Abstract P5-01-15: The uptake of 18F-fluorodeoxyglucose (18F-FDG) by normal breast tissues as measured by a dedicated breast positron emission tomography (PET) scanner: A preliminary study

Abstract

Abstract Introduction Breast positron emission tomography (PET ) is a molecular imaging method which identifies breast cancers with high sensitivity and specificity. Dedicated breast PET scanners have an improved spatial resolution compared to whole body PET scanners, and are able to differentiate between glandular and fat tissues within the breast. The aim of this study is to determine how normal breast tissues take up 18F-FDG with time. Method In this IRB-approved prospective study, patients with a newly diagnosed invasive breast cancer who desired breast conservation surgery were recruited. Participants underwent bilateral breast PET scans using a two-ring dedicated breast PET scanner (MAMMI breast PET, Oncovision, GEM Imaging S.A.) after receiving a standard 18F-FDG dose of 5 mCu. After an uptake phase of 60 minutes, all patients were scanned at 3 time points: at 60 minutes, 90 minutes and 120 minutes post-injection. Reconstructed images obtained on the MAMMI breast PET scanner were then read and processed using the OsiriX software. For each scan performed at each time point, a series of continuous axial images through the central portion of the breast containing the nipple as a landmark was identified. Two elliptical 1cm2 regions of interest (ROI) were drawn, one on the central portion of the glandular parenchyma and a second on the fat. This was propagated through the included slices, after ensuring that the ROI lay entirely within the desired component of the breast in the same region for each breast. In the ipsilateral breast, the quadrant opposite the index tumor was used to avoid contamination. The mean SUV values for breast parenchyma and breast fat were measured, compared to the mammographic density of the breast tissues and tabulated against time. Results 9 patients participated in the study, yielding a total of 54 breast PET scans for analysis (bilateral scans for each patient at 3 time points). The mean SUV measurements for breast parenchyma ranged from 0.7 to 2.8 and the mean SUV measurements for breast fat ranged from 0.1 to 0.8. The mean SUV of breast parenchyma was approximately 3 to 4 times that of the mean SUV of breast fat at each time point. There was a gradual increase in the mean SUV of breast parenchyma and breast fat with time, although the increase appeared more pronounced with breast parenchyma. Patients with dense breast tissues tended to have a higher parenchymal mean SUV value. Conclusion Normal breast parenchyma demonstrates a greater uptake of 18F-FDG compared to breast fat tissues at a ratio of approximately 3-4 to 1. There is accumulation of 18F-FDG with time in both parenchymal and fatty tissues within the breast, more so with the former. Knowledge of the background SUV measurement of parenchymal tissues is important as this affects the SUV measurement of the underlying breast cancer. Increasing accumulation of FDG with time may decrease the contrast resolution of a cancer, especially in patients with dense breast parenchyma. Citation Format: Sze Yiun Teo, Jasper Chaal, Jung Ah Lee, Michel Herranz. The uptake of 18F-fluorodeoxyglucose (18F-FDG) by normal breast tissues as measured by a dedicated breast positron emission tomography (PET) scanner: A preliminary study [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 P5-01-15.