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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5184_Библиотеки_им_академика_М_И_Перельмана.pdf
Temporomandibular Joint: Review
oftheAnatomy, Pathology,
andMagnetic Resonance Imaging
Techniques
FranciscoAbaeteChagas-Neto, JoséLuizde SáNeto,
andPauloMoraesAgnollitto
1 Introduction: Acquisition
Techniques andProtocols
MR is considered the most effective imaging technique for examining intra-articular processes within
the temporomandibular joint (TMJ). Its superior
ability to provide high contrast resolution of soft
tissues makes it the current gold standard for
diagnosing disc disorders in the TMJ [1, 2].
The assessment of the temporomandibular joint
(TMJ) in a clinical setting may lack specicity due
to the similarities in symptoms observed in cases
of internal derangement and myofascial pain dysfunction. When there is a suspicion of an abnormality in the internal structure of the joint, it is
advisable to include magnetic resonance imaging
1.5 or 3T (MRI) as a standard part of the evaluation process. MRI offers excellent resolution and
tissue contrast, enabling a comprehensive assessment of both the anatomical and biomechanical
F. A. Chagas-Neto (*)
TS Health Center, Hospital Geral de Fortaleza - HGF/
One Laudos, Unifametro and Fatesa, Fortaleza,
CE, Brazil
J. L. de SáNeto
Department of Radiology and Diagnostic Imaging,
Pontical Catholic University’s Hospital (PUCCampinas), Campinas, SP, Brazil
P. M. Agnollitto
Radiology Division, Department of Medical Imaging,
Hematology and Clinical Oncology, University of
São Paulo, Ribeirão Preto Medical School,
Ribeirão Preto, SP, Brazil
aspects of the joint by capturing images with the
mouth in both open and closed positions [1].
All patients undergoing TMJ MRI examination are positioned in a supine position with their
arms adducted (Fig. 1). They are advised to
remove any metallic objects, such as hairpins,
coins, or earrings, to ensure accurate imaging and
prevent interference. Before the procedure
begins, the process is carefully explained to the
patients to provide reassurance. They are
informed about the duration of the examination
and the importance of remaining still during the
imaging process. This helps to minimize motion
artifacts and obtain clear images [1, 3].
To conduct a dynamic study, patients are
instructed to slowly open and close their mouths.
This allows for the evaluation of movement and
function during the examination. By following
these instructions, patients can actively participate in the imaging process and contribute to the
comprehensive assessment of their TMJs [4, 5].
When assessing the temporomandibular joints
(TMJs), it is crucial to examine them while the
mouth is closed and the teeth are in maximum
intercuspation, meaning they are aligned in their
most natural biting position (Fig.2). This position allows for reliable evaluation of the spatial
relationships between the TMJ components,
ensuring an accurate diagnosis. Additionally,
images taken with the mouth in the open position
provide information about the position of the
condyle (the round protrusion on the mandible)
and the disc [4–6].
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2024
B. C. Stack Jr. et al. (eds.), Craniofacial Pain, https://doi.org/10.1007/978-3-031-57563-1_6
91
92
F. A. Chagas-Neto et al.
Fig. 1 Patient lying in supine position
Fig. 2 Patient with closed mouth and aligned teeth in the
natural biting position
For patients who are unable to maintain their
mouths open and stable throughout the scanning
process, a prefabricated mouth prop can be used
Fig. 3 Mouth prop device to evaluate the TMJ in the open
mouth position
(Fig. 3). This device is designed to mimic and
sustain the patient’s maximum mouth opening,
effectively stabilizing it during imaging. In some
cases, a third scan may be requested with a splint
inserted between the teeth. This splint, created by
a dentist, alters the relationship between the condyle and the fossa (the concave depression in the
temporal bone). It helps evaluate the impact of
the splint on the position of the condyle and the
surrounding soft tissues [5, 6].
Dual-surface coils are small bilateral coils
used to provide excellent detail of the joint with a
small eld of view, high signal-to-noise ratio, and
simultaneous bilateral acquisition (Fig. 4).
Modern multichannel head coils and exible
coils with great parameters can also be used with
satisfactory results (Fig.5) [5].
The specic protocol for conducting an MR
study of the temporomandibular joint (TMJ) can
vary among different institutions. However,
there are some key sequences that are com-
Temporomandibular Joint: Review of the Anatomy, Pathology, and Magnetic Resonance Imaging…
Fig. 4 TMJ’s dual-surface coil
93
Fig. 5 Multichannel exible coil
monly employed. Typically, the examination
begins with an axial T1- or T2-weighted spin
echo (SE) sequence, which uses a large eld of
view (FOV) to capture both temporomandibular
joints. This sequence helps in planning the subsequent oblique sagittal and oblique coronal
sequences (as shown in Fig.6) and allows for
comparison of the orientation of the mandibular
condyles [7].
The next essential sequence is an oblique coronal T1-weighted sequence for each TMJ.This
sequence is crucial for evaluating the morphology of the mandibular condyle and assessing the
sagittal position of the disc relative to the condyle. Several oblique sagittal sequences are also
fundamental. These sequences are used to evaluate the relative coronal position of the disc in
relation to the condyle, which is often the most
signicant nding in TMJ assessment. Typically,
a T1-weighted or proton density (PD)-weighted
SE sequence is used, and some institutions opt to
acquire both sequences to enhance the sensitivity
and specicity of the examination. It is important
to evaluate the relationship of the disc with the
osseous structures both in the resting position
and during the open-mouth position. Lastly, a
94
Fig. 6 Large FOV
T2-weighted axial
sequence. Planning of
oblique coronal and
oblique sagittal
sequences according to
the orientation of the
mandibular condyle
F. A. Chagas-Neto et al.
T2-weighted fast spin echo (FSE) sequence is
employed to identify and assess joint effusion.
Overall, the specic sequences used may vary,
but the key sequences typically include axial T1or T2-weighted SE, oblique coronal T1-weighted,
oblique sagittal T1-weighted or PD-weighted SE
(or both), and T2-weighted FSE for joint effusion
evaluation [6, 8].
Dynamic information of the temporomandibular
joint (TMJ) can be captured using MR imaging
through a technique called progressive image acquisition. This involves acquiring static images using
spin echo techniques at gradual intervals from the
closed position to the open position. These images
are then displayed sequentially in a back-and-forth
closed cine loop, creating a dynamic visual representation of the TMJ movement [7, 8].
In addition to spin echo techniques, some
researchers have explored the use of a balanced
steady-state free procession (bSSFP) sequence for
dynamic MR imaging of the TMJ.This sequence,
typically performed at a magnetic eld of 3T, offers
advantages in terms of imaging speed and contrast.
It allows for the assessment of dynamic TMJ movements and can provide valuable information about
the joint function and any abnormalities. Both the
progressive image acquisition with spin echo techniques and the utilization of bSSFP sequences offer
ways to capture dynamic information during TMJ
imaging, enabling a more comprehensive evaluation
of the joint’s movement and functionality [7, 8].
Intravenous contrast is ordinarily not needed
and may be used in suspected inammatory disorders (such as juvenile idiopathic arthritis) or in
suspected malignancy. We provide at the end of
the chapter some examples of protocols from different institutions [9].
While MR is a valuable imaging modality for
evaluating temporomandibular joint (TMJ) disorders, it does have some limitations. MR is not
capable of capturing biochemical alterations and
early pathological changes in the TMJ disc and
related muscles before structural damage becomes
evident. Additionally, MR may be less sensitive in
detecting bony components of the TMJ compared
to cone beam CT.These limitations can result in a
Temporomandibular Joint: Review of the Anatomy, Pathology, and Magnetic Resonance Imaging…
95
non-comprehensive evaluation, potentially leading
to misdiagnosis and mistreatment of TMJ disorders. However, in recent decades, there have been
advancements in MRI hardware and techniques,
resulting in signicant improvements in image
quality and the ability to perform real-time
dynamic imaging of TMJ disorders [10–12].
Furthermore, with the development of various
MRI sequences and sophisticated post- processing
algorithms, quantitative and functional evaluation of
multiple biochemical properties of TMJ structures
has become feasible. These advancements allow for
a better understanding of the TMJ structures and a
deeper comprehension of its disorders [8, 12].
Additionally, the novel technique of zero echo
time (ZTE) has been introduced, which has achieved
comparable diagnostic value for detecting osseous
abnormalities in the TMJ within an MRI setting.
Table 1 Summary of recent advanced MRI techniques in TMD imaging
MR
technique Sequence Basic principles Advantages Disadvantage Applications in TMJ
DWI FSE Incorporates
Real-time
imaging
DTI Enhances the basic
GRE, SE Employs rapid
diffusion-sensitizing
gradients into
T2-weighted
spin-echo (SE)
sequences, typically
utilizing echo planar
imaging
sequences with
high-efciency
k-space pathways
(such as radial) and
employ sophisticated
reconstruction
algorithms,
occasionally
incorporating parallel
imaging techniques
DWI by incorporating
a minimum of six
independent
sensitizing gradients,
followed by
conducting an
analysis of
eigenvectors and
eigenvalues
– Measurement
of diffusion
properties
– Optimal
temporal
resolution
– Satisfactory
image delity
– Swift
acquisition
– Visualization of
ber
orientations
– Measurement
of directional
diffusion
anisotropy
Overall, while MRI has its limitations, ongoing advancements in hardware, techniques, and
post-processing algorithms have enhanced its
capabilities, enabling improved image quality,
real-time dynamic imaging, and quantitative
assessment of TMJ structures. These developments contribute to a more comprehensive evaluation and better understanding of TMJ disorders
and will ultimately help its early diagnosis, treatment planning, therapeutic efcacy evaluation,
and even image-guided intervention. To validate
the reliability of previous ndings and delve
deeper into the clinical signicance of advanced
MRI techniques in various temporomandibular
disorder (TMD) scenarios, additional research
involving a substantial number of patients is necessary. A summary of recent advanced MRI techniques in TMD is shown in Table1 [4, 8, 12].
– Susceptibility
artifacts
– Restricted
volumetric
imaging
capability
– Complex
reconstruction
processes
– Necessity for
specialized
computational
hardware
– Inadequate
spatial
resolution
– Lack of a
standardized
protocol
– Establishes a
correlation
between ADC
values and the
perception of
pain in
masticatory
muscles
– Captures the
dynamic and
natural motion
of the TMJ
under (patho)
physiological
conditions
– Visualizes
collagen bers
within the TMJ
disc and ber
bundles within
masticatory
muscles invivo
– Quanties the
alterations in
DTI parameters
before and
after treatment
(continued)
96
(continued)
Table 1
MR
technique Sequence Basic principles Advantages Disadvantage Applications in TMJ
IVIM Expands the
UTE UTE
T2
mapping
TMD temporomandibular joint disorders, TMJ temporomandibular joints, GRE gradient echo, SE spin echo, FSE fast
spin echo, DWI diffusion-weighted imaging, ADC apparent diffusion coefcient, IVIM intravoxel incoherent motion,
DTI diffusion tensor imaging, UTE ultrashort echo time
sequence
SE Incorporates multiple
mono-exponential
DWI model to a
biexponential model
incorporating multiple
b values
Employs a brief
radiofrequency (RF)
pulse and initiate data
acquisition promptly
after the completion
of excitation. The data
collection takes place
simultaneously with
the activation of the
readout gradient
TEs within a single
TR and employ
exponential decay
curve tting to
ascertain T2
relaxation times using
signals acquired at
each TE
– Measurement
of both
diffusion and
perfusion
characteristics
– Collecting
signals from
tissues
characterized
by ultrashort T2
relaxation times
– Simple
– Measurement
and evaluation
of biochemical
characteristics
– Geometric
distortions
– Dependence
on high
gradient
performance
– Restricted
availability of
suitable
software
– Extended
acquisition
durations
– Magic angle
effect
– Sensitivity to
joint effusion
F. A. Chagas-Neto et al.
Establishes a
connection between
IVIM parameters and
various TMD
conditions
– Visualize the
TMJ disc,
brocartilaginous surface,
and condylar
morphology
– Evaluate
osseous
alterations
associated with
TMD
– Measure the
biochemical
properties of
the TMJ disc
– Establishes a
correlation
between T2
values and the
pain in
masticatory
muscles and
alterations in
condylar bone
marrow
– Facilitates
ultrastructural
analysis to
examine the
composition of
the TMJ disc
and retrodiscal
tissue
2 MRI TMJ Anatomy
andBiomechanics
Interpreting TMJ imaging requires an understanding of the normal anatomy of the joint. The TMJ is
an unusual synovial joint in that the articular surfaces are covered with brocartilage rather than
hyaline cartilage, located between the glenoid
fossa of the temporal bone and the mandibular
condyle. There are four main anatomical components of the temporomandibular joint. These components consist of the mandibular condyle, the
mandibular fossa, the articular eminence of the
temporal bone, and the articular disc (also known
as the articular meniscus). The articular disc plays
a crucial role in the function and dysfunction of the
joint, as explained in the following sections. It is a
biconcave brocartilaginous structure that can be
divided into three distinct zones: an anterior thick
Temporomandibular Joint: Review of the Anatomy, Pathology, and Magnetic Resonance Imaging…
97
band, a posterior thick band, and a thinner intermediate zone. By separating the articular synovial
space into two separate compartments (superior
and inferior) unless there is a disc rupture, the
articular disc plays a critical role [13, 14].
Additionally, there are other signicant anatomical structures within the temporomandibular
joint. One such structure is the lateral pterygoid
muscle, which is divided into two heads or bellies. While the attachments of these heads may
vary, the inferior head typically inserts onto the
anterior aspect of the mandibular condyle, while
the superior head may attach exclusively to the
anterior band of the articular disc or both the disc
and the condyle. Both heads actively contribute
to the mastication process and jaw movements. In
cases of temporomandibular joint dysfunction, it
is believed that the inferior head functions as a
stabilizer of the joint and may undergo morphological changes due to hyperactivity, which
should be assessed and reported in MRI scans
[15–18].
Another important anatomical area is the
bilaminar zone, also known as the retrodiscal tissue. This zone is located posteriorly to the posterior band of the articular disc and consists of two
retrodiscal layers (superior and inferior) with
neurovascular structures in between. These layers are continuous with the posterior band of the
disc and act as ligaments that help maintain the
proper placement of the disc. It is essential to
actively evaluate this area in MRI scans because
a rupture in these layers may be the cause or consequence of disc luxation and temporomandibular joint dysfunction.
In addition to these structures, the temporomandibular joint is further stabilized by various
extra-articular structures, including the temporomandibular, sphenomandibular, and stylomandibular ligaments, as well as the medial pterygoid,
masseter, temporal, and suprahyoid muscles. The
mentioned anatomical structures of the temporomandibular joint are illustrated in Fig.7 [13–15,
18].
On MRI scans, the condyle exhibits a high
signal intensity on T1-weighted images due to
the presence of marrow fat. Both the cortical
bone and the disc display low signal intensity on
both T1-weighted and T2-weighted images. This
is attributed to their low proton density and short
T2 relaxation times. However, there are instances
where the central portion of the disc may exhibit
3
3
7
7
6
2
2
10
10
14
14
16
16
15
15
6
5
5
12
12
4
4
13
13
1
1
11
11
17
17
8
8
9
9
Fig. 7 Illustration and MRI of TMJ anatomy. (1)
Mandibular condyle; (2) articular eminence of temporal
bone; (3) mandibular fossa; (4) articular disc (anterior
band); (5) articular disc (intermediate zone); (6) articular
disc (posterior band); (7 and 8) bilaminar zone (superior
and inferior retrodiscal layers); (9) bilaminar zone (neuro-
vascular structures); (10 and 11) superior and inferior capsular insertions; (12 and 13) superior and inferior joint
recesses; (14 and 15) superior and inferior heads of the
lateral pterygoid muscle; (16) interpterygoid space; (17)
external auditory canal
98
Fig. 8 MRI TMJ anatomy. Note the slightly hyperintense
signal of the intermediate zone and the center of the posterior band
high signal intensity on T2-weighted and proton
density images, resembling the hydration pattern
seen in the central region of a vertebral disc.
Apart from this, the disc appears homogeneous,
hypointense, and biconcave in shape [15, 16].
The center of the posterior band of the disc
may exhibit slight hyperintensity due to the presence of loose areolar tissue (Fig.8). The posterior
attachment of the disc appears to have higher signal intensity than muscle on proton density- and
T1-weighted images, primarily due to the presence of fatty tissue. The bilaminar zone, seen as
structures with intermediate signal intensity, is
visible as well [14, 18].
In the closed-mouth position, the junction
between the posterior band and the posterior
attachment is typically located above the condylar head, close to the 12 o’clock position. The
posterior band and retrodiscal tissue are best
visualized in the open-mouth position. In this
position, the intermediate zone of the disc lies
between the condyle and the articular eminence,
while the posterior band rests against the posterior surface of the condyle [19].
The superior belly of the lateral pterygoid
muscle attaches to the anterior band of the disc,
while the inferior belly of the lateral pterygoid
attaches to the anterior surface of the condylar
neck via a thin linear hypointense brous band
(Fig.7). This band is situated just below the position of the disc and can sometimes be mistaken
F. A. Chagas-Neto et al.
Fig. 9 MRI TMJ anatomy in the coronal plane. The disc
is crescent shaped, and no abnormal bulges are seen
beyond the borders of the lateral and medial capsules
for the disc, particularly when the disc is displaced
medially or laterally. In the coronal plane, the disc
appears crescent-shaped, with its medial and lateral borders attaching to the respective aspects of
the condylar head and joint capsule. The lateral
and medial capsules do not exhibit any outward
bulges beyond their normal borders (Fig.9) [14,
16, 19].
Jaw movement requires a high level of interaction and coordination among various structures
such as the bilateral mandibular condyles, disc,
muscles, and ligaments of the temporomandibular joints (TMJs). The functional interactions
within the TMJ are complex and not yet fully
understood. A simplistic view of the complex
interactions in open- and closed-mouth positions
is described below [20].
In a healthy joint, the thin intermediate zone of
the disc always separates the condyle and the temporal bone in both closed-mouth and open- mouth
positions to prevent articular damage. The disc is
positioned between the condyle (inferiorly) and
the glenoid fossa (superiorly), while the articular
eminence is located anterior to the disc. Normally,
the disc is aligned so that the anterior band is in
front of the condyle, and the junction of the poste-
ab
Temporomandibular Joint: Review of the Anatomy, Pathology, and Magnetic Resonance Imaging…
20 degrees
+
−
12
39
6
99
(a) Normal position of the joint structures in
Fig. 10
closed-mouth position. The mandibular condyle is aligned
with the mandibular fossa, and the posterior border of the
disc is within 20° of a vertical line traced from the condyle
to be within the 95th percentile of normal. Because the
rst denition may result in up to 30% false positives,
Rammelsberg and colleagues suggested that a disc should
be considered anteriorly displaced beyond 30° from the
rior band and bilaminar zone lies just above the
condylar head near the 12 o’clock position. It
must be positioned with the limit of its posterior
band aligned with a vertical line drawn from the
center of circle with the condyle diameter, as
shown in Fig.10a. A variability of −10° to +10° is
considered within normal limits [3, 13].
However, there is some controversy regarding
the range of normal disc positions. In the normal
vertical. (b) Anterior displacement with reduction. (A)
Sagittal proton density-weighted magnetic resonance
imaging (MRI) in the closed-mouth position demonstrates
anterior displacement of the disc (arrow) in front of the
mandibular condyle (the letter, c). (B) Sagittal proton
density-weighted MRI in the open-mouth position demonstrates reduction of the disc (arrow) between the articular eminence (a) and the mandibular condyle (c)
population, there is signicant variation in the
relationship between the posterior band and
bilaminar zone, leading to incorrect classication
of anterior disc displacement. Rammelsberg etal.
propose that disc positions up to +30° from the
vertical should be considered normal. Other
authors have suggested using the intermediate
zone as the reference point, so that in a healthy
joint, it is always interposed between the condyle
100
F. A. Chagas-Neto et al.
and the temporal bone regardless of the joint
position [1, 20].
3 Traumatic Lesions:
Temporomandibular Joint
Temporomandibular joint (TMJ) is a complex
joint that connects the mandible to the skull,
responsible for the movements of the lower jaw.
Traumatic injuries to the TMJ can cause signicant morbidity and can lead to chronic pain and
dysfunction. Diagnosis of TMJ injuries can be
challenging, and imaging plays a crucial role in
identifying the extent and severity of the injury.
Various imaging modalities have been used to
evaluate TMJ injuries, including conventional
radiography, computed tomography (CT), and
magnetic resonance imaging (MRI). Among
these, MRI has gained popularity in recent times
due to its ability to provide detailed information
on soft tissue injuries. This essay aims to explore
the role of MRI in the evaluation of traumatic
injuries to the TMJ, including its advantages,
limitations, and current advancements [10, 21].
Traumatic injuries to the TMJ can occur due to
various reasons, including direct trauma, indirect
trauma, or repetitive microtrauma. Direct trauma
to the TMJ can occur due to a blow to the jaw or
face, resulting in fractures of the mandible or the
temporal bone. Indirect trauma can occur due to
whiplash injuries, resulting in dislocation or subluxation of the joint. Repetitive microtrauma can
occur due to chronic teeth grinding or clenching,
resulting in joint degeneration and pain [19, 22,
23].
3.1 Role ofMRI inTMJ Injury
Evaluation
MRI is a noninvasive imaging modality that uses
a strong magnetic eld and radio waves to produce detailed images of soft tissues. MRI is useful in the evaluation of TMJ injuries as it can
provide detailed information on the extent and
severity of soft tissue injuries. MRI can also distinguish between acute and chronic injuries,
which is essential in the management of TMJ
injuries.
MRI is particularly useful in the evaluation of
disc displacement, which is a common TMJ injury.
Disc displacement occurs when the articular disc
moves out of its normal position, resulting in pain,
clicking, or locking of the joint. MRI can provide
detailed information on the position of the disc, the
presence or absence of perforations or tears, and
the extent of joint effusion. MRI can also distinguish between various types of disc displacements,
including anterior disc displacement with reduction, anterior disc displacement without reduction,
and posterior disc displacement [24, 25].
MRI is also useful in the evaluation of joint
degeneration, which is a common consequence
of chronic TMJ injuries. Joint degeneration can
result in osteoarthritis, which can cause signicant pain and dysfunction. MRI can provide
detailed information on the extent and severity of
joint degeneration, including the presence or
absence of bone erosions, joint effusion, and
synovial hypertrophy [24, 25].
3.1.1 Advantages
1. Detailed soft tissue evaluation: MRI is partic-
ularly useful in the evaluation of soft tissue
injuries, including ligamentous and muscular
injuries, which are not visible on conventional
radiographs or CT scans. MRI can provide
detailed information on the extent and severity of soft tissue injuries, making it an excellent tool for the assessment of TMJ injuries.
2. Noninvasive: MRI is a noninvasive imaging
modality that does not use ionizing radiation,
making it a safe option for the evaluation of
TMJ injuries, especially in children and young
adults.
3. Multiplanar imaging: MRI can provide
images in multiple planes, including axial,
sagittal, and coronal, allowing for a comprehensive evaluation of the TMJ.
4. Differentiation between acute and chronic
injuries: MRI can differentiate between acute
and chronic injuries, which is essential in the
management of TMJ injuries.
5. Improved patient comfort: MRI is a painless
imaging modality that does not require the use