Does integrated shimming improve lesion detection in whole-body diffusion-weighted examinations of patients with breast cancer?

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.