Diffusion-weighted imaging of the head and neck: comparison between integrated slice-specific dynamic shimming and simultaneous multi-slice readout-segmented echo-planar sequences

Abstract

Objectives To compare integrated slice-specific dynamic shimming (iShim) and simultaneous multi-slice (SMS) readout-segmented echo-planar imaging (RESOLVE) for diffusion-weighted imaging (DWI) of malignant head and neck tumors. Methods In this prospective study, forty-five patients with malignant head and neck lesions underwent iShim- and SMS-RESOLVE imaging with two b-values (0, 800 s/mm2) at 3 T. Subjective image quality scores (lesion distortion, signal loss, fat saturation, and artifacts), quantitative lesion distortion, quantitative image quality (signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and SNR efficiency), ADC values, and total acquisition times of iShim- and SMS-RESOLVE imaging were evaluated and compared. Results iShim-RESOLVE (3 minutes 7 seconds) had longer acquisition times than SMS-RESOLVE (2 minutes 1 second). iShim-RESOLVE images had much better overall image quality, geometric distortion, fat saturation, and signal loss than SMS-RESOLVE (p＜0.05). The quantitative tumor distortion in iShim-RESOLVE images was significantly smaller than those of SMS-RESOLVE, measured either with b = 0 s/mm2 or b = 800 s/mm2 (p＜0.05). Using the iShim technique, the SNR, CNR of high b-value images, and SNR efficiency were significantly higher than those of SMS-RESOLVE (p＜0.001). The ADC measurements with excellent agreement of iShim-RESOLVE images were higher than those of SMS-RESOLVE. Conclusions iShim-RESOLVE can decrease lesion distortion and improve overall image quality compared with SMS-RESOLVE in head and neck region. Advances in knowledge iShim-RESOLVE DWI may serve as a promising technique for reducing distortion and assessing head and neck lesions in clinical practice.