Renographic indices for evaluation of changes in graft function

Abstract

Radionuclide renal diagnostic studies play an important role in assessing renal allograft function, especially in the early post-transplant period. In the past two decades various quantitative parameters have been derived from the radionuclide renogram to evaluate changes in perfusion and/or function of the kidney allograft. In this review article we discuss the quantitative parameters that have been used to assess graft condition, with emphasis on the early postoperative period. These quantitative methods are divided into parameters used for assessing renal graft perfusion and parameters used for evaluating parenchymal function. The blood flow in renal transplants can be quantified (a) by measuring the rate of activity appearance in the kidney graft, (b) by calculating the ratio of the integral activity under the transplanted kidney and arterial curves and (c) by calculating the renal vascular transit time. In this article we review a number of parenchymal uptake and excretion indices, such as the accumulation index, the graft uptake capacity at 2 and 10 min, the excretion index and the elimination index. The literature on these parameters shows that they have some practical disadvantages. In addition, values suffer from significant overlap when various graft pathologies coexist. A retrospective study was designed in our institution to evaluate the clinical usefulness of some of the frequently used previously published methods in which the graft function is quantitatively assessed in the early post-transplant period. The quantitative parameters studied which were reasonably reproducible in our hands included: global perfusion index (GPI), cortical perfusion index (CPI), vascular transit time, and the parenchymal parameters uptake capacity at 2 min (UC2) and elimination index (K3/20). The patient population in this study consisted of 43 patients with 157 technetium-99m mercaptylacetyltriglycine renograms. The perfusion indices GPI and CPI did not allow differentiation of the acute tubular necrosis (ATN) group from the acute rejection (AR) group; however, they were of value in monitoring the improvement in the condition of the graft dysfunction in both the AR and ATN groups. As for the parenchymal parameters, both UC2 and K3/20 were able to differentiate stable graft function (SGF) versus AR and ATN groups but were unable to separate AR from ATN dysfunction. The ability of these parenchymal parameters to detect improvement in the graft function was poor and statistically non-significant. From the literature data and our own findings it is concluded that radionuclide scintigraphy of renal transplants has assumed an important role, especially if performed serially, in monitoring graft function in the post-transplant period. Many quantitative parameters have been derived from the radionuclide renogram to evaluate changes in perfusion and/or function of the kidney allograft. It appears that these quantitative numerical values are unable to differentiate unequivocally between grafts with ATN and AR cases. The real valu...

Estudio de los hallazgos de la gammagrafía renal inmediata y su influencia en la supervivencia del injerto renal

“…Por contra, estas exploraciones no son específicas y los hallazgos que se obtienen en ellas son similares en diferentes situaciones clínicas 6,7 . En este sentido, la mayor parte de la literatura científica se ha centrado en el estudio de su sensibilidad a la hora de establecer un diagnóstico claro en la disfunción inicial del injerto, diferenciando el rechazo agudo de la necrosis tubular pura 8,9 .…”

Estudio de los hallazgos de la gammagrafía renal inmediata y su influencia en la supervivencia del injerto renal

“…Por contra, estas exploraciones no son específicas y los hallazgos que se obtienen en ellas son similares en diferentes situaciones clínicas 6,7 . En este sentido, la mayor parte de la literatura científica se ha centrado en el estudio de su sensibilidad a la hora de establecer un diagnóstico claro en la disfunción inicial del injerto, diferenciando el rechazo agudo de la necrosis tubular pura 8,9 . Existen pocos estudios que valoren la asociación de los hallazgos gammagráficos inmediatos y el pronóstico a largo plazo del injerto.…”

Renography within 1 Hour of Renal Transplantation: Technical Feasibility and Clinical Utility

“…Time-activity curves for these regions were analyzed for the following parameters: perfusion index, time to maximum transplant uptake (T max ), time to half-maximum transplant uptake (T 1/2 max ), and functional uptake index. Both images and quantitative data were interpreted using previously described techniques and standards [7,[12][13][14][15][16][17][18][19] . Interpretation included visual analysis of the fl ow study and sequential functional images as well as quantitative analysis of T max , T 1/2 max , perfusion index and functional uptake index ( fi g. 1 ).…”