Mitsuaki Tatsumi MD, PhD, Presenter: Nothing to Disclose

Kayako Isohashi, Abstract Co-Author: Nothing to Disclose

Tadashi Watabe, Abstract Co-Author: Nothing to Disclose

Eku Shimosegawa, Abstract Co-Author: Nothing to Disclose

Noriyuki Tomiyama MD, PhD, Abstract Co-Author: Nothing to Disclose

Jun Hatazawa MD, PhD, Abstract Co-Author: Nothing to Disclose

Follicular lymphoma (FL) often represents rather low FDG uptake in PET exams, which potentially affects results of treatment response. In the present study, quantitative response evaluation with PET response criteria in solid tumors (PERCIST) was applied in FL patients. The results were compared to ones from revised response criteria (RRC), which is usually used in clinical situations.

This study included 45 pre- and posttreatment FDG PET/CT exam sets in 42 FL patients during Jul 2007 and Nov 2012. SUVmax was obtained in the hottest lesion in each exam. Changes of SUVmax after treatment were evaluated according to PERCIST and compared to the visual results of RRC. PET/CT exam sets were classified into high and low FDG uptake groups based on the pretreatment SUVmax (>5: high). Results in each group were also evaluated and compared to RRC. In the visually-negative posttreatment exams (complete remission <CR> cases), reduction of SUVmax was calculated at the same area as pretreatment SUVmax to recognize the ranges of change.

SUVmax in the hottest lesion ranged from 2.7 to 17.8 before treatment (mean: 6.8±3.5, median: 5.7). 25 and 20 exam sets were classified into high and low FDG uptake groups, respectively. Of all 45 exam sets, 38 (84%) exhibited concordant results with RCC (CR: 23, PR: 13, and PD: 2). 7 discordant results were all due to the combination of SD in PERCIST and PR in RRC. Subgroup analysis revealed 22 (88%) of 25 high- and 16 (80%) of 20 low uptake groups showed concordant results with RRC (no statistical difference). Reduction of SUVmax in PR cases was 61±11% for high- (n=8) and 57±12% for low (n=5) uptake groups, respectively. No statistical difference was observed between the groups. Reduction of SUVmax in CR cases ranged from 32 to 74% with a mean of 58±13% for low uptake group (n=10). Most of them (70%) showed >50% reduction.

This study demonstrated quantitative response evaluation with PERCIST provided similar results to RRC in most instances in follicular lymphoma. Effective treatment caused enough reduction of SUVmax to meet PERCIST even in cases with low FDG uptake before treatment.  

Quantitative response evaluation with PERCIST was considered to be feasible in follicular lymphoma, even in cases with low FDG uptake before treatment.

Tatsumi, M, Isohashi, K, Watabe, T, Shimosegawa, E, Tomiyama, N, Hatazawa, J, Feasibility of Quantitative Response Evaluation with PERCIST in Follicular Lymphoma: With Special Focus on the Cases with Low FDG Uptake  .  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007634.html