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Vascular: Renal Arteries Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Vascular ❯ Renal arteries

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  • Renal Artery Stenosis
    • Majority of renal artery stenosis (90%) is due to atherosclerosis.
    • Risk factors
       - age
       - diabetes
       - aortoiliac occlusive disease
       - hypertension
       - coronary artery disease
  • Renal Artery Stenosis
    • Describe locations
       - atherosclerotic lesions usually arise in the proximal 2 cm or proximal 1/3 of the artery
    • Grade stenosis
    • Characterization of plaque
       - atherosclerotic lesions often calcified
    • Delineation of any secondary findings
  • Renal Artery Stenosis
    • Role of revascularization vs medical therapy for atherosclerotic renal artery stenosis remains controversial
    • Restenosis rate is lower in renal arteries than coronary arteries
    • Emboli into renal vascular bed and elsewhere remains a major concern
  • RAS: Benefits of Stenting
    • improves hypertension
    • stabilizes renal failure
    • reduces recurrent cardiac events such as flash pulmonary edema
  • Fibromuscular Dysplasia: Facts
    • FMD causes less than 10% of renal artery stenosis
    • young or middle aged women
    • associations:
       - smoking
       - hormones
       - vasa vasorum disorders
    • In symptomatic patients, lesions are bilateral in 71%
  • Fibromuscular Dysplasia
    • medial fibroplasia
    • perimedial fibroplasia
    • medial hyperplasia
    • medial dissection
    • intimal fibroplasia
    • adventitial fibroplasia
  • Fibromuscular Dysplasia
    • medial fibroplasia- mid to distal RA
    • perimedial fibroplasia
    • medial hyperplasia
    • medial dissection
    • intimal fibroplasia
    • adventitial fibroplasia
  • Fibromuscular Dysplasia
    • “string-of-beads”
       - beading is larger than normal artery diameter
    • focal, concentric stenos(es)
    • smooth, long stenosis
    • aneurysm(s)
    • dissection
       - intimal and periarterial FMD
    • thrombosis
       - intimal and periarterial FMD
  • Renal Artery Aneurysm
    • hypertension
    • systemic atherosclerosis
    • extrarenal aneurysms
    • FMD
    • arteritis
    • dissection
    • smoking
    • Marfan syndrome
    • Ehlers-Danlos syndrome
    • Neurofibromatosis
    • aortic coarctation
    • infectious etiologies
  • Renal Artery Aneurysms
    • Usually incidental
    • May be symptomatic: pain, hematuria
    • 60% at main artery bifurcation or mainstem artery
    • Bilateral in 19%
    • Multiple in 25-33%
    • ~1/3 of patients have ipsilateral renal artery stenosis
  • Renal Artery Aneurysms : Complications
    • hypertension
    • rupture
    • RA thrombosis
    • infarction by distal embolization
    • AV fistula
  • Renal Artery Aneurysms : Complications
    • Some recommend repair in the setting of pain, or complications, such as dissection or embolization.
    • Endovascular repair has become an alternative treatment option
    • CT can be used to confirm patency following stent-graft occlusion
  • Renal Artery Aneurysms : Repair
    • All aneurysms > 2 cm
    • Most renal artery aneurysms 1.5 to 2 cm
    • RAA> 1 cm in conjunction with risk factors
       - hypertension
       - ipsi or contralateral renal artery stenosis
       - women of childbearing age
  • Renal Artery Aneurysms : Complications
    • Risk of rupture increases during pregnancy and correlates with aneurysm size.
    • Surgical treatment
       - decreased blood pressure in 47-60% of those with preoperative hypertension
       - renal function may be improved
  • Renal Artery Dissection
    • Extension from an abdominal aortic dissection
    • Trauma (blunt or iatrogenic)
    • FMD
    • Anti-phospholipid antibody association
    • Ehlers Danlos
    • Idiopathic
  • Renal Artery Thrombosis
    • Thromboembolic disease- cardiac most common
    • Renal Artery insult
       - Spontaneous/traumatic dissection
       - Fibromuscular dysplasia (FMD)
    • Hypercoaguability
       - Antiphospholipid Syndrome
       - Nephrotic Syndrome
  • Renal Artery Thrombosis: CT Findings
    • Axial image from arterial phase CT
    • Elongated filling defect in right renal artery
    • Sharply demarcated cortical hypoenhancement in right kidney secondary to infarct
    • Infarcts are subtle on early CT
  • Renal AVM
    • Rare, congenital malformation
    • May be large (aneurysmal) and solitary or numerous and small (cirsoid type).
       - Cirsoid type more common. 
    • Usually located in renal sinus
    • Usually solitary and right sided

  • Renal AVM: Presentation
    • gross hematuria
    • hypertension
    • flank pain
    • high cardiac output failure
  • “Although renal infarcts are common after FEVAR, the clinical relevance of these events appears to be limited, with less than one-quarter of patients with renal infarcts experiencing a decline in renal function.”

    
Incidence and Clinical Significance of Renal Infarct After Fenestrated Endovascular Aortic Aneurysm Repair 
Burke LMB et al.
AJR 2017; 208:885–890 



  • “Renal ischemia remains a known compli- cation of FEVAR, with clinical studies showing variable rates of renal impairment after FEVAR of juxtarenal abdominal aortic aneurysms. Studies show that 11– 35% of patients experience a transient increase in serum creatinine levels (defined as a > 30% increase in serum creatinine level), and 0–4% of patients require temporary or permanent dialysis.”

    
Incidence and Clinical Significance of Renal Infarct After Fenestrated Endovascular Aortic Aneurysm Repair 
Burke LMB et al.
AJR 2017; 208:885–890

  • “Our data show a gradual mild increase in baseline serum creatinine level in all patients undergoing FEVAR, regardless of whether the patient had a renal infarct. This nding mirrors a recent study from France , which found an increase in serum creatinine level during the first week after FEVAR.” 


    Incidence and Clinical Significance of Renal Infarct After Fenestrated Endovascular Aortic Aneurysm Repair 
Burke LMB et al.
AJR 2017; 208:885–890

  • “Although the presence of renal infarct af- ter FEVAR is relatively common in our pa- tient population, it seems to carry little clini- cal relevance. This information is useful to interpreting radiologists when determining the urgency to report such findings, as well as when explaining the clinical relevance to referring clinicians and to patients undergo- ing FEVAR.”

    
Incidence and Clinical Significance of Renal Infarct After Fenestrated Endovascular Aortic Aneurysm Repair 
Burke LMB et al.
AJR 2017; 208:885–890

  • “In contradistinction to atherosclerotic stenosis, which are seen in the proximal renal artery, FMD-related stenosis tend to occur in the middle to distal portion of the renal artery.”

    
Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “RAAs 1.0–1.5 cm in diameter should be evaluated with surveillance imaging every 1–2 years. Patients with RAAs larger than 1.5 cm should be referred for definitive treatment. Additional indications for treatment of RAAs include uncontrolled hypertension and symptomatic cases due to peripheral vascular bed embolism.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “The main renal artery normally arises from the abdominal aorta, below the level of the superior mesenteric artery at the L2 vertebral body level.The main renal artery is typically 4–6 cm in length and 5–6 mm in diameter.The right main renal artery is longer and often originates slightly superior to the left renal artery. The right renal artery is the only major vessel to course posterior to the inferior vena cava (IVC).”

    
Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “In contrast to accessory renal arteries, which enter the kidney through the hilum, aberrant renal arteries, also known as polar arteries, enter the kidney through the capsule outside the hilum.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “ Prehilar branches of the main renal artery that arise less than 1.5–2.0 cm from the origin should be noted in patients who are being evaluated as possible renal donors, because these early branches may complicate the surgical arterial anastomosis.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “The main renal vein usually lies anterior
to the renal artery at the renal hilum.The left renal vein has an average length of 6–10 cm and normally courses anteriorly between the superior mesenteric artery and aorta before emptying into the medial aspect of the IVC. The right renal vein has an average length of 2–4 cm and joins the lateral aspect of the IVC.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “RAS is the most common cause of secondary hy- pertension and is found in 1%–5% of all patients 
who have hypertension. In greater than two- thirds of cases of RAS, focal narrowing of the renal artery lumen is caused by atherosclerosis. The majority of affected individuals are male and older than 50 years. Atherosclerotic renovascular disease correlates with overall atherosclerotic burden, and the prevalence of this condition is higher among patients with known coronary artery disease.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “RAS leads to reduced perfusion to the kidney, which then results in systemic hypertension due 
to activation of the renin-angiotensin system . RAS is also an important factor of end-stage renal disease, particularly in persons older than 50 years . RAS caused by atherosclerosis typically occurs at the origin of the renal artery or within the proximal 2 cm of the renal artery. When stenosis 
is detected, careful inspection of the contralateral renal artery is important, as bilateral lesions occur in 30% of cases.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “Fibromuscular dysplasia (FMD) is a nonath- erosclerotic noninflammatory vascular disease of medium-sized and large arteries that results in focal areas of irregular wall thickening . FMD is the second most common cause of RAS and is found in younger patients, with 
a female-to-male ratio of 9:1. The most commonly affected vessel is the renal artery (in 75% of cases) followed by the internal carotid artery.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “FMD results in stenosis, aneurysm, dissection, and occlusion of the involved vessels. FMD is subclassi ed into three categories based on the involved arterial layer: medial fibroplasia, which accounts for 80%–90% of cases; intimal fibroplasia, which accounts for 10% of cases; and adventitial fibroplasia, which has an unknown frequency.”

    
Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “In contradistinction to atherosclerotic stenosis, which are seen in the proximal renal artery, 
FMD-related stenosis tend to occur in the middle to distal portion of the renal artery. When FMD is discovered in a renal artery, close inspection of the contralateral renal artery is prudent, because FMD occurs bilaterally in two- thirds of patients. Up to 10% of all cases of FMD have associated renal artery aneurysms (RAAs) .”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “The most common subtype, medial fibrobroplasia, is characterized by alternating segments of stenosis and dilatation, which create the “string of pearls” appearance . The intimal medial fibroplasia subtype is characterized by focal long- segment tubular areas of luminal stenosis. CT angiography has been shown to be 100% sensitive for the diagnosis of FMD, and MR angiography is reported to have a sensitivity of 97% and a specificity of 93% for this diagnosis.”

    
Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “However, spontaneous renal artery dissection is a rare entity that occurs without
a known inciting event. Predisposing factors include FMD, malignancy-related hypertension, severe atherosclerosis, Marfan syndrome, Ehlers- Danlos syndrome, subadventitial angioma, cystic medial necrosis, cocaine abuse, and extreme physical exertion.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “Aneurysms of the renal artery are true aneurysms caused by degeneration and weakening of the elastic fibers of the arterial wall, with subsequent expansion caused by high intraluminal pressure. The estimated prevalence of RAAs is approximately 0.1%; most of them are detected incidentally in asymptomatic patients. However, patients may present with findings of rupture, thrombosis, or embolism.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “The management of RAAs is based in part on the size of the aneurysm and the clinical setting; however, size does not have a direct correlation with rupture. RAAs 1.0–1.5 cm in diameter should be evaluated with surveillance imaging every 1–2 years. Patients with RAAs larger than 1.5 cm should be referred for definitive treatment . Additional indications for treatment of RAAs include uncontrolled hypertension and symptomatic cases due to peripheral vascular bed embolism. Pregnant women also are at high risk for RAA rupture.”

    
Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “Pseudoaneurysms of the renal artery occur as a result of direct injury to the arterial wall with subsequent disruption and extravasation of the blood contained in the arterial adventitia or surrounding tissues . Pseudoaneurysms occur most often in response to iatrogenic or penetrating trauma . Multiple intraparenchymal pseudoaneurysms can develop with vasculitis and as a result of amphetamine use. A pseudoaneurysm rupture may manifest as hematuria, and pain, and/or hypotensive shock.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “Vascular abnormalities are found in 0.4%–6.4% of patients with NF-1, and the renal artery is the most commonly involved artery, being affected in 41% of patients with associated vascular abnormalities. Unlike atherosclerotic stenosis, NF-1–associated stenosis often occur in patients younger than 50 years, spare the renal artery origin, are long and tapered, and extend into segmental and intrarenal branches. The stenosis involved with NF-1 are bilateral in 32% of patients. Less commonly, NF-1 manifests with RAAs.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “Renal arteriovenous malformations (AVMs) are developmental anomalies in which an abnormal connection is present between a renal artery and renal vein owing to a nidus consisting of a network of abnormal vessels. Renal AVMs are usually symp- tomatic; gross hematuria results from the rupture of small venules into calyces that is caused by abnormally increased intravascular pressure. Other symptoms include renovascular hypertension, high-output cardiac failure, and flank pain.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “An arteriovenous fistula (AVF) is an abnormal direct connection of an artery to a vein without an intervening capillary bed. Most renal AVFs are acquired, and they usually have an iatrogenic cause such as percutaneous nephrostomy or result from penetrating trauma. In up to 18% of cases, AVFs occur after renal biopsy. Idiopathic cases are postulated to occur when an RAA ruptures into an adjacent vein. Most patients are asymptomatic, although they may present with hematuria and flank pain.”
Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “The nutcracker phenomenon occurs when the left renal vein is compressed between the aorta and superior mesenteric artery and consequently results in left renal vein hypertension. The term nutcracker syndrome refers to the clinical signs and symptoms that can result from this anatomic finding.”

    
Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “Nutcracker syndrome is commonly found in thin young females. A history of recent substantial weight loss also is implicated in cases of nutcracker syndrome. Hematuria and and pain are common clinical symptoms. Additional symptoms related to pelvic congestion syndrome also may be present. Compression of the left renal vein can cause left renal vein–to–gonadal vein reflux that results in lower limb varices and varicoceles in males.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “Thrombosis that leads to narrowing or occlu- sion of the renal vein can be caused by a bland or tumor thrombus. Patients present with gross hematuria, flank pain, and signs of renal failure. Risk factors of bland renal vein thrombosis include glomerulonephritis, collagen vascular disease, diabetes, and trauma.”


    Radiologic Assessment of Native Renal Vasculature: A Multimodality Review 
Sayf Al-Katib et al.
RadioGraphics 2017; 37:136–156
  • “RCC is the most common primary tumor leading to solitary pancreatic metastases.These lesions are usually round or ovoid masses, well-delineated, and show brisk enhancement in the pancreatic late arterial phase and washout on delayed phase images. Based on enhancement alone, it can be difficult to differentiate these metastatic lesions from hypervascular neuroendocrine tumors of the pancreas.”

    Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation 
Price M, Patino M, Sahani D
Radiol Clin N Am 54 (2016) 55–70
  • “In a CT angiographic study of potential renal donors, dilated ovarian veins were found in 16 (47%) of 34 asymptomatic women . In another CT study of patients with severe ovarian vein reflux, but without PCS, both right and left parauterine veins were tortuous and dilated in all cases, with a mean vein diameter of 5.9 ± 1.6 mm (range, 4.3-8.0 mm). Pelvic varices, and early opacification and dilation of the gonadal veins, may occur without venous reflux, particularly if uterine fibroids or other pelvic abnormalities are present.”

    Managing Incidental Findings on Abdominal and Pelvic CT and MRI, Part 2: White Paper of the ACR Incidental Findings Committee II on Vascular Findings

    Khosa F et al
    J Am Coll Radiol. 2013 Oct;10(10):789-94
  • “RAA is uncommon, occurring in about 0.09% of the population . Etiologies include fibromuscular dysplasia (FMD), atherosclerosis, and pseudoaneurysms that may occur after trauma. In a review of 168 patients with 252 RAAs, 34% had FMD, 25% had atherosclerosis, 6.5% had concurrent aneurysms of other vessels, and 73% had hypertension [22]. RAAs are usually detected incidentally at cross-sectional imaging, are small, are asymptomatic, and have uncertain clinical relevance. However, they may rupture, especially if they enlarge, and may be associated with renal arterial hypertension.”

    Managing Incidental Findings on Abdominal and Pelvic CT and MRI, Part 2: White Paper of the ACR Incidental Findings Committee II on Vascular Findings

    Khosa F et al
    J Am Coll Radiol. 2013 Oct;10(10):789-94
  • “One approach that has been suggested is to repair all aneurysms ≥1 cm in patients with uncontrolled hypertension. An incidentally discovered RAA measuring 1.0 to 1.5 cm can be safely followed . In a series of 86 RAAs with a mean size of 1.3 cm, none ruptured after an average follow-up of 72 months. We recommend that a reasonable imaging follow-up interval in these asymptomatic individuals is every 1 to 2 years. Larger aneurysms, measuring >1.5 to 2.0 cm, should be considered for surgical or endovascular repair .”

    Managing Incidental Findings on Abdominal and Pelvic CT and MRI, Part 2: White Paper of the ACR Incidental Findings Committee II on Vascular Findings

    Khosa F et al
    J Am Coll Radiol. 2013 Oct;10(10):789-94
  • “Outside of the splenic and renal circulations, visceral aneurysms can affect the celiac, hepatic, gastroduodenal, pancreaticoduodenal, gastric, or mesenteric arteries. After splenic and renal arterial aneurysms, the hepatic artery is the next most common location. When discovered incidentally, these aneurysms are typically caused by atherosclerosis and may be associated with aneurysmal disease elsewhere. They can also be mycotic, traumatic (including iatrogenic trauma for hepatic aneurysms after liver biopsy), or, less commonly, related to polyarteritis nodosa, FMD, or visceral inflammatory disease, such as pancreatitis.”

    Managing Incidental Findings on Abdominal and Pelvic CT and MRI, Part 2: White Paper of the ACR Incidental Findings Committee II on Vascular Findings

    Khosa F et al
    J Am Coll Radiol. 2013 Oct;10(10):789-94
  • CTA of the Normal Renal Arteries
    - Between 70% and 75% of people have one renal artery per kidney, with the remainder being expected to have two or more renal arteries on each side. Renal arteries typically arise at the level of the upper margin of the second lumbar vertebral body, 1 cm below the origin of the superior mesenteric artery. Each renal artery supplies smaller, inferior adrenal arteries, which may be single or multiple.
    - In a study of 400 cadaver donors with 800 kidneys, Pollak et al found that 23% had double renal arteries, 4% had triple arteries, and 1% had quadruple arteries. Multiple renal arteries occur on the left side in 26%–32% of people and on the right side in 23%–29%. Bilateral multiple renal arteries occur in 15%. Higher or lower origins are not uncommon among accessory arteries.
  • “ Identification of renal variants and pathologies is important because it has clinically critical consequences, especially before kidney related procedures such as laparoscopic donor or partial nephrectomy, vascular reconstruction for renal artery stenosis or abdominal aortic aneurysm. MDCT angiography and CE-MR angiography are excellent imaging studies because they are fast and non-invasive and provide highly accurate and detailed evaluation of renal vascular anatomy.”
    Contrast-enhance CT and MRI imaging of renal vessels
    Tuna IS, Tatli S
    Abdom Imaging (2014) 39;875-891
  • CTA of the Renal Arteries: Classic Clinical Applications
    - Renal donor anatomy
    - UPJ evaluation
    - Renal artery stenosis
    - Fibromuscular dysplasia of the renal arteries
    - Vasculitis involving the renal artery
    - Renal artery aneurysm or pseudoaneurysm
    - AV malformation involving the renal artery
    - Presurgical evaluation including partial nephrectomy planning
  • CTA for Renal Donor Evaluation
    - Renal artery disease was identified in 3.4% of potential donors, including renal artery stenosis, possible fibromuscular dysplasia, and renal artery aneurysm.
    - Significant CT findings also contributed to the selection of the right kidney in 29 donors (of 470 donors), most commonly due to presence of ipsilateral vascular disease or complex left vascular anatomy.
    - Renal parenchymal and vascular abnormalities are common in asymptomatic potential kidney donors. Although most of these represent incidental CT findings, abnormalities can exclude potential renal donors and alter the surgical approach in a small minority of cases
    - AJR Am J Roentgenol. 2012 Nov;199(5):1035-41. doi: 10.2214/AJR.11.8058.
  • Renal Artery Stenosis: Facts
    - Atherosclerosis is cause in up to 70% of patients
    - Eccentric irregular narrowing is classic and more commonly proximal vessel
    - Decreased renal function and loss of cortex/scarring is common
  • Fibromuscular Dysplasia: Facts
    - Second most common cause of renal hypertension
    - Usually in woman between age 30 and 55
    - Usually occurs in both renal arteries and is in the mid and distal segments of the arteries
    - “string of bead” appearance is most classic with alternating areas of stenosis and dilatation
  • Renal Artery Aneurysm: Etiology
    - Atherosclerosis
    - FMD
    - Neurofibromatosis
    - Polyarteritis nodosa
    - Trauma
    - Intervention common if aneurysm greater than 2 cm or for any size in woman of child bearing age
  • “RAAs are extremely rare clinical entities, which constitute localized dilations of renal arteries and/or branches. RAAs can be classified into 4 basic categories: the saccular, fusiform, dissecting, or intrarenal,and saccular RAA is the most common type.”
    Rupture of Renal Artery Aneurysm: A Rare Urologic Emergency Entity
    Zhou H et al.
    DOI: 10.1016/j.urology.2014.08.002
  • “RAAs are extremely rare clinical entities, which constitute localized dilations of renal arteries and/or branches. RAAs can be classified into 4 basic categories: the saccular, fusiform, dissecting, or intrarenal,and saccular RAA is the most common type.”
    Rupture of Renal Artery Aneurysm: A Rare Urologic Emergency Entity
    Zhou H et al.
    DOI: 10.1016/j.urology.2014.08.002
  • “ Predisposing factors encompass congenital malformations of the kidneys, untreated hypertension, atherosclerosis, pregnancy, trauma, malignancy, renal angiomyolipoma, radiation, and consumption of cyclophosphamide.”
    Rupture of Renal Artery Aneurysm: A Rare Urologic Emergency Entity
    Zhou H et al.
    DOI: 10.1016/j.urology.2014.08.002
  • “There is an increased mortality in type IV EDS, mostly because of vascular complications such as spontaneous arterial rupture, aneurysmal degeneration with subsequent rupture or dissection, and arteriovenous fistulas.”
    Thromboembolic renal infarction due to a renal artery aneurysm in a patient with Ehlers-Danlos syndrome type IV
     Abramowitz Y et al.
    Eur J Vascular Med Vol 17, Issue 5, August 2006, Pages 377–379
  • Renal Artery Dissection: Etiologies
    - Most common cause is extension from an abdominal aortic aneurysm
    - Trauma (blunt or iatrogenic)
    - FMD
    - Anti-phospholipid antibody association
    - idiopathic
  • Renal Artery Thrombosis: Etiologies
    - Trauma
    - Instrumentation
    - Embolism (due to atrial fibrillation, myocardial infarction, rheumatic mitral stenosis)
    - Hypercoagulability states
  • Renal AV Malformations: Facts
    - Very rare CT findings
    - Usually congenital but may be due to underlying tumor
    - May be large (aneurysmal) and solitary or numerous and small (cirsoid type). Cirsoid type more common.
    - Usually located in renal sinus
    - Usually solitary and right sided
    - Presentation may be gross hematuria, hypertension, flank pain and high cardiac output failure
  • Renal Veins: Pathologies
    - Renal vein thrombus
    - Rein vein tumor thrombus
    - Spontaneous splenorenal shunt
    - Nutcracker syndrome
    - Renal varix
    - AV malformation
  • Renal Artery Dissection: Facts
    - SRAD is postulated as a result of intramural hemorrhage from the vasa vasorum or by penetration of blood into the arterial wall through an intimal tear.1 Several risk factors were associated with SRAD.
    - SRAD has an incidence of 0.05%, with a predilection to affect middle-aged males.
    -  The rarity and nonspecific presentation of SRAD led to diagnostic delay or misdiagnoses.
    - Spontaneous Renal Artery Dissection Complicating With Renal Infarction
    - Tsung-Han Tsai  et al.
    - Urology Vol 76, Issue 6, December 2010, Pages 1371–1372.
  • “RAAs are extremely rare clinical entities, which constitute localized dilations of renal arteries and/or branches. RAAs can be classified into 4 basic categories: the saccular, fusiform, dissecting, or intrarenal,and saccular RAA is the most common type.”
    Rupture of Renal Artery Aneurysm: A Rare Urologic Emergency Entity
    Zhou H et al.
    DOI: 10.1016/j.urology.2014.08.002
  • “ Predisposing factors encompass congenital malformations of the kidneys, untreated hypertension, atherosclerosis, pregnancy, trauma, malignancy, renal angiomyolipoma, radiation, and consumption of cyclophosphamide.”
    Rupture of Renal Artery Aneurysm: A Rare Urologic Emergency Entity
    Zhou H et al.
    DOI: 10.1016/j.urology.2014.08.002
  • “There is an increased mortality in type IV EDS, mostly because of vascular complications such as spontaneous arterial rupture, aneurysmal degeneration with subsequent rupture or dissection, and arteriovenous fistulas.”
    Thromboembolic renal infarction due to a renal artery aneurysm in a patient with Ehlers-Danlos syndrome type IV
    Abramowitz Y et al.
    Eur J Vascular Med Vol 17, Issue 5, August 2006, Pages 377–379
  • CTA of the Renal Arteries: Clinical Applications
    - Renal donor anatomy
    - Renal artery stenosis
    - Fibromuscular dysplasia of the renal arteries
    - Vasculitis involving the renal artery
    - Renal artery aneurysm or pseudoaneurysm
    - AV malformation involving the renal artery
    - Partial nephrectomy planning
  • Normal Renal Artery Anatomy: Facts
    - Length of 4-6 cm
    - Width of 5-6 mm in diameter
    - Multiple renal arteries are seen in up to one-third of patients
    - Bilateral multiple renal arteries are seen in approximately 12% of the population
    - Renal arteries usually arise off the aorta but may arise from the iliac, lumbar, lower thoracic or mesenteric arteries
  • Renal Artery Stenosis: Facts
    - Atherosclerosis is cause in up to 70% of patients
    - Eccentric irregular narrowing is classic and more commonly proximal vessel
    - Decreased renal function and loss of cortex/scarring is common
  • Fibromuscular Dysplasia: Facts
    - Second most common cause of renal hypertension
    - Usually in woman between age 30 and 55
    - Usually occurs in both renal arteries and is in the mid and distal segments of the arteries
    - “string of bead” appearance is most classic with alternating areas of stenosis and dilatation
  • Renal Artery Aneurysm: Etiology
    - Atherosclerosis
    - FMD
    - Neurofibromatosis
    - Polyarteritis nodosa
    - Trauma
    - Intervention common if aneurysm greater than 2 cm or for any size in woman of child bearing age
  • Renal Artery Dissection: Etiologies
    - Most common cause is extension from an abdominal aortic aneurysm
    - Trauma (blunt or iatrogenic)
    - FMD
    - Anti-phospholipid antibody association
    - idiopathic
  • Renal Artery Thrombosis: Etiologies
    - Trauma
    - Instrumentation
    - Embolism (due to atrial fibrillation, myocardial infarction, rheumatic mitral stenosis)
    - Hypercoagulability states
  • Renal Arteries: Miscellaneous Conditions
    - Takayasu’s aortitis
    - Renal artery trauma
    - Tumor encasement by renal cell carcinoma or lymphoma
    - Retroperitoneal process like retroperitoneal fibrosis
  • “ CT is the modality of choice for patients with pacemakers, automatic implantable cardioverter defibrillator or other non-MR compatible devises. CT also is generally preferred when very high spatial resolution is required or when it is particularly important to demonstrate peripheral arteries (i.e. fibromuscular dysplasia or vasculitis).”
    Contrast-enhance CT and MRI imaging of renal vessels
    Tuna IS, Tatli S
    Abdom Imaging (2014) 39;875-891
  • “ Identification of renal variants and pathologies is important because it has clinically critical consequences, especially before kidney related procedures such as laparoscopic donor or partial nephrectomy, vascular reconstruction for renal artery stenosis or abdominal aortic aneurysm. MDCT angiography and CE-MR angiography are excellent imaging studies because they are fast and non-invasive and provide highly accurate and detailed evaluation of renal vascular anatomy.”
    Contrast-enhance CT and MRI imaging of renal vessels
    Tuna IS, Tatli S
    Abdom Imaging (2014) 39;875-891
  • Renal AV Malformations: Facts
    - Very rare CT findings
    - Usually congenital but may be due to underlying tumor
    - May be large (aneurysmal) and solitary or numerous and small (cirsoid type). Cirsoid type more common.
    - Usually located in renal sinus
    - Usually solitary and right sided
    - Presentation may be gross hematuria, hypertension, flank pain and high cardiac output failure
  • “ Renal arteriovenous malformations (AVMs) are rare lesions and may be acquired or congenital. Acquired renal AVMs (arteriovenous fistulas [AVFs]) are relatively rare, accounting for 3% to 5% of all renal AVMs. Hematuria is the major and most common symptom; other clinical manifestations, such as hypertension, left ventricular hypertrophy, cardiac failure, and abdominal pain are also usually associated with AVMs.”
    Gross hematuria caused by a congenital intrarenal arteriovenous malformation: a case report
    Carrafiello G et al.
    J Med Case Reports 2011;5: 510
  • “Congenital renal arteriovenous fistulas are the most uncommon form, but their incidence may be underestimated because patients are usually asymptomatic.”
    Gross hematuria caused by a congenital intrarenal arteriovenous malformation: a case report
    Carrafiello G et al.
    J Med Case Reports 2011;5: 510
  • “Congenital AVMs are uncommon and Color Doppler ultrasonography, MSCT, angiography, and DSA are the most important tools for making the diagnosis in an urgent setting. The therapeutic decision must be made by considering the general condition of the patient and his or her symptoms. The only therapy considered in the past was nephrectomy, but embolization by selective catheterization can be considered safe and effective. However, many studies need to be done to confirm the role of embolization.”
    Gross hematuria caused by a congenital intrarenal arteriovenous malformation: a case report
    Carrafiello G et al.
    J Med Case Reports 2011;5: 510
  • CTA Evaluation of the Renal Arteries: Aneurysms
    -  Variable in size
    - Single to multiple in number
    - May be partially or totally calcified
    - May be a result of atherosclerosis, IVDA, vasculitis
  • Renal Artery Stenosis: Facts
    - The cause of hypertension in adults in less than 5% of cases
    - Potentially curable
    - Diameter stenosis greater than 50% often hemodynamically significant
  • “ MDCT is a minimally invasive study for evaluating the renal arteries in normal individuals and patients with suspected renal pathology. The ability to obtain thin sections and cover a large area may improve the detection and characterization of renal artery anomalies and disease.”
    Multidetector Computed Tomographic Evaluation of the Renal Artery
    Pannu HK, Fishman EK
    Abdom Imaging 27:611-619 (2002)
  • Renal Artery Fibromuscular Dysplasia (FMD): Facts
    - Younger patient
    - Predominately female population
    - “String of pearls” appearance (due to multiple stenosis) are classic appearance
  • Fibromuscular Dysplasia: Classification
    - Medial fibromuscular disease
    - 65-70% of cases
    - String of beads appearance
    - Perimedial (subadventitial form)
    - 15-20% of cases
    - Aneurysm formation or focal stenosis
  • Fibromuscular Dysplasia: Classification
    - Medial hyperplasia
    - 8-10% of cases
    - No classic radiologic appearance
    - Isolated intimal or adventitial involvement
    - 1-2% of cases
  • “ More recently, in a study comparing 4-slice MDCT to digital subtraction angiography, the sensitivity and specificity for all degrees of renal artery stenosis were 100% and 98.6%, respectively. For stenosis greater than 50%, sensitivity was 100% and specificity 97.3%.”
    Computed Tomography Angiography of the Renal and Mesenteric Vasculature: Concepts and Applications
    Johnson PT, Fishman EK
    Seminars in Roentgenology
    2011: 115-124
  • Renal Artery Aneurysms: Treatment
    -Surgery for aneurysms over 2 cm in size
    -Stents can be placed in aneurysms especially those under 2 cm
    -Surgery for aneurysms over 1 cm may be indicated with risk factors of hypertension, renal artery stenosis or woman of child bearing age
  • Renal Artery Aneurysms: Facts
    -Most common location is the main renal artery bifurcation or main renal artery (60%)
    -May be multiple in up to 25-33% of patients and may be bilateral in 19% of cases
    -Complications include hypertension, rupture, renal arterial thrombosis, infarction by distal embolization and AV fistula
    -Risk of rupture increases during pregnancy and with increasing aneurysm size
  • Renal Artery Aneurysms: Common Associations
    -Hypertension
    -FMD
    -Atherosclerosis
    -Extrarenal aneurysms
    -Arteritis
    -Marfan’s syndrome
    -Ehlers Danlos syndrome
    -Neurofibromatosis
    -Smoking
  • CT Angiography of the Renal Arteries: Fibromuscular Dysplasia
    -Causes less than 10% of cases of renal artery stenosis
    -More common in young or middle aged woman
    -Associations include smoking, hormones, and vasa vasorum disorders
    -FMD may appear as a “string of beads” appearance
    -May be bilateral in 71% of cases when symptomatic
  • CT Angiography of the Renal Arteries: Renal Artery Stenosis
    Etiology
    -Atherosclerotic disease (90%)
    -Age
    -Diabetes
    -Aortoiliac occlusive disease
    -Hypertension
    -Presence of coronary artery disease
  • CT Angiography of the Renal Arteries: Renal Artery Stenosis
    -Reconstruction of data required to define and quantify presence and degree of stenosis
    -MIP can lead to overcalling the degree of stenosis
    -VRT when used correctly has a 95-100% accuracy
  • “ Studies using angiography have revealed that 3.8%-6.6% of potential renal donors have fibromuscular dysplasia (FMD), which was bilateral in 43% to 71%. Atherosclerotic lesions were much less common, identified in 2%.”
    Computed Tomography Angiography of the Renal and Mesenteric Vasculature: Concepts and Applications
    Johnson PT, Fishman EK
    Seminars in Roentgenology
    2011: 115-124
  • CT Angiography of the Renal Arteries: Renal Donor Evaluation
    -Number and location of the renal arteries including presence of prehilar branching
    -Detection of renal artery stenosis  and fibromuscular dysplasia (FMD)
    -Presence of renal mass or other important renal findings (horseshoe kidney, scarring of the kidney)
    -Renal vein and collecting system also evaluated on venous and delayed topogram
  • CT Angiography of the Renal Arteries: Protocols
    -Images reconstructed with narrow collimation (.75 mm) reconstructed at .5 mm intervals
    -All datasets analyze with a combination of axial, multiplanar (coronal and sagittal planes) and 3D rendering (volume rendering (VRT) and maximum intensity projection (MIP))
  • CT Angiography of the Renal Arteries: Protocols
    -Phases required depend on the application with two phases usually necessary
    -Contrast injection rate is 4-5 cc/sec with contrast volumes in the 80-120 cc volume range
    -Contrast used is Omnipaque-350 or Visipaque-320 depending on the patients creatinine or GFR levels
    -Arterial phase imaging is usually with a 25-30 second delay and nephrographic phase is at 55-60 seconds
  • CT Angiography: Renal Applications
    -Renal donor evaluation
    -Renal artery stenosis
    -Renal artery aneurysm

     

  • "Sensitivity, specificity, and negative and positive predictive values were 100%, 95%, and 100% and 56% respectively, for the detection of RA ISR of more than 50% with 64-detector CT RA angiography."

    64-Detector CT Angiography in Renal Artery Stent Evaluation: Prospective Comparison with Selective Catheter Angiography
    Steinwender C et al.
    Radiology 2009; 252:299-305

  • "All nine cases of renal artery in stent restenosis of more than 50% were diagnosed with 64-detector CT RA angiography in accord with conventional selective catheter RA angiography."

    64-Detector CT Angiography in Renal Artery Stent Evaluation: Prospective Comparison with Selective Catheter Angiography
    Steinwender C et al.
    Radiology 2009; 252:299-305

  • "Sixty four detector CT renal artery angiography can provide an excellent noninvasive technique to help detect and evaluate ISR (in-stent restenosis) within the RA stents used in our study."

    64-Detector CT Angiography in Renal Artery Stent Evaluation: Prospective Comparison with Selective Catheter Angiography
    Steinwender C et al.
    Radiology 2009; 252:299-305

  • Fibromuscular Dysplasia (FMD): Facts

    - Involves mid and distal vessels (not proximal)
    - Results in areas of stenosis and dilatation of small and mid size vessels
    - Cause of hypertension in females under age 40
  • "The average time to generate simple MIPs at the console was 3.4 minutes (range 1.7-4.4 minutes), and 22.3 minutes (range 15-30 minutes) to create images at the 3D workstation."

    Semiautomated MIP Images Created Directly on 16 Section Multidtector CT Console for Evaluation of Living Renal Donors
    Singh AK et al.
    Radiology 2007; 244:583-590
  • "CT Angiography produced interpretable multiplanar images of the renal artery, even with a a metallic stent in place, and was adequate for determining stent patency. Compared with catheter angiography, the intrastent luminal diameter was underestimated in most patients who underwent CT Angiography."

    Thin-Section Multidetector CT Angiography of Renal Artery Stents
    Behar JV et al.
    AJR 2002;178:1155-1159
  • "The diameter of the renal artery stent lumen measured on catheter angiography (mean, 5.9 +/- 1.3 mm) was greater than that on CT angiography (mean stent lumen diameter for direct axial plane was 4.6 +/- 1.0 mm)."

    Thin-Section Multidetector CT Angiography of Renal Artery Stents
    Behar JV et al.
    AJR 2002;178:1155-1159
  • Polyarteritis Nodosa: Facts

    - Systemic necrotizing vasculitis that affects small and medium size arteries
    - GI tract involvement is seen in up to 50% of patients
    - Common sites of involvement; kidneys, heart, liver, CNS and skin
  • Polyarteritis Nodosa: Angiographic Findings

    - Aneurysms in the 1-5 mm range
    - Vascular ectasia
    - Stenosis or occlusion of vessels
    - Intraparenchymal infarction
    - Aneurysm rupture
© 1999-2017 Elliot K. Fishman, MD, FACR. All rights reserved.