The value of ¹⁸F‐FDG PET/CT quantitative indexes in the diagnosis of nondestructive posttransplant lymphoproliferative disorders after pediatric liver transplantation

Posttransplant lymphoproliferative disease (PTLD) is a serious complication after pediatric liver transplantation (pLT), which may lead to death. 18 F-FDG PET/CT is rarely considered in PTLD after pLT and lacks clear diagnostic guidelines, especially in the differential diagnosis of nondestructive PTLD. The aim of this study was to find a quantifiable 18 F-FDG PET/CT index to identify nondestructive PTLD after pLT.This retrospective study collected the data of patients who underwent pLT, postoperative lymph node biopsy, and 18 F-FDG PET/CT at Tianjin First Central Hospital from January 2014 to December 2021. Quantitative indexes were established using lymph node morphology and the maximum standardized uptake value (SUVmax).A total of 83 patients met the inclusion criteria and were included in this retrospective study. To distinguish between PTLD-negative cases and nondestructive PTLD cases, according to the receiver operating characteristic curve, (the shortest diameter of the lymph node at the biopsy site [SDL]/the longest diameter of the lymph node at the biopsy site [LDL])*(SUVmax at the biopsy site [SUVmaxBio]/SUVmax of the tonsils [SUVmaxTon]) had the maximum area under the curve (0.923; 95% confidence interval: 0.834-1.000), and the cutoff value was 0.264 according to the maximum value of Youden's index. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 93.6%, 94.7%, 97.8%, 85.7%, and 93.9%, respectively.(SDL/LDL)*(SUVmaxBio/SUVmaxTon) has good sensitivity, specificity, positive predictive and negative predictive values, and accuracy, and can be used as a good quantitative index for the diagnosis of nondestructive PTLD.