[Regional renogram and functional imaging with I-123-orthoiodohippurate in obstructive nephropathy].

Renal scintigraphy and regional renography using I-123- orthoiodohippurate were performed in 26 cases of obstructive nephropathy. After 1 mCi of I-123- orthoiodohippurate was given intravenously, serial renal scintigrams were obtained for 25 minutes and regional renogram curves were derived from the whole kidney, the cortical and pelvic areas. At the same time, renal functional images with Tmax as the peak arrival time were processed. Tmax in normal cases ranged from 2 to 3 minutes in the cortex and from 4 to 5 minutes in the pelvis, while there was some delay in Tmax in the obstructive nephropathy. In the case of acute ureteral obstruction by stones, most of the regional renograms in the cortex and pelvis improved soon after the removal of the obstruction. On the contrary, in the case of chronic obstructive nephropathy obstructive patterns on renogram curves was usually observed postoperatively. However, in some cases, functional images in cortical and/or pelvic areas showed marked recovery before improvement of findings on renograms or IVP. I-123- orthoiodohippurate renoscintigraphy is a useful adjunct for assessing pre- and post-operative renal function in obstructive nephropathy. Particularly, the analysis of regional renogram curves enables early prediction of postoperative recovery, and the functional image enables early detection of the functional recovery of the hydronephrotic kidney.