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.     

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.     

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.     

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.     

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.     

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.     

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.     

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%.     

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.     

Incremental hydraulic jaw opener for MR imaging of the temporomandibular joint.

Magnetic resonance (MR) imaging in the open- and closed-mouth positions is the method of choice for visualizing the temporomandibular joint (TMJ). To analyze the TMJ in response to various degrees of mouth opening, the authors constructed a hydraulic incremental jaw opener. This apparatus enables obtaining of reproducible and stable positions of TMJ articulation. With modified gradient pulse sequences, the technique yields good spatial resolution of joint anatomy, including that of the articular disk. The application of a cine program allows cinematographic display of TMJ motion, which in conjunction with static open- and closed-mouth views can be useful in the diagnosis of TMJ dysfunction. The authors used the incremental jaw opener to examine the disk-condyle complex at each open-mouth position, with particular attention to extreme open-mouth positions.     

Optimizing joint imaging: MR imaging techniques

For optimizing MR of the joints, a sophisticated knowledge of MR system hard-and software condition, and coil technologies, sequence and contrast preparation techniques, and the use of paramagnetic contrast agents is necessary. This review article discusses the basic principles of the appropriate use of surfacecoilsas well as the different conventional and fast imagingsequences, including three-dimensional (3D)MR imaging. In addition, the applications of contrast agents as well as the most important contrast prepaation techniques are reviewed.     

MR imaging of the temporomandibular joint: a cadaver study of the value of coronal images

Recent studies comparing cryosectional anatomy of the temporomandibular joint (TMJ) to its MR appearance have shown that the assessment of disk displacement is inaccurate when based on the sagittal plane alone. This article describes the MR appearance of the normal and abnormal (positional and osseous changes) TMJ in the coronal plane and compares these findings with their cryosectional anatomy. Twenty-two TMJs from unselected frozen cadavers were embedded in paraffin. Coronal and sagittal MR imaging was performed; specimens were then cut in the same plane as the coronal images. Disk position by cryosection was normal in 14 cases and abnormal in eight cases. Coronal MR images alone correctly depicted the TMJ disk position in 17 cases (77%) (13 normal, four abnormal). Complementary sagittal images were necessary for diagnosing anterior displacement in two cases (9%). MR was inaccurate in three cases (14%) of severe degenerative joint disease. Bone condition was correctly diagnosed on the basis of coronal images alone in all cases. Our study shows that coronal MR imaging alone of the TMJ in cadavers accurately shows disk position in 77% of cases. Complementary sagittal images were of benefit in the diagnosis of an additional 9% with anterior displacement. Disk position was assessed inaccurately in either plane in patients with severe degenerative joint disease. For a full MR assessment of the TMJ for disk position and bone condition, we recommend imaging in both coronal and sagittal planes.     

The normal temporomandibular joint: MR and arthrographic correlation

Magnetic resonance (MR) images of 28 normal temporomandibular joints were obtained and correlated with respective arthrograms. There was a spectrum in the configuration and thickness of normal articular menisci. The anterior band varied from thin with a flat inferior margin to thick with a bulbous, convex inferior margin. The anatomic configuration of the meniscus as seen with MR correlated directly with normal variations of the anterior recess seen with arthrography. Concavity of the superior aspect of the anterior recess as seen on arthrography was caused by a thick, bulbous anterior band of the meniscus, whereas a flat anterior recess resulted from a thin anterior band without a convex inferior margin. This study emphasizes that the appearance of a concave anterior recess on static arthrograms is not necessarily due to a displaced meniscus.     

Rapidly destructive osteoarthritis of the hip: MR imaging findings

OBJECTIVE: The purpose of our study was to use an artificial neural network to differentiate benign from malignant pulmonary nodules on high-resolution CT findings and to evaluate the effect of artificial neural network output on the performance of radiologists using receiver operating characteristic analysis. MATERIALS AND METHODS: We selected 155 cases with pulmonary nodules less than 3 cm (99 malignant nodules and 56 benign nodules). An artificial neural network was used to distinguish benign from malignant nodules on the basis of seven clinical parameters and 16 radiologic findings that were extracted by attending radiologists using subjective rating scales. In the observer test, 12 radiologists (four attending radiologists, four radiology fellows, and four radiology residents) were presented with high-resolution CT images, first without and then with the artificial neural network output. Observer performance was evaluated by means of receiver operating characteristic analysis using a continuous rating scale. RESULTS: The artificial neural network showed a high performance in differentiating benign from malignant pulmonary nodules (A(z) = 0.951). The average A(z) value for all radiologists increased by a statistically significant level, from 0.831 to 0.959, with the use of the artificial neural network output. CONCLUSION: Our computerized scheme using the artificial neural network can improve the diagnostic accuracy of radiologists who are differentiating benign from malignant pulmonary nodules on high-resolution CT.     

Image quality using dynamic MR imaging of the temporomandibular joint with true-FISP sequence.

We evaluated the quality of dynamic magnetic resonance (MR) imaging of the temporomandibular joint (TMJ) in 20 normal volunteers with 40 TMJs. To confirm TMJ, we obtained static proton density weighted images (PDWI) before performing dynamic MR imaging with true-fast imaging in a steady-state precession (true-FISP) sequence. Four sequences of the first 10 volunteers were examined to determine the optimal sequence. The 4 sequences included the integrated parallel acquisition technique (iPAT) and/or fat saturation technique. The optimal sequence was then determined and performed in all 20 volunteers. The quality of imaging was evaluated, especially with respect to the conspicuity of the articular disk, mandibular condyle, articular eminence and lateral pterygoid muscle. One of 3 confidence levels was assigned for this evaluation. Neither iPAT nor fat saturation obtained the best quality imaging. Detection rates in the 20 volunteers were 83% for the articular disk, 95% for the mandibular condyle, 96% for the articular eminence and 7.5% for the lateral pterygoid muscle. We recommend dynamic MR imaging of the TMJ with the true-FISP sequence using neither iPAT nor fat saturation. Nevertheless, dynamic MR imaging was inferior to static imaging in detecting the articular disk and still requires improvement.     

Dynamic display of the temporomandibular joint meniscus by using "fast-scan" MR imaging

In order to display temporomandibular joint (TMJ) images as a dynamic or motion study, a protocol was developed to obtain MR images of the TMJ in multiple phases of opening by using the "fast-scanning" capabilities of the GE Signa MR scanner. To facilitate this procedure a prototype device was also developed to passively open the patient's mouth from resting (closed) to fully open in user-defined increments (minimum 1 mm). MR imaging (surface coil) was carried out at each successive station using the GRASS, pulse-sequence data base of the GE Signa system operating at 1.5 T. Image-acquisition parameters were optimized in studies of cadavers and volunteers to obtain the clearest delineation of the TMJ meniscus and to determine any potential tradeoffs between total imaging time per slice (image quality), patient tolerance, and other practical considerations. For viewing, the images were sequentially placed in the video memory of the operating console and displayed in a back-and-forth-closed cine loop or "movie" mode at variable (operator-selectable) speeds. The dynamic sequences in four individuals were compared with static open- and closed-mouth views obtained with routine pulse sequences. Any single image from the dynamic display lacked the high resolution of the routine static images because of technical limitations of the pulse-sequence data base. However, in the movie mode the pertinent joint structures (such as meniscus and condyle) were clearly delineated, as were several of the important muscles of mastication. The anterior motion (translation) of the meniscus during jaw opening is particularly evident and suggests great potential for functional evaluation. These results show the feasibility of dynamic TMJ imaging with MR. The added information of the cine display potentially complements the routine static images and may prove extremely valuable in the assessment of TMJ dysfunction.