Abstract

High-resolution diffusion-weighted MRI of the breast using readout-segmented EPI and single-shot EPI

Author(s): Shotaro Kanao*, Masako Kataoka, Mami Iima, Ayami Ohno, Rena Sakaguchi, Akane Ohashi, Maya Honda, Masakazu Toi, David A Porter & Kaori Togashi

Objective: Compared to dynamic contrast enhanced MRI (DCE-MRI), image quality in diffusion-weighted MR imaging (DW-MRI) is generally poor because of low image spatial resolution and distortion. Readout-segmented EPI (RS-EPI) is a recently-developed technique to obtain high resolution DW-MRI with less distortion. The study aimed to evaluate the feasibility of high-resolution DW-MRI of the breast, using RS-EPI and single-shot EPI (SS-EPI).

Methods: With IRB approval, 26 patients with clinically suspected breast cancer were prospectively enrolled. Breast MRI was performed on a 3.0 T scanner using a 16-channel breast coil. Sequences include T2-weighted imaging (T2WI) with fat saturation, a 3D DCE-MRI series and DW-MRI (b values of 0 and 850 s/mm2 for RS-EPI and SS-EPI). To evaluate image distortion, the antero-posterior (AP) extent of the mammary gland on DW-MRI with RS-EPI and SS-EPI were measured and differences from values obtained from T2WI were calculated. The artefacts on both sequences were scored. Diagnostic performance of lesions on both sequences was assessed using BI-RADS classification and the category was compared to that determined by DCE-MRI.

Results: The average difference in the measured AP extent on DW-MRI with RS-EPI was significantly less than that on DW-MRI with SS-EPI (2.3 ± 2.0 versus 12.5 ± 4.7 mm, respectively, p<0.01). Distortion artefacts were significantly lower on DW-MRI with RS-EPI than that with SS-EPI in all cases. The sensitivity of DW-MRI with RS-EPI was higher than that with SS-EPI (88.9 and 77.8%, respectively).

Conclusion: DW-MRI with RS-EPI has an advantage of less distortion compared to that with SS-EPI.