Shika Hoshasen

In Japan, 3T MRI was approved in 2003 under the Pharmaceutical Affairs Law. The spread of 3T equipment has since progressed due to improvements in hardware and software. On the other hand, the head and neck have many conditions that are disadvantageous for MRI usage due to factors such as involuntary movements, inhomogeneous magnetic fields due to the presence of metal prostheses and air spaces, and complex anatomy. As radial sampling is useful for motion compensation, it has been incorporated into many MR units. Static magnetic field correction is useful for reducing metal artifacts, which also leads to improvement of fat-suppressed imaging.
In this review, we summarize the effects of 3T equipment on image quality and methods for addressing problems specific to the maxillofacial region, and present specific clinical applications.
As an example of clinical application, we introduce contrast-enhanced T1-weighted imaging using compressed sensing and distortion-free diffusion-weighted imaging. Next, for assessing biochemical information, we introduce the estimation of fat fraction using the six-point Dixon method and trace components using the chemical exchange saturation transfer effect.

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Tokushima University Hospital has undergone many changes in recent years. In order to assess these changes, we extracted the number of patients who visited and underwent X-ray imaging examinations at the Oral & Maxillofacial Radiology department over the 10-year period from April 2012 to March 2022 from patient data obtained from the Hospital Information System and the Radiology Information System. The number of dental radiographs decreased, whereas the number of panoramic radiographs increased due to the improvement of image quality. The number of patients seen in the dental department decreased in 2021 due to the impact of restrictions on hospital visits because of the spread of the new coronavirus （COVID-19）. As of 2022, the number of patients and the number of X-rays taken have not yet returned to the level before the spread of COVID-19. The number of requests for panoramic radiographs of patients before surgery, radiation, or chemotherapy increased due to the increase in referrals from medical departments to dental departments for preoperative intraoral screening as a result of the progress of multidisciplinary cooperation in the hospital. As dental radiology is a department that does not perform primary care, our findings suggest that it is affected by the social environment and healthcare system factors such as public insurance reimbursement.

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