Effect of Warm Ischemia on Renal Function During Partial Nephrectomy: Assessment With New 99mTc-Mercaptoacetyltriglycine Scintigraphy Parameter

OBJECTIVE A decrease in renal function after partial nephrectomy caused by ischemic damage or nephron loss cannot be distinguished by conventional methods. We quantified renal function using a new Tc-99m-mercaptoacetyltriglycine (Tc-99m-MAG3) renal scintigraphy parameter. MATERIAL AND METHODS We included 32 patients with a normally functioning contralateral kidney who received open partial nephrectomy with average warm ischemic time of 26.0 (range 14-46) min in this study. Effective renal plasma flow (ERPF) was calculated from Tc-99m-MAG3 renal scintigraphy before and at 1 week and 6 months after surgery. We also analyzed regional Tc-99m-MAG3 uptake in the surgically nonaffected parts. RESULTS One week after surgery, average ERPF in the operated kidney decreased to 66.4% from baseline (from 177.8 to 116.9 mL/min/1.73 m(2)) and regional Tc-99m-MAG3 uptake decreased to 83.4%. A stronger correlation was found between ischemic time and the decrease in regional Tc-99m-MAG3 uptake (P<.001) compared with ERPF (P=.029). The decrease in regional Tc-99m-MAG3 uptake remained at 6 months in the group with ischemic time >= 25 minutes, whereas it recovered when ischemic time was <25 minutes. CONCLUSION This new parameter quantified ischemic renal damage better than the conventional split functional evaluation. When warm ischemic time was >= 25 minutes, irreversible diffuse damage was seen in surgically preserved nephrons. UROLOGY 79: 160-165, 2012. (C) 2012 Elsevier Inc.