Sirong Chen, Presenter: Nothing to Disclose

William Cheung, Abstract Co-Author: Nothing to Disclose

Yim Lung Leung, Abstract Co-Author: Nothing to Disclose

Thomas KC Cheng MBBS, Abstract Co-Author: Nothing to Disclose

Ka Nin Wong, Abstract Co-Author: Nothing to Disclose

Chor Sang Chim, Abstract Co-Author: Nothing to Disclose

Chi Lai Ho, Abstract Co-Author: Nothing to Disclose

11C-acetate PET/CT is useful for the detection of multiple myeloma (MM) because it was previously shown that myeloma cell lines prefer fatty acid over glucose metabolism for growth. We aim to compare the diagnostic value of 11C-acetate PET/CT in relapsed MM with treatment naive MM patients.

From year 2010 to 2013, 66 MM patients were referred for 11C-acetate PET/CT: 37 relapsed (M: 23, F: 14; mean age=61.4±7.7y) and 29 newly diagnosed (M: 17, F: 12; mean age=63.1±10.6y). All patients were confirmed by trephine bone marrow biopsy. 20 subjects with normal marrow were recruited as controls (M: 12, F: 8; mean age=59.8±10.9y). Active myeloma disease was first visually assessed as having focal or diffuse pattern on PET. SUVmax of L3 was chosen as the representative site for quantitative assessment of marrow disease activity for patients with diffuse MM. ROC analysis was performed between MM and normal subjects to define the individual SUVmax_L3 cut-off values for newly diagnosed and relapsed patients with diffuse MM pattern.

For the detection of focal MM, 11C-acetate PET/CT had a detection sensitivity of relapsed MM (31/33: 93.9%) comparable to that of newly diagnosed MM (15/16: 93.8%). For diffuse MM, the ROC-defined thresholds of SUVmax_L3 were 3.78 and 3.80 (AUC=0.97 vs 0.97) in relapsed and newly diagnosed groups, respectively. At these thresholds, 11C-acetate PET/CT had a slightly better sensitivity for detection of diffuse MM in the relapsed group (22/25: 88.0%) than newly diagnosed group (22/27: 81.5%). The average marrow activity in relapsed group was higher than that of newly diagnosed group (SUVmax_L3=6.57±3.59 vs 5.10±1.78, P=0.065), suggesting that relapsed MM patients had more severe marrow infiltration. The overall detection sensitivity of focal and/or diffuse MM disease by 11C-acetate PET/CT was also slightly better in relapsed (34/37: 91.9%) than in newly diagnosed MM (24/29: 82.8%) patients.

11C-acetate PET/CT is sensitive for detection of both relapsed and newly diagnosed MM. It has even better diagnostic performance in relapsed patients with diffuse MM pattern, which is the group of MM patients known to have the greatest diagnostic challenge.

In addition to its high detection sensitivity in newly diagnosed MM, 11C-acetate PET/CT is also sensitive in assessment of MM relapse, hence with potential to suggest when to re-initiate treatment.

Chen, S, Cheung, W, Leung, Y, Cheng, T, Wong, K, Chim, C, Ho, C, Comparison of 11C-acetate PET/CT for the Evaluation of Newly Diagnosed and Relapsed Myeloma.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017302.html