Abstract P5-01-10: Correlation of apparent diffusion coefficient with standardized uptake value in invasive lobular carcinoma of breast using in hybrid 18F-FDG PET/MR

Purpose: To compare the apparent diffusion coefficient (ADC) with maximum standardized uptake values (SUV) derived from combined 18F-FDG PET/MRI in invasive lobular carcinoma (ILC) patients. Methods: From 2012 Aug to 2015 Feb, 53 women with histologically proven ILC (mean age, 50.3 ± 7.7 y-o) underwent hybrid 18F-FDG PET/MR (Siemens Biograph mMR) scan for preoperative assessment. During PET acquisition, simultaneous diffusion-weighted imaging (DWI, b values: 0, 400, 800 s/mm 2 ) was performed using breast coil. ILC over than 2 Cm in size were analyzed. Regions of interest (ROI) were drawn covering the entire ILC on the attenuation-corrected PET-image and the monoexponential ADC-map on PET/MR workstation. All the patients were received surgical treatment within 3 weeks after scan. Spearman rank correlation coefficient (ρ) was calculated to examine the correlation between SUVmax and ADC value. Results: Total 25 ILC (5.4±1.3 cm; 2.1-6.3 cm) of 22 women were enrolled. 24 ILC showed ER (+)/PR (+) and all ILC showed HER2 (-). 15 patients were confirmed metastatic axillary lymph nodes. The mean of SUVmax was 2.14 ± 2.2 (0.91-11.9) and mean of ADC was 1.02 ×10-3 (0.82 -1.31 ×10-3) mm 2 /s. Higher histologic grade was correlated with higher SUV (ρ = -0.6, p=0.001). And SUV showed inverse correlation with ADC (ρ = -0.48, p=0.016). Conclusion: The present data show inverse correlation between increased glucose-metabolism and cellularity in ILC patients. 18F-FDG PET and DWI thus may offer complementary information for the evaluation of treatment response in ILC. Citation Format: Choi JE, Kang SH, Lee SJ, Kong EJ. Correlation of apparent diffusion coefficient with standardized uptake value in invasive lobular carcinoma of breast using in hybrid 18F-FDG PET/MR. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-01-10.