Quantitative scintigraphic parameters for the assessment of renal transplant patients

Radionuclide renal diagnostic studies play an important role in assessing r enal allograft function especially in the early post transplant period. In the last two decades various quantitative parameters have been derived from the radionuclide renogram to facilitate and confirm the changes in perfusi on and/or function of the kidney allograft. In this review article we discu ss the quantitative parameters that have been used to assess graft conditio n with emphasis on the early post-operative period. These quantitative meth ods were divided into parameters used for assessing renal graft perfusion a nd parameters used for evaluating parenchymal function. The blood flow in r enal transplants can be quantified by measuring (a) the rate of activity ap pearance in the kidney graft; (b) the ratio of the integral activity under the transplanted kidney and arterial curves e.g. Hilson's perfusion index a nd Kircher's kidney/aortic ratio; (c) calculating the renal vascular transi t time by deconvolution analysis. The literature overview on these paramete rs showed us that they have some practical disadvantages of requiring high quality bolus injection and numerical variations related to changes in the site and size of regions of interest. In addition, the perfusion parameter values suffer from significant overlap when various graft pathologies coexi st. Quantitative evaluation of the graft parenchymal extraction and excreti on was assessed by parameters derived from I-123/I-131-OIH, Tc-99m-DTPA or Tc-99m-MAG3 renograms. We review in this article a number of parenchymal pa rameters which include (1) plasma clearance methods like glomerular filtrat ion rate (GFR) and effective renal plasma flow (ERPF); (2) renal transit ti mes such as parenchymal mean transit time, T-max, T-1/2; (3) parenchymal up take and excretion indices as the accumulation index, graft uptake capacity at 2 and 10 min, excretion index and elimination index. These indices, how ever, are non-specific and far from defining a specific cause for graft par enchymal dysfunction. In conclusion, despite that the literature is replete with mathematical strategies for quantitating perfusion and parenchymal fu nctions, none of these have enough diagnostic power for specific diagnosis of graft dysfunction. In addition, no universal agreement on the use of cer tain quantitation parameters in transplant patients has been reached. (C) 1 998 Elsevier Science Ireland Ltd. All rights reserved.