title: Evaluating heterogeneity of primary tumor (18)F-FDG uptake in breast cancer with a dedicated breast PET (MAMMI): a feasibility study based on correlation with PET/CT.
abstract: OBJECTIVE
  The aim of the study was to evaluate the heterogeneity of primary tumor F-fluorodeoxyglucose ((18)F-FDG) uptake in breast cancer patients using a dedicated breast PET.
  
  
  METHODS
  A positron emission tomography/computed tomography (PET/CT) of the thorax was performed 60 min after administration of 180-240 MBq of (18)F-FDG in patients with breast cancer. Subsequently, 110 min after injection, a scan was taken with a dedicated high-resolution breast PET [MAMmography with Molecular Imaging (MAMMI)]. Both procedures were performed with the patients in the prone position. Four-point scores were used to compare the intensity (0: none; 1: mild; 2: moderate; 3: high) and heterogeneity (0: none; 1: mild; 2: moderate; 3: high) of (18)F-FDG uptake between PET/CT and MAMMI images.
  
  
  RESULTS
  Thirty-five patients in whom the primary tumor was visualized on both scans were included in this analysis. The mean primary tumor size was 35.1 mm (range 10-108 mm). The mean intensity score was similar on both devices (2.4 for PET/CT and 2.3 for MAMMI; P=0.439), but the mean heterogeneity score on MAMMI images was significantly higher (PET/CT 1.9 vs. MAMMI 2.3; P=0.005). MAMMI showed a higher heterogeneity score in 11 (31%) of 35 patients, especially in tumors with moderate or high intensity. Significantly higher heterogeneity scores on both PET/CT and MAMMI were seen in large tumors (P=0.005 and 0.014, respectively) and in tumors with high intensity scores (P=0.012 and P<0.001, respectively).
  
  
  CONCLUSIONS
  Heterogeneous tumor (18)F-FDG uptake in breast cancer is frequently observed, particularly in large tumors with intense (18)F-FDG uptake. It is more often seen on MAMMI PET than on conventional PET/CT. Although the observed heterogeneity should be proven histopathologically, this finding offers a rationale for (18)F-FDG-guided biopsies.
authors.affiliation: aDepartment of Nuclear Medicine, Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands bDepartment of Nuclear Medicine, Hospital Clínic Barcelona, Barcelona cCorpuscular Physics Institute (IFIC), Valencia, Spain.
authors.forename: Bas B
authors.initials: BB
authors.lastname: Koolen
authors.forename: Sergi
authors.initials: S
authors.lastname: Vidal-Sicart
authors.forename: José M
authors.initials: JM
authors.lastname: Benlloch Baviera
authors.forename: Renato A
authors.initials: RA
authors.lastname: Valdés Olmos
mesh_terms: D000328:Adult; D000368:Aged; D001692:Biological Transport; D001940:Breast / Q000000981:diagnostic imaging* / Q000378:metabolism; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D005240:Feasibility Studies; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18