Abstract P1-02-02: Locoregional assessment by FDG PET/CT in stage II/III breast cancer patients: A multivariate analysis
Authors: Teixeira Suzana C , Koolen Bas B , Vogel Wouter V , Stokkel Marcel P , Vrancken-Peeters Marie-Jeanne , van der Noort Vincent , Rutgers Emiel J Th , Valdés-Olmos Renato A 
Published: May 2015

Abstract
Aim : Previously we demonstrated the additional value of PET/CT in prone position for breast cancer detection. The purpose of the present study was to evaluate, with a multivariate analysis, the factors influencing detection and quantification of FDG–avid primary tumors (PT) and regional lymph node metastases (LN) detected with PET/CT in patients with stage II/III breast cancer.
Materials and methods : From August 2010 to April 2012 we included 198 patients (mean 51 yr, range 26–82), with stage II/III breast cancer. A dose of 18F–FDG between 180–240 MBq, was administered intravenously. After 60±10 minutes a PET/CT of the thorax in prone position was acquired, scanning 3.00 min per bed position and reconstructed in high–resolution using 2x2x2 mm voxels and 2 mm CT slice thickness. Subsequently, a standard PET/CT was performed in supine position from skull base to thighs, scanning 1.30 min per bed position and using a standard reconstruction with 4x4x4 mm voxels, a standard 5mm CT slice reconstruction and an extra 2 mm CT slice reconstruction. On all PET/CT images we quantitatively assessed the SUVmax of FDG–avid PTs and LNs. We qualitatively assessed tumor multifocality, PT visibility, LN detection in defined regions and the occurrence of anatomical mismatch between PET and CT. The obtained results were then evaluated with a multivariate analysis for scanning position, patient age, breast size, tumor volume, number of FDG–avid lesions, lymph node location and anatomical mismatch between PET and CT.
Results: Prone position imaging positively influenced the visualization of tumor multifocality (p&lt;0.001), the total number of lymph nodes (p&lt;0.001) and of axillary LNs (p&lt;0.001). PT visibility was not significantly influenced by any of the parameters.
A higher SUVmax of the primary tumor was found solely with increased tumor volume (p=0.001) or breast size (p&lt;0.001). The standard 5mm CT slice reconstruction of the supine PET/CT was the only factor causing an increase in anatomical mismatch between PET and CT for axillary lymph nodes (p=0.004).
Conclusion: Prone position for PET/CT influences the visualization of primary tumor multifocality and the number of FDG avid loco-regional lymph nodes. Tumor FDG-uptake appears to be most influenced by tumor volume and breast size. Both results can be important for adequate staging and subsequent breast cancer treatment.
Citation Format: Suzana C Teixeira, Bas B Koolen, Wouter V Vogel, Marcel P Stokkel, Marie-Jeanne Vrancken-Peeters, Vincent van der Noort, Emiel J Th Rutgers, Renato A Valdés-Olmos. Locoregional assessment by FDG PET/CT in stage II/III breast cancer patients: A multivariate analysis [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-02-02.