Analysis of 371 cases of Non-Hodgkin’s Lymphoma : Answer of Longstanding Controversial Cutoff Value of FDG Uptake Between Aggressive and Indolent Non-Hodgkin's Lymphoma

Objectives: To confirm or disprove the controversial cutoff value of FDG uptake between aggressive and indolent Non-Hodgkin's lymphoma (NHL). Methods: About four thousands FDG- PET/CT for patients with NHL in period 2008-2015 were retrospectively studied , three hundreds seventy one patients were selected with the following criteria : have biopsy proven histopathological sub-type of NHL , no transformation, and have pre-therapy FGD-PET/CT or after 6 months since the last therapy. Maximum standardized uptake value (SUVmax) of all abnormal foci were measured and the highest focus was reported in each patient. Results: 209 cases with aggressive NHL and 162 with indolent NHL. Mean of SUVmax in aggressive NHL was 14.24 +/- 8.8 , range ( 1.95 - 56.58). Mean of SUVmax in indolent NHL was 6.38 +/-3.93, range ( 0.1 - 19.8 ). There is extremely significant difference between aggressive and indolent NHL ( P = 0.0001). By using receiver operating characteristic ( ROC) curve, the most reasonable SUVmax cutoff is 9.7 , with area under the curve (AUC) 0.80, Specificity 81.2 % , sensitivity 70 % , Positive predictive value (PPV) 78.92% and negative predictive value (NPP) 73%. Our results are nearly concordant with previous smaller study by Schöder H et al 2005 , they studied ninety seven patients of NHL , that study showed SUVmax of 10 as the best cutoff value with 81% specificity . Conclusion: 9.7 is a good SUVmax cutoff value of FDG uptake between aggressive and indolent NHL.