Improved image quality and T-staging accuracy using FOCUS-MUSE DWI in gastric cancer: a prospective comparison with SS-EPI

OBJECTIVE: To compare the image quality and diagnostic value of field-of-view optimized and constrained undistorted single-shot multiplexed sensitivity-encoding diffusion-weighted imaging (FOCUS-MUSE DWI) with single-shot echo-planar imaging (SS-EPI) DWI in gastric cancer. MATERIALS AND METHODS: Patients with biopsy-proven gastric cancer who underwent FOCUS-MUSE and SS-EPI DWI were enrolled in this prospective study between February and October 2024. Qualitative image quality was evaluated by two radiologists using a standardized five-point scale. Quantitative comparisons of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) were conducted for all measurable lesions. Preoperative T-staging accuracy was compared between the two techniques, with pathological or surgical findings as the reference. Agreement between estimations was evaluated using weighted kappa values and Bland-Altman plots. Pairwise differences between sequences were assessed using the Wilcoxon signed-rank and McNemar tests. RESULTS: Among 177 patients (age 65.4 ± 9.8 years, mean ± standard deviation; 133 males), FOCUS-MUSE DWI outperformed SS-EPI DWI in lesion conspicuity and overall image quality (median scores, 5 versus 4; both p < 0.001). For 148 patients with measurable lesions, FOCUS-MUSE yielded higher SNR (33.6 and 34.6 versus 26.9 and 26.9) and CNR (7.1 and 7.7 versus 5.3 and 5.9; all p < 0.001). Among 128 patients with pathologically T1-4a (pT1-T4a), surgically T4b (sT4b), or pathologically T4b (pT4b), T-staging accuracy was higher with FOCUS-MUSE (64.8% and 63.3%) than SS-EPI (44.5% and 47.7%; both p < 0.001). Intra- and inter-reader agreement was good to excellent. CONCLUSIONS: FOCUS-MUSE DWI demonstrated higher image quality and T-staging accuracy than SS-EPI DWI in gastric cancer. RELEVANCE STATEMENT: FOCUS-MUSE DWI provides improved image quality compared with conventional SS-EPI DWI and enables more accurate preoperative T staging in gastric cancer. These findings support the potential role of advanced DWI techniques in improving local tumor assessment. KEY POINTS: FOCUS-MUSE DWI demonstrated higher image quality compared to SS-EPI DWI in gastric cancer. FOCUS-MUSE DWI significantly improved preoperative T-staging accuracy over SS-EPI DWI. This advanced DWI technique shows potential to enhance preoperative risk stratification and surgical planning.