Prognostic value of imaging diagnosis in patients (pts) with malignant lymphoma (ML): CT/MRI with International Working Group Criteria (IWC) vs. FDG-PET with Revised Response Criteria (RRC)

Objectives To compare a post-treatment imaging evaluation based on IWC and RRC with a recurrence during follow-up period in ML pts.

Methods Thirty nine pts (Hodgkin’s Lymphoma:7, non-Hodgkin's Lymphoma:32) underwent CT/MRI in suspected lesions and whole-body PET or PET/CT before and after therapy from October 1998 to December 2008. All PET or PET/CT scans after therapy were performed according to the RRC. Each size of ML lesions on CT/MRI was evaluated according to IWC. The presence of abnormal FDG uptake was evaluated visually and interpreted according to RRC. The CT/MRI based and FDG-PET based imaging evaluation at the end of therapy was investigated in relation to progression -free survival (PFS) during later follow-up period.

Results Median follow-up period was 802 days (25-1988 days). The concordance of complete remission (CR) according to IWC and RRC was found in 17 of 40 evaluations (two evaluations in one patient) at the end of therapy. All these did not show relapse during the later follow-up period. The concordance of partial remission (PR) was found in 10 evaluations, and 3 of 10 relapsed. The discrepant evaluation between CT/MRI (PR according to IWC) and PET (CR according to RRC) was found in 10 evaluations, and 5 of 10 relapsed. The 2-year actuarial PFS rate was 100% for the pts evaluated with CR according to IWC and 67% evaluated with CR according to RRC (p=0.07).

Conclusions The concordance of CR with CT/MRI-based IWC and PET-based RRC at the end of therapy predicted a longer PFS in ML pts.