Coronal reduced field-of-view diffusion-weighted imaging improves image quality and T staging of upper tract urothelial carcinoma compared with conventional axial DWI: a retrospective study.

PURPOSE: To evaluate whether coronal reduced field-of-view (r-FOV) diffusion-weighted imaging (DWI) improves image quality and local T staging of upper tract urothelial carcinoma (UTUC) compared with conventional axial full field-of-view (f-FOV) DWI.

METHODS

In this retrospective single-center study, 60 patients with pathologically confirmed UTUC who underwent preoperative magnetic resonance urography (MRU) were included. The imaging protocol comprised both axial f-FOV DWI and coronal r-FOV DWI acquired on a 3.0-T scanner. Two radiologists independently assessed subjective image quality (sharpness, distortion, artifacts, and lesion conspicuity). Tumor contrast and apparent diffusion coefficient (ADC) values were measured. Local T staging was performed using each DWI sequence, with particular focus on identifying locally advanced disease (≥ T3). Histopathology from radical nephroureterectomy served as the reference standard.

RESULTS

Coronal r-FOV DWI demonstrated significantly higher image quality scores across all subjective parameters than axial f-FOV DWI (all p ≤ 0.003). Tumor contrast was higher on r-FOV DWI (p < 0.001), and ADC values measured on r-FOV DWI were significantly lower than those on f-FOV DWI (p < 0.001), with a strong correlation between the two techniques (r = 0.765). High-grade UTUC showed significantly lower ADC values than low-grade tumors on both sequences (p < 0.05). For detecting locally advanced disease (≥ T3), coronal r-FOV DWI achieved higher sensitivity (91.7% vs. 75.0%), specificity (80.6% vs. 75.0%), and overall accuracy (85.0% vs. 75.0%) compared with axial f-FOV DWI. The addition of coronal r-FOV DWI was subjectively considered diagnostically useful in 91.7% of cases.

CONCLUSION

Coronal r-FOV DWI significantly improves image quality, tumor conspicuity, and local T staging performance in UTUC compared with conventional axial f-FOV DWI. When incorporated as a complementary sequence in MRU, coronal r-FOV DWI provides added diagnostic value, particularly for identifying locally advanced disease.