Acute renal failure: common occurrence of preservation of corticomedullary differentiation on MR images.

The purpose of this study was to evaluate the relationship between renal corticomedullary differentiation (CMD) on MR imaging and serum creatinine (sCr) level in patients with acute renal failure (ARF). Twenty-one patients with ARF were retrospectively investigated. In all 21 patients, sCr levels were obtained on the same date as the MR study, and within 8 days before and after the MR study. CMD was assessed on non-contrast T(1)-weighted images and immediate post-gadolinium spoiled gradient echo (Gd-SGE) images. Presence of CMD was graded into 3 groups as 'preserved', 'intermediate', or 'loss'. On non-contrast T(1)-weighted images, 12/21 (57%) showed loss of CMD and 9/21 (43%) showed preserved CMD. On immediate Gd-SGE images, 5/21 (24%) showed loss of CMD, 12/21 (57%) preserved CMD, and 4/21 (19%) intermediate CMD. The sCr levels of 9 patients with preserved CMD on non-contrast T(1)-weighted images ranged from 1.4 to 10.5 mg/dl (mean 4.6 mg/dl), while those of 12 patients with loss of CMD ranged from 1.6 to 7.6 mg/dl (mean 4.8 mg/dl), which was not statistically significant (p > 0.2). Renal CMD can remain preserved on non-contrast T(1)-weighted or immediate Gd-SGE images in patients with acute presentation of ARF, independent of sCr level.