Multi-orientation and prone-position ZOOMit diffusion-weighted imaging for predicting T stage in distal gastric cancer.

PURPOSE

To compare the image quality of ZOOMit diffusion-weighted imaging (ZOOMit DWI) of distal gastric cancer in prone vs supine positioning and to determine whether multi-orientation ZOOMit DWI (M-ZOOMit) offers additional diagnostic value over axial ZOOMit DWI (A-ZOOMit).

METHODS AND MATERIALS

This two-phase study enrolled patients with biopsy-confirmed distal gastric cancer who underwent pre-treatment MRI. In phase 1 (November 2021 to February 2022), participants underwent ZOOMit DWI in both standard supine and prone positions. Two radiologists independently evaluated image quality on supine and prone ZOOMit DWI using a 5-point Likert scale. In phase 2 (March 2022 to September 2023), participants were imaged solely in the prone position; they subsequently underwent radical surgery. Histopathological findings served as the reference standard. The accuracy of T staging based on uni-orientation (axial, coronal, and sagittal) vs M-ZOOMit was assessed by four additional radiologists. Reader consistency and agreement on image quality scores were evaluated using κ-agreement and Kendall W analyses.

RESULTS

Phase 1 enrolled 30 patients (mean age, 62.0 years ± 11.5 [standard deviation]; 19 men); phase 2 enrolled 134 patients (mean age, 60.9 years ± 11.7; 81 men). Image quality scores assigned by both readers were significantly higher for prone ZOOMit DWI than for supine ZOOMit DWI (p < 0.001). Regarding overall T staging, M-ZOOMit and coronal ZOOMit DWI (C-ZOOMit) demonstrated significantly better performance relative to A-ZOOMit (both p < 0.05).

CONCLUSION

ZOOMit DWI in the prone position provides superior image quality. M-ZOOMit and C-ZOOMit enhance T staging accuracy compared to A-ZOOMit for distal gastric cancer.

KEY POINTS

Question DWI is a powerful technique, but poor image quality has remained a key limitation, hindering diagnostic accuracy for distal gastric cancer. Findings The prone-position ZOOMit DWI improved the image quality. Besides, multi-orientation and coronal ZOOMit DWI demonstrated superior performance relative to A-ZOOMit DWI for T staging. Clinical relevance The prone-position and M-ZOOMit DWI is a better imaging protocol for the T staging assessment of distal gastric cancer patients, replacing the conventional supine-position and axial DWI.