Utility of diffusion-weighted images using fast asymmetric spin-echo sequences for detection of abscess formation in the head and neck region

Objective. The objective of this study was to evaluate the utility of new diffusion-weighted magnetic resonance images (DWI) using fast asymmetric spin-echo (FASE) sequences for the detection of abscess formation in patients with phlegmon in the oral and maxillofacial regions. Methods. We compared diffusion-weighted images using FASE sequences with those using the gradient-echo type of echo-planar images (EPI) in 10 control volunteers and 10 patients with phlegmon in the oral and maxillofacial regions. Results. Many kinds of tissues in the oral and maxillofacial regions were relatively well visualized in all subjects on FASE-DWI, but not well on EPI-DWI. Apparent diffusion coefficients calculated from FASE sequences in abscess areas of patients with phlegmon were significantly lower than those in abscess-free areas; however, apparent diffusion coefficients calculated from EPI were not significantly different due to prominent distortion in small sample size study. Conclusions. We could accurately recognize the presence of abscess formation within inflammatory tissue in 5 patients with phlegmon using FASE-DWI. As an additional magnetic resonance examination, FASE-DWI might be useful in the detection of abscess formation in the oral and maxillofacial regions.