Purpose: To evaluate the feasibility of proposed integrated slice-by-slice shimming (iShim) for whole-body diffusion weighted imaging (WB-DWI) in comparison to conventional 3D shim in patients with breast cancer.
Materials and methods: Retrospective analysis of 116 consecutive patients (116 lesions) who underwent whole-body PET/MR using iShim (iShim group) were performed and compared with historical control of 103 patients (105 lesions) using 3D Shim (3D Shim group).
Results: As compared with dynamic contrast-enhanced (DCE) breast MRI, the apparent diffusion coefficient (ADC) value could not be determined for 15 (14%) of the 105 lesions of the 3D shim group and for 10 (9%) of the 116 lesions on iShim group. The intergroup difference failed to reach statistical significance (P = 0.1843). On the other hand, there was a significant difference in the frequencies of PET-positive and DWI-negative lesions between the 3D shim and iShim group (8.6% vs. 1.7%, respectively, P = 0.01942).
Conclusion: In regard to detectability of breast cancers by DWI, iShim may allow improved detectability as compared to conventional 3D shim.
Keywords: Apparent diffusion coefficient; Breast carcinoma; Diffusion-weighted imaging; Integrated slice-by-slice shimming; PET/MRI.