Utility of High-Resolution Semiconductor Positron Emission Tomography/Computed Tomography in the Assessment of Breast Cancer Extent: Comparison with Magnetic Resonance Imaging
Akina Miyamoto, Takeshi Yoshizako, Hiroyuki Kuroda, Rika Yoshida, Nobuko Yamamoto, Yasushi KajiAbstract
Objective
This study aims to compare the potential of whole-body silicon photomultiplier positron emission tomography/computed tomography (WB SiPM PET/CT) in the prone position with dynamic magnetic resonance imaging (MRI) in determining the extent of breast cancer.
Methods
This retrospective study included 77 patients with 84 breast cancers who underwent both PET/CT and MRI, excluding those who received neoadjuvant chemotherapy. Four tumour thresholds for 18F-fluorodeoxyglucose uptake were defined based on the mean standardised uptake value (SUVmean) and standard deviation (SD) of normal breast tissue: SUVmean+2SD, SUVmean+3SD, 1.5SUVmean+2SD, and 1.5SUVmean+3SD. Semiautomatic measurements of tumour size for each threshold and MRI were compared against pathological tumour size and analysed by menopausal status and Ki-67 expression.
Results
PET/CT failed to visualise two lesions. No significant differences in the image-to-pathological tumour size ratio were observed between MRI and the 1.5SUVmean+2SD. All MRI and SUV threshold measurements exhibited strong correlations with pathological size. The 1.5SUVmean+2SD demonstrated the highest pathological concordance rate, comparable to MRI. Subgroup analysis revealed that the 1.5SUVmean+2SD was superior for premenopausal patients (60.6%, p < 0.05), while MRI excelled in postmenopausal patients (61.2%). Both 1.5SUVmean+2SD and MRI achieved the highest concordance rates (62.2%) in the high-Ki-67 group.
Conclusion
The 1.5SUVmean+2SD of prone WB SiPM PET/CT offers a diagnostic performance equivalent to MRI for assessing breast cancer extent, particularly in premenopausal patients, while MRI remains optimal for postmenopausal patients. Both modalities are also highly effective in high Ki-67 tumours.
Advances in knowledge
These findings highlight the potential of high-resolution semiconductor PET/CT for assessing breast cancer extent.