Patrick Veit-Haibach MD, Presenter: Nothing to Disclose

Klaus Strobel MD, Abstract Co-Author: Nothing to Disclose

Niklaus Schäfer MD, Abstract Co-Author: Nothing to Disclose

Jan David Soyka MD, Abstract Co-Author: Nothing to Disclose

Thomas F. Hany MD, Abstract Co-Author: Nothing to Disclose

Hans C. Steinert MD, Abstract Co-Author: Nothing to Disclose

SUVmax and modified RECIST evaluations are established clinical parameter for therapy assessment in patients with malignant pleural mesothelioma (MPM). The aim of this study was to compare SUVmax measurements and CT measurements derived from the same PET/CT procedure in therapy assessment.

22 patients with proven MPM underwent 91 FDG-PET/CT in a prospective study. All patients received first line chemotherapy with Pemetrexed and additionally platinum-based chemotherapy. SUV max was measured with a rectangular ROI. SUV measurements were calculated as percentages compared to the previous PET/CT scan and were classified as stable disease (SD), progressive disease (PD) and (partial) response (PR) according to the current EORTC criteria. CT images were evaluated using modified RECIST criteria and were classified in SD, PD and PR as well. Measurements of both groups were compared with the concordance coefficient (Kappa). Overall therapy assessment was calculated by adding all percental changes of SUV max and CT measurements after completion of the first line therapy. The sum of measurements was classified as SD, PR or PD as well.

91 PET/CT scans were assessed. SUVmax and CT showed concordant findings for SD in 30 PET/CTs(43 %), for PR in 2 PET/CTs(3%) and for PD in 10 PET/CTs(14 %). Discordant evaluations were found in 27 PET/CT scans (39%) in 17 patients. Only a low concordance coefficient (Kappa=0.29)was found. After evaluation of all PET/CT procedures per patient, SUVmax showed 4 patients with overall PR, 5 patients with overall SD and 13 patients with overall PD, whereas in CT 3 patients had overallPR, 12 patients had overall SD and 7 patients had overall PD. These were 13 concordant classifications and 9 discordant classifications (59%vs. 41%).

CT measurement with modified RECIST criteria and SUVmax measurements showed only a low concordance coefficient.. Furthermore we found a high rate of discordant findings in overall therapy assessment. Thus, a combined classification using a combination of PET and CT data has to be developed for therapy assessment with hybrid PET/CT.

A combined PET/CT classification has to be developed for therapy assessment.

Veit-Haibach, P, Strobel, K, Schäfer, N, Soyka, J, Hany, T, Steinert, H, Concordance of SUVmax and Modified RECIST Criteria in PET/CT-based Therapy Assessment in Patients with MPM.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5009432.html