Curvilinear areas in the perinephric fat seen on MR images

AIM: On magnetic resonance (MR) images, strands correspond to curvilinear a reas running in the perinephric fat, and haloes to those lying on the renal surface. Our aim was to examine the diagnostic significance and histopatho logical basis of these areas. PATIENTS AND METHODS: MR images obtained in 46 patients without renal disea se and 96 patients with renal disease were assessed for the signal intensit y and extent of strands and haloes, and their degree of right-left asymmetr y, RESULTS: Strands usually revealed lon signal intensity on TI-weighted MR im ages and high signal intensity on fat-suppressed T2-weighted images and con trast-enhanced fat-suppressed T1-weighted images. Haloes revealed high sign al intensity on fat-suppressed T2-weighted images, but most of haloes were not clearly depicted on T1-weighted images or contrast-enhanced fat-suppres sed T1-weighted images. Strands and haloes were common and usually symmetri cal or only mildly asymmetrical in both patient groups. However, in 11 of t he 96 patients with renal disease, prominent strands and/or haloes appeared with remarkable asymmetry and likely represented definite changes in the p erinephric fat. At histopathology, vascular loose fibrous tissue was found at the sites of strands and haloes, CONCLUSION: Strands and haloes usually represent normal anatomical variatio ns, However, the presence of prominent strands or haloes with remarkable ri ght-left asymmetry implies abnormality and may provide additional informati on in the evaluation of renal disease, (C) 1999 The Royal College of Radiol ogists.