Failed temporomandibular joint prostheses: MR imaging

Magnetic resonance (MR) imaging with surface coils was performed on 43 temporomandibular joints with disk prostheses in 28 patients who had pain, dysfunction, or both after implantation of the prostheses. Fracture was diagnosed prospectively as a discontinuity of the prosthesis on the MR examination; the sensitivity and specificity of MR imaging for this diagnosis was determined on the basis of these studies. All patients underwent surgery, after which the final diagnosis was made. MR imaging was found to have a sensitivity of 0.81 and a specificity of 0.91. Other MR findings included an abnormal amount of soft tissue surrounding the disk, thinning of the disk, osteophytes, and erosion of the condyle. An as yet unexplained artifact was frequently seen and obscured the prostheses in four of the six false-negative studies. The one false-positive case resulted from the interpretation of a markedly thinned but intact region of the prosthesis as a fracture.     

Optimizing MR signal contrast of the temporomandibular joint disk

Purpose:

To use a tissue specific algorithm to numerically optimize UTE sequence parameters to maximize contrast within temporomandibular joint (TMJ) donor tissue.

Materials and Methods:

A TMJ specimen tissue block was sectioned in a true sagittal plane and imaged at 3 Tesla (T) using UTE pulse sequences with dual echo subtraction. The MR tissue properties (PD, T₂, T₂*, and T₁) were measured and subsequently used to calculate the optimum sequences parameters (repetition time [TR], echo time [TE], and θ).

Results:

It was found that the main contrast available in the TMJ could be obtained from T₂ (or T₂*) contrast. With the first echo time fixed at 8 μs and using TR = 200 ms, the optimum parameters were found to be: θ ≈ 60°, and TE2 ≈ 15 ms, when the second echo is acquired using a gradient echo and θ ≈ 120°, and TE2 ≈ 15 ms, when the second echo is acquired using a spin echo.

Conclusion:

Our results show that MR signal contrast can be optimized between tissues in a systematic manner. The MR contrast within the TMJ was successfully optimized with facile delineation between disc and soft tissues. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

CT and MR imaging of the temporomandibular joint

Through the medium of selected case reports, the authors present their experience with sectional imaging of the TMJ. The complementary roles of CT and MRI are emphasized.     

Normal and abnormal temporomandibular joint: MR imaging with surface coil

The normal temporomandibular joint (TMJ) was evaluated using magnetic resonance (MR) imaging with a surface coil in five subjects and compared with the abnormal joint in 37 patients (aged 14-59 years; total joints studied, 76). Multisection 3-mm-thick sagittal, coronal, and axial images were obtained with a 1.5-T MR system and 6.5-cm-diameter surface coil using both partial saturation and spin-echo sequences (TR = 1,000 msec, TE = 20 or 25 msec). A comparison with arthrography (n = 13 joints), computed tomography (CT) (n = 11), and surgical (n = 5) findings demonstrated that MR imaging with a surface coil provided an accurate depiction of both normal and abnormal TMJs. MR provided information about meniscal position, morphology, and histology that was not available with either arthrography or CT alone. The imaging potential of MR and its noninvasive characteristics warrant priority for further examination of MR as a useful modality in the diagnosis of TMJ pain and dysfunction.     

Pathologic changes of the lateral pterygoid muscle in patients with derangement of the temporomandibular joint disk: objective measures at MR imaging

BACKGROUND AND PURPOSE: The superior head of the lateral pterygoid muscle (SHLP), which inserts on the anterior disk of the temporomandibular joint (TMJ), can spasm, contracting and exerting forward traction on the disk. This mechanism can lead to anterior displacement. In TMJ dysfunction, it is hypothesized that the SHLP will demonstrate morphologic changes with measurable changes in signal intensity related to atrophy or muscular edema, or both. The goal of this study was to evaluate the lateral pterygoid muscle (LPM) in patients with TMJ dysfunction. MATERIALS AND METHODS: Patients with displacement of the TMJ disk with and without reduction were identified through a review of radiology reports. Absolute measurements of thickness as well as region-of-interest measurements were placed over the 2 heads of the LPM bilaterally on sagittal T1- and T2-weighted images. Statistically significant differences between the superior and inferior heads of the LPM were calculated with use of a 1-tailed Student t test and were correlated with the degree of disk derangement. RESULTS: In patients with disk derangement, significantly increased region-of-interest values on T2- and T1-weighted images were demonstrated within the SHLP. No patients with anatomically normal disks demonstrated a statistically significant difference in region-of-interest values between the superior and inferior heads of the LPMs. CONCLUSION: Correlation between increased region-of-interest values and pathologic alteration of the relationship between the condylar head and disk was identified. In patients with displacement of the anterior disk with and without reduction, region-of-interest values were significantly increased, which indicates abnormal signal intensity involving the superior head of the LPM.     

MR imaging of the juvenile temporomandibular joint: preliminary report.

Thirty-two children were evaluated by means of medical history and physical examination for signs and symptoms of internal derangement (ID) of the temporomandibular joint (TMJ) and mandibular dysfunction. These children also underwent magnetic resonance (MR) imaging of the TMJs. The study was double blind. At clinical examination, 19 patients (59%) had at least one positive finding of ID of the TMJ and/or mandibular dysfunction. MR images of the TMJ obtained in 60 of the 64 TMJs demonstrated 57 normal joints (95%) and three abnormal joints (5%). Two of these three joints had a mild anterior-lateral disk displacement, and one joint had an anterior dislocated disk. There were no false-positive MR examinations. MR imaging failed to depict abnormalities in 16 patients who had positive findings at history and/or physical examination. Although MR imaging may fail to depict ID of the TMJ in some patients, clinical techniques commonly used in population surveys probably overstate the prevalence of ID of the TMJ in children.     

Disk displacement of the temporomandibular joint: sonography versus MR imaging

OBJECTIVE: The purpose of this study was to determine the value of dynamic sonography in the evaluation of internal derangements of a temporomandibular joint (TMJ) during maximal mandibular range of motion. SUBJECTS AND METHODS: Maximal mandibular range of motion was performed during high-resolution sonography of the TMJ in 64 consecutive patients (128 joints; nine males and 55 females; age range, 17-65 years; mean age, 35 years 6 months), all of whom subsequently underwent MR imaging. MR imaging confirmed disk displacement with reduction in 27 joints and disk displacement without reduction in 60 joints of the 128 examined. The high-resolution sonography and MR imaging findings for these 27 and 60 TMJs, respectively, were analyzed. RESULTS: Dynamic high-resolution sonography performed during the maximal range of motion helped to detect 81 instances (93%) of internal derangement, 22 instances (82%) of disk displacement with reduction, and 50 instances (83%) of disk displacement without reduction. There was one false-positive finding for internal derangement. The accuracy of prospective interpretation of high-resolution sonograms of internal derangement, disk displacement with reduction, and disk displacement without reduction was 95%, 92%, and 90%, respectively. CONCLUSION: When real-time images are interpreted by expert radiologists, dynamic sonography performed during maximal mandibular range of motion may provide valuable information about disk displacement of the TMJ.     

MR imaging of the temporomandibular joint: a validation experiment in vitro

RATIONALE AND OBJECTIVES: The authors compared magnetic resonance (MR) image quality obtained from 3- and 1-mm-thick sections in the depiction of the temporomandibular joint (TMJ) and its adjacent structures. MATERIALS AND METHODS: Eight TMJ specimens from four adult cadaver heads were depicted with MR imaging. Both 3- and 1-mm-thick sections were generated. One oral and maxillofacial radiologist, who was blinded to section thickness, evaluated the anatomic details of the images. Subsequently, the joints were surgically explored by two oral and maxillofacial surgeons, and the physical findings were recorded. RESULTS: Some statistically significant differences were found between the physical findings and the 3-mm-thick section images, while no significant differences were found with the 1-mm-thick sections. CONCLUSION: The TMJ and its adjacent structures were better depicted by thinner MR images.     

Pseudodynamic MR imaging of temporomandibular joint disorders]

Magnetic resonance (MR) imaging of the temporomandibular joint (TMJ) has now been established as a procedure of choice in the evaluation of TMJ disorders. In this study, we evaluated the dynamics of TMJ motion on MR imaging, which resembles arthrography. Sixty-eight TMJs in 38 symptomatic patients and one healthy volunteer were examined using pseudodynamic images with gradient echo sequences using a 0.5 Tesla MR unit and 8 cm circular planar surface coil. For depiction of each compartment of the meniscus, the optimum sequence was 200/15/2 (TR/TE/excitations) with 50 degrees or 60 degrees flip angle in gradient refocused acquisition in steady-state (GRASS) sequences. Three contiguous slices on sagittal MR images were routinely obtained at 14-18 different phases of the opening cycle and displayed in closed-loop cine fashion. Internal derangement was observed in 57% of 68 joints. The most common type was anterior meniscal displacement without reduction. Sideway and rotational displacements, observed in 10% each, were noted on both sagittal multislice images and axial reference images. As a pseudodynamic MR technique, jaw movement specifically designed to check bite procedure to adjust splints is useful for detecting the exact time of meniscal redisplacement on the second click. After conservative therapy for arthrosis, pseudodynamic MR provided information on changes in the meniscus and condylar relationship. Pseudodynamic MR with multiple phases is suitable for evaluating subtle motion abnormality of the meniscus and for post-therapeutic monitoring.     

Rheumatic disease of the temporomandibular joint: MR imaging and tomographic manifestations

Thirty-six temporomandibular joints (TMJs) in 28 symptomatic patients (aged 14-40 years) with rheumatic disease (mostly rheumatoid arthritis) were studied with magnetic resonance (MR) imaging and hypocycloidal tomography. MR images of four TMJs were normal. Another four TMJs showed internal derangement. Of the 28 TMJs presumed to show rheumatic disease involvement (26 with condylar destruction or deformation), 23 showed abnormal disk structure--five showing severe disk destruction and 18 showing less severe abnormalities (inhomogeneous structure, fragmentation, poor delineation, and severe flattening). MR images showed bone abnormalities in 27 of the 36 TMJs, and tomography showed abnormalities in 25 of the 36 TMJs. Good agreement between the two imaging modalities regarding surface irregularities was found. However, MR imaging demonstrated more extensive bone abnormalities than did tomography in 11 TMJs. The potential of MR imaging for depicting bone and soft-tissue abnormalities associated with rheumatic TMJ involvement was clearly demonstrated.     

Rheumatic and nonrheumatic disease in the temporomandibular joint: gadolinium-enhanced MR imaging.

Magnetic resonance (MR) imaging of 36 temporomandibular joints (TMJs) in 27 patients and six healthy volunteers was performed before and after injection of gadopentetate dimeglumine. Twelve asymptomatic joints were used as controls, 12 TMJs had symptomatic internal derangement, and 12 TMJs had rheumatic inflammatory disease. A small or moderate joint effusion was seen in one asymptomatic joint, four joints with internal derangement, and one joint with rheumatic involvement; in all of these, contrast enhancement of the effusion was observed. A large effusion in one rheumatic joint was enhanced only after delayed imaging. In healthy controls and patients with internal derangement, no or only minimal enhancement of intraarticular tissues was seen. Eleven of the 12 rheumatic TMJs showed moderate or intense soft-tissue enhancement along the disk and articular surfaces (ie, in areas normally devoid of synovial membrane). The one rheumatic joint without enhancement had bony ankylosis and no remaining soft tissue within the joint space. Gadolinium-enhanced MR imaging of the TMJ may effectively depict the proliferating synovium of rheumatic inflammatory joint disease.     

Interobserver variability of dynamic MR imaging of the temporomandibular joint

Purpose

This study investigated the interobserver variability of dynamic magnetic resonance (MR) imaging of the temporomandibular joint (TMJ).

Materials and methods

Sixty-two patients with internal derangement of the TMJ (124 TMJs) were investigated with a 1.5-T MR imaging system during physiological opening and closing of the mouth. Two readers evaluated independently the quality of the dynamic examination (Q: nondiagnostic, diagnostic, optimal), condylar motion (CM: limited, suboptimal, optimal), condylar orientation (CO: in-plane, through-plane shift), disc visibility and movement (DV: visible, nonvisible; DM: normal, reducing, nonreducing dislocation) and joint effusion (JE: present, absent). For each TMJ, the condylar path was measured by tracing the position of the condyle in the frames of the dynamic acquisition. Agreement between the two readers was assessed with Cohen??s Kappa and the Bland-Altman method.

Results

Interobserver agreement was almost perfect for Q (nondiagnostic, diagnostic, optimal: 0.8%, 4.9%, 94.3%; ??=1), CM (limited, suboptimal, optimal: 14%, 26.4%, 59.5%; ??=0.84) and DV (visible, nonvisible: 100%, 0%). Substantial agreement was found for DM (normal, reducing, nonreducing: 66.1%, 14.8%, 19.1%; ??=0.64) and JE (present, absent: 41.3%, 58.7%; ??=0.67). Moderate agreement was found for CO (in-plane, through-plane shift: 94.2%, 5.8%; ??=0.41). As for the condylar path, the means of the percentage differences and limits of agreement (LA) were ?3% (LA: ?34.5%, 28.3%) on the right and ?1.2% (LA: ?35%, 32.6%) on the left.

Conclusions

In dynamic imaging of the TMJ, qualitative assessment of condyle-disc movement and joint effusion is minimally dependent on the reader??s evaluation. Measurement of the condylar pathway shows an interobserver variability of ±30%.     

Permanent Proplast temporomandibular joint implants: MR imaging of destructive complications

We studied the radiologic and pathologic changes in 30 patients (34 joints) in which there were locally destructive bone and soft-tissue complications associated with previously inserted permanent temporomandibular joint (TMJ) Proplast-Teflon implants. The cases were selected as representative examples of patients with failed Proplast interpositional arthroplasty, in whom images of the TMJ were obtained with conventional radiography, tomography, and MR, and in whom both surgical and histologic findings were available. Clinical indications for imaging included joint pain, restricted joint motion, crepitus, preauricular swelling, regional lymphadenopathy, malocclusion either acquired or changed since implant surgery, and facial deformity. Surgery was then performed for the purposes of implant retrieval and joint debridement because of destructive soft-tissue and osseous changes observed from the imaging analysis in conjunction with significant clinical signs and symptoms. The pathologic changes, observed 4-54 months after implant surgery, included a destructive foreign-body-type granuloma and avascular necrosis of the mandibular condyle and condylar neck. Our findings suggest that MR is useful in the detection and evaluation of destructive complications that may accompany failed Proplast-Teflon implants in the TMJ. MR is superior to conventional radiography and tomography in detecting soft-tissue lesions and avascular necrosis of bone. Tomography more accurately delineates soft-tissue calcifications and cortical margins of osseous structures.     

The diagnosis of temporomandibular joint disease: two-compartment arthrography and MR

The reliability and accuracy of two-compartment temporomandibular joint (TMJ) arthrography was compared with MR imaging on the basis of an analysis of surgical findings obtained from joints that had been studied preoperatively with arthrography or MR or, in some cases, both procedures. Seven hundred forty-three consecutive TMJ arthrograms were successfully obtained in a total of 443 patients by using a single 27-gauge needle and a two-compartment technique in each joint. There was a 100% correlation with surgical findings in 218 radiologically abnormal joints operated on within 90 days of arthrography with respect to the presence or degree of meniscus displacement and normal or abnormal disk morphology and function. In 604 patients 1052 TMJs were studied with high-field-strength surface-coil MR. Surgical findings were available for correlation in 170 of the joints studied. Forty-three joints were studied with both two-compartment arthrography and MR. Eight operated joints had been imaged successfully with both two-compartment arthrography and MR. Both methods of evaluation provided highly reliable and accurate information regarding meniscus position and shape. Arthrography was superior to MR in detecting capsular adhesions and the presence or absence of perforation of the disk or meniscus attachments. Simple meniscectomy (with or without insertion of a temporary Silastic TMJ implant) was the most frequently performed surgical procedure in the series, followed by meniscus repositioning procedures. Joint effusions, failed TMJ implants, and avascular necrosis were demonstrated best with MR. Soft-tissue lesions, including intrinsic degeneration of the meniscus, anomalous muscle development, muscle atrophy, tendinitis, and injuries such as contusions and hematomas, were demonstrated only with MR. Partial-flip-angle GRASS (gradient-recalled acquisition in the steady state) techniques permit both fast scanning and study of functional joint dynamic. Joint fluid may appear as high signal intensity on GRASS images because of T2*-weighting. We recommend MR as the procedure of choice for diagnosis of uncomplicated internal derangements of the TMJ. Two-compartment arthrography with videofluoroscopy is an important ancillary procedure that should be performed whenever capsular adhesions or perforations are suspected and not demonstrated with MR and whenever MR is inconclusive.