Diagnosis of renal artery stenosis with magnetic resonance angiography: update 2003.

Three-dimensional (3D) gadolinium magnetic reso-nance angiography (MRA) has been established as asafe and reliable technique for detection and gradingof renal artery stenosis. Due to the lack of need fornephrotoxic contrast agents and ionizing radiation,this technique is particularly attractive for patientswith kidney transplants or those with renal failure.With the introduction of high performance MRsystems with fewer upfront costs and cheaper main-tenance, the technique has gained widespread use evenin community hospitals and private practices.Despite its overall significant role in the diagnosticwork-up of patients with renal artery stenosis, the tech-nique currently faces several new challenges to beovercome. Although a reproducible quality of the 3Dgadolinium MRA images with a high level of accuracyhas been well documented in numerous studies, doubtshave been cast on the results recently by new data frommulticentre trials [1,2]. These studies question theinitially reported high sensitivities and specificitiesexceeding 95%. However, at the same time, the evolu-tion of the 3D gadolinium MRA technique itselfhas continued, and therefore new data on MRA withimproved spatial resolution might again lead to moreoptimistic results. A second problem, which has beenwell documented recently by a number of authors, isthe high interobserver variability of the technique,which directly contributes to the ambiguous results[3–5]. Thirdly, renal artery stenosis is now viewed asonly one manifestation of a systemic arterioscleroticprocess. Recent improvements of MR scanners nowallow coverage of large anatomic areas in a single scan,thereby offering the possibility to screen almost allvascular territories of the human body [6]. Finally,several studies have shown that patients with renalartery stenosis often do not improve after angioplastydespite technical success [7]. Therefore, the severity ofstenosis cannot be considered a valuable predictor ofpost-intervention improvement.