, susceptibility-weighted imaging may help differentiate it from haemorrhagic transformation.

Answer 70

**E. Skip lesions Yes --- Yes** In patients with proved or suspected Crohn’s disease, cross-sectional images should be analysed specifically for the presence and character of a pathologically altered bowel segment (wall thickness, pattern of attenuation, degree of enhancement, length of involvement), stenosis and prestenotic dilatation, skip lesions, fistulas, abscess, fibrofatty proliferation, increased vascularity of the vasa recta (comb sign), mesenteric adenopathy and other extra intestinal disease involvement.

Answer 71

**C. If serum creatinine is above normal range, metformin should be withheld for 24 hours.** Metformin is not recommended for use in diabetics with renal impairment because it is excreted exclusively via the kidneys. Accumulation of metformin may result in the development of lactic acidosis - a serious complication. There is lack of any valid evidence that lactic acidosis is really an issue after administration of iodinated contrast media in patients taking metformin. The problems caused to patients and clinicians by stopping the drug and its increasing use in poorly controlled diabetic patients regardless of renal function have been considered when formulating this advice. It does, however, remain the case that renal function should be known in patients taking metformin who require intravenous or intra-arterial iodinated contrast medium administration. There is no need to stop metformin after contrast in patients with serum creatinine within the normal reference range and/or eGFR >60 ml/min/1.73 m2. If serum creatinine is above the normal reference range or eGFR is below 60, any decision to stop metformin for 48 hours following contrast medium administration should be made in consultation with the referring clinic.

Answer 72

**A. Feeding central vessel on Doppler imaging.** US features characteristic of benign lesions have been described. These include hyperechogenicity compared to fat, an oval or well-defined, lobulated, gently curving shape and the presence of a thin echogenic pseudocapsule. Doppler examination of benign lesions shows displacement of normal vessels around the edge of the lesion. In contrast, malignant lesions show abnormal vessels that are irregular and centrally penetrating.

Answer 73

**C. It is nearly always associated with failure of neural tube closure.** Chiari II malformation is characterised by a caudally displaced fourth ventricle and brain stem, as well as tonsilar/vermian herniation through the foramen magnum. Spinal anomalies are extremely common: lumbar meningomyelocele (>95%) and syringohydromyelia. Supratentorial abnormalities arc common: dysgenesis of corpus callosum (>80%), obstructive hydrocephalus following closure of meningocoele, absent septum pellucidum, to name a few. CT and MRI show colpocephaly (enlarged occipital horn and atria), ‘batwing' configuration of frontal horns on coronal view (pointing inferiorly secondary to enlarged caudate nucleus), ‘hourglass ventricle', excessive cortical gyration (stenogyria), interdigitation of medial cortical gyri, cerebellar peg sign’, thin elongated fourth ventricle exiting below the foramen magnum, dysplastic tentorium, towering cerebellum, tethered cord and cervico medullary kink among multiple other cranial and spinal anomalies. It is not associated with basilar impression/Cl assimilation/Klippel Feil deformity.

Answer 74

**A. Direct inguinal hernia: The hernial sac lies lateral to the inferior epigastric artery and above the pubic tubercle.** There are several sites on the abdominal wall prone to herniation. The first site is the deep inguinal ring, where an indirect inguinal hernia occurs. Here, herniated structures enter the inguinal canal lateral to the inferior epigastric artery and superior to the inguinal ligament, extending for a variable distance through the inguinal canal. A second site of herniation is at the inferior aspect of the Hesselbach’s triangle, where a direct inguinal hernia usually occurs. This weakened area is just lateral to the conjoint tendon and medial to the inferior epigastric artery, in contrast to the indirect inguinal hernia, which originates lateral to the inferior epigastric artery. A third weakened area is inferior in relation to the inguinal ligament and lateral to the lacunar ligament, where a femoral hernia occurs, typically medial and adjacent to the femoral vessels. The fourth area is at the lateral margin of the rectus abdominis muscle, superior to the inferior epigastric artery as it crosses the linea semilunaris, where a spigelian hernia occurs, indirect inguinal hernias are most common regardless of sex; femoral hernias are more common in women.

Answer 75

**B. Ewings sarcoma** The main differential in such findings would be between infection and a primary bone tumour. Because infection has not been given as an option, the choices would be between osteosarcoma and Ewings sarcoma. Ewing’s sarcoma tends to occur in both the appendicular and axial skeleton equally, whereas osteosarcoma mostly occurs in the appendicular skeleton. Ewings sarcoma usually begins in the diaphysis of the long bones, whereas osteosarcoma tends to occur in the metaphysis. Ewing’s sarcoma may also have a large extra osseous component. The two are often differentials of each other, as each can have a large overlap of imaging findings, but the above traits can help one sway towards the other.

Answer 76

**C. Reduced diastolic flow is specific for acute rejection.** Acute rejection is a cell-mediated reaction seen within 1-4 weeks. Doppler shows decreased diastolic flow, causing a high resistance index (>0.8) and low pulsatility index. However, it is a non-specific finding also seen with acute tubular necrosis, cyclosporine toxicity, acute pyelonephritis, obstruction, renal vein thrombosis and compression by perirenal collections. A high resistive index, more than 0.9, is relatively specific for acute rejection. Some centres use pulsatility index. A PI of more than 1.5 is used for diagnosing rejection. MRI shows increased cortical signal intensity and loss of corticomedullary differentiation on T1-weighted scans. Acute tubular necrosis is common m the early post-operative period and results in reduced function, which gradually recovers over the next few weeks to months. There is no graft tenderness or fever, unlike acute rejection. The scintigraphic findings are abnormal immediately after surgery. The perfusion phase is relatively maintained well; later phases show' slow washout and persistent isotope accumulation. In contrast, if the isotope study is normal in the early post-operative phase and becomes abnormal subsequently, acute rejection can be diagnosed confidently. Thrombosis of the renal vein is rare and typically occurs in the early post-operative phase. The transplant appears swollen and hypoechoic on US. Doppler US shows the absence of flow in the veins and sharp systolic waves, with reversed diastolic flow. Resistivity' index is markedly elevated. Cyclosporine is nephrotoxic and causes a dose-dependent reduction of renal function. The imaging findings are non-specific. The perfusion phase of the 99m Tc-DTPA study is normal, but there is prolonged clearance of 99mTc MAG3. Normal perfusion and delayed excretion are also seen in obstruction.

Answer 77

**A. It is an unstable injury.** Unilateral facet joint dislocation occurs from a flexion/distraction injury with a rotatory component. It is a stable form of facet joint dislocation (cf. with highly unstable bilateral facet joint dislocation). The naked facet sign is seen involving one facet joint on CT, and on plain radiograph there is often an overlapping appearance to the facet joints. Mild anterolisthesis and widening of the interspinous space at the level of injury is a common finding. Up to 30% of patients have a neurological deficit.

Answer 78

**A. Microbleeds have a worse prognosis than haematoma.** Haemorrhagic transformation demonstrates a spectrum of findings ranging from small microbleeds to large parenchymal haematoma. Several studies have reported that microbleeds are present in one-half to the majority of patients with ischaemic stroke and are seen around 48 hours after onset of symptoms. Studies have shown that these areas of microbleeding are not associated with a worse outcome, and guidelines state that the presence of fewer than five areas of microbleeding on initial MRIs does not contraindicate thrombolysis. Parenchymal haematoma is a rarer type of haemorrhagic transformation that results from vessel wall rupture caused by high reperfusion pressure. It is more common with cardio-embolic events, is associated with hyperglycaemia, most commonly occurs in the basal ganglia, and confers a much worse prognosis. Haemorrhagic transformation is rare in the first 12 hours after stroke onset (the hyperacute stage), particularly within the first 6 hours. When it occurs, it is usually within the first 24-48 hours and, in almost all cases, is present 4-5 days after stroke. Studies have reported that the presence of early parenchymal enhancement within 6 hours of stroke is associated with a higher risk for clinically significant haemorrhagic transformation.

Answer 79

**C. SWI is based on homogeneity of magnetic field.** Gradient-echo and susceptibility-weighted sequences are the most sensitive sequences for depicting haemorrhagic transformation in patients with ischaemic stroke, particularly susceptibility-weighted imaging. Susceptibility-weighted MRI utilises magnetic artefacts generated by in-homogeneities of the magnetic field. Deoxyhaemoglobin produces a non-uniform magnetic field, which accounts for signal changes seen in acute haemorrhages and for the blood oxygen level dependent effect. With SWI, intraparenchymal haemorrhages can be seen within the first hour of bleeding, with high sensitivity and accuracy. SWI enables the visualisation of multiple cerebral microbleeds, which have been shown to be a risk factor for intracranial haemorrhage after stroke, both with and without thrombolytic therapy.

Answer 80

**A. Pulmonary' interstitial emphysema** MRFs excellent tissue contrast resolution allows easy differentiation between organs, allowing prenatal diagnosis of congenital diaphragmatic hernia. MRI is also useful in the evaluation of foetal lung maturation through volume and signal intensity. Congenital cystic adenomatoid malformation (CCAM) is the most commonly diagnosed lung malformation. In CCAM, abnormal branching of the immature bronchioles and lack of normal alveolar development results in a solid/cystic intrapulmonary mass. Most pulmonary sequestrations detected prenatally are extralobar, with an anomalous vein that drains into the systemic circulation. On T2-weighted images, they are seen as well-defined hyperintense masses with or without hypointense septa. Intralobar sequestration may be difficult to differentiate from CCAM. MRI is also useful for evaluating other pulmonary and thoracic anomalies. Bronchogenic cysts are identified as hyperintense lesions on T2-wcightcd sequences; they are usually single lesions, located in the lung or mediastinum. Oesophageal duplication cysts are also identified as hyperintense mediastinal lesions. Congenital lobar emphysema can be difficult to distinguish from intralobar sequestration and from CCAM. Pulmonary interstitial emphysema refers to the abnormal location of air within the pulmonary interstitium, resulting from rupture of over-distended alveoli following barotrauma in infants who have surfactant deficiency lung disease.

Answer 81

**D. Infective endocarditis** Extracardiac Complications of Infective Endocarditis: * *Central nervous:* Embolic stroke, intracranial haemorrhage, intracranial mycotic aneurysm, system brain abscess, meningitis * *Thoracic:* Septic pulmonary emboli, pulmonary oedema, pulmonary abscess, pleural effusion/empyema, pneumothorax * *Abdominal:* Renal infarction, renal failure, splenomegaly, splenic infarction, hepatic infarction, mesenteric ischaemia * *Musculoskeletal:* Spondylodiscitis, osteomyelitis, septic arthritis, peripheral soft-tissue abscess. * *Vascular:* Major arterial emboli, mycotic aneurysm (including aortic aneurysm), vasculitis (including aortits).

Answer 82

**C. Bronchogenic** Pericardial metastases are much more common than primary pericardial tumours. Breast and lung cancers are the most common sources of metastases in the pericardium, followed by lymphomas and melanomas.

Answer 83

**C. Scleroderma** Systemic sclerosis, or scleroderma, is characterised by excessive collagen production, autoimmune disease-induced inflammation, and microvascular injury. It is divided into two subtypes: limited cutaneous systemic sclerosis and diffuse cutaneous systemic sclerosis. Limited cutaneous systemic sclerosis typically manifests as CREST syndrome, which stands for calcinosis cutis, Raynaud phenomenon, oesophageal dysmotility, sclerodactyly and telangiectasia and is generally anticentromere-antibody positive. The systemic manifestations of systemic sclerosis are diverse. Abnormalities of the circulatory system (most notably Raynaud phenomenon) and involvement of multiple organ systems - such as the musculoskeletal, renal, pulmonary, cardiac and gastrointestinal systems - with fibrotic or vascular complications are most common. Nearly 90% of patients with systemic sclerosis have evidence of gastrointestinal involvement, which is, ultimately, a substantial cause of morbidity. The underlying pathologic change consists of smooth muscle atrophy and fibrosis caused by collagen deposition primarily in the tunica muscularis. Oesophageal involvement typically affects the distal two thirds of the oesophagus because of the lack of striated muscle in the upper one-third. Findings of oesophageal involvement include decreased or absent oesophageal peristalsis combined with prominent gastroesophageal reflux from an incompetent lower oesophageal sphincter. Oesophagitis is frequently present, and associated complications such as oesophageal stricture or Barrett metaplasia are fairly common. Small bowel findings include hypomotility from smooth muscle atrophy and fibrosis, which leads to stasis, dilatation and pseudo obstruction. The ‘hide-bound’ sign of valvular packing is a fairly specific finding and may be seen in as many as 60% of patients with scleroderma.

Answer 84

**C. Histiocytosis X** Space-occupying lesions affect the hypothalamic neurohypophyseal axis, which is the central nervous system site most commonly and often earliest involved in Langerhans cell histiocytosis. MRI findings have been correlated with symptoms of diabetes insipidus, which is a clinical hallmark of the condition. Typically, the formation of Langerhans cell histiocytosis granulomas leads to a loss in the normally high signal intensity of the posterior neurohypophysis on T1-weighted images. Furthermore, the hypothalamus, the pituitary stalk or both are frequently- enlarged and demonstrate gradually increasing homogeneous enhancement after an intravenous injection of gadolinium, without subsequent washout. The differential diagnosis includes other infundibular diseases, such as adenohypophysitis, which can be differentiated from Langerhans ceil histiocytosis by a sharp increase in contrast enhancement and rapid washout after the administration of the intravenous contrast medium. Granulomatous diseases such as sarcoidosis, Wegener disease and leukaemia must also be considered in the differential. Rarer differentials are germ cell tumours (germinoma, teratoma) and haemangioblastoma. These produce the same MR] features, with the same pattern of enhancement at dynamic imaging. The second most frequent pattern of central nervous system involvement in Langerhans cell histiocytosis is characterised by intra-axial neurodegenerative changes. Bilateral symmetric lesions in the cerebellum, especially the dentate nucleus, basal ganglia, or brainstem, are most often observed. The differential diagnosis includes ADEM, acute multiphasic disseminated encephalitis, disseminated encephalitis, various metabolic and degenerative disorders, leukoencephalopathy secondary- to chemotherapy or radiation therapy, and paraneoplastic encephalitis. Less frequently, Langerhans cell histiocytosis granulomas, which resemble tumours, are observed in the extra axial space (in the meninges, pineal gland, choroid plexus and spinal cord).

Answer 85

**A. Focal nodular hyperplasia** Focal nodular hyperplasia (FNH) is the second most common benign liver tumour after haemangioma. FNH is classified into two types: classic (80% of cases) and non-classic (20%). Distinction between FNH and other hypervascular liver lesions such as hepatocellular adenoma, hepatocellular carcinoma and hypervascular metastases is critical to ensure proper treatment. An asymptomatic patient with FNH does not require biopsy or surgery. MRI has higher sensitivity and specificity for FNH than does US or CT. Typically, FNH is iso- or hypointense on T1-weighted images, is slightly hyper- or isointense on T2-weighted images, and has a hyperintense central scar on T2-weighted images. FNH demonstrates intense homogeneous enhancement during the arterial phase of gadolinium-enhanced imaging and enhancement of the central scar during later phases.

Answer 86

**B. Anechoic mass** Carcinomas are irregular in outline, ill-defined and hypoechoic compared to the surrounding fat. They are taller than wide (AP dimension more than transverse dimension). There may be an ill-defined echogenic halo around the lesion, particularly the lateral margins, and distortion of the adjacent breast tissue, akin to spiculations, may be evident. Posterior acoustic shadowing is frequently observed, due to attenuation of the US beam by dense tissue. Doppler examinations of malignant lesions show abnormal vessels that are irregular and centrally penetrating.

Answer 87

**E. Sarcoidosis** Cardiac thrombus tends to occur in older adults with a history of atrial fibrillation or ventricular aneurysm due to prior myocardial infarction. Right ventricular thrombus has been reported in patients with deep venous thrombosis, Behcet’s syndrome, Löffler syndrome, endocarditis, Churg-Strauss syndrome and right atrial aneurysms. Cardiac thrombus appears as a lobular, intracavitary mass. The density and signal intensity depend on the age of the thrombus. Cardiac thrombus does not enhance. Patients with cardiac thrombus are treated with anticoagulation.

Answer 88

**B. Dorsal intercalated segment instability (DISI)** DISI and VISI injuries refer to malalignment of the carpal rows with emphasis of the relation of the lunate to the capitate. In DISI (associated with tear of scapholunate ligament), the lunate is tilted dorsally with an increased scapholunate angle (>60 degrees) and capitolunate angle (>30 degrees). In VISI (associated with tear of the luno triquetral ligament), there is a volar tilt of the lunate with decreased scapholunate angle (less than 30 degrees) and increased capitolunate angle (>30 degrees).

Answer 89

**D. Primary cardiac lymphomas mostly affect the left side of the heart.** Secondary malignancies involving the heart are 20-40 times more frequent than primary cardiac neoplasms. Angiosarcoma is the most common primary cardiac malignancy of adulthood. The tumour typically involves the right atrium, and so presenting symptoms are related to obstruction to right cardiac filling and pericardial tamponade. They are heterogeneously high signal on Tl and T2-weighted images with heterogeneous enhancement. Undifferentiated sarcoma mostly arises in the left atrium, although they can also involve the cardiac valve. It appears as an isointense irregular mass infiltrating the myocardium. Primary cardiac lymphomas are exceedingly rare, are typically of the non-Hodgkin B-cell type and are confined to the heart or pericardium. They most commonly involve the right side of the heart, in particular the right atrium, with frequent involvement of more than one chamber and invasion of the pericardium. At MRI, they are isointense on T1-weighted images and heterogeneously hyperintense on T2-weighted images; they demonstrate heterogeneous enhancement after administration of gadolinium contrast material. Rhabdomyosarcomas do not arise from any specific chamber, but they are more likely than any other primary cardiac sarcomas to involve the valves.

Answer 90

**D. Low signal on T1W MRI is seen >8 hours.** A good rule of thumb is that if the signal intensity on ADC maps is low, the stroke is less than 1 week old. Most literature indicate that in patients with ischaemic stroke, findings on FLAIR images are positive 6 12 hours after onset of symptoms. Sometimes the presence of restricted diffusion with negative findings at FLAIR imaging alone has been enough to initiate treatment. High signal intensity is not usually seen at T2-weighted imaging until at least 8 hours after the initial ischaemic insult and continues into the chronic phase. Low signal intensity is not usually seen at T1 weighted imaging until 16 hours after the onset of stroke and persists into the chronic phase. The pattern of contrast enhancement may help determine the age of the stroke. In ischaemic stroke, enhancement may be arterial, meningeal, or parenchymal. Arterial enhancement, dubbed the ‘intravascular enhancement’ sign, usually occurs first and may be seen as early as 0-2 hours after the onset of stroke. Meningeal enhancement is the rarest type of enhancement. It occurs within the first week after onset of stroke. If parenchymal enhancement persists longer than 8 12 weeks, a diagnosis other than ischaemic stroke should be sought.

Answer 91

**C. There is caudate lobe atrophy in chronic Budd-Chiari.** Budd-Chiari syndrome is a heterogeneous group of disorders characterised by hepatic venous outflow obstruction at the level of the hepatic veins, the IVC, or the right atrium. Budd-Chiari syndrome has variable imaging features. Hepatic vein or IVC thrombosis, with resultant changes in liver morphology and enhancement patterns, venous collaterals, varices, and ascites may be directly observed. Duplex Doppler US is a useful method for detecting Budd-Chiari syndrome because it allows easy assessment of hepatic venous flow and detection of hepatic parenchymal heterogeneity. CT and MR imaging also can depict hepatic venous flow or thrombosis and IVC compression or occlusion. In the presence of acute disease, the imaging features correspond with histologic findings of liver congestion and oedema. The liver is globally enlarged, with lower attenuation on CT images, decreased signal intensity on T1 - weighted MRIs, and heterogeneously increased signal intensity on T2 weighted MRIs, predominantly in the periphery. Differential contrast enhancement between the central and peripheral areas of liver parenchyma is a feature of acute Budd-Chiari syndrome. The more oedematous and congested peripheral regions demonstrate decreased contrast enhancement, whereas stronger enhancement is seen in the central parenchyma. After the administration of contrast material, increased enhancement is seen in areas of venous drainage that are less affected, such as the caudate lobe. The development of intra- and extrahepatic collateral veins in subacute Budd-Chiari syndrome permits the egress of venous flow, producing a more homogeneous enhancement pattern with persistent signs of oedema. In chronic Budd-Chiari syndrome, there is atrophy of the affected portions of the liver, and the parenchymal oedema is replaced by fibrosis, which results in decreased T1- and T2-weighted signal intensity at unenhanced MRI and in delayed enhancement in contrast-enhanced studies. Hypertrophy of the caudate lobe, irregularities of the liver contour, and regenerative nodules are prominent features of chronic Budd-Chiari syndrome.

Answer 92

**C. Ductus venosus** The single umbilical vein extends from the umbilicus to the left portal vein. When blood from the umbilical vein reaches the left portal vein, it is directed to the ductus venosus, which originates from the left portal vein immediately opposite the insertion site of the umbilical vein and courses cephalad to the inferior vena cava. The preferred location of the tip of the umbilical venous catheter is typically in the cephalad portion of the inferior vena cava or at the inferior vena caval-right atrial junction. An umbilical venous catheter can be distinguished from an umbilical arterial catheter as the UVC travels cranially in the umbilical vein while the UAC travels caudally in an umbilical artery to reach a common iliac artery.

Answer 93

**A. Fourth ventricle enlargement** Isodense subdural haematoma are a recognised pitfall on CT, which is often difficult to recognise. Indirect signs are hence critical, midline shift; compression of the ipsilateral lateral ventricle; effacement of cerebral sulci; medial displacement of junction of grey and white matter (white matter buckling); and dilatation of contralateral lateral ventricle, which is a bad prognostic sign. In case of bilateral collections, the frontal horns lie closer than normal, giving ‘rabbit ear' appearance.

Answer 94

**E. Scheuermann disease** Scheuermann disease is a spinal disorder named after Dr Holger Scheuermann, who, in 1921, first described a structural thoracic kyphosis mainly affecting adolescents. Its best-known manifestations are multiple wedged vertebrae and thoracic kyphosis known as Scheuermann kyphosis. Its classic diagnostic criterion was '3 or more consecutive wedged thoracic vertebrae'. However, the pathological changes also include disc and end plate lesions, primarily Schmorl node and irregular vertebral end plate. Therefore, the diagnosis of ‘atypical Scheuermann disease' was proposed for patients with only one or two wedged vertebrae and no notable kyphosis but characteristic disc/end plate lesions. Because atypical Scheuermann disease tends to affect the lumbar or thoracolumbar junction region instead of the thoracic spine, it is also called *lumbar Scheuermann disease.*

Answer 95

**E. Routine breast screening** Ultrasound is not a screening tool. It is used for assessment of a palpable lump, particularly in young patients (below 30 years) and mammographically dense breasts, and in characterisation of a mammographic or palpable mass as solid or cystic. It is used for evaluation of mammographically uncertain lesion or for confirmation of lesion seen on a single projection. It is used for assessing breast discharge, suspected silicone leaks, follow-up of lesions seen on US and for guiding cyst aspiration, biopsy or wire localisation.

Answer 96

**B. Bilateral occipital subdural haemorrhage** Subdural haemorrhage (SDH) and subarachnoid haemorrhage (SAH) are common abusive injuries. Epidural haematoma is much more often accidental. Probably the most common location of inflicted SAH, and SDH diagnosed radiologically is a layer of hyperattenuating material adjacent to the falx; bleeding at this site represents an interhemispheric extra-axial haemorrhage. In this location, it is often difficult, radiologically, to distinguish SAH from SDH, and SDH and SAH may coexist.

EXAM 1 Flashcards

(120 cards)