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Renal Angiography
Vasopressin at 0.2 Dim in for 24 hours. Vasopressin at 0.1 Dim in for 24 hours. Infusion discontinued if no clinical evidence of further bleeding. If the initial infusion dose rate is 0.4 Dlmin, the regimen is as follows: Vasopressin at 0.4 D/min for 6-8 hours. Vasopressin at 0.3 D/min for 16 hours. Vasopressin at 0.2 D/min for 16 hours. Vasopressin at 0.1 D/min for 16 hours. Infusion is discontinued if no clinical evidence of further bleeding.
References Athanasoulis CA, et al. Interventional Radiology. Philadelphia, PA: WB Saunders, 1982:121. Addendum After vasopressin has been tapered, an approximate 6-8-hour infusion of saline through the indwelling catheter is indicated. Thus, if the patient rebleeds, the catheter is already in place, and vasopressin may be restarted. At this point, an alternate therapy should be considered (for example, surgery, superselective catheterization, and embolization, or a subsequent course of vasopressin therapy). 4:00 pm Renal Angiography Harold A. Mitty, MD Mount Sinai School of Medicine New York, New York Learning objectives: As a result ofattending the lecture on renal angiography, the attendee will be able to: 1) List seven causes of renal artery stenosis; 2) Describe the vascular patterns of renal cell carcinoma, transitional cell carcinoma, oncocytoma, and angiomyolipoma,. 3) Distinguish between subcapsular and pericapsular hematomas; 4) Recognize retroaortic renal vein and circumaortic renal vein; and 5) Recognize renalparenchymal vascular diseases such as polyarteritis nodosa, sclerodenna, necrotizing angiitis, chronic glomerulonephritis, and nephrosclerosis. Indications Indications for renal angiography will vary depending on factors such as referral patterns, size of the urology service, and especially the presence of a transplant service. In addition, there have been changes in indications as other imaging modalities have become Widely available. This is illustrated in Table 1. It is apparent from these statistics that the current primary role of renal arteriography is in the evaluation of renal donors and in the treatment of significant renal artery stenosis. With the increased sensitivity of MRA, the need for conventional renal arteriography will decrease.
Table 1 Indications for Renal Angiography: 50 Consecutive Patients Per Year Mount Sinai Hospital, New York, NY
Mass? Neoplasm Donor Hemaruria RAS (Rule out) PTRA RAS (transplant) Embolus peN or Bx bleed Abscess Aneurysm Renal fa ilure
1976
1986
19%
23
o
25 9
28
8 7
6
o 1
o 1
o 5
o o 2
4
o
1
1
3
1
1
4 3 5 5 4
o o o o
Anatomic Features and Development Multiple Arteries and Origins Twenty percent to thirty percent of normal adults have two renal arteries supplying one kidney. This common variation is one of the major reasons for performing initial aortography before selective renal arteriography. Multiple renal arteries are also mOre common with anomalies of renal ascent and horseshoe kidneys. Surgeons generally prefer to use the left kidney of donors. In the event of more than one left renal artery or very early bifurcation, the right kidney may be selected.
Course The course of the right renal artery is posterior to the inferior vena cava. This is of importance in surgery for large renal cell carcinomas. Because the surgeon uses an anterior approach, the vena cava must be mobilized to allow clamping of the renal artery. If the renal vein is clamped or compressed during this process, the kidney and tumor will become engorged. In selected cases, preoperative embolization of the kidney and tumor will allow the surgeon to clamp the renal vein before the artery without kidney engorgement as a side effect. Branches a) Inferior Adrenal Adrenal arteriography is rarely performed today. It is important to be sure that large vascular lesions in the area of the upper pole are not mistaken for renal cell carcinomas when the major feeding vessels are adrenal in origin. Because these masses become velY large, the organ of origin may not be clear on imaging studies. Arteriography may be helpful in such cases. On rare occasions, adrenal venography may be performed to confirm or mle out the adrenal origin of a mass that cannot be separated from the kidney. b) Capsular The capsular artery may supply tumors arising from the kidney or adrenal gland. Capsular sarcomas often are vascular and derive most of their blood supply from this branch. The capsular artery often is displaced by renal
427
masses. Its displacement may be the major arteriographic sign of hematoma of renal origin. Subcapsular hematomas characteristically flatten the renal contour. Pericapsular hematomas displace the capsular artery from its normal course in the perirenal space; these hematomas must be followed to resolution because underlying neoplasms as a source of the bleeding have been reported.
tively. Careful sectioning of the kidneys demonstrates communications between the calyceal fornix and small veins in some of these patients. The etiology of this finding is unknown. The results of angiogram and retrograde venogram are usually normal. The negative angiogram and imaging studies are important because they proVide support for the conservative clinical management of these patients.
c) Pelviureteric This branch may provide blood supply to ureteral neoplasms. Because it provides supply to the renal collecting system and upper ureter, it must be maintained when kidneys are harvested for transplant.
Neoplasms Renal Cell Carcinoma (RCC) This lesion is vascular to hypervascular in the majority of patients. A variety of terms (puddling, staining, bizarre) have been used to describe a vascular pattern of RCC. In general, a vascular renal parenchymal water density mass in the adult is most often RCC. Five percent of RCCs are "avascular." Arteriovenous shunting is a feature that is relatively uncommon. When it is florid and the tumor is small, it may be difficult to differentiate between a vascular malformation and RCC. Identifying the mass associated with the tumor is helpful in such cases. Later phase films obtained during the arteriogram may demonstrate vascularized tumor thrombus in the renal vein. These tumor vessels have been described as "threads and strings" and may extend into the vena cava and right atrium.
Capillary Phase It is important to evaluate this phase of the arteriogram. Medical diseases such as acute tubular necrosis, glomerulonephritis, arteritis, as well as infiltrating neoplasms may cause important alterations in the normal "capillary nephrogram. " Venous Phase Multiple veins are important to identify in the preoperative patient. They are reported to occur in 10% of kidneys. a) Retroaortic Renal Vein This anomaly results during persistence of left supracardinal veins so that the renal vein lies posterior to the aorta. It is present in 2% of patients. It may be recognized by its inferior course from the left renal hilum before crossing the midline to join the vena cava. b) Circumaortic Renal Vein (collar) This anomaly, which occurs in 5% of of the population, is very important to identify in the preoperative patient. It results from persistence of both subcardinal and supracardinal precursors of the renal vein so that there is both anterior and posterior left renal veins. There are reports of identifying only the anterior component of this anomaly and mobilizing the kidney or crossclamping the aOl1a, leading to tearing of the posterior vein. The resultant bleeding may lead to nephrectomy or even death. c) "Nutcracker Phenomenon" Because the left renal vein passes between the superior mesenteric vessels and the aorta, extrinsic pressure on the left renal vein may result in restricted flow. Venous pressure elevation proximal to this point has been identified and is believed to be a cause for hematuria in some of these patients. It is important to look for the dilated ureteric and gonadal veins that may be seen both on the venous phase of an arteriogram or during selective renal venography when studying patients with unexplained hematuria.
428
d) Venous-Calyceal Communications Five percent to eight percent of gross hematuria is unexplained. These patients should be managed conserva-
Transitional Cell Carcinoma (TCC) This tumor can arise from any part of the urothelium. When it arises in the collecting system, arteriography may demonstrate a fine reticular vascular pattern. When transitional cell carcinoma infiltrates the renal parenchyma, normal renal arteries become encased or even occluded. In addition, the normal capillary nephrogram becomes less intense. The kidney may enlarge at the site of the tumor but tends to keep a reniform shape. Pelviureteric vessels may enlarge to supply the tumor. Squamous cell carcinoma results when there is metaplasia of the transitional cell epithelium. These lesions have essentially the same appearance as transitional cell carcinoma on arteriography. Renal vein involvement does occur but is less common than with RCC. Metastatic tumors to the kidney tend to involve the cortex and also to encase normal renal vessels. Angiomyolipoma This benign tumor occurs coriunonly in patients with tuberous sclerosis. It also is encountered in the general population as an isolated finding. The usual presentation is as an incidental finding on sonography or CT scans. When it presents clinically, the patients tend to be middle-aged women with abdominal pain due to retroperitoneal bleeding associated with rupture of one of the small aneurysms commonly associated with this tumor. Often, there is one major feeding branch to the tumor, so these lesions are ideally suited for embolotherapy. Because the presence of fat arid no calcification essentially rules out malignancy, these tumors need not be resected.
When the amount of fat is large and embolization is performed, liquifaction of the lesion can result. Oncocytoma There has been much interest in this benign lesion, which can extend locally into the perirenal space or renal vein. The characteristic angiographic "spokewheel" appearance is not always present, and some RCCs may mimic this appearance. The CT scan often demonstrates a stellate central scar in the mass. Because the CT and angiographic appearance is not specific, this remains a surgical lesion. Nevertheless, it is important to suspect the diagnosis so that renal sparing surgery can be considered as an option. Wilms Tumor Ninety percent of these lesions occur in patients younger than 5 years of age and rarely come to arteriography. It is important to remember that 25% of these lesions involve the renal vein, and they may extend into the vena cava. This tumor is soft, and so extension into the inferior vena cava is more prone to result in embolization when handled at surgery. Renal Vascular Disease The presence of a renal artery stenosis does not mean the lesion is hemodynamically Significant. The presence of a small kidney, delayed flow distal to the stenosis, and the presence of collateral flow are indicators of a significant lesion.
Atherosclerosis The lesion of atherosclerosis involves the origin or proximal third of the artery. It may coalesce with aortic plaques, in which case it often is referred to as ostial. Atherosclerotic lesions usually are localized to this main renal artelY and vary in appearance from small eccentric plaques to total occlusion. The reported results of percutaneous renal artery angioplasty for hypertension vary considerably. A cure rate of 12%, improvement in 52.5%, and a total benefit of 68% is the mean of 10 larger series. In the group of patients having PTRA for azotemia, 40-50% will benefit from angioplasty of renal artery stenosis. Fibrodysplastic Lesions This group of lesions have been categorized in a variety of systems. In general, they are more common in young adults and involve the midportion to distal main renal al1ery. PTRA for fibrodysplastic disease results in cure in 38% of cases, improvement in 49%, and total benefit in 87.5%. Thus, PTRA is the treatment of choice for renovascular hypertension in this group of patients. a) Medial fibroplasia Most common in young women (mean age at diagnosis, 35 years), accounting for 75% of cases, and has the "string of beads" appearance. It is bilateral in 40% of patients. Half of patients have branch artery involvement. This appearance is due to the alternating areas of
narrowing due to thickening of media with collagen and areas of dilation due to weakened internal elastic lamina and media. Aneurysms may result when the wall is significantly weakened. The disease process may extend into brancl1es. b) Intimal fibroplasia Seen in children and young adults. Focal tubular narrowing to membrane-like appearance. Branch involvement is common. Most prone to dissect and thrombose. c) Fibromuscular hyperplasia (medial hyperplasia) Two percent to five percent of cases, mostly seen in teens and middle-aged men. Short, smooth narrowing that may be progressive and tends to thrombosis. d) Subadventical fibroplasia (perimedial fibroplasia) Young women most commonly affected. Also produces a beaded appearance, but the aneurysms do not extend beyond the expected renal artery contour. Transplant Renal Artery Stenosis There is some controversy as to the role of angioplasty in transplant renal artery stenosis. Some authors recommend surgical revision for strictures at the anastomosis, which are presumed to be the result of problems in surgical technique. Some response in this group has been noted, so that angioplasty may be tried before committing the patient to repeat surgery. Strictures in other segments of the transplant kidney are thought to be due to an immunologic response and often respond to dilation. Takayasu's Arteritis An idiopathic inflammatory artentls most frequent in young women. It usually involves the vessels of the aortic arch ("pulseless disease"), but visceral vessels, including the renal arteries, may be involved. The stenoses is usually smooth in appearance, involVing the main renal artery. The stenosis responds to angioplasty and may require high pressure for effective dilation. Neurofibromatosis Stenosis of major renal artelY branches may be seen in patients with neurofibromatosis due to intimal proliferation or actual neurofibromatoses nodules in the arterial wall. Aneurysms may be associated, and hypertension is common. Aneurysms True aneurysms contain all layers of the arterial wall. Saccular configuration is most common, and calcification is seen in 30-50% of cases. Hypertension may be associated and is thought to be due to slow flow distal to the aneurysm. Associated distal embolization or dissection also may lead to hypertension. False aneulysms that do not contain the layers of the arterial wall usually follow trauma. Mycotic aneurysms are saccular in appearance
429
and most often are associated with intravenous drug abuse and immune deficiency states.
Angiomyolipoma of the kidney. An angiographic review. ACTA Radiol 1973;14:561.
Arteriovenous Fistulas These lesions may be acquired after trauma and tumor erosion into the venous system. Arteriovenous fistulas after renal biopsy are common, but most resolve spontaneously. Those that persist may be treated effectively byembolotherapy.
8. Bonavita ]A, Pollack HM, Banner MP. Renal oncocytoma: Further observations and literature review. Urol Radiol 1981;2:229.
Arteriovenous Malfonnation These lesions are often congenital and present as bleeding or hypertension. Careful demonstrations of the feeding vessels is mandatory so that embolotherapy can be planned in such a fashion as to allow for obliteration of the "nidus." Emboli Larger emboli to the renal arteries may be associated with infarction. It is not unusual to have temporary loss of perfusion of the vascular bed due to associated spasm. Untreated emboli may lyse in time, leaving a diminished overall kidney size and corresponding reduction in diameter of the recanalized artery. Lysis with urokinase can be performed in selected cases. Chronic Renal Abscess Infection leading to abscess formation may be treated with antibiotics. If the collection is not drained, the granulation tissue formed in the wall of the abscess proliferates. This new blood supply may mimic tumor vessels on the angiogram.
References 1. Cuttino]T ]r, Clark RL. The normal vasculature of the genitourinary tract: Embryology, anatomy, and hemodynamics. In: Pollack's Clinical Urography. Philadelphia, PAc W.B. Saunders Co, 1990:2076-2091. 2. Mitty HA. Circumaortic renal collar: A potentially hazardous anomaly of the left renal vein. Am ] Roentgenol 1975;125:307-310. 3. Pollack HM, Popky GL. Roentgenographic manifestations of spontaneous renal hemorrhage. Radiology 1974;110:1-8. 4. Mitty HA, Shapiro RS, Parsons RB, Silberzweig ]E. Renovascular hypertension. Radiol Clin North Am 1996;34:1017-1036 5. Working Group on Renovascular Hypertension. Detection, evaluation, and treatment of renovascular hypertension-final report. Arch Intern Med 1987; 147:820-829. 6. Sos TA, Trost DE. Renal artery angioplasty and stenting. Presented at the Third Annual Symposium on Current Issues and New Techniques in Interventional Radiology, New York, New York, November 1995.
430
7. Becker ]A, Kinhabwal AM, Pollack H, Bosniak M.
9. Hillman B]. Disorders of the renal arterial circulation and renal vascular hypertension. In: Pollack's Clinical Urography. Philadelphia, PAc W.B. Saunders Co, 1990:2127-2187. 10. Stanley]C, Gewertz BL, Bove EL, et al. Arterial fibrodysplasia. Arch Surg 1976;110:561-565. 11. Sharma S, Thatai D, Sapona A, et al. Renovascular hypertension resulting from nonspecific aortoarteritis in children: Midterm results of PTRA and predictors of restenosis. Am] Roentgenol 1996;166:157-162.
4:30 pm Endocrine Angiography John 1. Doppman, MD National Institute ofHealth Bethesda, Maryland Learning objectives: As a result of attending the categorical course on vascular diagnosis, specifically endocrine angiography, the attendee will: (1) Understand the indications for and techniques ofparathyroid arteriography for localization in patients with failed previous surgery; (2) Appreciate the technical problems of adrenal venous sampling and interpretation of results in patients with hyperaldosteronism; (3) Understand the most effective angiographic and sampling techniquesfor patients with functioning islet cell tumors of the pancreas; (4) Appreciate the pitfalls ofpetrosal sinus sampling in patients with functioning pituitary tumors; (5) To illustrate the limited but critical role of arteriography in the localization of endocrine tumors not visualized on cross-sectional imaging or scintigraphy; (6) To appreciate the importance of venous sampling for truly occult parathyrOid adrenal and islet cell tumors; (7) To introduce the concept of arterial stimulation and nonselective venous sampling in the localization of insulinomas, gastrinomas, and parathyroid adenomas. Adrenal Glands Pheochromocytomas Computed tomography and MIBG scanning have solved most of the localization problems of pheochromocytomas. Extra-adrenal pheos are generally in the abdomen in the vicinity of the renal hilum. Pheochromocytomas in the organ of Zuckerkandl are supplied by the inferior mesenteric artery but arteriography is rarely required preoperatively. Extra-adrenal pheochromocytomas are readily demonstrated by screening coronal MRIs by virtue of their high signal intensity on T2-weighted and Sh011 inversion time inversion recovery (STIR) images. Ectopic pheochromocytomas of the urinary bladder may be missed on MRI because of the high signal intenSity of
References Athanasoulis CA, et al. Interventional Radiology. Philadelphia, PA: WB Saunders, 1982:121. Addendum After vasopressin has been tapered, an approximate 6-8-hour infusion of saline through the indwelling catheter is indicated. Thus, if the patient rebleeds, the catheter is already in place, and vasopressin may be restarted. At this point, an alternate therapy should be considered (for example, surgery, superselective catheterization, and embolization, or a subsequent course of vasopressin therapy). 4:00 pm Renal Angiography Harold A. Mitty, MD Mount Sinai School of Medicine New York, New York Learning objectives: As a result ofattending the lecture on renal angiography, the attendee will be able to: 1) List seven causes of renal artery stenosis; 2) Describe the vascular patterns of renal cell carcinoma, transitional cell carcinoma, oncocytoma, and angiomyolipoma,. 3) Distinguish between subcapsular and pericapsular hematomas; 4) Recognize retroaortic renal vein and circumaortic renal vein; and 5) Recognize renalparenchymal vascular diseases such as polyarteritis nodosa, sclerodenna, necrotizing angiitis, chronic glomerulonephritis, and nephrosclerosis. Indications Indications for renal angiography will vary depending on factors such as referral patterns, size of the urology service, and especially the presence of a transplant service. In addition, there have been changes in indications as other imaging modalities have become Widely available. This is illustrated in Table 1. It is apparent from these statistics that the current primary role of renal arteriography is in the evaluation of renal donors and in the treatment of significant renal artery stenosis. With the increased sensitivity of MRA, the need for conventional renal arteriography will decrease.
Table 1 Indications for Renal Angiography: 50 Consecutive Patients Per Year Mount Sinai Hospital, New York, NY
Mass? Neoplasm Donor Hemaruria RAS (Rule out) PTRA RAS (transplant) Embolus peN or Bx bleed Abscess Aneurysm Renal fa ilure
1976
1986
19%
23
o
25 9
28
8 7
6
o 1
o 1
o 5
o o 2
4
o
1
1
3
1
1
4 3 5 5 4
o o o o
Anatomic Features and Development Multiple Arteries and Origins Twenty percent to thirty percent of normal adults have two renal arteries supplying one kidney. This common variation is one of the major reasons for performing initial aortography before selective renal arteriography. Multiple renal arteries are also mOre common with anomalies of renal ascent and horseshoe kidneys. Surgeons generally prefer to use the left kidney of donors. In the event of more than one left renal artery or very early bifurcation, the right kidney may be selected.
Course The course of the right renal artery is posterior to the inferior vena cava. This is of importance in surgery for large renal cell carcinomas. Because the surgeon uses an anterior approach, the vena cava must be mobilized to allow clamping of the renal artery. If the renal vein is clamped or compressed during this process, the kidney and tumor will become engorged. In selected cases, preoperative embolization of the kidney and tumor will allow the surgeon to clamp the renal vein before the artery without kidney engorgement as a side effect. Branches a) Inferior Adrenal Adrenal arteriography is rarely performed today. It is important to be sure that large vascular lesions in the area of the upper pole are not mistaken for renal cell carcinomas when the major feeding vessels are adrenal in origin. Because these masses become velY large, the organ of origin may not be clear on imaging studies. Arteriography may be helpful in such cases. On rare occasions, adrenal venography may be performed to confirm or mle out the adrenal origin of a mass that cannot be separated from the kidney. b) Capsular The capsular artery may supply tumors arising from the kidney or adrenal gland. Capsular sarcomas often are vascular and derive most of their blood supply from this branch. The capsular artery often is displaced by renal
427
masses. Its displacement may be the major arteriographic sign of hematoma of renal origin. Subcapsular hematomas characteristically flatten the renal contour. Pericapsular hematomas displace the capsular artery from its normal course in the perirenal space; these hematomas must be followed to resolution because underlying neoplasms as a source of the bleeding have been reported.
tively. Careful sectioning of the kidneys demonstrates communications between the calyceal fornix and small veins in some of these patients. The etiology of this finding is unknown. The results of angiogram and retrograde venogram are usually normal. The negative angiogram and imaging studies are important because they proVide support for the conservative clinical management of these patients.
c) Pelviureteric This branch may provide blood supply to ureteral neoplasms. Because it provides supply to the renal collecting system and upper ureter, it must be maintained when kidneys are harvested for transplant.
Neoplasms Renal Cell Carcinoma (RCC) This lesion is vascular to hypervascular in the majority of patients. A variety of terms (puddling, staining, bizarre) have been used to describe a vascular pattern of RCC. In general, a vascular renal parenchymal water density mass in the adult is most often RCC. Five percent of RCCs are "avascular." Arteriovenous shunting is a feature that is relatively uncommon. When it is florid and the tumor is small, it may be difficult to differentiate between a vascular malformation and RCC. Identifying the mass associated with the tumor is helpful in such cases. Later phase films obtained during the arteriogram may demonstrate vascularized tumor thrombus in the renal vein. These tumor vessels have been described as "threads and strings" and may extend into the vena cava and right atrium.
Capillary Phase It is important to evaluate this phase of the arteriogram. Medical diseases such as acute tubular necrosis, glomerulonephritis, arteritis, as well as infiltrating neoplasms may cause important alterations in the normal "capillary nephrogram. " Venous Phase Multiple veins are important to identify in the preoperative patient. They are reported to occur in 10% of kidneys. a) Retroaortic Renal Vein This anomaly results during persistence of left supracardinal veins so that the renal vein lies posterior to the aorta. It is present in 2% of patients. It may be recognized by its inferior course from the left renal hilum before crossing the midline to join the vena cava. b) Circumaortic Renal Vein (collar) This anomaly, which occurs in 5% of of the population, is very important to identify in the preoperative patient. It results from persistence of both subcardinal and supracardinal precursors of the renal vein so that there is both anterior and posterior left renal veins. There are reports of identifying only the anterior component of this anomaly and mobilizing the kidney or crossclamping the aOl1a, leading to tearing of the posterior vein. The resultant bleeding may lead to nephrectomy or even death. c) "Nutcracker Phenomenon" Because the left renal vein passes between the superior mesenteric vessels and the aorta, extrinsic pressure on the left renal vein may result in restricted flow. Venous pressure elevation proximal to this point has been identified and is believed to be a cause for hematuria in some of these patients. It is important to look for the dilated ureteric and gonadal veins that may be seen both on the venous phase of an arteriogram or during selective renal venography when studying patients with unexplained hematuria.
428
d) Venous-Calyceal Communications Five percent to eight percent of gross hematuria is unexplained. These patients should be managed conserva-
Transitional Cell Carcinoma (TCC) This tumor can arise from any part of the urothelium. When it arises in the collecting system, arteriography may demonstrate a fine reticular vascular pattern. When transitional cell carcinoma infiltrates the renal parenchyma, normal renal arteries become encased or even occluded. In addition, the normal capillary nephrogram becomes less intense. The kidney may enlarge at the site of the tumor but tends to keep a reniform shape. Pelviureteric vessels may enlarge to supply the tumor. Squamous cell carcinoma results when there is metaplasia of the transitional cell epithelium. These lesions have essentially the same appearance as transitional cell carcinoma on arteriography. Renal vein involvement does occur but is less common than with RCC. Metastatic tumors to the kidney tend to involve the cortex and also to encase normal renal vessels. Angiomyolipoma This benign tumor occurs coriunonly in patients with tuberous sclerosis. It also is encountered in the general population as an isolated finding. The usual presentation is as an incidental finding on sonography or CT scans. When it presents clinically, the patients tend to be middle-aged women with abdominal pain due to retroperitoneal bleeding associated with rupture of one of the small aneurysms commonly associated with this tumor. Often, there is one major feeding branch to the tumor, so these lesions are ideally suited for embolotherapy. Because the presence of fat arid no calcification essentially rules out malignancy, these tumors need not be resected.
When the amount of fat is large and embolization is performed, liquifaction of the lesion can result. Oncocytoma There has been much interest in this benign lesion, which can extend locally into the perirenal space or renal vein. The characteristic angiographic "spokewheel" appearance is not always present, and some RCCs may mimic this appearance. The CT scan often demonstrates a stellate central scar in the mass. Because the CT and angiographic appearance is not specific, this remains a surgical lesion. Nevertheless, it is important to suspect the diagnosis so that renal sparing surgery can be considered as an option. Wilms Tumor Ninety percent of these lesions occur in patients younger than 5 years of age and rarely come to arteriography. It is important to remember that 25% of these lesions involve the renal vein, and they may extend into the vena cava. This tumor is soft, and so extension into the inferior vena cava is more prone to result in embolization when handled at surgery. Renal Vascular Disease The presence of a renal artery stenosis does not mean the lesion is hemodynamically Significant. The presence of a small kidney, delayed flow distal to the stenosis, and the presence of collateral flow are indicators of a significant lesion.
Atherosclerosis The lesion of atherosclerosis involves the origin or proximal third of the artery. It may coalesce with aortic plaques, in which case it often is referred to as ostial. Atherosclerotic lesions usually are localized to this main renal artelY and vary in appearance from small eccentric plaques to total occlusion. The reported results of percutaneous renal artery angioplasty for hypertension vary considerably. A cure rate of 12%, improvement in 52.5%, and a total benefit of 68% is the mean of 10 larger series. In the group of patients having PTRA for azotemia, 40-50% will benefit from angioplasty of renal artery stenosis. Fibrodysplastic Lesions This group of lesions have been categorized in a variety of systems. In general, they are more common in young adults and involve the midportion to distal main renal al1ery. PTRA for fibrodysplastic disease results in cure in 38% of cases, improvement in 49%, and total benefit in 87.5%. Thus, PTRA is the treatment of choice for renovascular hypertension in this group of patients. a) Medial fibroplasia Most common in young women (mean age at diagnosis, 35 years), accounting for 75% of cases, and has the "string of beads" appearance. It is bilateral in 40% of patients. Half of patients have branch artery involvement. This appearance is due to the alternating areas of
narrowing due to thickening of media with collagen and areas of dilation due to weakened internal elastic lamina and media. Aneurysms may result when the wall is significantly weakened. The disease process may extend into brancl1es. b) Intimal fibroplasia Seen in children and young adults. Focal tubular narrowing to membrane-like appearance. Branch involvement is common. Most prone to dissect and thrombose. c) Fibromuscular hyperplasia (medial hyperplasia) Two percent to five percent of cases, mostly seen in teens and middle-aged men. Short, smooth narrowing that may be progressive and tends to thrombosis. d) Subadventical fibroplasia (perimedial fibroplasia) Young women most commonly affected. Also produces a beaded appearance, but the aneurysms do not extend beyond the expected renal artery contour. Transplant Renal Artery Stenosis There is some controversy as to the role of angioplasty in transplant renal artery stenosis. Some authors recommend surgical revision for strictures at the anastomosis, which are presumed to be the result of problems in surgical technique. Some response in this group has been noted, so that angioplasty may be tried before committing the patient to repeat surgery. Strictures in other segments of the transplant kidney are thought to be due to an immunologic response and often respond to dilation. Takayasu's Arteritis An idiopathic inflammatory artentls most frequent in young women. It usually involves the vessels of the aortic arch ("pulseless disease"), but visceral vessels, including the renal arteries, may be involved. The stenoses is usually smooth in appearance, involVing the main renal artery. The stenosis responds to angioplasty and may require high pressure for effective dilation. Neurofibromatosis Stenosis of major renal artelY branches may be seen in patients with neurofibromatosis due to intimal proliferation or actual neurofibromatoses nodules in the arterial wall. Aneurysms may be associated, and hypertension is common. Aneurysms True aneurysms contain all layers of the arterial wall. Saccular configuration is most common, and calcification is seen in 30-50% of cases. Hypertension may be associated and is thought to be due to slow flow distal to the aneurysm. Associated distal embolization or dissection also may lead to hypertension. False aneulysms that do not contain the layers of the arterial wall usually follow trauma. Mycotic aneurysms are saccular in appearance
429
and most often are associated with intravenous drug abuse and immune deficiency states.
Angiomyolipoma of the kidney. An angiographic review. ACTA Radiol 1973;14:561.
Arteriovenous Fistulas These lesions may be acquired after trauma and tumor erosion into the venous system. Arteriovenous fistulas after renal biopsy are common, but most resolve spontaneously. Those that persist may be treated effectively byembolotherapy.
8. Bonavita ]A, Pollack HM, Banner MP. Renal oncocytoma: Further observations and literature review. Urol Radiol 1981;2:229.
Arteriovenous Malfonnation These lesions are often congenital and present as bleeding or hypertension. Careful demonstrations of the feeding vessels is mandatory so that embolotherapy can be planned in such a fashion as to allow for obliteration of the "nidus." Emboli Larger emboli to the renal arteries may be associated with infarction. It is not unusual to have temporary loss of perfusion of the vascular bed due to associated spasm. Untreated emboli may lyse in time, leaving a diminished overall kidney size and corresponding reduction in diameter of the recanalized artery. Lysis with urokinase can be performed in selected cases. Chronic Renal Abscess Infection leading to abscess formation may be treated with antibiotics. If the collection is not drained, the granulation tissue formed in the wall of the abscess proliferates. This new blood supply may mimic tumor vessels on the angiogram.
References 1. Cuttino]T ]r, Clark RL. The normal vasculature of the genitourinary tract: Embryology, anatomy, and hemodynamics. In: Pollack's Clinical Urography. Philadelphia, PAc W.B. Saunders Co, 1990:2076-2091. 2. Mitty HA. Circumaortic renal collar: A potentially hazardous anomaly of the left renal vein. Am ] Roentgenol 1975;125:307-310. 3. Pollack HM, Popky GL. Roentgenographic manifestations of spontaneous renal hemorrhage. Radiology 1974;110:1-8. 4. Mitty HA, Shapiro RS, Parsons RB, Silberzweig ]E. Renovascular hypertension. Radiol Clin North Am 1996;34:1017-1036 5. Working Group on Renovascular Hypertension. Detection, evaluation, and treatment of renovascular hypertension-final report. Arch Intern Med 1987; 147:820-829. 6. Sos TA, Trost DE. Renal artery angioplasty and stenting. Presented at the Third Annual Symposium on Current Issues and New Techniques in Interventional Radiology, New York, New York, November 1995.
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7. Becker ]A, Kinhabwal AM, Pollack H, Bosniak M.
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4:30 pm Endocrine Angiography John 1. Doppman, MD National Institute ofHealth Bethesda, Maryland Learning objectives: As a result of attending the categorical course on vascular diagnosis, specifically endocrine angiography, the attendee will: (1) Understand the indications for and techniques ofparathyroid arteriography for localization in patients with failed previous surgery; (2) Appreciate the technical problems of adrenal venous sampling and interpretation of results in patients with hyperaldosteronism; (3) Understand the most effective angiographic and sampling techniquesfor patients with functioning islet cell tumors of the pancreas; (4) Appreciate the pitfalls ofpetrosal sinus sampling in patients with functioning pituitary tumors; (5) To illustrate the limited but critical role of arteriography in the localization of endocrine tumors not visualized on cross-sectional imaging or scintigraphy; (6) To appreciate the importance of venous sampling for truly occult parathyrOid adrenal and islet cell tumors; (7) To introduce the concept of arterial stimulation and nonselective venous sampling in the localization of insulinomas, gastrinomas, and parathyroid adenomas. Adrenal Glands Pheochromocytomas Computed tomography and MIBG scanning have solved most of the localization problems of pheochromocytomas. Extra-adrenal pheos are generally in the abdomen in the vicinity of the renal hilum. Pheochromocytomas in the organ of Zuckerkandl are supplied by the inferior mesenteric artery but arteriography is rarely required preoperatively. Extra-adrenal pheochromocytomas are readily demonstrated by screening coronal MRIs by virtue of their high signal intensity on T2-weighted and Sh011 inversion time inversion recovery (STIR) images. Ectopic pheochromocytomas of the urinary bladder may be missed on MRI because of the high signal intenSity of