Breast implant evaluation of the breast cancer patient: comparison of DECT (Dual Energy Computed Tomography) vs MRI (Magnetic Resonance Imaging) through preclinical anthropomorphic phantom analysis

INTRODUCTION Breast MRI is currently the gold standard for the study of the integrity of breast implants and the detection of ectopic silicone, however not all patients can undergo an MRI. Recent studies have demonstrated that DECT allows an evaluation of implants and of ectopic silicone similar to MRI. AIM AND OBJECTIVES OF THE STUDY The aim of this study is to determine whether DECT can be considered an alternative to MRI in case of patient with contraindications to the latter through the evaluation of the DECT x-ray beam attenuation, the evaluation of the minimum size of silicone deposits identifiable by DECT and MRI and the analysis of the accessibility of the modalities even to radiologists non-experienced in breast imaging. MATERIALS AND METHODS 1st study: The evaluation of DECT x-ray beam attenuation was conducted on an anthropomorphic phantom with breast implants on the chest scanned using all kV combinations and slice thickness; the silicone Contrast Ratio Noise (CNR) was calculated and logarithmic regression curves applied. 2nd study: The detection limit of the silicone gel was determined on a hand-made non-magnetic phantom composed of 21 silicone samples arranged on plexiglass sheets fixed in a plastic box subsequently filled with different liquid matrices mimicking thoracic body tissues. Silicone Contrast Ratio Noise (CNR) was calculated again for both modalities. 3rd study: All the images from the samples’ phantom were blinded evaluated by radiologists with different experience in breast imaging to determine the highest detection rate profile. RESULTS 1st study: The quantitative evaluation of the prostheses silicone signal shows a higher CNR in the lowest density environment and in medium to low density environment the highest CNR is detected in lowest kV within the maximum separation spectrum. 2nd study: For all kV ranges used in DECT, a high CNR value is found in the 70-150 kV range for all the liquid matrices. In the seven MRI sequences performed, the calculated CNR signal is notably higher in VISTA and SPAIR sequences, regardless the thickness. 3rd study: Samples raters’ visibility in DECT is always positive for greater specimens than MRI, suggesting a fundamental ability of the second method to detect silicone. Through Fleiss’ kappa measuring, concordance in DECT is reliable even considering different environments and different software profiles. In MRI a wider difference of inter-rater reliability is observed in every environment. DISCUSSION AND CONCLUSION The finding suggests that DECT may achieve better results in breasts with higher adipose content, rather than those with a predominance of glandular tissue using a 80-150 kV clinical range but systematic in vivo studies are still required before DECT can be legitimately considered an alternative to MRI.