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 99mTc-mercaptoacetyltriglycine (99mTc-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 99mTc-MAG3 renal scintigraphy before and at 1 week and 6 months after surgery. We also analyzed regional 99mTc-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 m2) and regional 99mTc-MAG3 uptake decreased to 83.4%. A stronger correlation was found between ischemic time and the decrease in regional 99mTc-MAG3 uptake (P<.001) compared with ERPF (P=.029). The decrease in regional 99mTc-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.