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Specialty Imaging: Temporomandibular Joint - Isbn:9780323442978

Category: Medical

  • Book Title: Specialty Imaging: Temporomandibular Joint
  • ISBN 13: 9780323442978
  • ISBN 10: 0323442978
  • Author: Dania F Tamimi, David C. Hatcher
  • Category: Medical
  • Category (general): Medical
  • Publisher: Elsevier Health Sciences
  • Format & Number of pages: 800 pages, book
  • Synopsis: ... as scavengers to keep synovial fluid free of debris □ Suface filopodia □ Plasma membrane invaginations □ Pinocytotic vesicles – Type B cells □ Fibroblast-like □ Rough ... Ten Cate's Oral Histology: Development, Structure, and Function.

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Color atlas of temporomandibular joint surgery Quinn

C H A P T E R O N E

" Who shall decide when doctors disagree? »

ALEXANDER POPE IN " O F THE USE or RICHES"

learly, one of the most vexing problems for oral and maxillofacial surgeons has been selecting the proper surgical option for those patients who have exhausted all conservative methods of dealing with temporomandibular joint pain and dysfunction. Well-reasoned controversy can complicate decision making in temporomandibular joint surgery for internal derangement, trauma, and management of benign and malignant disorders. Several excellent comprehensive textbooks on temporomandibular joint disorders explore the basis for these controversies and provide a historical and scientific overview of this problematic area of

The intent of this text is simply to illustrate the technical aspects of the various surgical procedures on the temporomandibular joint. No attempt was made to champion a single approach to temporomandibular joint surgery. Ultimately, only well-designed clinical studies can prove or disprove the safety and efficacy of the individual procedures. It is our hope scientific evidence will one day provide the sine qua non that will dictate the proper role for all the potential surgical modalities, including arthroscopy, meniscal repair, and the use of both autogenous and alloplastic materials in joint reconstruction. Although serious mistakes have been made in the management of the temporomandibular joint, surgeons cannot allow the sins of the past to obscure the needs of the future.

This text is based on the assumption that primarily extraarticular conditions are most amenable to nonsurgical care. Patients with true internal derangements may benefit from nonsurgical care, and all these modalities should be exhausted before proceeding with any surgical option. The following algorithms are useful as guidelines but must always be modified according to the needs of the individual patient. Because several excellent comprehensive texts dealing with arthroscopic techniques are available, this book deals only with open joint surgical procedures.

D I A G N O S T I C I M A G I N G OF

T H E T E M P O R O M A N D I B U L A R J O I N T

B ecause of the anatomic complexity of the temporomandibular joint and its proximity to the temporal bone, mastoid air cells, and auditory structures,

imaging of the joint structures can be problematic.

PLAIN FILM, TOMOGRAMS, AND PANORAMIC RADIOGRAPHY

Initial screening for gross osseous abnormalities can be performed with standard transcranial (lateral oblique) views. The x-ray beam is angled superiorly to project the joint away from the base of the skull. The transcranial perspective provides a global view of gross bony architecture of the articular surfaces. If possible, a submental vertex film can be taken to allow the lateral oblique transcranial projection to be angled directly through the long access of the condyle. This improves the image quality and also allows standardization of subsequent transcranial views.

Tomography has been widely available since the early 1 940s and provides finer detail for the examination of osseous abnormalities than that detected by plain film techniques. The angle-corrected tomograms for sagittal tomography are recommended so that the sectioning is always perpendicular to the long axis of the condyle. This gives a truer picture of the condylar position and allows subsequent comparative studies to be performed by use of a standard method. The angle can be determined by measuring the angle between the condylar axis and a horizontal baseline on a submental vertex view.

Panoramic radiographs have been described as "curved tomograms." They are, in fact, laminograms of a single plane that are adequate for gross screening but limited because of inherent problems with distortion, "ghost" images, magnification (approximately 2 0 % ). and a loss of sharpness compared with multiplecut, angle-corrected, condylar tomograms.

Newer units allow for separate positioning of right and left joints, creating more correct placement of the condyle in the zone of focus.

Plain films and tomographic images are a great benefit in assessing osseous changes in the condyle and eminence. However, the use of these films to assess condylar position with any accuracy is questionable at best. Several studies have shown that the position of the condyle, as depicted in these radiographic techniques, is of little clinical significance. Openand closed-mouth tomographic views can provide valuable information with regard to condylar translation. Although

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Articles

Specialty Imaging: Temporomandibular Joint E-Book, 1st Edition

Specialty Imaging: Temporomandibular Joint E-Book, 1st Edition Key Features
  • Includes extensive, in-depth explanations of the underlying mechanisms of normal vs. abnormal temporomandibular joints and how those present on radiographic imaging.
  • Provides coverage of hot topics such as understanding the temporomandibular joint through biomechanical engineering, structure/function of the temporomandibular joint in normal and pathologic joints, and clinicoradiological correlation of temporomandibular joint findings.
  • Details anatomic and functional interrelationships in conjunction with radiology.
Dania Tamimi

Affiliations and Expertise

Oral and Maxillofacial Radiology Consultant, Private Practice, Beamreaders, Inc. Orlando, Florida

Recent Publication

Product Not available

David C. Hatcher

Affiliations and Expertise

Clinical Professor, Orofacial Sciences, University of California, San Francisco, California

Recent Publication

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Temporomandibular Joint Total Joint Replacement – TMJ TJR

Temporomandibular Joint Total Joint Replacement – TMJ TJR A Comprehensive Reference for Researchers, Materials Scientists, and Surgeons

Editors: Mercuri. Louis G. (Ed.)

  • Constitutes the first book solely dedicated to TMJ TJR
  • Provides comprehensive coverage of basic science, design, materials, and outcomes to date
  • Describes the basic and advanced operative procedures of primary and revision TMJ TJR in detail with text, images and illustrations
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  • ISBN 978-3-319-21389-7
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Hardcover $159.00
  • ISBN 978-3-319-21388-0
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This is the first text that deals specifically with TMJ TJR. Each chapter is authored by either a basic science researcher or clinician known for their interest and expertise in this field. The text provides the reader with state-of-the-art analysis of all aspects of total temporomandibular joint replacement (TMJ TJR), starting with cutting-edge evidence on the biomechanics of the TMJ. The intriguing history of TMJ TJR is presented to provide an understanding of why some prior TMJ TJR devices failed and how what was learned from those failures has led to the improvements exhibited in present TMJ TJR devices. Expert chapters discuss both stock and custom designs, their indications and contraindications, primary operative techniques, combined TMJ TJR and orthognathic surgical techniques, and the devices' adaption for use as segmental or total mandibular replacement devices after ablative surgery. Clinical outcomes and avoidance as well as management of complications are detailed. Numerous helpful illustrations and radiographs are presented to assist readers in understanding and carrying out the described procedures. Important evidence from both the orthopedic and TMJ TJR literature relating to material sensitivity and mechanical wear will be reported. Finally, the role bioengineered tissue may hold for the future of TMJ TJR will be discussed.

Table of contents (12 chapters)

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www.springer.com

Imaging of Meniscus Abnormalities in the Temporomandibular Joint: Overview, Radiography, Computed Tomography

Imaging of Meniscus Abnormalities in the Temporomandibular Joint Preferred examination

The initial modality used to image meniscus abnormalities in the temporomandibular joint (TMJ) is usually plain radiography or conventional tomography, because arthritic changes and congenital bone abnormality are visualized fairly well on plain films. [1, 2, 3, 4] (See the images below.)

Anteroposterior projection skull radiograph showing an osteoma (O) involving the right temporal bone and the temporomandibular joint.

Conventional tomogram of the right temporomandibular joint showing a normal joint. Note that the bony detail is visualized well.

MRI is the examination of choice, because it is the only modality that directly visualizes the meniscus and other soft-tissue joint components. Bony components are visualized better on computed tomography (CT) scans than on MRI scans. [5, 6, 7, 8]

At the authors' institution, planar radionuclide imaging using technetium-99m methylene diphosphonate/hydroxymethylene diphosphonate ( 99m Tc MDP/HMDP) and single-photon emission computed tomography (SPECT) scanning using 99m Tc MDP/HMDP have been found to be sensitive methods for the diagnosis of TMJ disorders. [9, 10, 11, 12] The tendency is to use them as screening tests and, if normal, the authors usually do not proceed to other imaging techniques, such as MRI.

Arthrography/arthroscopy provide the criterion standard in the investigation of TMJ meniscus abnormality, but they are invasive and presently are used very selectively. [13]

Imaging allows accurate staging of internal derangement for operative planning. Patients in whom surgery is planned on 1 side frequently require evaluation of the asymptomatic joint, because silent TMJ dysfunction is frequent.

Ultrasound studies have been done in cases of disk displacement. [14, 7, 15]

Although arthrography is said to be the criterion standard, MRI appears to be fast becoming the examination of choice. Unlike arthrography, MRI is noninvasive, requires no ionizing radiation for image acquisition, readily obtains multiplanar images in an infinite array of anatomic sections, allows direct visualization of soft-tissue components (including disk and joint structures), allows easy bilateral assessment, allows assessment of joint effusion and inflammation, and easily can image structures outside the joint, such as the joint capsule and muscles of mastication. [16, 17, 18, 19, 20]

As a primary imaging modality for internal derangement of the TMJ, CT scanning has fallen into disfavor because of the superiority of MRI, but it does have specialized imaging capabilities for assessing bone detail, for taking disk density measurements, and for permitting 3-dimensional (3D) assessment of congenital, traumatic, and postsurgical conditions involving the TMJ.

Relative advantages of MRI over CT scanning include a lack of ionizing radiation, the ability to perform primary imaging in multiple planes without imaging the patient, the superior image detail of articular soft-tissue components, the presence of fewer artifacts resulting from dense bone, and the ability to image bone marrow of the condyle.

Etiology and epidemiology

Symptomatic TMJ dysfunction affects 28% of the adult population, with a smaller, although significant, percentage experiencing severe impairment. [21, 22] The clinical problem is complex, because TMJ dysfunction is multifactorial. Although most occurrences are related to internal derangement, many joints are painful secondary to nondiskogenic causes, such as referred pain from spondylosis of the upper cervical spine and other inflammatory and neoplastic bone lesions in the vicinity of the TMJ. A variety of pathologies may affect the TMJ, of which internal derangement is the most common.

The etiology of internal derangement is obscure, although in 25% of patients, a history of trauma is elicited; in these cases, 30% of the causes are iatrogenic and result, for example, from procedures that necessitate jaw extension. These include tonsillectomy, endoscopy, and molar tooth extraction.

Typically, the patient with TMJ dysfunction is a young woman aged 20-40 years who has experienced symptoms for 3-5 years. Not uncommonly, misdiagnosis continues for several years, particularly during childhood and adolescence, because of a variety of poorly understood presenting symptoms. As a result, severe degenerative changes in the TMJ are observed even in children.

Treatment

The objective of conservative and surgical treatment is to shorten the period of the patient's symptoms and to reduce the incidence of long-term joint disfigurement, such as osteoarthrosis, ankylosis, and avascular necrosis. A variety of splints are used to change the position of the meniscus and/or occlusion, but although splints may stabilize the joint, they cannot reverse joint pathology. [23] The most commonly performed surgical procedures include diskal plication with repositioning of the disk, and simple diskectomy, with or without the employment of a disk implant. [24]

Various alloplastic and autogenous materials can be used to fashion a disk implant, such as Teflon, silicon, silastic, and fascial, dermal, and rib grafts. The object of the disk implant is to reduce the probability of osteoarthrosis, adhesions, and recurrent pain and dysfunction. In more advanced cases, condylectomy and reduction osteotomy of the articular eminence may be necessary. The complications of joint stabilization may cause continued TMJ pain; these complications include avascular necrosis, osteochondritis dissecans, and osteoporosis, which may lead to progressive bone remodeling.

Advances in imaging have contributed greatly to the understanding and treatment of TMJ dysfunction and related pathologies. Currently, magnetic resonance imaging (MRI) is regarded as the modality of choice in the evaluation of TMJ dysfunction, although other modalities still have specific roles to play. [16, 17, 18, 25]

Limitations of techniques

A wide variety of abnormalities can present with signs and symptoms mimicking a possible problem in the TMJ. Studies have shown that physical examination alone is inaccurate in determining the status of the joint. Accuracy of the clinical diagnosis for the specific status of the joint is only 50-65%. The primary rationale for imaging the TMJ lies in the fact that mechanical internal derangement resulting from an anteriorly displaced disk and its concomitant pathology is treated differently from the multiple miscellaneous disorders of the TMJ and from myofascial pain dysfunction (MPD) syndrome. MPD is a common disorder affecting a considerable population, and clinical features include jaw pain, limited opening, headache, and earache.

Plain film and tomographic examinations are useful screening modalities. They are valuable for determining the presence of osseous changes and traumatic injury to the osseous components of the joint. Negative findings on plain film are most frequent but do not provide information regarding the presence or absence of soft-tissue disease.

Disadvantages of MRI include its high cost, its inability to visualize perforations of the posterior attachment or of the disk, and difficulty in assessing accurate jaw position for the initiation or adjustment of protrusive splint therapy.

Relative disadvantages of MRI compared with CT scanning include the high initial cost of the scanner, the fact that MRI is not widely available, the presence of claustrophobia in 10% of patients (who can be scanned in the prone position to increase acceptability), the length of scanning time, and the inferior images obtained of hard tissues.

Radionuclide imaging is a highly sensitive technique for evaluating the TMJ but is not specific; arthritis, tumor, inflammation, and trauma can give rise to similar appearances.

Arthrography is a sensitive and highly specific technique in the evaluation of TMJ meniscus abnormalities, but it is invasive and uncomfortable for the patient. See the image below.

Tomogram through the left temporomandibular joint showing osteopenia with minor remodeling. Both sides were examined with the mouth open and closed. Note the limitation of movement on both sides.

Radiography

Radiography and conventional tomography have been used most frequently to image the temporomandibular joint (TMJ). For radiography, as well as for conventional tomography, a multitude of projections and techniques have been described. [1]

Findings of radiography and conventional tomography

The techniques are successful in detecting the shape of the condyle, joint outline, and osseous changes (including flattening, osteophytosis, sclerosis, and erosion). Comparisons of techniques indicate that tomography is superior to radiography, but it requires an experienced operator, requires more imaging time, and renders a higher radiation dose. However, if a strong clinical need exists for determining the position of the condyle in the glenoid fossa, tomography should be used. A transcranial projection is not reliable for determining the condylar position. (See the images below.)

Conventional tomogram of the right temporomandibular joint showing a normal joint. Note that the bony detail is visualized well.

Conventional tomogram of the right temporomandibular joint showing a normal joint. Note that the bony detail is visualized well (same patient as in the previous image).

Tomogram through the left temporomandibular joint showing osteopenia with minor remodeling. Both sides were examined with the mouth open and closed. Note the limitation of movement on both sides.

Tomogram through the left temporomandibular joint showing osteopenia with minor remodeling. Both sides were examined with the mouth open and closed. Note the limitation of movement on both sides.

Other useful information that can be obtained on radiography is the extent of condylar translation at the maximal mouth opening. Restriction of anterior condylar translation at the maximal mouth opening implies that the condyle does not translate all the way to the most inferior aspect of the articular eminence. This is an indication that soft tissue is interposed between the joint components, which may indicate disk displacement without reduction but is not pathognomonic. However, these methods are ineffective in evaluating internal derangement of the TMJ.

Arthrography

TMJ arthropathy implies radiographic imaging of the TMJ after introduction of radiographic contrast into the upper and/or lower joint spaces of the TMJ. TMJ arthrography is indicated for evaluating soft-tissue components, especially disk position, function, and morphology (eg, perforation, swelling, adhesions) in patients presenting with a suggested internal derangement of the TMJ. [13] The ability to assess soft-tissue components of the TMJ allows arthrography to go beyond simple delineation of osseous structures, as in transcranial or tomographic radiographs.

The objective of arthrography is to evaluate disk function during opening and closing maneuvers of the jaw. If the disk is displaced and reduces on jaw opening, the dynamic events are depicted more clearly with fluoroscopic analysis. The smooth to-and-fro flow of contrast material from the anterior recess in the closed-jaw position to the posterior recess in the open-jaw position indicates normal function. A continual collection of contrast material in the anterior recess of the lower joint compartment and progressive deformity of the anterior recess with jaw opening help to confirm the diagnosis of disk displacement without reduction. Perforations are detected easily during initial filling of the joint by observing contrast material flow from the inferior compartment to the superior compartment.

Arthrography can be performed as a single-contrast examination in which iodinated contrast is injected into one or both of the TMJ spaces, or as double-contrast arthrography in which the injection of iodinated contrast is combined with a gas contrast medium. Double-contrast arthrography, or more specifically, dual-space, double-contrast arthrography, is technically more difficult to perform and usually takes longer than does a single-contrast examination. However, double-contrast images depict with greater detail the articular surfaces, the extent of the joint spaces, and the configuration of the disk.

A side-by-side comparison of single-contrast arthrography with the double-contrast form of the modality has shown that single-contrast, lower-compartment arthrography is better for demonstrating joint dynamics. Double-contrast, dual-space arthrotomography better demonstrates anatomic features of the joint, such as shape of the joint spaces and the configuration of the disk in its different mediolateral sections. Perforation between the lower and upper joint spaces is best diagnosed with the help of single-contrast, lower-compartment arthrography, because contrast overflows from the lower joint space into the upper one.

Degree of confidence

Radiographic and tomographic examinations are useful screening modalities. They are valuable for determining the presence of osseous changes and traumatic injury to the osseous components of the joint. Negative radiographs are most frequent; however, they do not provide information regarding the presence or absence of soft-tissue disease or, in particular, the state of the meniscus.

False positives/negatives

The differential diagnosis of meniscus derangement includes the following [1] :

Osteoarthritis (OA) - OA of the TMJ is a common clinical problem, and most TMJ meniscus dysfunction results in degenerative arthritis. Primary OA, OA resulting from trauma, mandibular asymmetry, and calcium pyrophosphate dihydrate crystal deposition diseases also are well-known causes of degenerative arthritis.

Rheumatoid arthritis (RA) and other erosive arthritides - RA affecting the TMJ is not uncommon; some patients with RA may first seek dental consultation because of TMJ-related problems. Imaging findings in an RA-affected TMJ are similar to findings elsewhere and include erosions, osteoporosis, joint narrowing, and restricted range of movement associated with flattening of the condyle and glenoid fossa. CT scanning demonstrates the changes better than does conventional radiography, although MRI can be useful in demonstrating joint effusion and pannus, as well as the morphology of the disk. Other erosive arthritides, such as psoriatic arthritis, ankylosing spondylitis, and systemic lupus erythematosus, can present in a clinically and radiologically similar manner.

Septic arthritis - Infections affecting the TMJ, including pyogenic or granulomatous conditions, are rare. Most infections of the TMJ result from extension of oral infections or as a complication of TMJ surgery. The clinical setting/presentation is sufficiently characteristic to avoid being confused with other TMJ pathology.

Gout - Gout is an exceptional cause of TMJ arthritis. As elsewhere, the presentation may be acute, usually in a patient with known gouty arthritis who has appropriate serum biochemistry; aspirate for negatively birefringent crystals.

Tumor - Tumors of the TMJ are rare. Osteosarcomas of the TMJ are the most common malignant tumors, but osteomas, giant cell tumors, fibrous cortical defects, and nonossifying fibromas can affect the TMJ (see the image below). Malignant tumors usually affect the TMJ by direct extension of a mandibular tumor, such as a metastatic deposit or an osteosarcoma. Tumors may be seen equally well on conventional radiography, radionuclide scanning (particularly SPECT), CT scanning, and MRI, all of which are complementary.

Anteroposterior projection skull radiograph showing an osteoma (O) involving the right temporal bone and the temporomandibular joint.

Nonneoplastic miscellaneous conditions - Some nonneoplastic processes that affect other body joints, such as osteochondromatosis, pigmented villonodular synovitis, and ganglion cysts, also may involve the TMJ. Clinical presentation and imaging findings also are similar. Pathologically, synovial chondromatosis is characterized by proliferation of the synovium with formation of foci of hyaline cartilage, which may calcify and eventually detach and form loose bodies within the joint. Demonstration of calcified bodies in and around the TMJ on conventional radiographs, but particularly on CT scans, suggests the diagnosis. Usually, the TMJ shows changes of OA on conventional radiographs in the form of marginal sclerosis and lytic changes.

Ganglion cysts - Ganglion cysts are mucin-containing cystic structures; they may develop because of herniation of the joint synovium into para-articular tissue. The TMJ is a rare site for this complication, and only a dozen or so cases have been reported. Plain radiography has little to contribute.

Congenital malformations - Congenital malformations of the TMJ are uncommon and are usually associated with abnormalities of the external auditory canal and the middle ear. Rarely, they may clinically mimic diskal abnormality. The most common malformation is condylar hyperplasia, which presents with development of facial asymmetry and dental occlusion. The hypertrophied condyle also may be confused with benign bone tumors. These changes are demonstrated well on conventional radiography.

Computed Tomography

In the past, CT scanning was used extensively to study the complex anatomic structures of the temporomandibular joint (TMJ). Direct sagittal images (see the images below) and axial images of the TMJ allow noninvasive imaging of osseous and soft-tissue abnormalities related to disk damage and dysfunction. [9, 10, 11, 12] High-resolution CT scanning can depict bony and soft-tissue changes that are not detectable using conventional radiography. CT scan attenuation values have been used as a diagnostic approach to delineating tissues of different densities.

Sagittal CT cut through the temporomandibular joints examined on a bone window, elegantly demonstrating the right and left temporomandibular joints.

Sagittal CT cut through the temporomandibular joints examined on a bone window, elegantly demonstrating the right and left temporomandibular joints (same patient as in the previous image).

In assessment of bone detail, CT scanning is a superior imaging method, because it is not subject to the projectional limitations of conventional radiography (see the images below). Multiplanar reconstructions provide superior morphologic evaluation of the osseous joint structures. Currently, computer-generated analysis and displays of 3D imaging data are routinely available in conjunction with CT scanning. In particular, 2 techniques have been described as useful in the assessment of TMJ internal derangement: direct sagittal imaging and axial imaging with parasagittal reconstruction.

Coronal 5-mm CT cut through the anterior cranial fossa and sinuses showing a right maxillary tumor invading the lateral sinus wall and destroying the right ramus and condyle of the mandible.

Coronal 5-mm CT cut through the anterior cranial fossa and sinuses showing a right maxillary tumor invading the lateral sinus wall and base of the anterior cranial fossa and destroying the right ramus and condyle of the mandible. Note the brain invasion (small arrow).

Coronal 5-mm CT cut through the anterior cranial fossa and maxillary antra showing a right maxillary tumor invading the lateral sinus wall and eroding the right ramus and condyle of the mandible (arrow). The right condyle is no longer articulating at the mandibular fossa.

Coronal 5-mm CT cut through the anterior cranial fossa and the maxillary antra showing a right maxillary tumor invading the lateral sinus wall and eroding the right ramus and condyle of the mandible. Note the erosion and fragmentation of the right mandible (arrow). The right condyle is no longer articulating at the mandibular fossa.

For the assessment of internal derangement, the angle between the condylar head and the glenoid fossa is examined closely on each scan. The ability of direct sagittal CT scanning to evaluate osseous structures is an important advantage of the technique. Diagnosis of degenerative joint disease is based on the criteria of bone erosion, eburnation, fragmentation, remodeling of the articular eminence or condylar head, and osteophyte formation.

Degree of confidence

For assessment of bone detail, CT scanning is a superior imaging method, because it is not subject to the projectional limitations of conventional radiography. Multiplanar reconstructions allow superior morphologic analyses of the osseous joint structures. Computer-generated analysis and displays of 3-D imaging data are routinely available in conjunction with CT scanning.

False positives/negatives

CT scanning does not visualize the disk directly but shows osseous changes that are nonspecific, such as joint space narrowing and changes of osteoarthritis secondary to meniscus abnormalities. CT scanning does not differentiate osteoarthritis resulting from meniscal dysfunction from other types of arthritides.

Magnetic Resonance Imaging

MRI is the diagnostic modality of choice for most disorders of the temporomandibular joint (TMJ). [16, 18, 19, 20, 26, 27] Routine examination of the TMJ consists of conventional spin-echo, T1-weighted coronal, sagittal, and axial MRI scans as well as fast spin-echo, T2-weighted axial images in the closed-mouth position. Fat-suppressed proton density (PD) and 2-dimensional (2D)–gradient, refocused-echo (2D-GRE) sagittal images are performed in the sagittal plane in the open and closed position to look at the meniscus. Some investigators use cephalometrically corrected sagittal images by obtaining images in an oblique plane that is perpendicular to the horizontal long axis of the condyle.

MRI yields superb images of the TMJ, and disk morphology is demonstrated elegantly (see the image below).

Phased-array temporomandibular joint coil with right and left temporomandibular joint images acquired simultaneously. Cine acquisition shows the temporomandibular joints from the closed to open positions in a volunteer patient.

MRI of the TMJ is especially helpful in the following:

Determination of position, function, and form of the disk

Differential diagnosis of facial pain of uncertain etiology

Differential diagnosis of headache aggravated by jaw function

Internal derangement (ie, disk displacement or deformation) and degenerative joint disease are the most common findings in patients with TMJ dysfunction (see the images below); however, other abnormalities (eg, joint effusion, bone marrow edema, tumors) also may be detected. [17]

Coronal T1-weighted MRI sequence through the left temporomandibular joint of a 37-year-old man previously treated conservatively for a left meniscus dysfunction. Flattening and sclerosis of the mandibular condyle (c) is noted but no meniscus is identified as a result of automeniscectomy (confirmed on sagittal T1-weighted scans).

The right mandibular condyle (c) appears normal and the normal meniscus is seen clearly (arrow).

Sagittal T1-weighted MRI image through the left temporomandibular joint showing an anterior disk displacement (open mouth) without recapture of the meniscus (closed mouth). A small arrow has marked the meniscus.

Sagittal T1-weighted MRI image through the left temporomandibular joint showing an anterior disk displacement (open mouth) without recapture of the meniscus (closed mouth). A small arrow has marked the meniscus.

MRI clearly demonstrates postoperative granulation tissue, joint effusion, and marrow edema; it also directly visualizes disk implants. However, following disk plication or diskoplasty, clinical findings and MRI appearances correlate poorly. Failed implants resulting from foreign body reaction are visualized as bone erosions similar to septic arthritis and RA. Plain radiographs are useful in differentiating joint calcification from the hypo-intense, postoperative scar and in distinguishing remodeling following surgery for OA.

Degree of confidence

Multiple clinical and experimental studies have shown a high diagnostic accuracy for MRI in the assessment of position and form of the disk.

MRI is helpful in demonstrating TMJ arthropathies, such as joint effusion, pannus formation, and the morphology and position of the meniscus. MRI is also useful in the diagnosis of miscellaneous conditions, such as synovial chondromatosis and ganglion cysts. In synovial chondromatosis of the TMJ, MRI usually shows a large joint effusion and calcified loose bodies that are seen as foci of signal void. Ganglion cysts are demonstrated as low-signal masses on T1-weighted sequences and as high-signal cystic structures on T2-weighted sequences in close association with the TMJ.

Nuclear Imaging

Radionuclide bone scanning can detect the early changes in the temporomandibular joint (TMJ) that affect the adjacent bones and that may occur in meniscus abnormalities (see the first image below). [28] The TMJ is ideally suited for SPECT scanning, because it is small and lies close to the base of the skull and the paranasal sinuses. SPECT imaging can effectively produce high-quality images of the TMJ isolated from other high bone density areas, which is not possible on planar images (see the second and third images below).

Frontal and lateral (right and left) radionuclide images of the skull showing intense activity in the left temporomandibular joint in a 41-year-old woman with an MRI-confirmed temporomandibular joint meniscus dysfunction.

Coronal and transaxial sections generated after single-photon emission computed tomography imaging in a patient with right temporomandibular joint ankylosis. Increased uptake is seen in the right temporomandibular joint region in both sections.

Coronal and transaxial sections generated after single-photon emission computed tomography imaging in a patient with left temporomandibular joint ankylosis. Increased uptake is seen in the left temporomandibular joint region in both sections.

Subsequently, the TMJ may be studied by one of the following techniques:

The 3-phase technique is composed of a 30-second perfusion study in which images are obtained every 3 seconds with computed analysis of perfusion, immediate soft-tissue views of the head and anterior or lateral projections with the mouth open and closed, and delayed views of the TMJ

Delayed views of the TMJ are SPECT scans, as well as planar views in anterior, posterior, and both lateral projections

Radionuclide findings include the following:

Abnormal activity on flow studies in the TMJ is seen in patients in whom disease has an inflammatory component; the activity reflects increased perfusion and hyperemia in the joint.

Usually, images also demonstrate an abnormal increase in activity on immediate views.

Increased activity on delayed views may vary from mildly to markedly increased.

SPECT scanning has exquisite sensitivity in the detection of abnormally increased uptake in the TMJ, which can be quantified. The primary disadvantage of SPECT scanning is that it is a nonanatomic examination.

Although a region of increased uptake suggesting repair phenomena or abnormal stresses on the TMJ can be readily diagnosed, the cause of these findings may remain obscure. Mechanical internal derangement, OA, infection, and a host of other arthropathies demonstrate the same finding.

Usually, condylar hyperplasia is a slowly developing enlargement of the condyle and condylar neck that results in malocclusion and facial asymmetry. Disturbances in the growth pattern of a condyle during the normal growth period or during adulthood may result in condylar hyperplasia. Radionuclide imaging of the TMJ also is performed to exclude active condylar growth in patients with condylar hyperplasia. The objective is to determine whether the condylar growth has ceased or is still progressing. This helps in planning the extent of orthognathic surgery. If the condition is progressive, the entire condyle and neck may be removed; otherwise, the enlarged condyle is only trimmed.

Degree of confidence

Radionuclide bone scanning using 99m Tc MDP/HMDP is extremely sensitive in detecting bone pathology. TMJ meniscus abnormalities are bound to affect the underlying bone metabolically. In the authors' studies (unpublished data), a sensitivity of 68.75% and a specificity of 61.88% were found in the detection of TMJ meniscus abnormalities. These results can be improved considerably—to a sensitivity of 100% and a specificity of 83.33%— using SPECT scanning and semiquantitative methods. Planar imaging, which usually is combined with SPECT scanning, also can show other lesions that may mimic TMJ meniscus abnormalities and cause referred pain to the TMJ, such as upper cervical spine OA, bone metastases, and dental and sinus pathology.

Although the sensitivity of radionuclide imaging is high, its specificity is low. Usually, any inflammatory/traumatic/neoplastic lesion demonstrates increased isotope uptake, which is an advantage and a disadvantage. The authors find radionuclide scanning to be an effective screening tool.

Anteroposterior projection skull radiograph showing an osteoma (O) involving the right temporal bone and the temporomandibular joint.

Conventional tomogram of the right temporomandibular joint showing a normal joint. Note that the bony detail is visualized well.

Conventional tomogram of the right temporomandibular joint showing a normal joint. Note that the bony detail is visualized well (same patient as in the previous image).

Tomogram through the left temporomandibular joint showing osteopenia with minor remodeling. Both sides were examined with the mouth open and closed. Note the limitation of movement on both sides.

Tomogram through the left temporomandibular joint showing osteopenia with minor remodeling. Both sides were examined with the mouth open and closed. Note the limitation of movement on both sides.

Sagittal CT cut through the temporomandibular joints examined on a bone window, elegantly demonstrating the right and left temporomandibular joints.

Sagittal CT cut through the temporomandibular joints examined on a bone window, elegantly demonstrating the right and left temporomandibular joints (same patient as in the previous image).

Coronal 5-mm CT cut through the anterior cranial fossa and sinuses showing a right maxillary tumor invading the lateral sinus wall and destroying the right ramus and condyle of the mandible.

Coronal 5-mm CT cut through the anterior cranial fossa and sinuses showing a right maxillary tumor invading the lateral sinus wall and base of the anterior cranial fossa and destroying the right ramus and condyle of the mandible. Note the brain invasion (small arrow).

Coronal 5-mm CT cut through the anterior cranial fossa and maxillary antra showing a right maxillary tumor invading the lateral sinus wall and eroding the right ramus and condyle of the mandible (arrow). The right condyle is no longer articulating at the mandibular fossa.

Coronal 5-mm CT cut through the anterior cranial fossa and the maxillary antra showing a right maxillary tumor invading the lateral sinus wall and eroding the right ramus and condyle of the mandible. Note the erosion and fragmentation of the right mandible (arrow). The right condyle is no longer articulating at the mandibular fossa.

Phased-array temporomandibular joint coil with right and left temporomandibular joint images acquired simultaneously. Cine acquisition shows the temporomandibular joints from the closed to open positions in a volunteer patient.

Coronal T1-weighted MRI sequence through the left temporomandibular joint of a 37-year-old man previously treated conservatively for a left meniscus dysfunction. Flattening and sclerosis of the mandibular condyle (c) is noted but no meniscus is identified as a result of automeniscectomy (confirmed on sagittal T1-weighted scans).

The right mandibular condyle (c) appears normal and the normal meniscus is seen clearly (arrow).

Sagittal T1-weighted MRI image through the left temporomandibular joint showing an anterior disk displacement (open mouth) without recapture of the meniscus (closed mouth). A small arrow has marked the meniscus.

Sagittal T1-weighted MRI image through the left temporomandibular joint showing an anterior disk displacement (open mouth) without recapture of the meniscus (closed mouth). A small arrow has marked the meniscus.

Frontal and lateral (right and left) radionuclide images of the skull showing intense activity in the left temporomandibular joint in a 41-year-old woman with an MRI-confirmed temporomandibular joint meniscus dysfunction.

Coronal and transaxial sections generated after single-photon emission computed tomography imaging in a patient with right temporomandibular joint ankylosis. Increased uptake is seen in the right temporomandibular joint region in both sections.

Coronal and transaxial sections generated after single-photon emission computed tomography imaging in a patient with left temporomandibular joint ankylosis. Increased uptake is seen in the left temporomandibular joint region in both sections.

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