In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. Resistive index (RI) has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34] or persistent AKI in critically ill patients [35] and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI as RI depends on multiple physiologic and pathologic factors, including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 2: Renal failure. Chronic kidney disease (CKD). Initial imaging. Arteriography Kidney Arteriography is reserved for intervention rather than for initial diagnosis. Treatment of renal artery stenosis may be considered, but a recent meta-analysis does not indicate a benefit in the preservation of renal function [38]. CT Abdomen and Pelvis Unenhanced CT is useful for further evaluation of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi [15]. Although CT can determine if there is hydronephrosis and assess renal size/volume, it is generally not considered the first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because of body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast for initial evaluation of CKD.
Renal Failure. In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. Resistive index (RI) has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34] or persistent AKI in critically ill patients [35] and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI as RI depends on multiple physiologic and pathologic factors, including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 2: Renal failure. Chronic kidney disease (CKD). Initial imaging. Arteriography Kidney Arteriography is reserved for intervention rather than for initial diagnosis. Treatment of renal artery stenosis may be considered, but a recent meta-analysis does not indicate a benefit in the preservation of renal function [38]. CT Abdomen and Pelvis Unenhanced CT is useful for further evaluation of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi [15]. Although CT can determine if there is hydronephrosis and assess renal size/volume, it is generally not considered the first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because of body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast for initial evaluation of CKD.