MR-derived renal morphology and renal function in patients with atherosclerotic renovascular disease

Appropriate selection of patients with atherosclerotic renovascular disease ( ARVD) for revascularization might be improved if accurate non-invasive investigations were used to assess severity of pre-existing parenchymal damage. The purpose of this study was to evaluate the associations between magnetic resonance imaging ( MRI)-measured renal morphological parameters and single-kidney glomerular filtration rate ( GFR) in ARVD. Three-dimensional ( 3D)-MRI was performed on 35 ARVD patients. Renal bipolar length ( BL), parenchymal volume, parenchymal ( PT), and cortical thicknesses ( CT) were measured in 65 kidneys. Thirteen kidneys were supplied by normal vessels, 13 had insignificant ( < 50%) renal artery stenosis ( RAS), 33 significant ( >= 50%) RAS, and six complete vessel occlusion. All patients underwent radioisotopic measurement of single-kidney GFR ( isoSK-GFR). Overall, 3D parameters such as parenchymal volume were better correlates of isoSK-GFR ( r = 0.86, P < 0.001) than BL ( r = 0.78, P < 0.001), PT ( r = 0.63, P < 0.001) or CT ( r = 0.60, P < 0.001). Kidneys with >= 50% RAS did show significant reduction in mean CT compared to those supplied by normal vessel ( 5.67 +/- 1.63 vs 7.28 +/- 1.80mm, P = 0.002; 22.1% reduction) and an even greater loss of parenchymal volume ( 120.65 +/- 47.15 vs 179.24 +/- 86.90ml, P < 0.001; 32.7% reduction) with no significant reduction in BL. In a proportion of >= 50% RAS kidneys, a disproportionately high parenchymal volume to isoSK-GFR was observed supporting a concept of 'hibernating parenchyma'. 3D parameters of parenchymal volume are stronger correlates of isoSK-GFR than two-dimensional measures of BL, PT or CT. 3D morphological evaluation together with isoSK-GFR might be useful in aiding patient selection for renal revascularization. Kidneys with increased parenchymal volume to SK-GFR might represent a subgroup with the potential to respond beneficially to angioplasty.