Scan time reduction in diffusion-weighted imaging of the pancreas using a simultaneous multislice technique with different acceleration factors: How fast can we go?

Objectives: To investigate the feasibility of simultaneous multislice-accelerated diffusion-weighted imaging (sms-DWI) of the pancreas with different acceleration factors and its influence on image quality, acquisition time and apparent diffusion coefficients (ADCs) in comparison to conventional sequences.

Methods: DWI of the pancreas was performed at 1.5T in ten healthy volunteers and 20 patients with sms-accelerated echo-planar DWI using two different sms-acceleration factors of 2 and 3 (sms2/3-DWI). These DWI sequences were compared to conventional DWI (c-DWI) in terms of image quality parameters (5-point Likert scale) and ADC measurements.

Results: c-DWI and sms2-DWI offered equivalently high overall image quality (4 [1; 5]) with scan time reduction to one-third (c-DWI: 173 s, sms2-DWI: 56 s). Sms3-DWI showed significantly poorer overall image quality (3 [1; 5]; p < 0.0001). ADC values were significantly lower in sms3-DWI compared to c-DWI in the pancreatic body and tail (body: c-DWI 1.4 x 10 mm/s, sms3-DWI 1.0 x 10 mm/s, p = 0.028; tail: c-DWI 1.3 x 10 mm/s and sms3-DWI 1.0 x 10 mm/s, p = 0.014).

Conclusions: Accelerated multislice DWI of the pancreas offers high image quality with a substantial reduction of acquisition time. Lower ADC values in multislice DWI should be considered in diagnostic reading.

Key Points: • Simultaneous multislice-accelerated diffusion-weighted imaging (sms-DWI) promises scan time minimisation. • Sms-DWI of the pancreas offers diagnostic image quality in volunteers and patients. • Sms-DWI with an acceleration factor of 2 offers high image quality. • Higher acceleration factors in sms-DWI do not provide sufficient diagnostic image quality. • ADC values may be lower in sms-DWI.