Use of Renal Duplex To Detect Renal Artery Stenosis in Fibromuscular Dysplasia

Introduction: Duplex ultrasonography is widely used to evaluate renal artery stenosis (RAS), but diagnostic criteria are largely derived from atherosclerotic RAS and may not apply to fibromuscular dysplasia (FMD). We evaluated associations between renal duplex parameters and hemodynamically significant RAS in patients with FMD. Methods: Patients with renal FMD who underwent renal duplex followed by renal artery angiography within 3 months were included. Duplex parameters were compared between arteries with and without RAS (Pd/Pa<0.9, fractional flow reserve (FFR)<0.8, systolic pressure gradient >20 mm Hg, or %stenosis >70%). Receiver operating characteristic (ROC) analysis was used to evaluate diagnostic performance. Changes following angioplasty were compared. Results: 55 renal arteries from 33 patients with renal FMD were included. Peak systolic velocity (PSV), end diastolic velocity (EDV), and acceleration time (AT) were higher in arteries with RAS. Resistive index (RI) was lower in RAS. Renal aortic ratio (RAR) did not differ between groups. PSV demonstrated good discrimination with a cut-off of 275 cm/sec yielding 79% sensitivity, 78% specificity, and an area under the curve (AUC) of 0.81. Incorporating additional parameters did not improve performance compared with PSV alone. Following angioplasty, PSV, EDV, and AT decreased, RI increased, RAR remained unchanged. Conclusion: In renal FMD, duplex ultrasound parameters, particularly PSV and RI, are associated with hemodynamically significant RAS. However, overlap in PSV between arteries with and without RAS suggests that PSV alone may not reliably determine lesion significance. These findings support duplex ultrasonography for evaluating renal FMD while highlighting the need for FMD-specific diagnostic criteria.?