Diffusion-weighted imaging of cervical cancer: Feasibility of ultra-high b-value at 3T.

PURPOSE: We sought to evaluate the image quality and compare the signal intensity (SI) and apparent diffusion coefficient (ADC) maps of ultra-high b-value (2000 s/mm2; B2) images against those of 800 s/mm2 b-value (B1) images of diffusion-weighted imaging (DWI) for cervical cancer.

METHOD: This study was approved by the institutional review board. Sixty patients diagnosed with cervical cancer by pathology were prospectively included. Female pelvic magnetic resonance imaging was performed using a 3 T magnetic resonance scanner; B1 and B2 images were obtained for evaluation. Two radiologists blinded to the scan parameters evaluated the images for signal loss in the background, spatial distortion, image ghosting, confidence in the lesion delineation, and overall image quality using a 5-point scoring system. The scores were compared using a paired Wilcoxon test. SI was measured in the B1 and B2 images for the tumour and normal reference tissues. Additionally, the SI contrast ratios were calculated and compared using the Mann-Whitney U test, the ADC values of tumours and normal tissues were measured, and the maximum tumour diameters were measured from the B1 and B2 images and compared with those from the T2-weighted images, which was the reference standard.

RESULTS

The signal loss in the background, confidence of the lesion delineation and overall image quality scores were higher for the B2 images than for the B1 images (all p < 0.001). The contrast ratios of the tumour-to-normal SI were also higher for the B2 images than for the B1 images (p < 0.01). The mean ADC values derived from the B2 images showed better correlations with the tumour differentiation grades than those from the B1 images. The tumour diameters measured from the B2 images experienced less bias than those from the B1 images.

CONCLUSIONS

B2 images of DWI are technically feasible to acquire and provide more promising additional information for the delineation of cervical cancer tumours than B1 images of the female pelvis.