Breast cancer; Prone or not Prone??

Objectives: Prone position 18F fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) may improve the localization of the tumor, delineate the exact distance from areola which is utmost important for the surgical planning and separation of deep anatomic parts especially axillary lymph nodes. The aim of this study was to compare the PET CT metabolic and anatomic parameters by prone versus supine 18 FDG-PET in newly diagnosed breast cancer. MATERIALS AND METHODS: Locally Institutional Review Board approved this prospective study. Total of 39 breast cancer patients whom newly diagnosed underwent both prone and supine FDG-PET/CT at the same scanning day. Two readers performed an independent review of all scans. Differences between the observers were resolved at a consensus reading session. Primary tumor SUVmax, SUV peak, SUVmean40%, MTV40%, TLG40, Thresh40, SUVmean70%, MTV70%, TLG70, and Thresh 70 values were calculated for both supine and prone positions. Also, differences between distance of primary tumor from the areola and pectoral muscle involvements and axillary lymph node status were evaluated by two interpreters.

Results: Prone position mean primary tumor SUVmax was 12,78±8,91, supine position mean primary tumor SUVmax was 13,26±9,73. Categorization of anatomic disease distribution has concordant between prone and supine scanning in 35 patients. Prone position; mean 40% MTV±STD:13±25 and mean 70%MTV±STD:1,98±2,53. Supine position mean40% MTV was 13,87±25,54 and mean70%MTV was 2,26±2,85. By far away prone position gives better anatomical location, exact distance from the areola and gives better visual assessment ability of pectoral muscle; as expected. In the 27 patients with breast and axillary disease, equal numbers of metastatic lymph nodes were identified on prone and supine scanning in 15 patients, whereas in the remaining 12 patients, prone scanning diagnosed in a higher number of visualized lymph nodes.

Conclusions: Both prone and supine position FDG-PET/CT scanning gives identical information on locoregional disease distribution in Locally Advanced Breast Cancer. But prone position scanning may perform better than supine for assessing the number of metastatic lymph nodes, distance from the areola and delineation of pectoral muscle involvement. Prone position FDG-PET/CT may be useful for surgical planning in future clinical and research studies, including PET and magnetic resonance imaging (MRI) fusion applications.