Multi-band vs. conventional diffusion-weighted MRI of the abdomen in children and young adults.

Objectives: Implementation of diffusion-weighted imaging (DWI) for abdominal imaging in children has challenges due to motion artifacts exacerbated by long acquisition times. We aimed to compare acquisition time and image quality between conventional DWI and multi-band (MB) DWI of the liver in children and young adults.

Methods: Clinical MRI exams from May 2023 to January 2024 were reviewed, including four DWI sequences: respiratory-triggered (RTr, clinical standard), free-breathing (FB), MB-DWI with shift factor 1 (MBsf1), and MB-DWI with shift factor 2 (MBsf2). Acquisition times were recorded, and signal intensity and apparent signal-to-noise ratio (aSNR) were calculated for the liver and spleen. Six blinded pediatric radiologists independently assessed image quality, artifacts, and lesion visualization on a 5-point Likert scale and identified their preferred sequence. Statistical comparisons were made using Kruskal-Wallis and ANOVA tests.

Results: Median acquisition times were significantly reduced with MB-DWI (43 s for MBsf1/MBsf2) compared to FB (84 s) and RTr (240 s). Image quality and artifact scores were highest for RTr and FB sequences (p < 0.0001). Mean image quality scores were 3.7 (RTr, FB), 3.4 (MBsf1), and 3.5 (MBsf2), while artifact scores followed a similar trend (higher score = fewer artifacts). Lesion visualization scores were comparable across sequences (p = 0.11), and reviewers expressed no preference in 47% of cases. Apparent diffusion coefficient (ADC) values were consistent across all sequences (p > 0.05).

Conclusion: MB-DWI significantly reduces acquisition time while maintaining acceptable image quality and lesion visualization, making it a valuable option for pediatric abdominal MRI.