99mTc MAG3 and 99mTc DTPA; comparison to evaluate renal functions in renal transplant patients

ABSTRACT

Renal scintigraphy evaluates the renal function non-invasively. The present study was conducted to compare 99mTc MAG3 and 99mTc DTPA in renal transplant patients for the evaluation of renal functions. Materials and 99mTc MAG3 and 99mTc DTPA studies were performed on 33 renal transplant patients and 10 normal subjects, with 1 day interval in between the two studies. Renal transplant patients were categorized as normal, acute tubular necrosis, rejection, urine outflow obstruction and urinary tract infection groups on the basis of routine clinical investigations and preliminary results of scintigraphic studies. Both radiopharmaceuticals, 99mTc MAG3 and 99mTc DTPA were having equal diagnostic efficacy, however image quality with 99mTc MAG3 was superior to that of 99mTc DTPA. Renograms clearly differentiated various renal groups. Correlation between glomerular filtration rate [GFR] and effective renal plasma flow [ERPF] was good [r=0.89 at P<0.00001]. In terms of perfusion index [PI] our results with both agents were similar [r=0.96 at p<0.00001], clearly differentiating all cases of rejection from acute tubular necrosis. PI was raised in rejection cases, while normal in all other groups. In cases of acute tubular necrosis and rejection, 99mTc MAG3 based parenchymal retention index [R-20/3] was markedly raised, compared to that of 99mTc DTPA [p<0.00001]. 99mTc- MAG3 and 99mTc DTPA have equal diagnostic efficacy in renal transplant patients. However visual delineations of the kidneys is better with 99mTc MAG3, especially in cases with compromised renal functions