Conflicting results were obtained for patients with more severe renal dysfunction with an eGFR of <30 mL/min/1.73 m2, with the 2013 Davenport et al study reporting an excess of acute kidney injury in these patients receiving intravenous contrast material versus controls but with the 2014 McDonald et al study showing no significant difference in acute kidney injury for contrast material recipients versus control patients with this baseline eGFR [8,60-63]. The ACR Manual on Contrast Media notes that if a threshold for CIN risk is used, an eGFR of 30 mL/min/1.73 m2 has the greatest level of evidence [7]. Reduced iodine dose should be considered in patients with borderline renal function, but other parameters are similar to patients with normal renal function. Unenhanced CT does not provide useful diagnostic information regarding RAS. MRA Contrast-enhanced MRA may be precluded because of the risk of NSF with eGFR <30 mL/min/1.73 m2. In these patients, unenhanced MRA techniques are available as an alternative to contrast-enhanced MRA to avoid the risk of NSF. Utsunomiya et al [64], comparing unenhanced SSFP MRA with CT or IADSA in 26 patients, found a sensitivity, specificity, positive predictive value, and negative predictive value of 78%, 91%, 64%, and 96%, respectively. Mohrs et al [65], comparing an SSFP technique with contrast-enhanced MRA in 45 patients, found a sensitivity, specificity, positive predictive value, and negative predictive value of 75%, 99%, 75%, and 99%, respectively, for detecting renal artery stenoses >50%. Braidy et al [66] compared an unenhanced SSFP technique to contrast-enhanced MRA with a sensitivity, specificity, positive predictive value, and negative predictive value of 85%, 96%, 94%, and 96%, respectively, but emphasized that when stenosis is found, other modalities should be employed for better estimation.
Renovascular Hypertension. Conflicting results were obtained for patients with more severe renal dysfunction with an eGFR of <30 mL/min/1.73 m2, with the 2013 Davenport et al study reporting an excess of acute kidney injury in these patients receiving intravenous contrast material versus controls but with the 2014 McDonald et al study showing no significant difference in acute kidney injury for contrast material recipients versus control patients with this baseline eGFR [8,60-63]. The ACR Manual on Contrast Media notes that if a threshold for CIN risk is used, an eGFR of 30 mL/min/1.73 m2 has the greatest level of evidence [7]. Reduced iodine dose should be considered in patients with borderline renal function, but other parameters are similar to patients with normal renal function. Unenhanced CT does not provide useful diagnostic information regarding RAS. MRA Contrast-enhanced MRA may be precluded because of the risk of NSF with eGFR <30 mL/min/1.73 m2. In these patients, unenhanced MRA techniques are available as an alternative to contrast-enhanced MRA to avoid the risk of NSF. Utsunomiya et al [64], comparing unenhanced SSFP MRA with CT or IADSA in 26 patients, found a sensitivity, specificity, positive predictive value, and negative predictive value of 78%, 91%, 64%, and 96%, respectively. Mohrs et al [65], comparing an SSFP technique with contrast-enhanced MRA in 45 patients, found a sensitivity, specificity, positive predictive value, and negative predictive value of 75%, 99%, 75%, and 99%, respectively, for detecting renal artery stenoses >50%. Braidy et al [66] compared an unenhanced SSFP technique to contrast-enhanced MRA with a sensitivity, specificity, positive predictive value, and negative predictive value of 85%, 96%, 94%, and 96%, respectively, but emphasized that when stenosis is found, other modalities should be employed for better estimation.