Abstract
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Objectives To assess therapeutic response it is critical to preserve spatial information for probing tumor heterogeneity. FDG-PET in the prone position facilitates serial coregistration and minimizes tumor distortion for accurate quantification. We sought to identify differences in prone vs. supine PET images acquired from breast cancer patients receiving neoadjuvant chemotherapy (NAC).
Methods Thirty-four patients diagnosed with locally advanced breast cancer (LABC) who were to receive NAC as part of routine clinical care underwent pretreatment FDG-PET/CT in both prone and supine positions. A subset of patients (N=24) also underwent prone and supine FDG-PET/CT at the conclusion of NAC prior to surgery. Prone imaging was conducted using a customized breast support device to facilitate longitudinal intermodal image coregistration. Images were evaluated via PERCIST.
Results For prone PET, pre- and post-NAC SULpeak (mean±SD) was 5.36±2.78 and 2.04±1.67, respectively. For supine PET, pre- and post-NAC SULpeak was 6.13±2.98 and 2.39±1.84, respectively. In patients who completed NAC no significant difference in the percentage change in SULpeak from pre- to post-NAC PET was observed between prone vs. supine images, even after correcting for variations in time lapse between FDG injection and image acquisition across patients (p = 0.308, Wilcoxon signed rank test).
Conclusions Quantitative FDG-PET/CT assessment of LABC in the prone position does not significantly differ from the corresponding data obtained in the standard supine orientation. This has clinical relevance in, for example, integrating and interpreting treatment response evaluation of breast lesions imaged with PET or MRI alone or with hybrid PET/MRI systems.