A clinical MRI investigation of the relationship between kidney volume measurements and renal function in patients with renovascular disease.

Recent improvements in MR image acquisition and post-processing techniques have allowed quantitative kidney volume measurements to be derived from patient studies. These morphological indices can provide "snapshot" assessments that may be related to kidney function. The study objective was to measure cortical and total kidney volumes in patients with renovascular disease (RVD) using contrast-enhanced MR angiography (CE-MRA) in order to assess the reproducibility of the technique and to investigate associations between volumes and renal function as measured by glomerular filtration rate (GFR) calculations. 50 patients with RVD were scanned using CE-MRA. Kidney lengths, volumes and renal artery stenoses (RAS) were evaluated, and GFR was calculated using clinical formulae and nuclear medicine isotope renography. Mean MRI kidney lengths were 10.3+/-0.2 cm, and mean MRI volumes were 74.9+/-3.6 cm3 (cortical) and 128.5+/-5.3 cm3 (total). Kidneys supplied by moderately stenosed arteries had enlarged lengths and volumes, whilst those supplied by severely stenosed arteries had significantly smaller lengths (p<0.001) and volumes (p<0.001). There was a clear association between MRI cortical volume and GFR (r = 0.74, p<0.001, n = 48), but less so between kidney length and GFR (r = 0.54, p<0.001, n = 48). For individual patients, left/right cortical volume differences were small provided that severe RAS was not present, but large left/right volume differences and a GFR reduction were noted when severe RAS was present. The cortical volume distribution provides a useful single-timepoint indication of kidney function as defined by GFR, with no additional data acquisition required other than that of standard CE-MRA examination.