Mika Otonari-Yamamoto

Composition of the blood supply in the sublingual and submandibular spaces and its relationship to the lateral lingual foramen of the mandible

OBJECTIVE The purpose of this research was to contribute to minimizing arterial disruption during mandibular surgical procedures by clarifying the course of the arteries supplying the sublingual and submental regions. STUDY DESIGN Heads of 75 human cadavers were dissected to identify the arterial supply of the sublingual and submental regions. Computed tomography scans were performed to visualize the lateral lingual foramina of the mandibles. RESULTS The facial artery was found to contribute to the composition of almost half of the sublingual arteries studied. Furthermore, it was demonstrated that the arterial supply to an incisor tooth is often from the submental artery. CONCLUSIONS Our data provide important information for coping with bleeding or hematoma occurring during surgical procedures in the mandibular region.

Comparison of accuracy of intravoxel incoherent motion and apparent diffusion coefficient techniques for predicting malignancy of head and neck tumors using half-Fourier single-shot turbo spin-echo diffusion-weighted imaging.

PURPOSE To evaluate the use of the intravoxel incoherent motion (IVIM) technique in half-Fourier single-shot turbo spin-echo (HASTE) diffusion-weighted imaging (DWI), and to compare its accuracy to that of apparent diffusion coefficient (ADC) to predict malignancy in head and neck tumors. PATIENTS AND METHODS HASTE DW images of 33 patients with head and neck tumors (10 benign and 23 malignant) were evaluated. Using the IVIM technique, parameters (D, true diffusion coefficient; f, perfusion fraction; D*, pseudodiffusion coefficient) were calculated for each tumor. ADC values were measured over a range of b values from 0 to 1000s/mm(2). IVIM parameters and ADC values in benign and malignant tumors were compared using Students t test, receiver operating characteristics (ROC) analysis, and multivariate logistic regression modeling. RESULTS Mean ADC and D values of malignant tumors were significantly lower than those of benign tumors (P<0.05). Mean D* values of malignant tumors were significantly higher than those of benign tumors (P<0.05). There was no significant difference in mean f values between malignant and benign tumors (P>0.05). The technique of combining D and D* was the best for predicting malignancy; accuracy for this model was higher than that for ADC. CONCLUSIONS The IVIM technique may be applied in HASTE DWI as a diagnostic tool to predict malignancy in head and neck masses. The use of D and D* in combination increases the diagnostic accuracy in comparison with ADC.

MR Evidence of Characteristics in Symptomatic Osteoarthritis of the Temporomandibular Joint: Increased Signal Intensity Ratio on Proton Density-Weighted Images of Bone Marrow in the Mandibular Condyle

Abstract The purpose of this study was to clarify the presence of pain and a correlation between pain and characteristics of signal intensity of mandibular bone marrow in temporomandibular joints (TMJ) with osteoarthritis (OA). A total of 196 joints in 98 patients with TMJ disorders were examined using magnetic resonance imaging (MRI). A pain score and signal intensity on mandibular bone marrow were analyzed in the TMJ with OA. TMJ with OA showed a higher degree of pain compared to those without (p<0.05). During opening, the joints in the higher signal intensity group showed a significantly higher degree of pain compared to the joints in the lower signal intensity group in those with OA on proton density weighted images (p<0.05). It was concluded that TMJ with osteoarthritis is related to pain and that a symptomatic osteoarthritic TMJ can accompany bone marrow changes in the condyle, showing an increased signal on proton density weighted images.

Potential of fluid-attenuated inversion recovery (FLAIR) in identification of temporomandibular joint effusion compared with T2-weighted images

OBJECTIVE The purpose of this study was to determine the potential of fluid-attenuated inversion recovery (FLAIR) sequence images in the identification of joint effusion (JE) compared with T2-weighted images. STUDY DESIGN A total of 31 joints (28 patients) with JE were investigated by magnetic resonance imaging (MRI). Regions of interest were placed over JE, cerebrospinal fluid (CSF), and gray matter (GM) on T2-weighted and FLAIR images and their signal intensities compared. The signal intensity ratios (SIRs) of JE and CSF were calculated with GM as the reference point. The Pearson product-moment correlation coefficient was used for the statistical analysis. RESULTS The SIR of JE showed a strong correlation between T2-weighted and FLAIR images. However, no correlation was observed for CSF. The average suppression ratio for JE was lower than that for CSF. CONCLUSIONS MRI using FLAIR sequences revealed that JE was not just water content, but a fluid accumulation containing elements such as protein. Further studies are needed, and FLAIR sequences could be useful for the diagnosis of pain and symptoms of the temporomandibular joint (TMJ).

Imaging of the mylohyoid muscle: separation of submandibular and sublingual spaces.

OBJECTIVE This article focuses on the anatomy of the mylohyoid muscle, a crucial landmark in imaging of the oral cavity and upper neck, showing dissected specimens and CT and MR images. CONCLUSION Identification of the relationship of a lesion in the sublingual space to the mylohyoid muscle using MDCT and high-resolution MRI is a key part of the imaging assessment of the oral cavity and upper neck.

Comparison of various methods for quantification of apparent diffusion coefficient of head and neck lesions with HASTE diffusion-weighted MR imaging

OBJECTIVES The purposes of this retrospective study were to compare various methods of apparent diffusion coefficient (ADC) measurement for head and neck lesions in half-Fourier single-shot turbo spin-echo (HASTE) diffusion-weighted imaging (DWI) and determine the threshold ADC value for predicting malignancy. STUDY DESIGN HASTE DW images of 46 lesions (10 cysts, 14 benign tumors, and 22 malignant tumors) were studied retrospectively. The ADC values were compared among the 0-1000 method, 500-1000 method, and weighted linear regression (WLR) fit. RESULTS The highest overall accuracies of 83.3%, 86.1%, and 88.9% were obtained when ADC values of 1.24 × 10(-3) mm(2)/s (0-1000 method), 0.98 × 10(-3) mm(2)/s (500-1000 method), and 1.23 × 10(-3) mm(2)/s (WLR fit), respectively, were used for the threshold. CONCLUSIONS The present results indicate that ADC measurement with HASTE DWI is useful in predicting malignancy of head and neck lesions.

3D-visualization of the temporomandibular joint with focus on the articular disc based on clinical T1-, T2-, and proton density weighted MR images

ObjectiveAn approach of 3D-visualization of the temporomandibular joint (TMJ) with special focus on the articular disc based on magnetic resonance imaging (MRI) was developed for the purpose of diagnosis support.Materials and methodsMandibular condyle and fossa were reconstructed as 3D-surfaces. Articular disc, retrocondylar tissue, and the lateral pterygoid muscle were visualized by means of direct volume rendering. By simultaneous visualization of both, the bony surfaces and the soft tissue, anterior disc displacement could be recognized in 3D-context. Additional superposition of the 3D-visualization with the original 2D-MRI slices allowed for a combination with conventional diagnostics. The method was tested for clinical T1-, T2-, and proton density weighted MRI data from four independent medical institutions.ResultsFor all cases, the skeletal anatomy could be reproduced. Applied validation approaches showed good results. Anterior disc displacement could be clearly depicted as well as the incidence of reduction of the disc. By several experienced observers, the approach was rated as significant.ConclusionAlthough partially non-standard in the clinical routine the new method provided promising results for efficient diagnosis support. Its validity in the medical practice, namely, its impact for dislocation/deformity of the mandibular disc will be further analyzed.

Signal intensity on fluid-attenuated inversion recovery images of condylar marrow changes correspond with slight pain in patients with temporomandibular joint disorders

AbstractObjectivesEdema and necrosis of the temporomandibular joint (TMJ) have been described in terms of bone marrow signal abnormalities in magnetic resonance imaging (MRI). However, painful joints often show no such signaling abnormalities, making the diagnosis of TMJ disorders difficult in the clinical setting. An association has been suggested between TMJ bone marrow change and TMJ pain, but even when such change results in slight pain, it may be too slight to be visually apparent on MR images. We hypothesized that fluid-attenuated inversion recovery (FLAIR) can be used to detect such minimal changes. The purpose of this study was to determine whether there is an association between signal intensity on FLAIR images and pain in the TMJ.MethodsThe study included 85 TMJs in 45 patients referred to our department for MRI. The signal intensity on FLAIR images was measured. Pain was evaluated based on the visual analog scale. An unpaired t test and Pearson’s product-moment correlation coefficient were used for the statistical analysis. A p value of <0.05 was considered statistically significant.ResultsSignal intensity on the FLAIR images was significantly higher in painful than in nonpainful TMJs, although a significant correlation was not observed between the signal intensity and the pain score.ConclusionsThe results of this study suggest an association between abnormalities in the marrow of the mandibular condyle and pain. They also indicate that FLAIR imaging is a useful tool in the clinical diagnosis of painful TMJs.

Effects of compression force on elasticity index and elasticity ratio in ultrasound elastography

OBJECTIVES The purpose of this study was to investigate the relationship between compression force and hardness values in ultrasound elastography. METHODS Ultrasound elastography was performed using an elastography phantom, comprising inclusions with different elasticities and echogenicities. The compression force was set to approximately 100 gw (light force) and approximately 500 gw (heavy force). The elasticity index (EI) of the inclusion was measured. The EI was a relative hardness value of a structure within an elastographic image. Similarly, the EI of the background was measured as a reference. The elasticity ratio (ER) was calculated as the EI of the inclusion divided by the EI of the reference. RESULTS The hardness of the phantom could be discerned with both the EI and ER, regardless of the compression force. The EI and ER with heavy force tended to be higher than those with light force, but the difference was not significant. A strong correlation was observed between the EI and ER of soft structures, whereas the correlation between the EI and ER of hard structures was weak, and the ER values varied widely. CONCLUSIONS The EI offers potential as a good indicator for assessing the hardness.

Analysis of elements in a minimal amount of temporomandibular joint fluid on fluid-attenuated inversion recovery magnetic resonance images

OBJECTIVE The aim of this study was to elucidate possible elements in minimal amounts of fluid (MF) in the temporomandibular joint by analyzing signal intensities in T2-weighted and fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) images. STUDY DESIGN Fifteen joints (15 patients) with MF were subjected to MR imaging to obtain T2-weighted and FLAIR images. Regions of interest were placed on MF, cerebrospinal fluid (CSF), and gray matter (GM), and their signal intensities were measured on both images. The signal intensity ratio (SIR) obtained by the signal intensity of GM between MF and CSF was compared in T2-weighted and FLAIR images. RESULTS The average SIR of MF was lower than that of CSF on T2-weighted images, whereas it was higher on FLAIR images. The average suppression ratio of the signal intensity was lower for MF (24.1%) than for CSF (71.4%). CONCLUSIONS MF may contain elements such as protein that are capable of inducing a shortened T1 relaxation time on MR images.