Comparison of readout-segmented echo-planar imaging and single-shot echo-planar imaging in the fetal brain

The diagnostic value of diffusion-weighted imaging (DWI) in fetal brain imaging has been established for various brain lesions, yet conventional DWI single-shot echo-planar imaging (SS-EPI) suffers from distortion and artifacts. Readout Segmentation of Long Variable Echo-trains (RESOLVE) is an advanced technology that can produce better image quality than SS-EPI. This study was aimed to evaluate the clinical effectiveness of RESOLVE and SS-EPI in visualizing the fetal brain.

We performed RESOLVE and SS-EPI on 190 fetal brains from December 2019 to December 2021, and two radiologists reviewed the two datasets separately. Qualitative analyses were conducted in susceptibility-related change, image distortion, lesion conspicuity, and overall image quality with a 5-point Likert scale. Inter-reader agreement was measured using a Cohen kappa statistic. The apparent diffusion coefficient (ADC) and signal-to-noise ratio (SNR) of the two sequences in bilateral centrum semiovales were measured and compared.

The readers had good agreement with their scores (k>0.6). All the subjective parameters between the two sequences showed statistical significance (all P<0.05). The respective mean (range) scores for SS-EPI and RESOLVE were 4 (3.5, 4) and 4.5 (4, 4.5) for susceptibility-related change, 4.5 (4, 4.5) and 5 (4.5, 5) for image distortion, 4 (3.5, 4.5) and 4.5 (4, 5) for lesion conspicuity, and 4 (3.5, 4) and 4.5 (4, 4.5) for overall image quality. The ADC values in the centrum semiovale did not differ between the two sequences (P=0.64). Last, the SNR was 45.53 for SS-EPI, significantly higher than that of RESOLVE at 35.57 (P<0.001).

In terms of distortion, susceptibility-related changes, and lesion conspicuity, RESOLVE was better at visualizing the fetal brain than SS-EPI. However, SS-EPI scored better than RESOLVE in the SNR.