- “ 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
|
