Clinical significance of T2 mapping MRI for the evaluation of masseter muscle pain in patients with temporomandibular joint disorders

Functional magnetic resonance imaging evaluation of masticatory muscle dysfunction in unilateral exodontia rabbits

Objective:

Occlusal alteration due to tooth loss may cause overload of masticatory muscle and promote muscle dysfunction. This study explored the feasibility of using functional magnetic resonance imaging (fMRI) to evaluate muscle dysfunction in an established unilateral exodontia animal model.

Methods:

six rabbits were extracted right maxillary molars. T2 mapping, T2* mapping and Iterative Decomposition of water and fat with Echo Asymmetry and Least Square Estimation (IDEAL-IQ) were performed one day before extraction and every 2 weeks (2th~12th week) after extraction. The T2 and T2* values and fat fraction (FF) of bilateral temporal muscle (TM), masseter muscle (MM) and medial pterygoid muscle (MPM) were measured and compared between the extraction side-and the contralateral side. Parameters of three monitoring time points (0th, sixth, 12th week) were also analyzed.

Results:

T2 values of MM on extraction side-were significantly higher than those of contralateral side-from fourth week to 12th week after extraction (p < 0.05). T2 values of MM and MPM on extraction side-and TM on contralateral side-were significantly higher in 12th week than those in 0th week (p < 0.05). And FF of bilateral MM was significantly higher in 12th week than those in 0th week (p < 0.05). T2* value showed no significant difference between extraction side-and contralateral side-and also at above three time points.

Conclusion:

T2 and T2* value and FF can be used as indicators of masticatory muscle dysfunction. fMRI is expected to be a non-invasive method for in vivo and real-time evaluation of masticatory muscle functional abnormality.

Quantitative assessment of the mandibular condyle in patients with diabetes mellitus using diffusion-weighted magnetic resonance imaging

OBJECTIVE

The purpose of this study was to quantitatively assess the mandibular condyle in patients with diabetes mellitus (DM) using the apparent diffusion coefficient (ADC) on diffusion-weighted magnetic resonance imaging (DWI).

STUDY DESIGN

102 patients with DM and temporomandibular joint (TMJ) pain who underwent magnetic resonance imaging (MRI) examination of the TMJs at our hospital between August 2006 and March 2020 were included in this study. 112 patients with temporomandibular disorders (TMD) who underwent MRI examination at our hospital between April 2019 and March 2020 were included as controls. The MRI findings were compared between the two groups.

RESULTS

The mean ADC values of the mandibular condyle in patients with DM were significantly greater than the controls (P < 0.01). Receiver operating characteristic (ROC) curve analysis revealed a cutoff of 0.98 for the ADC values of the mandibular condyle in patients with DM.

CONCLUSION

This study found that the ADC on DWI could be used for the quantitative assessment of the mandibular condyle in patients with DM. DWI might serve as a new and noninvasive method to assess the presence of DM.

Molecular imaging in masseter muscle observed by muscle function magnetic resonance imaging and 31 P-magnetic resonance spectroscopy in patients with a jaw deformity

Background

Skeletal mandibular protrusion would influence to the muscle fatigue of the masticatory muscles. Establishing a diagnostic procedures combining physiological and biochemical information is necessary for quantitative evaluation of masticatory muscle fatigue.

Objective

The transverse relaxation time (T2 time) of muscle functional magnetic resonance imaging (mfMRI), and ³¹P‐magnetic resonance spectroscopy (MRS) were used to investigate the reliability as parameters for measuring the masseter muscle in patients with skeletal mandibular prognathism.

Method

The subjects were 19 patients diagnosed as skeletal mandibular protrusions and 19 healthy subjects as a control group. Transverse relaxation time (T2 value) determined by mfMRI along with creatine phosphate (PCr) and inorganic phosphorus (Pi) determined by ³¹P‐MRS before, during, and after clenching were used for molecular imaging of muscle fatigue.

Results

The average T2 value of the patient group was significantly higher than that of the healthy control group at rest. Furthermore, the average T2 value transiently increased in both groups during experimental clenching. The PCr and Pi showed a tendency toward a transient decrease and increases, respectively. The pH in the masseter muscle showed a transient decrease in both groups prior to and following experimental clenching. The pH in the masseter muscle of the patient group was significantly lower than that in the healthy control group at rest and recovery.

Conclusion

We showed mfMRI and ³¹P‐MRS are useful for evaluating masseter fatigue during clenching, and the masseter muscle in the prognathic patients showed more severe fatigue than the healthy controls.

MRI of Temporomandibular Joint Disorders: Recent Advances and Future Directions

Temporomandibular joint disorders (TMDs) are a prevalent disease covering pain and dysfunction of temporomandibular joints and masticatory muscles, which can be detrimental to quality of life. Magnetic resonance imaging (MRI) is a powerful and noninvasive tool for the imaging and understanding of TMD. With the recent technical development of dynamic and quantitative MRI techniques, including diffusion-weighted imaging, T₂ mapping, and ultrashort/zero echo time, it is now feasible in TMD imaging and has been preliminarily investigated with promising results. In this review we will discuss the recent advances of MRI techniques in TMD and its future directions, and hope to highlight the scientific potential and clinical value of novel MRI techniques in diagnosing and treating TMD. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY STAGE: 3.

Quantitative Assessment of the Mandibular Condyle in Patients With Rheumatoid Arthritis Using Diffusion-Weighted Imaging

PURPOSE

The purpose of this study was to quantitatively assess the mandibular condyle in patients with rheumatoid arthritis (RA) using the apparent diffusion coefficient (ADC) on diffusion-weighted imaging (DWI).

PATIENTS AND METHODS

Thirty-one patients with RA and temporomandibular joint (TMJ) pain who underwent magnetic resonance imaging (MRI) examination of the TMJs at our hospital between August 2006 and March 2020 were included in this study. Twenty-one patients with normal TMJs who underwent MRI examination at our hospital between August 2006 and March 2020 were included as controls. The MRI findings were compared between the 2 groups.

RESULTS

The mean ADC values of the mandibular condyle in patients with RA were 1.20 ± 0.17 × 10^-3 mm²/second. The mean ADC values of the mandibular condyle in patients with RA were significantly greater than the controls (P < .01). Receiver operating characteristic curve analysis revealed a cutoff of 0.89 for the ADC values of the mandibular condyle in patients with RA. The receiver operating characteristic curve analysis revealed areas under the curve for maximum ADC values of 0.98.

CONCLUSIONS

Our study found that the ADC on DWI could be used for the quantitative assessment of the mandibular condyle in patients with RA, which indicated that the ADC on DWI could be useful for predicting RA.

Evaluating the mandibular condyles of patients with osteoarthritis for bone marrow abnormalities using magnetic resonance T2 mapping

OBJECTIVES

This study investigated whether erosion and osteophyte correlates with condyle bone marrow abnormalities (BMA), as detected with quantitative T2 mapping.

METHODS

Fifty-six joints (in 44 patients) that demonstrated evidence of bony erosion (ER) or osteophytes (OS) related to disc displacement without reduction were studied with MR images. A control group of 50 joints (in 50 patients) was included. The subjects were divided into five groups; noAR (control), noBMA-ER, BMA-ER, noBMA-OS, and BMA-OS. T2 mapping was performed and the regions of interest were placed over the bone marrow at the top of the condyle. The mean T2 values of the bone marrow of the mandibular condyle were calculated for all mapping images. After assessing age-related changes in T2 values of noAR group using Pearson's product-moment, differences in median T2 values of five groups were analyzed using Kruskal-Wallis test, and Steel-Dwass test (p < 0.05).

RESULTS

There was no significant correlation between age and T2 value in noAR group. The median T2 values of noBMA-ER and BMA-ER groups were significantly higher than those of noAR, noBMA-OS and BMA-OS groups. Those of noBMA-OS and BMA-OS groups were significantly lower than those of noAR, noBMA-ER and BMA-ER groups. There was no significant difference between noBMA and BMA groups.

CONCLUSIONS

It is suggested that erosion and osteophyte of the condyle may correlate with bone marrow abnormalities. T2 mapping could be show slight marrow changes of the arthritic condyle.

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.