Evaluation of Prone Breast PET/CT Imaging Using Phantoms

Abstract

The different patient orientations in breast PET/CT and breast MR imaging, supine versus prone, respectively, cause difficulty in integrating and interpreting the data acquired from these two types of imaging protocols. Prone breast PET/CT could be possible provided the assistance of a suitable support. The main purpose of this project is to evaluate the feasibility of prone breast PET/CT imaging using phantoms and to compare this protocol with the standard supine protocol from an image quality perspective. In this project, a rigid, weight-bearing, radiolucent foam support based on the dimensions and layout of the MRI breast coil for prone-pendant clinical breast imaging was devised for prone PET/CT imaging purposes. In order to scan the same test object in various configurations (prone versus supine), breast phantoms were investigated and tested to develop the most suitable combination of materials that can simulate breast morphology. Water-filled intravenous bags were determined to be the best choice for breast phantom development. The breasts containing lesions, along with a torso phantom, were scanned using a clinical PET/CT scanner in both prone and supine orientations. The acquired PET images were quantitatively evaluated in both orientations. Several image quality metrics such as signal-to-noise ratio, local contrast, contrast uniformity, and quantitative repeatability were assessed from the acquired PET data. As a result, prone PET images present better image quality than supine PETv images in terms of SNR and contrast uniformity. However, the uniformity of the signal intensity is worse in prone orientation, and there are several unexpected image artifacts. The paired t-test statistical results suggest that there are significant differences between prone and supine in terms of signal intensity and SNR. It can be concluded that prone PET/CT imaging is geometrically feasible with the assistance of the developed torso support. Prone PET/CT imaging holds advantages over supine PET/CT imaging considering registration with MRI.