title: (11)C-acetate as a new biomarker for PET/CT in patients with multiple myeloma: initial staging and postinduction response assessment.
abstract: OBJECTIVE
  We investigated the potential value of (11)C-acetate (ACT) PET/CT in characterizing multiple myeloma (MM) compared with (18)F-FDG PET/CT. Bone marrow histological and whole-body (WB) MRI findings served as the reference standards.
  
  
  METHODS
  In this prospective study, 15 untreated MM patients (10 men and 5 women, age range 48-69 years) underwent dual-tracer (11)C-ACT and (18)F-FDG PET/CT and WB MRI for pretreatment staging, and 13 of them had repeated examinations after induction therapy. Diffuse and focal bone marrow uptake was assessed by visual and quantitative analyses, including measurement of the maximum standardized uptake value (SUVmax). Between-group differences and correlations were assessed with the Mann-Whitney U test and the Pearson test.
  
  
  RESULTS
  At staging, all 15 patients had diffuse myeloma involvement upon bone marrow examination with 30-90 % of plasma cell infiltrates. Diffuse infiltration was detected in all of them (100 %) using (11)C-ACT with a positive correlation between bone marrow uptake values and percentages of plasma cell infiltrates (r = +0.63, p=0.01). In contrast, a diagnosis of diffuse infiltration could be established using (18)F-FDG in only six patients (40 %). Focal lesions were shown in 13 patients on both (11)C-ACT PET/CT and WB MRI, and in 10 patients on (18)F-FDG PET/CT. Focal lesions demonstrated (11)C-ACT uptake with a mean SUVmax of 11.4 ± 3.3 (range 4.6-19.6, n=59), which was significantly higher than the (18)F-FDG uptake (mean SUVmax 6.6 ± 3.1, range 2.3-13.7, n=29; p<0.0001). After treatment, the diffuse bone marrow (11)C-ACT uptake showed a mean SUVmax reduction of 66 % in patients with at least a very good partial response versus 34 % in those with at most a partial response only (p=0.01).
  
  
  CONCLUSIONS
  PET/CT using (11)C-ACT as a biomarker showed a higher detection rate for both diffuse and focal myeloma lesions at diagnosis than using (18)F-FDG, and may be valuable for response assessment.
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, No. 5 Fusing Street, Gueishan, 33305, Taiwan.
authors.forename: Chieh
authors.initials: C
authors.lastname: Lin
authors.forename: Chi-Lai
authors.initials: CL
authors.lastname: Ho
authors.forename: Shu-Hang
authors.initials: SH
authors.lastname: Ng
authors.forename: Po-Nan
authors.initials: PN
authors.lastname: Wang
authors.forename: Yenlin
authors.initials: Y
authors.lastname: Huang
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Lin
authors.forename: Tzung-Chih
authors.initials: TC
authors.lastname: Tang
authors.forename: Shu-Fan
authors.initials: SF
authors.lastname: Tsai
authors.forename: Alain
authors.initials: A
authors.lastname: Rahmouni
authors.forename: Tzu-Chen
authors.initials: TC
authors.lastname: Yen
mesh_terms: D000085:Acetates; D000368:Aged; D002250:Carbon Radioisotopes; D005260:Female; D006801:Humans; D060828:Induction Chemotherapy; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009101:Multiple Myeloma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology*; D009367:Neoplasm Staging; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes