A step towards scan time minimisation: simultaneous multislice-accelerated diffusion-weighted imaging of the liver

Purpose: To investigate the influence of different gradient preparation schemes and acceleration factors on acqusition time, image quality and quantitative parameters of simultaneous multislice-accelerated diffusion-weighted imaging of the liver in comparison to conventional sequences. Methods and Materials: Respiratory-triggered simultaneous multislice diffusion-weighted imaging (sms-DWI) of the liver was performed at 1.5 T in ten healthy volunteers using a monopolar (MP) versus a bipolar (BP) gradient preparation with an sms-acceleration factor (AF) of 2 and 3 and compared to conventional diffusion-weighted images (c-DWI). Qualitative image analysis was carried out by two independent readers. Signal-to-noise ratios (SNR) and apparent diffusion coefficient (ADC) values were measured in a region-of-interest analysis. Total scan time was measured. The Kruskal-Wallis test followed by Steel-Dwass comparisons was executed for statistical analysis with p-values < 0.05 considered significant. Results: Image quality in sms-DWI with AF2 was equivalenty high compared to c-DWI, with a reduction of scan time by 67%. AF3 resulted in only minor additional scan time reduction (by 69%) but was associated with a statistically significant deterioration of image quality. ADC values in sms-DWI were lower, SNR was higher as compared to c-DWI. Image quality was slightly higher using the MP diffusion preparation in sms-DWI and c-DWI. Conclusion: Sms-DWI with an AF of 2 is a promising approach for scan time minimization while maintaining high image quality in DWI of the liver. The diffusion preparation did not significantly influence image quality in sms-DWI. The lower ADC values in sms-DWI should be considered in diagnostic reading studies