Liver Flashcards

Question

12. 45-year-old man undergoes ultrasound scan of the abdomen 2 days following orthotopic liver transplantation, which demonstrates periportal oedema and a small fluid collection at the hilum of the liver. What is the most likely diagnosis? A. graft rejection B. hepatic arterial thrombosis C. portal vein stenosis D. bile leak E. normal post-transplantation findings

Answer 1

E. normal post-transplantation findings Orthotopic liver transplantation is the treatment of choice for patients with end-stage liver disease for which no other therapy is available. Surgery involves one arterial anastomosis (hepatic artery), at least two venous anastomoses (portal vein and IVC) and a biliary anastomosis, and complications may occur at any of these sites. Vascular complications are the most frequent cause of graft loss, and most commonly involve the hepatic artery, with portal venous and IVC complications being relatively infrequent. Biliary complications occur in up to 34% of cases, and are the second most common cause of liver dysfunction after graft rejection. They include leak, stricture and obstruction. Other complications include fluid collections, infection and malignancy. Normal findings following liver transplantation include a small amount of free intraperitoneal fluid in the perihepatic region, especially at the hilum, or in the fissure for the ligamentum teres, which usually resolves within a few weeks. Other normal findings are a right fluid pleural effusion, and periportal oedema, attributed to lymphatic cchannel dilatation due to lack of normal lymphatic drainage.

Answer 2

B. decreased signal intensity on T1W and T2Wimages In primary haemochromatosis, there is increased duodenal absorption and parenchymal retention of dietary iron, which is accumulated within the liver, pancreas, heart and pituitary gland. Intracellular iron deposits within hepatocytes result in a paramagnetic susceptibility effect, leading to marked shortening of T1 and T2 relaxation times of adjacent protons. This manifests as a marked reduction in liver signal intensity on T2Wand T2*W images, and a moderate loss of signal intensity on T1W images.

Answer 3

B. mucinous adenocarcinoma of the gastrointestinal tract Calcified liver metastases represent up to 3% of liver metastases, and are most commonly seen with mucinous carcinomas of the gastrointestinal tract. They are also seen in osteosarcoma, breast cancer, lung cancer and carcinoid, but these are less common.

Answer 4

C. portal hypertension The normal portal vein measures up to 13 mm in diameter when measured in the AP direction where the portal vein crosses the inferior vena cava during quiet respiration in a supine patient. Portal venous flow is normally 12–30 cm/s and demonstrates respiratory variation but little or no pulsatility, though this may be seen in thin patients. Normal flow is hepatopetal (anterograde flow into the liver). Portal hypertension is defined as an increase in portal venous pressure above10 mmHg, and is most commonly caused by cirrhosis in the western world. As portal pressure increases, portal vein diameter increases, and portal flow loses its respiratory fluctuation and becomes slow and turbulent. Reversed (hepatofugal) flow may occur in 8% of patients and is generally associated with a reduced portal vein diameter. Other findings include portosystemic collaterals, splenomegaly and ascites. In portal vein thrombosis, portal vein diameter increases, but no flow is seen on Doppler ultrasound scan. Echogenic thrombus may be seen within the lumen. Cavernoustrans formation of the portal vein may occur with chronic portal vein thrombosis, representing a conglomerate of collateral veins. Budd–Chiari syndrome affects the hepatic veins.

Answer 5

D. Kaposi's sarcoma Kaposi's sarcoma is a low-grade tumour of the blood and lymphatic vessels that primarily affects the skin but may cause disseminated disease in other organs. It is an AIDS-defining illness and is the most common AIDS-related neoplasm. The commonest manifestation is of multiple raised purplish skin lesions, but lymphadenopathy is the second commonest feature in AIDS-related Kaposi's sarcoma. Typical appearances are of abdominopelvic lymph nodes that enhance after intravenous contrast due to high vascularity, appearing to be of higher attenuation than skeletal muscle. Liver involvement occurs in 34% of cases at autopsy, and typically causes multiple 5–12 mm nodules that are hyperechoic on ultrasound scan and of low attenuation on CT. Skin lesions are present in most cases, and help to distinguish Kaposi's sarcoma from other conditions such as fungal microabscesses and multiple haemangiomas, which may have similar appearances on CT. Mycobacterial disease is characteristically associated with low-attenuation lymphadenopathy. Non-Hodgkin's lymphoma is the second commonest AIDS-related neoplasm, and may cause multiple low-attenuation liver lesions, but it is not associated with skin lesions or high-attenuation lymphadenopathy.

Answer 6

B. fatty liver related to chemotherapy Chemotherapeutic agents are commonly associated with fatty liver. Diffuse fat deposition (the commonest pattern) causes a generalized decrease in the attenuation value of the liver on CT, and may be diagnosed with an absolute liver attenuation value of less than 40 HU on contrast-enhanced CT. It may also be diagnosed at unenhanced CT if the liver attenuation value is at least 10 HU less than that of the spleen. Liver metastases usually present as focal, low-attenuation lesions on portal phase imaging. Hepatic venous congestion causes a diffuse decrease in attenuation but is associated with enlargement of the inferior vena cava and hepatic veins due to elevated central venous pressure. Amyloidosis can cause a generalized decrease in liver attenuation, but more commonly appears as discrete areas of low attenuation with reduced contrast enhancement. Budd–Chiari syndrome may also result in a diffuse decrease in liver attenuation, but there is usually patchy liver enhancement and poor visualization of the hepatic veins.

Answer 7

(a) Non-specific interstitial pneumonitis There is no increased risk of NSIP or any other interstitial lung disease as a result of cirrhosis. Patients with cirrhosis have altered immunity and undergo changes to the vascular bed both the liver and the lungs.

Answer 8

(a) Normal findings The normal liver has a density of 50-70 HU. Fatty infiltration will reduce this as the atomic numbers of the elements C, H and O. Iron and copper deposition can raise the density, as they have high atomic numbers.

Answer 9

(a) Hepatic artery stenosis The tardus et parvus waveform described here is seen distal to a stenosis. At the stenosis, a jet phenomenon may be seen with greatly increased flow.

Answer 10

(e) Cholangiocarcinoma Hepatocellular adenomas are uncommon benign tumours which comprise hepatocytes with no portal tracts or bile ducts. They are associated with the oral contraceptive pill and androgenic steroids. On imaging, they may have a scar or a pseudocapsule and enhance avidly in the arterial phase which can make differentiation from FNH difficult. There is a tendency to bleed or rupture, 1 % are thought to transform in to malignant lesions (HCC).

Answer 11

(a) Nodular regenerative hyperplasia Cystic fibrosis produces a range of abnormalities, which may lead to fibrosis, cirrhosis and portal hypertension. A micro-gallbladder is also seen commonly.

Answer 12

2 (c) The patient has classical features of underlying paroxysmal nocturnal haemoglobinuria (PHH), which predisposes to Budd-Chiari syndrorme. Budd-Chiari syndrome presents with these symptoms; the severity of the initial liver disease is variable depending upon the extent of venous occlusion.

Answer 13

(a) Hemangioma These are characteristic findings of a haemangioma. A cyst will enhance; and adenoma are benign hyper vascular lesions that equilibrate in the portal phase. HCC is hypervascular with washout on delayed imaging; the liver is usually cirrhotic.

Answer 14

(c) Partial Response A reduction of > 30%, falling short of a complete response, constitutes a partial response.

Answer 15

(b) Focal nodular hyperplasia These imaging features are characteristic of FNH. FNH is a tumour thought to represent a hyperplastic response to a pre-existing arterial malformation. It is most commonly seen in women and has no malignant potential. A central scar may be seen which shows delayed enhancement.

Answer 16

(a) Amyloidosis The most common cause of diffuse low attenuation is fatty infiltration; amyloidosis is another due to amyloid deposition. Amyloidosis can be a primary condition, or secondary to chronic infectious, chronic inflammatory disease (e.g. rheumatoid arthritis), or multiple myeloma. Answers (b) - (d) increase copper/iron deposition within the liver, which will lead to increased liver density on a pre-contrast CT.

Answer 17

(c) Segment III The Couinaud classification divides the liver into 8 functionally independent segments, each with its own blood supply and biliary drainage. The portal vein divides the liver into superior and inferior segments. The middle hepatic vein divides the left (segments I-IV ) and right lobes (segments V-VIII). The right hepatic vein divides the right lobe into anterior (V and VIII) and posterior (VI and VII) segments. The left hepatic vein divides the left lobe into medial (segments IV-A and IV-B) and lateral part (segments II and III); segment I is the caudate lobe, situated posteriorly.

Answer 18

(a) Ischaemia Ischaemia is the underlying cause in approximately 50% of cases; the bile ducts are supplied by the hepatic artery and their blood supply is inevitably disrupted to some extent during transplantation. Evaluation of the hepatic arterial supply to the graft is crucial as thrombosis usually requires re-transplantation in the adult population.

Answer 19

(e) Metastasis These are the characteristic features of a hypovascular metastasis. Lesions enhance in a fashion similar to that seen on CT or MRI.

Answer 20

(c) 3 lesions measuring 3 cm or less Transplantation is considered in patients with 1 lesion <5 cm or up to 3 lesions measuring 3 cm or less, the 'Milan Criteria’.

Answer 21

(b) II &III These segments are also referred to as the left lateral lobe. Resection of segment IV also is termed an extended left hepatectomy. Resection of V, VI, VII and VIII is a right hepatectomy. An extended right hepatectomy includes segment IV also. The caudate lobe is usually only resected during liver transplantation.

Answer 22

(a) It is seen in up to 30 % of the population Hepatic steatosis is seen in this proportion of the population; of these, 6-8% progress to NASH, where there is inflammation of the hepatocytes and abnormal liver function.

Answer 23

(c) Haemochromatosis The low signal within the liver parenchyma on T2-weighted images is due to the susceptibility artefact from iron overload. Patients with haemochromatosis deposit iron within the skin, heart, liver and pancreas. This degree of iron within the liver can be quantified using MRI

Answer 24

(c) Hydatid cyst Hydatid infection is caused by Echinococcus multilocularis, and may give rise to a number of appearances at US with cysts being uni- or multi-loculated, thin or thick-walled, with or without calcification. The appearance described here is referred to as daughter cysts. Cystadenoma gives rise to a large unilocular cyst or septated cyst. Caroli disease is due to duct abnormalities. Hepatocellular carcinoma and cholangiocarcinoma are solid lesions.

Answer 25

(a) Non-Hodgkin lymphoma Polycystic liver disease is a hereditary condition that may or may be associated with polycystic kidney disease. There is malignant potential within the cysts but complications may arise from the sheer size of the cysts, and therapeutic interventions. Aspiration, fenestration and enucleation may provide short term relief, but some cases will require repeated therapy or transplantation.

Answer 26

(c) Cirrhosis NRH is diffuse nodularity of the liver produced by regenerative nodules in the absence of hepatic fibrosis. Although a rare entity, it is commonly associated with portal hypertension (50% cases).

Answer 27

66 (b) The liver is affected most frequently, with involvement in up to 45% of liver transplant PTLDs, 40% of pancreas transplant PTLDs 23% of heart transplant PTLDs 0% of lung transplant PTLDs

Answer 28

9. c. Carcinoid tumour Of the options listed, carcinoid tumour is the only primary tumour that typically causes hypervascular liver metastases. Other causes of hypervascular liver metastases are pancreatic islet cell tumours, phaeochromocytoma and renal cell carcinoma. Stomach, breast, lung and colon cancers are associated with hypovascular liver metastases. Liver metastases from carcinoid tumours are more common with increasing size of the primary tumour. The incidence of metastases depends on the location of the primary tumour, where approximately 30% of carcinoids of the ileum metastasise compared to less than 5% of carcinoids of the appendix.

Answer 29

16. e. Adenoma The lesion is most likely to be a hepatic adenoma. None of the other diagnoses typically share these imaging characteristics. Adenomas are benign growths of hepatocytes and are most commonly seen in young women, particularly associated with oral contraceptive use. Eighty per cent are solitary and found in the right lobe of the liver. The high signal on T1-weighted sequences is due to the presence of fat and/or haemorrhage and can distinguish between this and many other lesions in the liver which tend to be of low T1 signal on MR (e.g. metastases, HCC, haemangiomas and FNH). Occasionally, imaging features can overlap with FNH and the two lesions can be difficult to distinguish. However, the majority of FNH lesions are less than 5 cm in size, whereas adenomas tend to be larger.

Answer 30

17. c. Fibrolamellar carcinoma Fibrolamellar carcinoma occurs in young adults in the absence of normal risk factors for hepatocellular carcinoma. On ultrasound, fibrolamellar carcinoma is of mixed or increased echogenicity, and the hyperechoic central scar is often evident. On unenhanced CT the lesion is of low attenuation, displaying heterogenous enhancement with intravenous contrast administration. The central scar is typically of low signal on both T1- and T2-weighted imaging, which can help differentiate it from FNH (whose scar typically is of low signal on T1 but high signal on T2-weighted imaging). The central scar is present in up to 60% of patients. Calcifications are present in up to 55% and are more common than in hepatocellular carcinoma.

Answer 31

28. a. Hydatid cyst The most likely diagnosis is hydatid cyst disease. This condition is caused by infection of the liver with the parasite Echinococcus granulosus. Blood eosinophilia is present in up to 50% of patients. It is more common in the right lobe of the liver and is multiple in 20% of cases. Daughter cysts are typical. Percutaneous aspiration of the cyst is positive for hydatid disease in 70%.

Answer 32

37. b. Amiodarone use The normal liver is between 30 and 70HU on unenhanced CT, and should be 10–15HU lower than spleen density. On portal venous phase the liver will be approximately 25HU less than the spleen. Amiodarone contains iodine and can cause the liver to appear of increased density on CT. Other causes include cisplatin use, haemochromatosis, Wilson disease and glycogen storage diseases. The more common finding on CT is a liver of decreased density due to a fatty liver. This has many causes including alcohol use, steroids, chemotherapy, diabetes and nutritional causes.

Answer 33

43. c. Budd–Chiari syndrome Budd–Chiari syndrome is outflow obstruction of the hepatic veins due to a wide variety of causes, but two-thirds are idiopathic. CT features include ‘flip-flop’ enhancement pattern as described in the question, ascites, hepatosplenomegaly, gallbladder wall thickening and increased portal vein diameter. An enlarged caudate lobe is seen in up to 88%, which enhances normally due its venous drainage passing directly into the IVC.

Answer 34

44. b. Focal fatty infiltration Focal fatty infiltration occurs typically in the periportal and centrilobar regions of the liver and is commonest adjacent to the falciform ligament. Ultrasound features include a hyperechoic area with geographic margins. CT shows an area of decreased attenuation which does not alter the course of blood vessels or liver contour. The lesions are of high signal on T1-weighted MR imaging, and isointense or low signal on T2-weighted imaging. Haemangiomas would also typically be of increased echogenicity on ultrasound, but would be expected to show increased peripheral enhancement with intravenous contrast on CT.

Answer 35

48. e. Focal nodular hyperplasia These imaging features are typical of focal nodular hyperplasia. This is the second most common benign liver tumour and typically occurs in women more often than in men. Adenomas are usually larger, enhance less brightly and do not typically have a central fibrous scar. Cavernous haemangiomas are usually high signal on T2-weighted images, and of blood pool intensity on contrast-enhanced T1-weighted images. Fibrolamellar carcinoma also has a central scar, but this is typically of low signal intensity on T2-weighted imaging. Regenerative nodules show high signal intensity on unenhanced T1-weighted imaging and do not have a scar.

Answer 36

49. a. Adenocarcinoma of the colon The most common primary tumours that cause brightly echogenic liver metastases are colonic adenocarcinoma, treated breast cancer and hepatoma. The differential here therefore lies between breast cancer and colon cancer. Colon cancer makes up at least 50% of highly echogenic metastases. In addition the question states that the patient has no significant past medical history, and therefore treated breast cancer is unlikely.?

Answer 37

51. d. HELLP syndrome Hepatic infarction is rare because of the dual blood supply to the liver via the hepatic arterial system and the portal venous system. Isolated pathology in either of these vascular supplies is unlikely to cause hepatic necrosis as the other supply will usually compensate. HELLP is characterised by haemolysis, elevated liver enzymes and low platelets and is one of the causes of liver infarction.

Answer 38

52. c. Cavernous haemangioma Metastases may show peripheral enhancement with complete fill-in on delayed images, but they typically show complete rather than nodular peripheral enhancement and washout on delayed phase imaging. Only haemangiomas typically show peripheral nodular enhancement. Cavernous haemangiomas are the most common benign liver tumours and are usually less than 4 cm in size. Seventy per cent are hyperechoic on ultrasound and they may show acoustic enhancement.

Answer 39

53. c. Adenoma – recommend endovascular embolisation Adenomas are vascular lesions comprising hepatocytes. They may occasionally present with massive haemorrhage, and are the most common liver lesion to do so in young people. In this scenario there is active extravasation of contrast implying active bleeding and haemoperitoneum. Urgent embolisation is the most appropriate treatment to halt bleeding. Conservative or surgical management is unlikely to provide rapid haemostasis. As a proportion of adenomas become malignant, they are usually removed surgically.

Answer 40

54. a. Peripheral washout on delayed imaging Peripheral washout of contrast on delayed imaging is virtually diagnostic of malignancy. On post-gadolinium-enhanced T1-weighted images most metastases are hypovascular compared with the surrounding liver and are most conspicuous at the portal phase of enhancement. However, virtually all metastases exhibit a complete ring of peripheral enhancement, which is best seen in the early arterial phase.

Answer 41

55. e. Peritoneal metastases Generally accepted contraindications to liver resection would include uncontrollable extrahepatic disease such as: non-treatable primary tumour; widespread pulmonary disease; locoregional recurrence; peritoneal disease; extensive nodal disease, such as retroperitoneal, mediastinal or portal nodes; and bone or CNS metastases. Patients with extrahepatic disease that should be considered for liver resection include: resectable/ablatable pulmonary metastases; resectable/a blatable isolated extrahepatic sites – for example, spleen, adrenal or resectable local recurrence; and local direct extension of liver metastases to, for example, the diaphragm or adrenal glands, which can be resected.

Answer 42

E The bony skeleton is the most common site for distant metastases. A localised paralytic ileus due to inflammatory change in the pancreas is known as the sentinel loop sign.

Answer 43

B HCC derives its blood supply primarily from the hepatic artery. HCC derives its blood supply from the hepatic artery (hence the rapid arterial phase enhancement). A large HCC will usually demonstrate heterogeneous reflectivity due to areas of necrosis, but smaller lesions are typically of homogeneous low reflectivity on ultrasound. HCC often invades the branches of the portal vein and the most frequent site of metastases is the lungs. Metastases to the brain are typically hypervascular and do not usually contain calcification.

Answer 44

C The lesion has a geographic margin and is of reduced echogenicity compared to that of the surrounding liver. Focal fatty sparing usually leads to geographic or wedge-shaped lesions of reduced echogenicity. There should be no mass effect or abnormal enhancement characteristics in focal fatty sparing or infiltration. Both focal fatty sparing and infiltration typically occur in sites such as the gallbladder fossa, falciform ligament and porta hepatis, due to the altered venous drainage of these areas.

Answer 45

A Carcinoid Most liver metastases are hypovascular and appear as lower attenuation than normal liver parenchyma on portal venous phase CT. Hypervascular metastases are less common and appear most prominently during the arterial phase (20-30 s) post contrast. Carcinoid, melanoma, thyroid and renal cancer are the most common causes of hypervascular liver metastases.

Answer 46

C Hepatic adenoma The MRI findings are highly suggestive of a hepatic adenoma and the history of rapid growth during pregnancy is supportive of this diagnosis.

Answer 47

C Segment 6 The Couinaud classification divides the liver into 8 independent segments, each of which has its own vascular supply and biliary drainage. The portal vein separates the superior and inferior segments, with further division based on the relationship to the nearest hepatic veins. Because of this division into self-containment’s, the Couinaud classification carries particular importance in the setting of resectable liver lesions, such as a solitary colorectal metastasis.

Answer 48

D Hepatic artery thrombosis Hepatic artery thrombosis is the most common and serious early vascular complication post liver transplant. Thrombolysis is an option in this setting, but many patients will ultimately require transplantation. Prompt and accurate diagnosis is therefore essential. A parvus et tardus waveform may be seen distal to stenosis of the hepatic artery, with associated elevated systolic velocity at the stenotic segment. Porta! vein thrombosis is less common and can result in the acute development of ascites and varices. IVC thrombosis is rare and usually related to surgical technique, whilst an arterioportal fistula is an infrequent complication of liver biopsy.

Answer 49

B Hydatid cyst A multiloculated cystic mass with daughter cysts and echogenic debris (‘hydatid sand’) is characteristic of a hydatid liver cyst.

Answer 50

D Reduced T2 signal in the liver and spleen In iron overload due to recurrent transfusions, there is increased iron deposition in the reticuloendothelial system. This leads to reduced Tl, T2 andT2* signal intensity in the liver and spleen. Haemochromatosis causes diffusely reduced T2 signal in the liver and may lead to cirrhosis, but the splenic signal intensity should remain normal. Diffuse fatty liver will lead to increased T2 signal in the liver with signal loss during out-of-phase images.

Answer 51

D Punctuate calcification in the lesion There is considerable overlap in the imaging appearances of these two conditions, but punctate calcification occurs in over half of patients with fibrolamellar carcinoma and is extremely unusual in FNH.

Answer 52

A Budd Chiari syndrome When contrast is injected into the hepatic veins, a ‘spider's web’ appearance of collateral vessels is diagnostic of Budd Chiari syndrome

Answer 53

A Amiodarone therapy Amiodarone contains iodine; therefore, deposition in the liver leads to increased density on CT.

Answer 54

C Hepatic adenomas typically demonstrate uniform enhancement in the arterial phase. Hepatic adenoma, HCC and focal nodular hyperplasia will usually show marked enhancement in the arterial phase. Hypervascular liver metastases are typically hypointense on Tl, hyperintense on T2. The characteristic behavior of a liver haemangioma—not HCC—is described in option E.

Answer 55

D Post transplant lymphoproliferative disorder (PTLD) Up to 5% of liver transplants develop PTLD: extra nodal disease is the most common pattern.

Answer 56

D Normal ultrasound appearances In acute viral hepatitis, there can be diffusely reduced reflectivity of the liver but the majority of patients have a normal ultrasound examination.

Answer 57

C Mucinous adenocarcinoma of colon Calcification occurs in 2—3% of liver metastases. Mucinous adenocarcinoma of the GI tract is the most frequent underlying primary tumour.

Answer 58

C Hemangioma Extended echo times will emphasize the high T2 signal intensity of liver hemangiomas, in comparison with surrounding structures.

Answer 59

D Melanoma metastases Melanoma metastases have a different appearance to most liver metastases as the paramagnetic effect of melanin leads to high Tl and low T2 signal.

Answer 60

11. B. Segment 5. For a review of the segmental anatomy of the liver, please see the reference below.

Answer 61

12. B. Haemangioma. The ultrasound findings describe a target lesion or bull’s eye lesion. Cavernous haemangioma scan have unusual appearances, but a small lesion such as described will normally have a uniform hyperechoic appearance. Of all the other lesions described, metastasis would be top of the differential, although this appearance is not the most classical for a colonic metastasis.

Answer 62

23. D. Focal nodular hyperplasia (FNH). This is the second most common benign liver tumour. It is thought to represent a hyperplastic response of hepatocytes to an underlying vascular malformation. It is most common in young adult females and is usually an asymptomatic solitary lesion. On histology, FNH consists of hyperplastic hepatocytes and small bile ductulus around a central scar. The bile ductulus of FNH do not communicate with the adjacent biliary tree. At ultrasound, FNH is isoechoic or hypoechoic. Colour Doppler may show prominent central vascularity. At CT, FNH is typically slightly hyperattenuating or isoattenuation to surrounding liver on precontract images. On postcontrast images, FNH is hyperattenuating in the arterial phase and isoattenuation in the portal venous phase with hypoattenuating central scar. The scar shows delayed enhancement. At MRI, FNH is iso- to hypointense on T1WI and slightly hyper- to isointense on T2WI. The central scar is hypointense on T1WI and hyperintense on T2WI. The enhancement pattern is similar to that on CT. If the appearances are atypical, MRI with hepatocyte-specific contrast agent (gadobenatedimeglumine) may be useful in confirming the hepatocellular origin of the mass. With gadobenatedimeglumine, FNH is iso- to hyperintense on the 1–3 hour delayed images in over 96% of cases.

Answer 63

25. D. Dual GE T1WI in phase and out of phase. Three basic MRI techniques are available for fat detection, which work on the basis of the difference in precessional frequency between water and fat protons. These are chemical shift imaging, frequency-selective imaging, and MR spectroscopy. Dual GE T1WI is the most useful sequence in clinical practice. It is based on the phase interference effect or chemical shift imaging of the second kind. When the fat and water protons are in phase there is constructive interference and when they are out of phase there is destructive interference. By comparing the signal intensities on the in-phase and out-of-phase images, fat detection is possible. Chemical shift imaging of the first kind, or chemical shift spatial misregistration, occurs at fat–water interfaces in the frequency-encoding direction, manifesting as alternating bands of high and low signal. It is present in all standard non-fat-saturated sequences, but it can be subtle and may be missed or mistaken for image noise. Frequency-selective imaging with selective excitation or saturation depends on the homogeneity of the magnetic field and the size of the lesion.MR spectroscopy is too time-consuming for routine clinical use.

Answer 64

29. D. Regenerative nodules. Regenerative nodules are formed in response to necrosis and altered circulation. They remain enhanced in the portal venous phase as opposed to HCC, which typically demonstrates contrast washout in the portal venous phase. Regenerative nodules have normal hepatocellular function and Kupffer cell density and therefore demonstrate uptake of both hepatocellular agents and SPIO particles. As dedifferentiation proceeds, the hepatocellular function and Kupffer cell density reduce.

Answer 65

30. C. Dilated hepatic veins and IVC. Elevated right atrial/central venous pressure due to cardiac decompensation results in impaired venous drainage from the liver, producing passive hepatic congestion. If prolonged, passive hepatic congestion can result in cardiac cirrhosis. On CT imaging, retrograde enhancement of dilated IVC and hepatic veins is seen in the arterial phase. In the portal venous phase, there is delayed/reduced enhancement of the hepatic veins due to impaired venous drainage. There is heterogenous enhancement of the liver parenchyma due to venous stasis. Other features of cardiac failure may be evident. Acute Budd–Chiari syndrome is characterized by narrowed hepatic veins and intrahepatic IVC (secondary to compression by the enlarged liver) and by flip-flop pattern of enhancement between the arterial and the portal venous phases.

Answer 66

31. D. Haemochromatosis. GE T2WI. A dual GE T1 in- and out-of-phase sequence is routinely used in identifying lipid content within an adrenal lesion. It is based on the phase interference effect. When the fat and water signals are in-phase, there is constructive interference and when they are out-of-phase there is destructive interference. This results in signal drop-off on the out-of-phase sequence. The reverse effect of decreased signal intensity on in-phase images compared to out-optacons is seen in iron deposition diseases. This is because the echo time for the in-phase sequence is longer than for the out-of-phase sequence, therefore the in-phase sequence is more susceptible to the paramagnetic (dephasing) effects of iron. Haemochromatosis is an autosomal recessive genetic disorder. There is abnormal deposition of iron in parenchymal organs such as the liver, pancreas, heart, etc. In hemosiderosis or secondary haemochromatosis, iron deposition is seen in the reticuloendothelial system of the liver, spleen, and bone marrow. This type of deposition is not associated with tissue damage. A GE T2 sequence demonstrates signal loss due to the magnetic field inhomogeneity produced by the paramagnetic effects of iron. GE sequences are more susceptible to paramagnetic effects than SE sequences, as there is no 180°rephasing pulse in gradient sequences.

Answer 67

37. C. Transient hepatic intensity difference (THID). THID on MRI or transient hepatic attenuation difference (THAD) on CT is a pseudo lesion caused by focal alteration in the hemodynamics of the liver due to either non-tumorous arterio-portal shunt or obstruction of distal portal venous flow. THID or THAD is seen as a focal area of enhancement in the arterial phase only, with no abnormality seen in the portal venous phase. Features suggestive of THID or THAD include peripheral location, wedge shape, straight margins, and normal vessels coursing through the area.

Answer 68

51. C. Osler–Weber–Rendu syndrome. Osler–Weber–Rendu syndrome or hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant multisystem vascular disorder characterized by angiodysplastic lesions in which there is communication between arteries and veins of varying sizes. It commonly affects the skin, lungs, and mucous membranes but any organ system may be involved. The liver is the most common site of abdominal HHT. Lesions range from tiny telangiectases to transient perfusion abnormalities and large confluent vascular masses. Coronal maximum intensity projection (MIP) images are useful in appreciating telangiectases. Liver involvement is associated with arterio-venous shunting, porto-venous shunting, or both, resulting in hyperdynamic circulation, which may lead to high-output cardiac failure. Budd–Chiari syndrome is hepatic vein thrombosis and Von Meyer burg complex is multiple biliary hamartomas.

Answer 69

70. B. Resistive index of 0.9 distal to the stenosis. Knowledge of the vessel ‘waveform signature’ and stenosis flow dynamics is essential in interpreting the Doppler findings. The hepatic artery is a low resistance vessel with continuous antegrade flow during systole and diastole. Generally, low-resistance arteries have a resistive index (RI) of 0.55–0.7. RIs higher or lower than this range are abnormal. RI is calculated by using the formula RI = (peak systolic velocity – end diastolic velocity)/peak systolic velocity. Most modern ultrasound machines calculate this automatically. A stenosis results in increased arterial resistance to the blood flow proximal to the stenosis. This causes a reduction in the end diastolic velocity disproportionately more than the peak systolic velocity, producing a high-resistance waveform and high RI (due to a greater difference between the peak systolic and end diastolic velocities). This finding is not specific to stenosis and may be seen in the postprandial state, and in patients of advanced age and diffuse peripheral microvascular disease or compression (cirrhosis, hepatic venous congestion, cold ischaemia, and any stage of transplant rejection). At and immediately distal to the stenosis there is turbulent flow and a jet phenomenon resulting in an increase in the peak systolic and end diastolic velocity and spectral broadening. Depending on the severity of the stenosis, the artery distal to the stenosis demonstrates the following findings: Tardus-parvus waveform that refers to the late and low systolic peak (i.e. increased acceleration time and reduced peak systolic velocity). Low RI due to a greater reduction in peak systolic velocity compared to the end diastolic velocity. Low RI may also be seen with distal vascular shunts (trauma, iatrogenic, cirrhosis, Osler–Weber–Rendu syndrome).

Answer 70

Answer B: Liver Duodenal injury is frequently associated with injury to other abdominal structures. The pattern of these associated injuries varies between blunt and penetrating trauma: blunt trauma: pancreas > liver > spleen > colon > small bowel > kidney. penetrating trauma: liver > pancreas > small bowel > kidney > colon > spleen.

Answer 71

Answer E: Decrease in hepatic T2 signal on MR Haemochromatosis can be primary or secondary. The primary form shows autosomal recessive inheritance and usually presents after middle age, particularly in women where menstruation is protective. Hepatomegaly and hyperpigmentation are seen in 90%. Diabetes can occur in up to 30% secondary to pancreatic beta cell damage. Significant signal loss on T2WI is very characteristic.

Answer 72

b Grade II laceration

Answer 73

b Echinococcus

Answer 74

Answer B: Haemangioma Hepatic haemangioma are the commonest benign liver tumours. They are typically hyperechoic on ultrasound and demonstrate centripetal enhancement with delayed `fill-in' on contrast-enhanced CT. Enhancing focal liver lesions can be usefully characterised according to the phase of their enhancement. Other lesions that show delayed (equilibrium phase) enhancement include: cholangiocarcinoma, solitary fibrous tumour and treated metastases.

Answer 75

Answer E: Uptake of hepatobiliary contrast Reticuloendothelial contrast agents, such as Ferrixan, carboxydextran-coated iron oxide nanoparticles (Resovist®) are taken up by both focal nodular hyperplasia (FNH) and adenoma. Hepatobiliary contrast agents, such as Gadolinium-Benzyloxypropionic tetra-acetate (Gd-BOPTA or MultiHance®) are not taken up by adenoma.

Answer 76

Answer C: Haemochromatosis Causes of increased liver attenuation pre-intravenous contrast include: haemochromatosis, haemosiderosis, iron overload, glycogen storage disease and amiodarone treatment.

Answer 77

Answer D: Schistosomiasis The described ultrasound appearances are typical of schistosomiasis. Radiological features rarely develop until the late stages and are signs of cirrhosis and fibrosis. Patients are at a significantly increases risk of hepatocellular carcinoma (HCC).

Answer 78

Answer C: Echogenic material in the portal vein lumen Echogenic material in the portal vein lumen (67%), increased in portal vein diameter (57%), portosystemic collateral circulation (48%), enlargement of a thrombosed portal vein above 15 mm (38 %).

Answer 79

38 Answer C: Chronic Budd-Chiari syndrome In acute Budd-Chiari syndrome the caudate lobe does not hypertrophy as it does in the chronic form (as it has separate drainage directly into the IVC). There are various causes of Budd-Chiari syndrome; 66% are idiopathic.

Answer 80

39 Answer C: Central scar

Answer 81

40 Answer A: Ascitic fluid The Child-Pugh score is derived from bilirubin and albumin levels, prothrombin time, hepatic encephalopathy and presence ascites.

Answer 82

41 Answer B: Colorectal Colorectal > Gastric > Pancreatic > Breast > Lung.

Answer 83

42 Answer B: Entarnoeba histolytica Amoebic abscesses typically present as a large solitary lesion in the right lobe of the liver. The contents have been described as `anchovy paste' or `chocolate sauce'.

Answer 84

43 Answer E: Budd-Chiari syndrome Occlusion of the hepatic veins/IVC, often due to thrombosis in hypercoagulable states such as pregnancy. Hepatosplenomegaly, with caudate hypertrophy, are early sonographic signs with non visualisation of the hepatic veins in 75%. Symptoms also include right heart failure and pulmonary oligaemia.

Answer 85

44 Answer C: Beta-thalassaemia All the options are causes of hepatosplenomegaly. Beta-thalassaemia is more common in the Mediterranean population and can cause microcytic anaemia and abnormal liver function. Affected patients are at increased risk of developing gallstones.

Answer 86

a HypointenseTi and hyperintense T2

Answer 87

39 Answer C: Increased periportal attenuation

Answer 88

40 Answer A: Adenoma Most focal liver lesions are hypointense on T1WI. Exceptions to this rule include: adenoma, fatty lesions, blood, proteinaceous material, melanoma metastases and contrast agents.

Answer 89

41 Answer C: MRI Sensitivity for detection of liver metastases: MR > CECT > FDG PET-CT.

Answer 90

42 Answer B: Hepatic artery Unlike pyogenic and amoebic infections, which usually enter the liver via the biliary ducts or portal vein, fungal infections typically enter via the hepatic artery.

Answer 91

43 Answer D: Budd-Chiari syndrome.

Answer 92

56 Answer C: Budd-Chiari syndrome This is the syndrome of clinical and pathological abnormalities seen with acute hepatic vein occlusion. Most cases are idiopathic but it can be related to radiation, chemotherapy, toxins and other causes. Hepatic veno-occlusive disease refers to occlusion of the post-sinusoidal venules with the inferior vena cava and major hepatic veins remaining patent.

Answer 93

1. (b) Haemangioma This is the commonest lesion seen with described appearance on ultrasound. Metastasis is also less likely given the age and features. Focal fatty deposition usually has angular margins and a ‘geographic appearance’ on ultrasound. Focal nodular hyperplasia has similar reflectivity to liver on ultrasound and may show mass effect. A Doppler signal can often be seen in the lesion.

Answer 94

4. (b) Malignant melanoma with hepatic metastases Melanoma metastases show increased signal on T1 because of the paramagnetic effects of melanin itself. Most liver metastases show low signal on non-contrast T1 images unless there is intralesional haemorrhage, when they can be seen as heterogenous lesions.

Answer 95

5. (b) Focal hepatic steatosis Focal fatty infiltration is typically diagnosed with in-phase and out-of-phase MRI, where the area involved demonstrates signal loss in out-of-phase imaging. This can be due to many causes including diabetes, alcoholism and obesity. Common locations include tip of segment 4, along the ligament teres and adjacent to the gallbladder. On MRI, this feature is not seen in any of the other conditions listed.

Answer 96

13. (d) Haemochromatosis In haemochromatosis there is excess deposition of iron in the liver resulting in increased density of the liver on CT and loss of T2 signal due to the paramagnetic effects of iron. This also causes skin pigmentation, diabetes and arthralgia.

Answer 97

15. (d) Focal nodular hyperplasia. These are the typical features of focal nodular hyperplasia as seen on MRI. Adenoma is heterogenous on all sequences and can be indistinguishable from hepatocellular carcinoma due to haemorrhage and necrosis. Haemangioma shows peripheral nodular enhancement with centripetal filling. Metastases are commonly heterogenous

Answer 98

22. (c) Pyogenic liver abscess A history of fever with the described imaging features is suggestive of this diagnosis. Haemangioma is hyperechoic on ultrasound and shows centripetal filling with contrast. Amoebic abscess are uncommon in the UK and may show septations with nodular walls. On ultrasound and CT a hydatid cyst shows septations, daughter cysts, debris and calcifications. A simple liver cyst has no debris and shows no marginal enhancement.

Answer 99

30. (a) Budd–Chiari syndrome This is caused by obstruction of one or more hepatic veins or the inferior vena cava. If the hepatic veins are seen on the grey scale but no flow is identified and reversed flow is not seen, Budd–Chiari syndrome is likely. There are numerous causes for Budd–Chiari syndrome, but most commonly it is idiopathic.

Answer 100

Answers: (a) Correct (b) Correct (c) Not correct (d) Correct (e) Not correct Explanation: Causes of hepato-cellular carcinoma are haemochromatosis, cirrhosis, hepatitis, Wilson’s disease, alpha 1 antitrypsin deficiency. Elevated alpha feto-protein levels are found in 50-60% cases of hepato-cellular carcinoma. On MRI, hepatoma shows increased signal intensity on T2-weighted images with peripheral gadolinium enhancement in 20% of the cases.

Answer 101

Answers: (a) Correct (b) Correct (c) Not correct (d) Correct (e) Correct Explanation: Caudate lobe is enlarged and hypertrophied in Budd chiari syndrome. Flip-flop enhancement pattern is seen with central hepatic enhancement in the early phase and peripheral enhancement in the late phase. Thrombosis in hepatic veins is more common cause than obstruction of the suprahepatic IVC.

Answer 102

Answers: (a) Correct (b) Not correct (c) Not correct (d) Not correct (e) Not correct Explanation: Hepatic adenoma increases in size during pregnancy. There are hypervascular lesions with significant risk of bleeding at the biopsy and hence biopsy is contraindicated. There are indistinguishable on all MRI sequences. There mostly located in the right lobe of liver in 60-75% of the cases.

Answer 103

Answers: (a) Not correct (b) Not correct (c) Correct (d) Not correct (e) Not correct Explanation: FNH is the second most common benign liver tumour after haemangioma. The usually occurs in young patients with more female ratio. There are multiple in 20% of the cases. A central scar is usually seen in FNH however it can be seen in giant haemangioma, hepato cellular carcinoma and hepatic adenoma. Central scar of FNH is non-enhancing on arterial phase however the rest of the tumour enhances significantly.

Answer 104

Answers: (a) Not correct (b) Not correct (c) Correct (d) Correct (e) Correct Explanation: Most common vascular complication of liver transplant includes hepatic artery thrombosis which occurs in 60% of the cases of vascular complications. It occurs within 15 days of transplantation. Portal vein thrombosis occurs in 1-2% cases of liver transplant.

Answer 105

Answers: (a) Not correct (b) Correct (c) Not correct (d) Not correct (e) Correct Explanation: Fibrolamellar carcinoma shows calcification in 40% of the cases. The tumour is unusually large, hypodense on unenhanced CT and hyperdense during the arterial phase following contrast administration. The not associated with elevated alpha-fetoprotein levels and chronic liver disease. On MRI, these tumours are heterogeneously hypointense on T1 and hyperintense on T2-weighted images.

Answer 106

Answers: (a) Correct (b) Not correct (c) Correct (d) Not correct (e) Not correct Explanation: Periportal low attenuation on contrast enhanced CT may be a feature of acute graft rejection, but it has poor sensitivity and specificity and is frequently seen with oedema of the periportal lymphatic vessels. Portal vein stenosis or thrombosis developsslowly, presenting with varices, splenomegaly and ascites. Portal vein stenosis may be treated by balloon dilatation, but once the thrombus is extensive and reaches the periphery of the intrahepatic portal vein branches, then a repeat liver transplant is only option.