![]() Nuclear medicine ACE inhibitor scintigraphy MR angiography may overestimate moderate stenosis and detection/evaluation of accessory and branch arteries can at times be problematic. Reported sensitivity and specificity for MR angiography is at around >95% >90% for detection of stenoses of 50% or greater in diameter. Three-dimensional reconstruction technique offers sensitivity and specificity values around 90-100% 7. In some cases, renal impairment does not permit the use of contrast, in which case TOF imaging is beneficial. Time of flight (TOF): whereby the high velocity of the blood jet at the level of stenosis appears as a loss of signal (black)Ĭontrast-enhanced MRA: gadolinium is used as a contrast agent MRĭifferent imaging methods can be used for renal MRA: Additionally, supernumerary arteries may be identified. Both the raw data and 3D reconstructions should be viewed. Sensitivity and specificity of 90-99% have been reported 7. The three-dimensional reconstruction of the renal vascular tree provides a reliable method of visualizing the entire vascular tree. Images are acquired with thin collimation and bolus tracking on the abdominal aorta. Intraparenchymal acceleration time >0.07 sĪcceleration index (AI): lower than 3 m/s 2 Pulsus parvus et tardus waveform (slow-rising) due to stenosisĭecreased (interlobar) renal arterial resistive index (RI): 5% 9 lower cut off values increase sensitivity but decrease specificity PSV renal/PSV aorta: usually taken as >3.5, although some advocate >3 4 or even >2 3 PSV renal artery (intrastenotic)/PSV interlobar (distal): some advocate values greater than 5 3 Increased renal-interlobar ratio (RIR), i.e. Increased peak systolic velocity (PSV): some advocate 180 cm/s 4 Ultrasound, although most freely available, cheap and often used first-line, is relatively operator-dependent and may prove time-consuming. Occurrence is not uncommon following a renal transplant. Neurofibromatosis type 1: most commonly involves the ostium Vasculitides: especially polyarteritis nodosa (PAN) (causes multiple microaneurysms), Takayasu arteritis, radiation Renal artery stenosis may be caused by several pathological processes:Ītherosclerosis (~75% of cases): involves the proximal renal arteryįibromuscular dysplasia (~20%): involves the distal renal artery, younger population Angiotensin II is responsible for vasoconstriction and release of aldosterone which causes sodium and water retention, thus resulting in secondary hypertension. Angiotensin I is then converted to angiotensin II with the help of angiotensin-converting enzyme (ACE) in the lungs. The kidney wrongly senses the reduced flow as low blood pressure (via the juxtaglomerular apparatus) and releases a large amount of renin that converts angiotensinogen to angiotensin I. When the stenosis occurs slowly, collateral vessels form and supply the kidney. Acute renal artery stenosis does not lead to hypersecretion of renin. When the process occurs slowly, it leads to secondary hypertension. ![]() Low probability of renal artery stenosis (or, elevated renal artery to aortic ratio may represent renal artery stenosis recommend clinical correlation).Renal artery stenosis (RAS) (plural: stenoses) refers to a narrowing of a renal artery. The pre-void bladder volume is _cc and the post-void residual volume is _cc (< 100 is normal).Ģ. The bladder is normal in appearance and its wall measures _mm (< 3 is normal). The peak systolic velocity is _cm/sec and the renal artery to aortic ratio is _. It is normal in echotexture and demonstrate no evidence of hydronephrosis. The left kidney measures _cm in length with a cortical thickness of _cm. The peak systolic velocity is _m/sec (< 1.8 is normal) and the renal artery to aortic ratio is _ (< 3 is normal). It is normal in echotexture and demonstrates no evidence of hydronephrosis. The right kidney measures _cm in length (10-13 is normal in adults) with a cortical thickness of _cm (> 1 is normal). Multiple sonographic images of the kidneys and bladder were assessed for gray scale appearance and color doppler flow.
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