MR imaging of renal vein occlusion in dogs

RATIONALE AND OBJECTIVES. MR findings of renal vein thrombosis are not consistent in the literature. Our goal was to evaluate MR findings of kidneys after renal vein occlusion in dogs. METHODS. Surgical ligation of renal veins was performed in seven dogs. Of these, five dogs were examined with MRI before surgery, on the day of the renal vein ligation, and on the 1st, 4th, 8th, 15th, and 30th days. The other two dogs underwent nephrectomy on the 4th and 8th days for histopathologic correlation. RESULTS. On T1-weighted images, corticomedullary differentiation was lost in all dogs by the 15th day. On T2- weighted images, the signal intensity of the renal cortex was significantly decreased beginning on the first day. The kidneys showed no medullary enhancement in the postcontrast period. The volume of the kidney began increasing at the time of renal vein ligation, started to decrease after the 4th day, and developed significant atrophy by the 30th day. CONCLUSIONS. After renal vein ligation, the renal cortex appears hypointense on T2- weighted images, corticomedullary differentiation is lost within 2 weeks on T1-weighted images, and the kidney becomes atrophic by 1 month.