Quantitative Tc-99m DTPA renal transplant scintigraphy predicts graft survival in the very early postoperative period

BACKGROUND: Early evaluation of renal allograft prognosis is important for identification and targeted management of 'at-risk' grafts but is difficult in the absence of established tests. Tc-99m diethylene triamine pentaacetic acid renal transplant scintigraphy is a useful noninvasive method for assessing graft function. We aimed to assess the relative role of quantitative scintigraphic parameters in the immediate postoperative period for the assessment of short-term and long-term prognoses. METHODS: Data from 290 dynamic renal transplant scintigraphy procedures, performed on 161 recipients on day 1 (D1) or day 4 (D4) after transplantation, were analysed to derive various perfusion parameters [Kirchner's Index, Hilson's Index (HI), kidney-to-aorta ratio and ΔP] as well as nonperfusion parameters (graft washout t (1/2), P : PI ratio, P : U ratio, R20/3, T10 and T20) using regions of interest within the whole renal graft and iliac artery. Information on graft survival up to 1 year (as a measure of short-term prognosis) and serum creatinine at 1 year (regarded as a predictor for longer-term prognosis) was collected. Mann-Whitney tests, receiver-operating characteristic curve analyses and odds ratios were used to assess the utility of each parameter in stratifying the risk for graft failure within 1 year. Correlations between each parameter and 1-year serum creatinine were tested using Spearman's rank correlation. RESULTS: Eleven grafts failed within 1 year. All perfusion parameters on both D1 and D4 showed significant differences between the failure and survival groups (P=0.026-0.0005). No significant between-group differences were observed for nonperfusion parameters except for R20/3 on D1 (P=0.0298). Receiver-operating characteristic analysis showed moderate accuracy for HI and ΔP on both D1 and D4 (area under the curve: 0.73-0.84); ΔP of longer than 6.0 s on D4 was associated with 24.9 times higher relative risk for graft failure within 1 year (sensitivity 88% and specificity 83%). For the assessment of long-term prognosis, a moderate correlation was found between most perfusion parameters (Kirchner's Index, HI and kidney-to-aorta ratio on both D1 and D4) and 1-year serum creatinine (ρ=0.40-0.50; P ≤ 0.0001). The nonperfusion parameters showed only weak correlation. CONCLUSION: Perfusion assessment using HI and ΔP is useful in the assessment of graft prognosis. This can be achieved as early as D1 and D4 after transplantation.