Lange Review Ultrasonography Examination, 4th Edition

Answers and Explanations

At the end of each explained answer, there is a number combination in parentheses. The first number identifies the reference source; the second number or set of numbers indicates the page or pages on which the relevant information can be found.

1. (C) Renal size decreases as the compromise to blood flow increases. The kidney size is generally <9 cm when the renal artery is occluded. (3:624; 7:461)

2. (D) Avessel that is diffusely dilated is considered “ectatic.” Saccular, fusiform, and spindle-shaped are terms used to describe the shape of aneurysms. (3:529; 4:253, 254)

3. (C) The first major branch of the abdominal aorta is the celiac artery, which originates from the anterior wall of the aorta just inferior to the diaphragm. One to two centimeters distal to the origin of the celiac artery, the superior mesenteric artery arises from the anterior aortic wall. These vessels may share a common trunk. (3:571)

4. (B) A concentric, spindle-shaped dilation of the abdominal aorta is termed “fusiform” and is used to describe aneurysms. A saccular aneurysm is created by an outpouching from the aortic wall. Dissecting is a term used to describe a tear in the intimal lining of an artery allowing blood to course between the intima and the media. Ectasia refers to a vessel that is diffusely dilated. (4:253–255).

5. (D) The branches of the celiac artery (common hepatic and splenic) form a “seagull” appearance in the transverse imaging plane. They arise almost perpendicular to the celiac trunk at its bifurcation. (2; 6:72)

6. (B) The three branches of the celiac artery are the common hepatic, splenic, and left gastric. (4:233)

7. (C) Patients with a ruptured aortic aneurysm usually present with abdominal or back pain that worsens in the upright or erect position. (6:82)

8. (C) Aortic aneurysms are most often located below the renal arteries and in the common iliac arteries. (3:532)

9. (A) The splanchnic circulation supplies blood flow to the gastrointestinal system and is composed of the celiac artery, the superior and inferior mesenteric arteries, and their branches. The renal arteries are part of the urogenital system. (3:571, 572)

10. (B) A doubling of velocity across segments of a vessel of similar diameter is consistent with >50% reduction in diameter; a fourfold increase in velocity signifies a narrowing >75%. (5:259, 260)

11. (A) The aortic stent graft (endograft) is inserted percu-taneously over a catheter advanced into the aorta from the femoral artery. The endograft excludes the aneurysm which remains. With surgical repair, the aneurysm is most often treated with graft replacement of the aorta. (7:482–485)

12. (C) Hypertension is not a common cause of aortic dissection although it results in increased pressure on the arterial wall. Because the medial layer of the arterial wall weakens with age, this is the most predisposing condition for aortic dissection. (3:531)

13. (B) Arterial dissection is characterized by a tear in the intima of the arterial wall. This allows blood to course between the intima and media, creating a true and false lumen. The intimal flap can be seen on real-time images as an echogenic, pulsating structure within the lumen of the artery. (3:531)

14. (A) The common hepatic artery divides into the gastro-duodenal artery in the hepatoduodenal ligament and the right gastric artery at the liver hilum. (2; 4:240)

15. (B) Gallbladder. The splenic artery supplies blood to the spleen, pancreas, left half of the greater omentum, greater curvature of the stomach, and part of the fundus of the stomach. The common hepatic artery supplies the gallbladder. (4:240; 6:72)

16. (D) The splenic artery is the largest branch of the celiac artery. (6:72)

17. (A) Approximately 1–2 cm of the left gastric artery may be seen longitudinally. This artery is not routinely examined during evaluation of the mesenteric arterial circulation. (6:73)

18. (C) The normal celiac artery Doppler spectral waveform exhibits the characteristics of blood flow to low resistance end organs. It has rapid systolic upstroke, rapid deceleration, and constant forward diastolic flow. The peak systolic velocity is normally <200 cm/sec and the end-diastolic velocity is <55 cm/sec. (3:576; 4:483)

19. (A) The waveform demonstrates low diastolic flow and the absence of turbulence. These are features of a normal vessel supplying blood to a high resistance end organ. Flow-reducing superior mesenteric artery (SMA) stenosis would cause the peak systolic and end-diastolic velocities to increase to >275 cm/sec and 45 cm/sec, respectively. A post-stenotic signal would be evident immediately distal to the stenosis as a consequence of the pressure-flow gradient that develops with significant vessel narrowing. (3:573, 577)

20. (A) The SMA originates from the anterior wall of the aorta 1–2 cm below the celiac artery and behind the pancreas. It courses anterior to the left renal vein and parallels the aorta as it moves caudally. (4:243; 7:467)

21. (D) Acute, severe abdominal ischemia is associated with sudden occlusion of one or more of the mesenteric arteries. Chronic mesenteric ischemia has an insidious onset as a consequence of progression of atherosclerotic disease. Clinically, patients present with a triad of symptoms: postprandial pain, “fear of food” syndrome, and weight loss. (3:572–574; 7:466)

22. (B) The diagnostic criteria for flow-reducing SMA stenosis are peak systolic velocity >275 cm/sec, end-diastolic velocity >45 cm/sec, and a classic turbulent post-stenotic signal. (3:576; 5:483; 7:471)

23. (C) The median arcuate ligament of the diaphragm can compress the celiac artery origin during respiration. Compression occurs during normal respiration but is relieved with deep inspiration and breath holding because of relaxation of the diaphragmatic crus. While portal hypertension may cause increased hepatic artery velocity, this would not vary with respiration and is uncommonly transmitted to the celiac artery. Flow-reducing celiac artery stenosis, and mesenteric ischemia due to significant disease in one or more mesenteric arteries, would cause velocity elevation in the celiac artery. The velocities would not vary with respiratory maneuvers. (7:470)

24. (D) The inferior epigastric artery is a collateral pathway for occlusive disease involving the aorto-iliac system. Occlusion of the proximal mesenteric arteries is compensated through collaterals that commonly arise from the inferior mesenteric artery and its branches or through the pancreaticoduodenal arcade. (3:270; 7:468)

25. (A) Standard contrast arteriography with selective lateral views has historically been used to confirm the sonographic findings and to define collateral pathways prior to revascularization. In recent years, CT scans have been used to localize disease and display relational anatomy. (8:239, 240)

26. (C) The left renal vein courses from the hilum of the left kidney, crosses the aorta anteriorly between the aorta and SMA, and moves inferior to the pancreas before entering the IVC. (4:288; 6:77)

27. (B) Arcuate arteries arise from the interlobar arteries. They curve around the base of the pyramids where they give rise to the lobular arteries that supply the cortex of the kidney. Their flow pattern is normally low resistance like that of the main renal artery and its larger branches. (4:245; 5:676)

28. (D) Flow-reducing renal artery stenosis is indicated if the renal-aortic ratio is >3.5, the peak systolic renal artery velocity is >180 cm/sec, and there is a post-stenotic signal. (5:664; 7:460, 461)

29. (B) If the renal-aortic velocity ratio is used to determine severity of renal artery stenosis, care must be taken to assure that the aortic velocity is between 40 and 100 cm/sec. Use of velocities outside those values in the calculation can result in over or under-estimation of the severity of disease. Example: renal artery velocity = 150 cm/sec and the aortic velocity = 30 cm/sec. The renal-aortic ratio = 5.0, suggesting significant renal artery stenosis. Similarly, if the renal artery velocity = 320 cm/sec and the aortic velocity = 120 cm/sec, the renal-aortic ratio will be 3.0 and flow-limiting renal artery stenosis would not be indicated. (7:460).

30. (A) This inverse relationship is caused by the impedance to arterial inflow that results from intrinsic disease. Such conditions are generally associated with endovasculitis and interstitial edema. In cases of marked renovascular resistance, the diastolic flow component of the Doppler spectral waveform may approach zero or reverse. (5:664)

31. (D) The Doppler spectral waveform associated with mild acute tubular necrosis may be indistinguishable from the signal recorded in a normal kidney. Most often, there is increased diastolic flow as a result of arterial-venous shunting. This is evident in a normal resistive index (RI). As AT progresses in severity, renovascular resistance increases and the RI is elevated. (4:247; 5:680)

32. (B) The fasting, normal inferior mesenteric artery demonstrates a high resistance waveform pattern typical of arteries feeding resting, muscular tissues (fasting SMA, peripheral arteries). The features of such waveforms are rapid systolic upstroke, rapid deceleration, and low diastolic flow. There may be a brief period of early diastolic flow reversal. The hepatic, renal and splenic arteries supply high flow demand organs and their waveform is characterized by constant forward diastolic flow. (3:577, 578; 5:696)

33. (C) The most common curable cause of renal-related hypertension is atherosclerotic renal artery stenosis. The second most common cause is due to medial fibromuscu-lar dysplasia. This is a non-atherosclerotic disease entity that commonly affects the mid-to-distal segment of the renal artery in young, hypertensive women. (7:458)

34. (A) The term “tardus parvus” refers to the delayed systolic upstroke and run-off evident in the dampened Doppler spectral waveforms recorded distal to flow-limiting stenosis or arterial occlusion. Medical renal disease, hydronephrosis and pyelonephritis cause increased renovascular resistance. The resultant waveform would demonstrate low diastolic flow. (3:620)

35. (C) When kidney size differs by more than 3.0 cm, occlusion of the renal artery on the side with the smaller kidney should be suspected. A small kidney with absent Doppler signals in the renal artery and dampened signals within the renal parenchyma from collateral vessels is consistent with renal artery occlusion. (7:457)

36. (A) A diastolic to systolic velocity ratio <0.20 is consistent with renal parenchymal disease (medical renal disease). Renal artery stenosis, occlusion, and fibromuscular dysplasia do not result in elevated vascular resistance in the kidney unless there is associated medical renal disease. (7:462)

37. (B) The right and left common iliac veins come together to form the IVC at the level of the fourth or fifth lumbar vertebrae. (4:200)

38. (B) The pathologic condition that most often affects the inferior vena cava is thrombosis. Primary tumors of the IVC are uncommon but tumor extension or compression of the IVC may occur. (3:545)

39. (D) Carcinomas of the kidney, adrenal gland, and liver often extend into the inferior vena cava via paracaval lymph nodes. (3:545)

40. (D) Pregnancy can result in extrinsic compression of the inferior vena cava but prolonged, severe stasis is uncommon and caval thrombosis is an infrequent complication of pregnancy. Stasis due to prolonged inactivity, including surgery, can lead to venous thrombosis. Conditions that lead to dehydration, such as sepsis, promote development of thrombosis. (6:186)

41. (C) A resistive index less than 0.70 is considered normal for an adult. (5:677).

42. (C) Continuous, non-phasic Doppler spectral waveforms will be recorded when the lumen of the inferior vena cava is partially compromised. (3:546, 547)

43. (B) Contrast arteriography would not be a procedure of choice for confirmation of inferior vena caval thrombosis. Arteriography will enhance definition of the lumen of arteries, but it is limited in its ability to define filling defect or absence of flow in the outflow circulation. (3:283)

44. (B) The right hepatic vein divides the right lobe of the liver into anterior and posterior segments. The middle hepatic vein divides the liver into right and left lobes. The left hepatic vein separates the medial and lateral segments of the left lobe of the liver. The portal vein enters the liver through the porta hepatis. (3:520)

45. (D) The “Playboy bunny” sign refers to the real-time image of at least two of the three major hepatic veins obtained with oblique, cephalic angulation of the transducer from a right paramedian approach under the xiphoid process. (6:76)

46. (A) The three major hepatic veins drain into the inferior vena cava. The portal vein is formed by the confluence of the splenic and superior mesenteric veins and carries oxygenated blood into the liver. (3:520; 7:438)

47. (B) The spectral waveform from the normal hepatic veins demonstrates somewhat chaotic, pulsatile flow. There are two cycles of forward flow toward the heart as a result of reflections of right atrial and ventricular diastole. These are followed by a third cycle which is brief and reversed, accompanying atrial systole. (3:523)

48. (D) The portal vein carries more than 50% of the oxygen required by the liver. While its responsibility for blood supply to the liver may increase when the portal venous flow is compromised, the hepatic artery most often supplies only 30% of the blood flow. The aorta and SMA do not provide flow directly to the liver. (10:319)

49. (B) The portal vein is formed by the confluence of the superior mesenteric and splenic veins. (2; 3:518)

50. (D) The portal vein lies anterior to the IVC, cephalad to the head of the pancreas, and caudal to the caudate lobe. (2; 7:438)

51. (B) The portal triad is composed of the portal vein, the hepatic artery, and the common bile duct. (7:439; 10:317)

52. (D) Hepatic veins are boundary formers which divide the segments of the liver. They course longitudinally toward the inferior vena cava, increasing in diameter as they approach the hepato-caval confluence. Portal veins course horizontally toward their origin at the porta hepatis. (2; 3:520)

53. (A) Portal venous flow exhibits low velocity, minimally phasic variation as a result of respiration-related changes in thoracic pressure. Flow direction is normally hepa-topetal (toward the liver). Pulsatility is common to the hepatic venous circulation. (3:520)

54. (C) Occlusion of one or more of the hepatic veins is termed Budd-Chiari syndrome. Cavernous transformation may follow portal vein thrombosis and appears as periportal collaterals in the porta hepatis. Hemangioma is a benign tumor of the liver. Fibromuscular dysplasia is a non-atherosclerotic disease entity that causes concentric narrowing and dilation of arteries. This condition is observed in renal and carotid arteries. (3:602; 4:294)

55. (D) Hepatic veins divide the liver into segments, coursing longitudinally toward the vena cava. For this reason, they are considered “boundary formers.” Unlike the portal veins which have echogenic walls due to the collagen within their boundaries, the hepatic vein walls lack echogenicity The veins usually are not compressed during a Valsalva maneuver, which increases abdominal pressure. (7:441)

56. (C) In Western nations, portal hypertension is most often caused by cirrhosis. Cirrhosis may be caused by hepatitis, but is not the direct cause of portal hypertension. Hepatocellular carcinoma and sclerosing cholangitis may be found in association with portal hypertension but are not the primary causes of this condition. (3:588)

57. (B) Portal vein thrombosis may be followed by development of serpiginous periportal collaterals within the hepatic hilum. This is referred to as cavernous transformation. (7:441)

58. (A) Normal blood pressure within the liver is 5–10 mm Hg. Portal hypertension is present when the pressure gradient from the portal vein to the hepatic veins or IVC exceeds 10 mm Hg. (3:585; 10:319)

59. (C) The most common type of portal hypertension is intrahepatic due to sinusoidal obstruction resulting from cirrhosis. (3:585)

60. (C) Portal hypertension causes the portal vein velocity to decrease due to increased resistance to flow and the flow pattern becomes continuous as respiratory variation disappears as a result of increased hepatic pressure. The portal vein enlarges to >13 mm in diameter and with severe disease, the flow direction in the portal vein reverses to decompress the liver. (3:588; 10:320)

61. (D) Mycotic aneurysms are arterial dilations that are infected. Marfan syndrome is associated with stretching and weakening of the aortic wall which may lead to development of an aneurysm. Injuries that cause penetration of the arterial wall may result in pseudoaneurysms. (6:82)

62. (C) Left portal vein. The paraumbilical (umbilical) vein is a branch of the left portal vein. It serves as a collateral pathway for decompression of the liver in patients with portal hypertension. It carries blood away from the liver, exiting in the ligamentum teres and forming a network of veins surrounding the umbilicus (caput medusa). (3:591; 4:295)

63. (A) The paraumbilical (umbilical) vein is a branch of the left portal vein. It serves as a collateral pathway for decompression of the liver in patients with portal hypertension. The coronary vein (left gastric vein) is another important collateral pathway in patients with portal hypertension. (3:591)

64. (C) Most often flow is shunted from the main portal vein to the right hepatic vein to empty into the systemic venous circulation (IVC). This is an effective, nonsurgical method used to decompress the liver in patients with portal hypertension. (7:442)

65. (A) The color-flow image and peak systolic velocity (>250 cm/sec) suggest stenosis of the TIPS. Velocities are normally in the range of 65–220 cm/sec with flow directed toward the shunt. (7:442; 9:290)

66. (C) Flow direction should remain normal, or hepatofugal, following placement of a TIPS. Hepatopetal flow would suggest that the shunt is not functional and flow will be diverted in the hepatic and portal vein to allow the liver to decompress. Flow is normally pulsatile in the hepatic veins. Continuous, non-phasic signals suggest obstruction to venous outflow. (9:291)

67. (A) The echogenic walls of the TIPS are apparent within the liver parenchyma. Hepatic venous stenosis is best demonstrated with color flow imaging. A hemangioma is a benign liver tumor. Hepatocellular carcinoma would not have echogenic boundaries. (9:290)

68. (C) Peak systolic velocity in a normally functioning TIPS ranges from 65 to 220 cm/sec. Flow is shunted toward the TIPS. Therefore, flow direction in the portal vein will be hepatopetal. Flow direction in the hepatic veins should remain hepatofugal. (9:291)

69. (B) These findings suggest TIPS stenosis. Normally, velocity in the main portal vein exceeds 100 cm/sec. Flow direction is hepatopetal. In this case, the shunt velocity has deteriorated to <60 cm/sec. This is consistent with compromised shunt flow. The direction of flow in the hepatic veins is hepatopetal, suggesting collateral flow to compensate for shunt dysfunction. (9:291)

70. (C) Renal arterial inflow may remain normal even though the renal vein is thrombosed. Given this, the Doppler spectral waveform demonstrates rapid systolic upstroke, rapid deceleration, but because outflow through the venous system is compromised, the diastolic flow is reversed and blunted. This is consistent with impedance to outflow through the renal vein. (7:454)

71. (B) Patients with renal vein thrombosis may initially have proteinuria, epigastric pain, fever, and hematuria. Renal vein thrombosis is seen more frequently in children than adults. (6:212)

72. (C) The Doppler spectral waveform demonstrates peak systolic velocity <200 cm/sec, end-diastolic velocity <55 cm/sec, and the absence of a post-stenotic signal. These findings are consistent with normal flow in the celiac artery. (3:579, 580)

73. (B) Note should be taken of the decrease in peak systolic velocity associated with deep inspiration. These findings are suggestive of median arcuate ligament compression of the origin of the celiac artery. The celiac artery velocity does not alter significantly in the postprandial state because the liver and spleen do not participate immediately in meeting the metabolic needs associated with digestion. Fixed stenosis and collateral compensatory flow are not affected by changes in respiration. (3:581, 582)

74. (C) If the urethra is obstructed, hydronephrosis will be bilateral because the urethra is the conduit for both ureters. Renal calculi are generally not chronically obstructive at ureteral level. (6:186).

75. (B) In cases of acute renal vein thrombosis, the kidney enlarges and becomes hypoechogenic. The pyramids are prominent but the corticomedullary junction is indistinct. With partial obstruction of the renal vein, the Doppler spectral waveform demonstrates absence of respirophasicity Unlike the findings with renal artery occlusion, the renal size is most often unaffected. (3:624, 625)

76. (B) In hydronephrosis, the kidney exhibits a cystic area within the echogenic renal sinus. This acoustic difference may be mild, moderate, or severe, dependent on the severity and length of the obstruction. Renal infarction produces wedge-shaped flow defects at the level of the renal hilum that may extend to the level of the renal cortex. Renal artery occlusion is evidenced by an absence of flow in the main real artery. Collateral flow may be documented within the renal parenchyma. Renal calculi are most often echogenic with sharp, marginated acoustic shadowing. (6:186)

77. (D) With obstructive hydronephrosis, the resistive index is most often >0.70. (4:86)

78. (A) A cadaveric liver transplant is termed orthotopic. The recipient’s liver and gallbladder are excised and the cadaveric liver is transplanted. When heterotopic transplantation is used, the recipient’s liver remains in place and a portion of the donor liver is transplanted. The terms “heterogeneous” and “homogeneous” refer to acoustic properties of atherosclerotic plaque or other tissue. (5:721)

79. (C) Because the recipient’s liver is removed, an orthotopic liver transplant requires at least three anastomoses: the extrahepatic portal vein, hepatic artery, and the suprahepatic IVC. A fourth anastomosis at the infrahepatic IVC may be necessary. (5:721)

80. (A) Sonography may define many of the vascular problems associated with liver transplant dysfunction, but it lacks sensitivity for diagnosis of liver transplant rejection. (7:443–445)

81. (D) The hepatic artery provides blood flow to the liver transplant. Thrombosis of the hepatic artery places the organ in jeopardy of failure. Hepatic artery and IVC stenoses can be compensated through collateral pathways. Thrombosis of a hepatic vein has little consequence while portal vein thrombosis may threaten the survival of the transplanted organ and recipient. (7:443)

82. (B) The elevation in peak systolic velocity, accompanied by delayed systolic upstroke as evidenced by the systolic acceleration time >0.8 and a low resistive index, is consistent with flow-limiting hepatic artery stenosis. There would be no evidence of flow if the hepatic artery were thrombosed. Portal vein obstruction would not cause delayed acceleration in the hepatic artery. (4:242)

83. (C) The “to- and-fro” spectral Doppler flow pattern in the neck of a pseudoaneurysm is diagnostic. The pattern is the result of high-pressure arterial flow entering the neck during systole and exiting to the lower pressure of the parent artery during diastole. This produces a rapid systolic upstroke and reverse diastolic flow (“to-fro”) pattern. Although spectral broadening is apparent due to rapid changes in direction, a post-stenotic signal is not present. Low resistance Doppler waveforms are associated with high flow demand organs and arteriovenous communications. An intimal tear may lead to arterial dissection. (3:393)

84. (C) The diameter of the portal vein, measured just above the IVC with the patient in quiet respiration, is normally <13 mm. With deep inspiration, the diameter may increase to 15–16 mm. (10:321)

85. (B) The common hepatic artery divides into the gastro-duodenal artery and the proper hepatic artery at the level of the hepatoduodenal ligament. (4:240)

86. (D) Renal medial fibromuscular dysplasia affects the mid-to-distal segments of the native renal artery, but is not associated with renal transplant dysfunction. (5:684–694; 9:322)

87. (C) The external iliac artery is most often chosen as the anastomotic vessel for the transplant renal artery. The transplant renal artery may be anastomosed to the aorta in children. (5:685; 9:324)

88. (D) Renal transplant rejection is suggested sonographically by an increase in renal volume, increased cortical echogenicity, an indistinct corticomedullary boundary, and thickening of the renal pelvis. (4:268)

89. (A) The Doppler spectral waveform pattern associated with acute renal transplant rejection is characterized by rapid systolic upstroke, rapid deceleration, and low or absent diastolic flow. Acute rejection is associated with endovasculitis and accumulation of interstitial fluid. These factors cause elevation of renovascular resistance. This impedes arterial inflow to the kidney and diastolic flow, consequently, decreases. (5:685–688)

90. (B) Moderate ATN is associated with slight increase in renovascular resistance. The Doppler spectral waveform is characterized by rapid systolic upstroke, rapid deceleration, and increased pulsatility as a result of increased resistance to arterial inflow. (5:688, 689)

91. (C) Transplant renal artery stenosis is suggested by a renal artery to iliac artery velocity ratio >3.0. Answers (A) and (B) are related to flow-limiting stenosis in a native renal artery. A diastolic to systolic velocity ratio is used to confirm medical renal disease. (5:691)

92. (D) The right renal artery has branches that supply blood to the adrenal and ureter, but not the pancreas. All other statements are true regarding this artery. (5:662; 7:452–456)

93. (C) Because of the transmission of high-pressure arterial flow into the low-pressure venous circulation, renal transplant arteriovenous fistulae demonstrate high-velocity turbulent arterial signals and pulsatile venous flow. (3:631)

94. (C) Splenic vein thrombosis is the most serious complication of pancreas transplantation as it threatens organ survival. While arterial inflow is maintained via multiple channels, drainage of the organ is principally through the splenic venous circulation. (9:327–329)

95. (B) Portal venous flow is normally toward the liver, or hepatopetal in direction. (10:319)

96. (C) Portal venous flow volume decreases with portal hypertension. Flow is diverted to the systemic circulation via collaterals such as the coronary vein and paraumbili-cal vein. Superficial venous collaterals are often apparent surrounding the umbilicus (caput medusa). (10:322)

97. (A) TIPSs are used to treat recurrent gastrointestinal bleeding and refractory ascites due to portal hypertension. The shunt is intrahepatic and carries blood from the portal vein to a hepatic vein for drainage into the systemic venous circulation (IVC). (9:289–291; 10:324)

98. (C) As renal artery stenosis progresses to occlusion, kidney size decreases due to restricted blood flow. A difference in kidney size >3.0 cm should raise suspicion of compromised blood flow on the side with the smaller organ. Kidney length is most often <8 cm. Unless the occlusion was acute, low-amplitude, low-velocity collateral flow signals will be found throughout the renal parenchyma. (7:457)

99. (D) The renal acceleration index is defined as the change in distance between the onset of systolic flow and the peak systolic velocity divided by the acceleration time. It is used to predict significant proximal renal artery stenosis. (9:314)

100. (C) A decrease in pressure and flow occurs in most vessels in the arterial system when the diameter of the artery is narrowed by 50–60%. This approximates a 75–80% area reduction. (3:10)

101. (B) Post-prandially, vascular resistance decreases in the tissues fed by the SMA. The Doppler spectral waveform reflects the change by altering its normally high resistance flow pattern to a low resistance pattern. This is characterized by rapid systolic upstroke, rapid deceleration, and forward diastolic flow. (5:700–702)

102. (C) The “seagull sign” formed by the celiac artery and its primary branches, the common hepatic and splenic arteries, can best be seen from a transverse image plane at the level of the SMA. The transducer should be angled slightly cephalad as the celiac artery arises from the anterior aortic wall approximately 1–2 cm proximal to the SMA. (3:513; 7:468, 469)

103. (A) Color artifact in the tissues surrounding arteries is most often due to turbulence associated with rapid disturbed flow. The chaotic flow causes vibration of the arterial wall and surrounding tissues and the movement is color encoded. This feature is used to identify the presence of bruits associated with significant flow disturbance, which can occur with sharp angulation of a vessel or flow-limiting stenosis. Although an arteriovenous fistula is possible, it is more likely that kinking or stenosis at the anastomotic site is responsible for the disturbed flow. Pseudoaneurysms are diagnosed by the “to-and-fro” flow pattern found in the neck that connects the pseudoaneurysm to the parent artery. (4:450)

104. (C) The “to-and-fro” Doppler spectral waveform is diagnostic of a pseudoaneurysm. It is caused by the change in pressure and flow direction within the neck of the false aneurysm as blood moves into the aneurysm in systole and returns through the neck to the native artery in diastole. (3:392)

105. (D) Acute occlusion of the renal artery would most likely result in the absence of collateral flow within the organ. Collateral vessels develop in patients who have flow-limiting disease and are evident as low-velocity, low-amplitude waveforms throughout the kidney. Absent diastolic flow indicates elevated renovascular resistance and medical renal disease. (7:457)

106. (C) There is a reported rupture rate of 10% per year for abdominal aortic aneurysms measuring >6 cm in diameter. For this reason, large aneurysms should be treated emergently to prevent risk of rupture. (3:532)

107. (A) The second most common cause of renovascular hypertension is fibromuscular dysplasia. This non-atherosclerotic disease entity most commonly affects the mid-to-distal segment of the renal artery and is found predominantly in younger women. (7:458)

108. (D) The color flow image illustrates an aortic dissection which is seen as “true” and “false” channels within the aortic lumen. The channels are separated by an Intimal flap. A saccular aneurysm appears as an “outpouching” from the aortic wall. Fusiform aneurysms are spindle-shaped as a result of concentric dilation of the artery. Mycotic aneurysms are infected aneurysms whose shapes are variable.

109. (D) The transverse image illustrates an echogenic flap of intima within the lumen of the aorta. This flap, created by a tear in the intima, allows blood to flow between the intima and media in true and false channels. (3:531)

110. (C) The left gastric artery is not routinely evaluated during a mesenteric duplex study. The artery is difficult to image unless it has enlarged as a result of increased flow volume when there is occlusive disease in the hepatic, splenic, or celiac arteries. (3:513, 514)

111. (D) The Doppler spectral waveform from the SMA represents flow-reducing SMA stenosis (peak systolic velocity >275 cm/sec, end-diastolic velocity >45 cm/sec, and a post-stenotic signal). This waveform demonstrates significantly elevated systolic velocity and pan-systolic spectral broadening consistent with turbulent flow. The end-diastolic velocity is well above 45 cm/sec. A post-stenotic signal is not shown. Velocities at the values illustrated in this study would not be consistent with those seen as a result of collateralization or eating. A fasting SMA waveform is characterized by low diastolic flow. (7:471)

112. (A) A rapid decrease in velocity and turbulent flow patterns distal to arterial stenosis are characteristic of a post-stenotic signal. This flow pattern is caused by a decrease in pressure and flow that occurs when the diameter of an artery is significantly reduced. Kinetic energy is decreased at the distal end of a stenosis. When tandem lesions are present, the entrance and exit effect on energy as blood moves through the lesions results in major energy loss distally. (5:160–168)

113. (A) The left renal vein can best be seen from a transverse image plane just inferior to the SMA. It will be noted to cross the aorta anteriorly in most patients. In a small percentage of patients, the left renal vein is retro-aortic or bifid with one limb crossing the aorta anteriorly and the other inferiorly. (7:454)

114. (B) The color-flow image illustrates two renal arteries on the right side. Multiple renal arteries occur in approximately 20% of the population and, for reasons that are not well understood, are more common on the left side. (7:456)

115. (B) In the normal portal vein, flow is hepatopetal in direction (toward the liver). Using the scan plane and transducer orientation described, the sound beam is pointed toward the direction of flow. The color bar indicates flow toward the transducer is red. (10:318, 319)

116. (D) Power Doppler is based on the intensity of the returned Doppler signal and the difference between that intensity and the signal returned from surrounding tissue. As such, it is not as angle-dependent as color Doppler because that modality relies on color-encodement of shifted frequencies. Power Doppler excels at demonstrating low-velocity flow, tissue perfusion, and vessel wall-to-lumen interfaces. Flow is highlighted by summing forward and reverse velocities relevant to the sound beam to produce a power spectrum. The shortcoming of power Doppler is that it cannot illustrate flow direction. (3:78)

117. (C) Distal to an 80% stenosis, the Doppler spectral waveform will assume a tardus parvus morphology. This is characterized by delayed systolic upstroke and delayed run-off. The early systolic peak is not apparent. Absence of diastolic flow is consistent with elevated renovascular resistance, which does not always accompany renal artery stenosis. (3:622)

118. (C) Heterotopic partial transplantation is the most common type of liver transplantation. Patients retain their liver and receive a portion of a liver from a donor. Ortho-topic transplantation is used for cadaveric liver transplants. (5:721–724)

119. (C) The abdominal aorta is considered if its diameter exceeds 3 cm or is 1.5 times larger than the proximal normal segment. (3:554)

120. (D) The IVC is not routinely interrogated during examination of a renal transplant. The vessels of interest are the inflow artery and vein (external iliacs), the transplant renal artery and vein, and the vessels within the renal parenchyma. (9:322, 323)

121. (A) The hepatic artery is not routinely interrogated during evaluation of a pancreas transplant. The celiac and superior mesenteric arteries are anastomosed to the recipient iliac and should be routinely evaluated to ensure arterial perfusion of the pancreas transplant. The venous drainage is through the portal venous system. Patency of the splenic vein must be confirmed, because thrombosis of this vessel has an impact on organ survival. (5:728)

122. (D) Dependent on the severity of portal venous compromise, patients may present with variceal bleeding, ascites, hepatomegaly, splenomegaly, and extensive collateral circulation. (10:321)

123. (C) The classic flow profile associated with significant arterial stenosis is characterized by increased velocity at the site of stenosis, post-stenotic turbulence, followed by return to laminar flow. Collateral compensatory flow will exhibit elevated velocity throughout the visualized length of the collateral vessel. There is no evidence of a pressure-flow gradient, and therefore, a post-stenotic signal is not present. (5:165–167)

124. (C) A complication of aortic stent grafts (endografts) that is not encountered with surgical repair of abdominal aortic aneurysms is risk of blood reentering the residual aneurysm sac. Blood within the sac is termed an “endoleak.” Endoleaks have been associated with all of the devices on the market and have appeared as long as 4–5 years after aneurysm repair. For this reason, it is likely that aortic stent grafts will require lifelong follow-up with sonography and/or other imaging modalities that have adequate sensitivity for endoleak detection. (7:482)

125. (D) Turbulent, chaotic flow patterns are not associated with endoleaks. Dependent on the source and classification of the endoleaks, flow patterns usually demonstrate high resistance with low diastolic flow or a to- and-fro flow pattern associated with changes in pressure gradients between the residual aneurysm sac and the feeding artery. The Doppler spectral waveform from the endoleak will differ in morphology from the spectral waveform recorded in the body or limb of the aortic stent graft. (3:556, 557)

126. (D) The right renal artery can be imaged satisfactorily in most patients from a transverse plane at the level of the left renal vein or from a right intercostal approach through a transverse image of the kidney. Additionally, it should be recognized that the right renal artery courses posterior to the IVC. The artery can be seen in cross-section from a longitudinal image of the IVC. This image plane is used for percutaneous placement of IVC filters under ultrasound guidance. (3:614, 615)

127. (B)

128. (D)

129. (B)

130. (C) When blood pressure is elevated in the liver, the organ will attempt to decompress through spontaneous shunting, which directs flow away from the liver into the systemic venous circulation. A common pathway is from the splenic vein to the left renal vein, which empties into the IVC. (7:437)

131. (D) Current diagnostic criteria for identification of flow-reducing SMA stenosis are: Peak systolic velocity >275 cm/sec, end-diastolic velocity >45 cm/sec, and a post-stenotic signal. (7:467–469)

132. (C) The caput medusa associated with portal hypertension is associated with superficial collateral veins surrounding the umbilicus. The veins originate within the liver from a recanalized umbilical vein, a branch of the left portal vein. (10:321, 322)

133. (C) The cruciate arteries are part of the peripheral arterial system. The segmental, interlobar and arcuate arteries are found within the renal parenchyma. (5:676)

134. (D) The adult kidney is normally 11–13 cm in length, 5–7 cm in width, and 2–3 cm in anteroposterior thickness. The size of the kidney decreases with progression of renal artery stenosis. (6:170)

135. (C) The peak systolic velocity in the adult aorta is normally between 70 and 140 cm/sec. The velocity decreases with age. (4:240)

136. (D) Elevated resistive index (RI) is consistent with impedance to arterial inflow to the kidney. This can be caused by the endovasculitis and interstitial fluid accumulations associated with acute rejection or the peritubular necrosis that is a signature of ATN. It should also be noted that pressure applied with the transducer to the tissues over the renal transplant is transmitted into the organ and increases resistance to arterial inflow. This is translated to elevated RI. (5:685)

137. (D) Blood flow in the suprarenal aorta is entering arterial branches that supply the low resistance vascular beds of the liver, spleen, and kidneys. The only high-resistance organ supply in a fasted patient is that of the superior mesenteric artery. Because the majority of flow is to high-demand end organs, the spectral pattern in the suprarenal abdominal aorta may be biphasic. Waveform morphology is in large part dependent on the compliance of the aorta and its branch arteries and the level of flow demand expressed by the fasting liver, spleen, and gastrointestinal circulation. Because of this, high-resistance triphasic waveforms, which are generally seen in the infrarenal aorta, may also be evident in the suprarenal segment. (3:575, 576)

138. (B) As the necrotic process associated with acute tubular necrosis progresses from moderate to severe, resistance to arterial inflow to the kidney increases. This is reflected in the Doppler spectral waveform which demonstrates rapid systolic upstroke and rapid deceleration because the obstructive process is distal to the renal artery. The amount, amplitude, and descent of the diastolic flow component are reduced and diastolic flow will be low or absent, dependent on the severity of disease. (9:324)

139. (C) A saccular aneurysm forms an outpouching from the aortic wall. While pseudoaneurysms may appear as outpouchings, they are distinguished from true saccular aneurysms by a puncture of one or more of the layers of the arterial wall, allowing blood to escape into the surrounding tissues. A fusiform aneurysm is characterized by concentric dilation of the artery. (3:532)

140. (A) The celiac artery arises from the anterior aortic wall. During normal respiration, the median arcuate ligament of the diaphragm can slide over the proximal celiac artery. This extrinsic compression causes narrowing of the arterial lumen and velocity increases. With deep inspiration, the ligament slides off the artery and normal blood flow is restored. (7:470)

141. (C) To prevent overestimation or underestimation of severity of renal artery stenosis, the renal-aortic ratio should only be used when the aortic velocity is between 40 cm/sec and 100 cm/sec. (7:460)

142. (A) The inferior mesenteric vein drains into the splenic vein to the left of the confluence of the portal and splenic veins. (10:317)

143. (B) The cystic vein, a branch of the portal vein, drains into the gallbladder. It is usually not visualized sonographically When drainage of the vein is compromised in patients with portal hypertension, varices can develop in the gallbladder wall. Search for these varices during sonographic evaluation may support the diagnosis of portal hypertension. (10:318)

144. (D) Pulsatility of the Doppler spectral waveform recorded in the portal vein is abnormal and most often suggests right heart failure, tricuspid regurgitation, a fistula between the hepatic vein and portal vein, or portal hypertension. The portal venous flow pattern is normally minimally phasic with respiratory variation. (10:318)

145. (C) Splenomegaly is diagnosed when the length of the spleen exceeds 13 cm. The measurement should be made from a cranio-caudad image plane to ensure accuracy. (10:320)

146. (B) The coronary vein is the most common collateral pathway in patients with portal hypertension and is found in >80% of patients. The paraumbilical (umbilical) vein is also an important pathway for decompression of the liver. (10:321)

147. (C) The coronary vein is considered to be enlarged when its diameter exceeds 6 mm. (10:321)

148. (A) When pressure increases in the liver, the flow direction in the coronary vein may reverse. Normal flow direction is toward the splenic and portal veins. (10:321)

149. (D) The portal vein courses throughout the liver with the hepatic artery and common bile duct. Together, they form the portal triad. The three structures are covered by Glis-son’s capsule, which is acoustically echogenic, accounting for the brightness of the walls of the triad. (6:94, 95)

150. (B) Because the aorta may be tortuous, the correct dimensions of abdominal aortic aneurysms can be obtained by following the axis of the aorta rather than the axis of the spine. (3:533)