Towards a fast PET/MRI protocol for breast cancer imaging: maintaining diagnostic confidence while reducing PET and MRI acquisition times

OBJECTIVES: To investigate the diagnostic feasibility of a shortened breast PET/MRI protocol in breast cancer patients. METHODS: Altogether 90 women with newly diagnosed T1(tumor-staged) (T1(ts)) and T2(tumor-staged) (T2(ts)) breast cancer were included in this retrospective study. All underwent a dedicated comprehensive breast [(18)F]FDG-PET/MRI. List-mode PET data were retrospectively reconstructed with 20, 15, 10, and 5 min for each patient to simulate the effect of reduced PET acquisition times. The SUV(max/mean) of all malign breast lesions was measured. Furthermore, breast PET data reconstructions were analyzed regarding image quality, lesion detectability, signal-to-noise ratio (SNR), and image noise (IN). The simultaneously acquired comprehensive MRI protocol was then shortened by retrospectively removing sequences from the protocol. Differences in malignant breast lesion detectability between the original and the fast breast MRI protocol were evaluated lesion-based. The 20-min PET reconstructions and the original MRI protocol served as reference. RESULTS: In all PET reconstructions, 127 congruent breast lesions could be detected. Group comparison and T1(ts) vs. T2(ts) subgroup comparison revealed no significant difference of subjective image quality between 20, 15, 10, and 5 min acquisition times. SNR of qualitative image evaluation revealed no significant difference between different PET acquisition times. A slight but significant increase of IN with decreasing PET acquisition times could be detected. Lesion SUV(max) group comparison between all PET acquisition times revealed no significant differences. Lesion-based evaluation revealed no significant difference in breast lesion detectability between original and fast breast MRI protocols. CONCLUSIONS: Breast [(18)F]FDG-PET/MRI protocols can be shortened from 20 to below 10 min without losing essential diagnostic information. KEY POINTS: • A highly accurate breast cancer evaluation is possible by the shortened breast [ (18) F]FDG-PET/MRI examination protocol. • Significant time saving at breast [(18)F]FDG-PET/MRI protocol could increase patient satisfaction and patient throughput for breast cancer patients at PET/MRI.