A Basic Study for Predicting Dysphagia in Panoramic X-ray Images Using Artificial Intelligence (AI)-Part 1: Determining Evaluation Factors and Cutoff Levels.

BACKGROUND: Dysphagia relates to quality of life; this disorder is related to the difficulties of dental treatment. PURPOSE: To detect radiographic signs of dysphagia by using panoramic radiograph with an AI system. METHODS: Seventy-seven patients who underwent a panoramic radiograph and a videofluorographic swallowing study were analyzed. Age, gender, the number of remaining teeth, the distance between the tongue and the palate, the vertical and horizontal hyoid bone position, and the width of the tongue were analyzed. Logistic regression analysis was used. For the statistically significant factors, the cutoff level was determined. The cutoff level was determined by using analysis of the receiver operations characteristic (ROC) curve and the Youden Index. RESULTS: A significant relationship with presence of dysphagia was only observed for the vertical hyoid bone position. The area under the curve (AUC) was 0.72. The cutoff level decided for the hyoid bone was observed to be lower than the mandibular border line. CONCLUSIONS: In cases where the hyoid bone is lower than the mandibular border line on a panoramic radiograph, it suggests the risk of dysphagia would be high. We will create an AI model for the detection of the risk of dysphagia by using the assessment of vertical hyoid bone position.

Evaluation of lateral pterygoid muscles in painful temporomandibular joints by signal intensity on fluid-attenuated inversion recovery images.

OBJECTIVES: Pathological changes of the lateral pterygoid muscle (LPM) have been investigated using various modalities, including magnetic resonance (MR) imaging and electromyography. Fluid-attenuated inversion recovery (FLAIR) is an MR sequence that we hypothesized can be used to evaluate abnormalities of the LPM. The purpose of this study was to analyze the FLAIR signal intensity of the LPM in painful temporomandibular joints (TMJs) and investigate the pathological changes of the muscle. METHODS: The study was based on 149 TMJs of 77 patients who were referred for MR imaging of the TMJ. Patients rated their degree of pain during chewing and mouth opening using a visual analog scale (VAS). Regions of interest were placed over the superior and inferior heads of the LPM and gray matter on FLAIR sagittal images. Using the signal intensity of gray matter as a reference, the signal intensity ratio (SIR) of the LPM was calculated. Spearman's rank-correlation coefficient was used to analyze the correlation between the SIR and the VAS score (p < 0.05). RESULTS: A significant correlation was present between the SIR on FLAIR images and the VAS score. CONCLUSIONS: These results suggest that the FLAIR signal intensity of the superior and inferior heads of the LPM significantly increases as TMJ pain becomes more severe. Thus, FLAIR could be useful in assessing the relationship between the MR signals of the LPM and clinical symptoms.

Atypical MRI and Histopathological Findings in Dermoid Cyst.

On images, a dermoid cyst is often described as resembling a "sack of marbles" or "marbles in a bag". Typically, it comprises an inhomogeneity filled with multiple nodules in a fluid matrix on both computed tomography and magnetic resonance imaging (MRI). How it appears, however, will vary depending on its histological contents, which may cause confusion in arriving at a diagnosis. This report describes a dermoid cyst in the floor of the mouth of a 55 year-old woman that showed an atypical internal appearance on MRI. Most of the lesion showed homogeneous high signal intensity on T1 - and T2-weighted images, suggesting that it was derived from fat. A small area within the mass, however, showed moderate signal intensity almost equal to that of muscle on T1-weighted images and high signal intensity on fat-suppressed T2-weighted images. Given the location of the lesion, a dermoid cyst was one possible diagnosis. A lipoma or lipoma variants were also considered, however, based on signal intensity. Histopathological section of the excised specimen revealed a dermoid cyst with sebaceous glands in its walls and keratin in its cavity. Dermoid cysts show variation in their internal structures and contents. Since MRI can reflect such histological variation, signal intensity requires careful interpretation.

Diagnosis of retrodiscal tissue in painful temporomandibular joint (TMJ) by fluid-attenuated inversion recovery (FLAIR) signal intensity.

AIMS: The purpose of the present study is to analyze the fluid-attenuated inversion recovery (FLAIR) signal intensity of the retrodiscal tissue in a painful temporomandibular joint (TMJ), and to develop a diagnostic system based on FLAIR data. METHODOLOGY: The study was based on 33 joints of 17 patients referred for MR imaging of the TMJ. Regions of interest were placed over retrodiscal tissue and gray matter (GM) on FLAIR images. Using signal intensities of GM as reference points, signal intensity ratios (SIR) of retrodiscal tissue were calculated. SIRs in painful TMJ were compared with those in painless TMJ. Wilcoxon's Rank Sum Test was used to analyze the difference in SIRs between the painful and painless groups (P<0·05). RESULTS: The SIRs of retrodiscal tissue were significantly higher in painful joints than in painless joints. CONCLUSION: FLAIR sequences provide a high signal in patients having painful TMJ, and it suggests that retrodiscal tissue in painful TMJ contains elements such as protein.