Sonography is an easy to apply, inexpensive, and non-invasive diagnostic modality.
Although tissues behind bony structures and deep tissues are not delineated, sonography can depict superficial soft tissues very clearly. In the head and neck region, however, it has not yet been widely performed, as the anatomical structures are complicated, and considerable experience is needed both to perform an examination and to make a diagnosis.
To perform examinations smoothly, operators must be familiar with the sonographic system in use, and take images at standard planes. To make a correct diagnosis, operators require knowledge of the sonographic anatomies on those planes, representative sonographic signs and artifacts, and common diseases and their typical sonographic findings.
In this paper, I have explained how to take sonographic images at standard planes, the sonographic anatomies on those planes, and sonographic findings of common diseases in the oral and maxillofacial regions.

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Interstitial brachytherapy（ISBT）is an established technique, and its biological advantages are well defined. ISBT for oral squamous cell carcinoma results in excellent dose concentration on the target volume. Furthermore, the use of a spacer results in a 50％ dose reduction at 10mm from the source.
High-dose rate（HDR）fractionated ISBT using the microSelectron-HDR has been used to treat carcinomas of the oral cavity, such as the tongue and floor of the mouth. This treatment has been available at Osaka University Hospital since 1991 as a replacement for low-dose rate（LDR）continuous ISBT. The main advantages of this method are（a）it can be easily performed under local anesthesia in patients for whom Ra-226 needle implants or the Ir-192 hairpin technique are indicated,（b）it prevents medical staff being exposed to radiation, and（c）medical care can be provided easier than in LDR ISBT.
In this review, the biologically effective dose, including the α/β ratio; treatment results; and late complications of LDR-ISBT and HDR-ISBT for squamous cell carcinoma of the tongue are described.

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Objective: The purpose of the present study was to develop an algorithm that could practically achieve super-resolution images on clinical panoramic X-ray equipment using the detector moving and frame additional technique （DEMOT）, a method for obtaining super-resolution images.
Materials and Methods: Simulations were performed to evaluate the resolution obtained by changing a combination of the frame rate, which was set at a sufficient level to achieve a super-resolution effect; the practical magnification ratio; and the focus size of the X-ray tube. The results were confirmed using panoramic X-ray equipment that could be used at clinical facilities.
Results: When evaluating the frame rate, as the amount of data added during each one-pixel movement increased, an improvement in contrast was recognized within each frequency band. As for the appropriate magnification ratio, an experiment using focus sizes ranging from 0.10mm to 0.15mm showed that the cut-off frequency improved as the magnification ratio increased. Therefore, greater resolution was achieved as the magnification ratio increased. When a focus size of 0.20mm was employed, the highest resolution was obtained with magnification ratios ranging from 1.45 to 1.50 times. When a focus size of 0.30mm was used, the highest resolution was obtained with magnification ratios ranging from 1.25 to 1.30 times. When a focus size of 0.50mm was employed, the highest resolution was obtained with magnification ratios ranging from 1.10 to 1.15 times.
Conclusion: The optimum technique for achieving super-resolution images with the DEMOT is to divide the memory by >4. By using standard panoramic X-ray equipment with magnification ratios ranging from approximately 1.2 to 1.3 times, an appropriate super-resolution effect can be obtained using an X-ray tube with a focus size of ≤0.2mm.

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Background and Purpose: MRI is frequently used in the region of the temporomandibular joint （TMJ）, particularly to examine disc position and configuration, posterior disc attachment and mandibular marrow status, and to assess the presence of joint effusion. Diffusion-weighted imaging （DWI） make use of the Brownian motion of water protons in biological tissue. This movement mirrors the tissue unique diffusion capacity and can be used to characterize the organization. The purpose of our present study was to investigate correlation between the mean of apparent diffusion coefficient values （ADC value） in the masticatory muscle and joint effusion.
Materials and Methods: We designed and implemented a retrospective cohort study, which was approved by our university ethics committee （EC15-12-009-1）. The study group comprised 51 patients （14 men, 37 women; 21-81 years of age, mean age 50.12 years） with a total of 112 TMJs （54 TMJs with joint effusion, 48 TMJs without joint effusion）who were examined by MRI. This group were divided into two groups: with joint effusion groups and without joint effusion groups. Furthermore, between each group of ADC values in the masticatory muscle differences were analyzed. Furthermore, calculated correlation using age as the criterion variable and ADC value of the masticatory muscle as explanatory variables.
Results: The mean ADC values of lateral pterygoid muscle were 1.23±0.14×10^－3mm²/s and 1.02±0.11×10^－3mm²/s, corresponding to with joint effusion group and without joint effusion group, respectively （P<0.01）. The mean ADC values of medial pterygoid muscle were 1.08±0.16×10^－3mm²/s and 0.97±0.10×10^－3mm²/s, corresponding to with joint effusion group and without joint effusion group, respectively （P<0.05）. The mean ADC values of masseter muscles were 1.09±0.12×10^－3mm²/s and 1.00±0.11×10^－3mm²/s, corresponding to with joint effusion group and without joint effusion group, respectively （P<0.05）. There was not significant correlation between age and ADC values （P>0.05）.
Conclusion: ADC values of the with joint effusion side were significantly higher than without joint effusion side. Our study found that change of ADC values in the masticatory muscle by joint effusion in the temporomandibular joint.

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Background and purpose: Rheumatoid arthritis （RA） is mainly characterized by inflammation of the synovial membrane, which leads to long-term joint damage, resulting in chronic pain, loss of function, and disability. The radiographic abnormalities of the bone, joints, and soft tissue in RA have been described. However, few studies have used MRI to evaluate the relationship between pannus and abnormal bone marrow signal in the mandibular condyle with RA patients. The purpose of this study was to evaluate the relationship between pannus and abnormal bone marrow signal in the mandibular condyle with RA patients using MRI.
Materials and methods: Twenty-seven patients with RA and temporomandibular joints （TMJ） pain who underwent MRI examination of the TMJs at our hospital from August 2006 to March 2019 were included in this study. The patients all had rheumatic symptoms in one or more joints and had been diagnosed with RA according to the diagnostic criteria of the American College of Rheumatology （ACR）. The following characteristics of the TMJ were evaluated on MR images: abnormal bone marrow signal in the mandibular condyle and synovial proliferation （pannus）. The between-group differences in these parameters were analyzed using a statistical software package （SPSS version 21.0^Ⓡ; IBM Japan Inc., Tokyo, Japan）. P-values less than 0.05 were considered to indicate statistical significance.
Results: The results showed that a significant difference in the relationship between pannus and abnormal bone marrow signal in the mandibular condyle with rheumatoid patients.
Conclusions: This study suggested that the relationship between pannus and abnormal bone marrow signal is clinically indicated in RA, and that pannus affects the mandibular condyle and causes abnormal bone marrow signal in the mandibular condyle.

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