下颌髁突脱位骨折后颞下颌关节软组织改变的MRI表现

目的 分析下颌髁突脱位骨折后颞下颌关节(TMJ)软组织改变的MRI表现.方法 应用矢状面和冠状面质子密度加权成像(PDWI)和T2WI连续检查103侧(77例)患有下颌髁突脱位骨折的颞下颌关节(TMJ).结果 MRI上,103侧髁突脱位骨折后的TMJ异常表现有:(1)髁突骨折断片向前下(102侧,99.0%)和前(1侧,10%)脱位;(2)关节盘移位(100侧,97.1%),其中矢状面MRI显示关节盘随脱位的髁突向前下移位者99侧,向前移位者1侧;(3)关节腔积液(103侧,100%);(4)关节盘后区信号异常(91侧,88.3%);(5)关节盘下后附着异常(89侧,86.4%);(6)关节囊异常(89侧,86.4%);(7)关节盘上后附着异常(37侧,35.9%);(8)关节盘变形(8侧,7.8%);(9)关节盘撕裂(8侧,7.8%);(10)颞骨关节窝骨折(4侧,3.9%).结论矢状面MRI上,多数下颌髁突脱位骨折以TMJ关节盘随脱位的髁突向前下移位,并伴有关节腔积液为特点.     

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.     

A computerized analysis of femoral condyle radii in ACL intact and contralateral ACL reconstructed knees using 3D CT

The bony geometry of the distal femoral condyles may have a significant influence on knee joint kinematics. The aim of this study was to analyze the relationship between the size of the medial and lateral femoral condyles in different planes. Seventy-four three-dimensional (3D) CT reconstructions of 37 patients with ACL intact and contralateral ACL reconstructed knees were used and the data were imported into a graphical software program. The radii of the medial and lateral femoral condyles were analyzed in the sagittal, coronal, and axial planes by digitally reconstructed circular arcs along the bony condylar profiles marked with multiple digital surface points. Intra- and interobserver testing was performed. In the intact knees the average sagittal radius of the distal medial and lateral femoral condyles was similar. There was a significant difference between the radii of the distal medial femoral condyles compared to lateral femoral condyles in the coronal plane (22.4 vs. 27.8 mm, P < 0.001) as well as between the radii of the medial femoral condyles in the axial plane in 90° knee flexion compared to the lateral femoral condyles (21.3 vs. 18.3 mm, P < 0.001). The average radius of the medial femoral condyles was significantly smaller in extension compared to 90° of flexion (21.2 vs. 22.4 mm, P = 0.05) and the average radius of the lateral femoral condyles was significantly larger in extension compared to 90° of flexion (27.8 vs. 18.3 mm, P < 0.001). The 37 ACL reconstructed knees demonstrated similar radii in all three planes when compared to the intact knees without any significant difference. The described method of assessing the architecture of the distal femoral condyles is non-invasive, reproducible, and provides reliable geometric parameters necessary for the 3D reconstruction of the femoral geometry in vivo. The radii of the FC were similar in the sagittal planes but demonstrate a significant asymmetry in the axial and coronal planes. The average radius of the lateral femoral condyles was significantly larger in extension whereas the radius of the medial femoral condyles was significantly larger in flexion. We did not find any significant difference in the shape of the femoral condyles in ACL intact and contralateral ACL reconstructed knees indicating that the geometry of the femoral condyles might not influence the injury mechanism of ACL rupture. The asymmetry between the femoral condyles may be considered when designing new anatomical femoral components in knee arthroplasty.     

MR of 732 TMJs: anterior,rotational, partial and sideways disc displacements

Objective: The purpose of this study was to determine the prevalence of anterior, sideways, rotational and partial anterior disc displacements, as well as degenerative changes in patients with clinical signs and symptoms of internal disorders. Materials and methods: 732 MR Images of temporomandibular joints (TMJ) were produced for 366 symptomatic patients. Image analysis included assessment of disc positions and mobility, as well as recapture in coronal and mediolaterally divided sagittal planes in closed and open positions. Results: Of these images, 545 TMJ showed an internal derangement comprised of 52% anterior disc displacements without reduction, 26% anterior disc displacements with reduction, 11% partial anterior disc displacement, 5% pure sideways displacements and 4% stuck discs. Rotational disc displacements were observed in 34% of the anterior disc displacements without reduction group and in 53% of the anterior disc displacements with reduction group. A total of 97% of the partial anterior disc displacement occurred laterally. Degenerative changes increased with age, mainly in the anterior disc displacements without reduction group. Conclusion: Magnetic resonance imaging (MRI) investigations show that the disc is subject to a great variety of displacements and that there is a need for further research to refine the clinical therapy for TMJ internal derangements.     

High-resolution MR imaging of triangular fibrocartilage complex (TFCC): comparison of microscopy coils and a conventional small surface coil

Objective To compare MR images of the triangular fibrocartilage complex (TFCC) using microscopy coils with those using a conventional surface coil qualitatively and quantitatively.Design and patients Proton density-weighted images and T2*-weighted images of the TFCC from ten normal volunteers were obtained with a conventional surface coil (C4 coil; 80 mm in diameter), a 47-mm microscopy surface coil and a 23-mm microscopy surface coil) at 1.5 T. Qualitative image analysis of MR images with three coils was performed by two radiologists who assigned one of five numerical scores (0, nonvisualization; 1, poor; 2, average; 3, good; 4, excellent) for five TFCC components, which were disc proper, triangular ligament, meniscus homologue, ulnotriquetral and ulnolunate ligament. Quantitative analysis included the signal-to-noise ratio (S/N) of the disc proper of TFCC, the lunate cartilage, the lunate bone and the contrast-noise-ratio (C/N) between articular cartilage and disc proper or bone marrow were measured.Results All structures show higher scores qualitatively on MR with microscopy coils than those with a C4 coil, and the difference was significant with the exception of the ulnolunate ligament. MR with microscopy coils showed significantly higher S/N values than those with a conventional surface coil (P<0.05 to P<0.001). T2*-weighted images using microscopy coils showed significantly higher cartilage-disc proper C/N and cartilage-bone marrow C/N (P<0.01 to P<0.001). On proton density-weighted images, the C/N between cartilage and disc proper with two microscopy coils was significantly higher (P<0.01) than that with a conventional coil.Conclusion High-resolution MR images of the normal wrist using microscopy coils were superior to those using a conventional surface coil qualitatively and quantitatively. High-resolution MR imaging with a microscopy coil would be a promising method to diagnose TFCC lesions.     

Temporomandibular joint: MR assessment of rotational and sideways disk displacements

The accuracy of coronal and sagittal magnetic resonance (MR) imaging was examined in the assessment of rotational and sideways displacements of the temporomandibular joint (TMJ) disk. Rotational disk displacement implies a combination of anterior and medial or lateral displacements, whereas sideways displacement implies pure medial or lateral displacement without an anterior component. Multiple 3-mm-thick coronal and sagittal MR images were obtained of 18 fresh TMJ autopsy specimens and compared with the observations in corresponding coronal cryosections. MR imaging correctly delineated the mediolateral position of the disk in 15 joints (83%) and incorrectly delineated it in three joints (17%). Osseous anatomy was correctly assessed in 17 joints (94%). On cryosections, six joints (33%) showed medial disk displacement and two joints (11%) showed lateral displacement. In five of these eight joints the medial or lateral displacement occurred in conjunction with an anterior displacement, that is, rotational displacement. Clinical MR imaging in 37 patients (61 joints with coronal images) showed medial or lateral disk displacement in 16 joints (26%). This study suggests that rotational and sideways displacements of the TMJ disk are an important aspect of internal derangement. The multiplanar capabilities of MR are suitable for an assessment of these abnormalities.     

High-resolution computed tomography of the osseous temporomandibular joint. Some normal and abnormal appearances

A standardized CT procedure for examination of the temporomandibular joint (TMJ) with axial and coronal scanning as well as reformatted coronal and sagittal sections, was performed on 32 adults. These included subjects with normal TMJ and patients suffering from muscular dysfunction/disc displacement, arthrosis or rheumatoid arthritis. Some normal CT appearances simulating disease were presented. Axial CT scanning appeared to be the most useful method for demonstrating osseous abnormalities of the TMJ. The diagnostic information was occasionally supplemented by the coronal scanning, which may be difficult to perform on patients with neck stiffness. Reformatted coronal or sagittal sections mostly confirmed TMJ abnormality and supplemented the findings at axial scans in about one third of the patients.     

Meniscal position on routine MR imaging of the knee

 Objective. To determine the prevalence of meniscal protrusion (i.e. location of the outer edge of a meniscus beyond the tibial articular surface), and to determine its relationship with internal derangement, joint effusion, and degenerative arthropathy. Design and patients. Sagittal and coronal MR images of 111 abnormal and 46 normal knees were evaluated for the presence of meniscal protrusion. We set 25% as the minimum amount of displacement considered abnormal because this was the smallest amount of displacement we could confidently discern. Presence of meniscal tear, anterior cruciate ligament (ACL) injury, joint effusion, or osteophytosis was also recorded. Results and conclusion. Normal examinations demonstrated protrusion of the medial meniscus in 6.5% of sagittal images and 15% of coronal images, and of the lateral meniscus in 2% and 13%, respectively. Fisher’s exact test demonstrated a statistically significant difference between the normal and abnormal groups for the medial meniscus on both sagittal (P<0.0001) and coronal (P=0.01) images, but not for the lateral meniscus in either plane (P>0.2). A protruding medial meniscus was associated with effusion and osteophytosis (P<0.05) but not with meniscal or ACL tear (P>0.1). Posterior protrusion of the lateral meniscus was only associated with ACL injury (P<0.0001); protruding anterior horns and bodies of lateral menisci were not associated with any of the four abnormalities. It is concluded that the medial meniscus may occasionally protrude more than 25% of its width, but protrusion is more often due to effusion and osteophytes. Protrusion of the posterior horn of the lateral meniscus is associated with ACL insufficiency, while protrusion of the body and anterior horn of the lateral meniscus is a normal variant.     

Correlation between temporomandibular joint morphology and disc displacement by MRI

Objectives:

The aim was to evaluate the morphology of the temporomandibular joint''s (TMJs) disc and condyle as well as its correlation with disc displacement, using MRI.

Methods:

190 TMJs were retrospectively analysed. The condyle morphology of each TMJ was evaluated by two observers using both axial and coronal views, as were their disc morphology and displacement, using sagittal view. Condyle morphology was classified as flat, convex, angled or rounded in the coronal sections and as anterior side flat/posterior side convex, biconvex, anterior side concave/posterior side convex, flat or biconcave in the axial view. Disc morphology was determined as biconcave, biplanar, biconvex, hemiconvex or folded. χ², Fisher exact and Bonferroni correction tests were used to evaluate the data. ANOVA followed by post hoc Tukey''s test was used to evaluate the interaction between age and disc displacement.

Results:

Anterior disc displacement with reduction; convex condyle morphology in the coronal view; anterior side concave/posterior side convex morphology in the axial view; and biconcave discs were found to be the most prevalent findings. An association was observed between disc morphology and disc displacement (p < 0.001). No correlation between condyle morphology and TMJ disc displacement was found (p = 0.291 for axial and p = 0.14 for coronal views).

Conclusions:

The results of this study suggest that TMJ disc morphology is associated with disc displacement.     

Association between high signal intensity in the posterior disc attachment seen on T2 weighted fat-suppressed images and temporomandibular joint pain

OBJECTIVES: We sought to determine whether high signal intensity in the posterior disc attachment (PDA) seen on T2 weighted fat-suppressed MRI is associated with temporomandibular joint (TMJ) pain and joint pathology. METHODS: This study was based on 283 TMJs of 177 patients (31 males and 146 females, mean age 32.7 years) with TMJ disorders showing anterior disc displacement. MRI evaluation included assessment of signal intensity in the PDA and TMJ status (disc displacement with reduction, disc displacement without reduction and disc displacement with bone changes). Clinical criteria that were considered positive indicators of TMJ pain included the presence of pre-auricular pain during palpation, jaw function and assisted or unassisted mandibular opening. Association of signal intensity in the PDA with joint pain and TMJ status was analysed using chi2 test. RESULTS: Joint pain was reported in 47 (77.0%) out of 61 joints with high signal intensity in the PDA and in 97 (43.7%) out of 222 joints with low signal intensity in the PDA (P<0.0001). High signal intensity in the PDA correlated closely with more advanced joint pathology. In joints with anterior disc displacement with bone changes, TMJ pain was more commonly reported in joints with high signal intensity in the PDA than with low signal intensity in the PDA (P<0.0001). CONCLUSIONS: High signal intensity in the PDA on T2 weighted fat-suppressed MRI is associated with TMJ pain in TMJ disorders with anterior disc displacement with bone changes in the mandibular condyles.     

The effects of defect size, orientation, and location on subchondral bone contact in oval-shaped experimental articular cartilage defects in a bovine knee model

Purpose

Chondral defects of the knee may lead to pain and disability, often requiring surgical intervention. The purpose of this study was to identify how size, location, and orientation influences subchondral bone contact within oval-shaped chondral defects.

Methods

Full-thickness defects were created in twelve bovine knees. Defect orientation was randomized between coronal and sagittal planes on both the medial and lateral femoral condyles (MFC and LFC). In extension, knees were statically loaded to 1,000 N. Area measurements were recorded using Tekscan sensors and I-Scan software. A MATLAB program computed defect area and the area within the defect demonstrating subchondral bone contact.

Results

Defect area, location, and orientation each had a significant effect on subchondral bone contact (p < 0.001), and significant interactions were found between defect area and both location and orientation. The size threshold (cm²) at which significant contact occurred on the subchondral bone within the defect was smallest for LFC/coronal defects (0.73 cm²), then LFC/sagittal (1.14 cm²), then MFC/coronal (1.61 cm²), and then MFC/sagittal (no threshold reached).

Conclusions

Intra-articular location and orientation of a femoral condyle chondral defect, in addition to area, significantly influence femoral subchondral bone contact within the defect and the threshold at which subchondral bone contact occurs within the defect. The parameters of defect location and shape orientation supplement current surgical algorithms to manage knee articular cartilage surgery. This may indicate different cartilage restorative procedures based on the effect on the subchondral bone from the defect geometry itself and the selected cartilage surgery.     

Usefulness of cone beam computed tomography in temporomandibular joints with soft tissue pathology

Objective

The aim of the study was to evaluate the usefulness of cone beam CT (CBCT) in temporomandibular joints (TMJs) with soft tissue pathology.

Methods

106 TMJs of 55 patients with temporomandibular disorder (TMD) were examined by MRI and CBCT. MR images were used for the evaluation of disc displacement, disc deformity, joint effusion and obscurity of temporal posterior attachment (TPA). CBCT images were evaluated for the presence or absence of osseous abnormalities. The χ² test was used to analyse the association between MRI and CBCT findings.

Results

MRI of 106 TMJs revealed disc displacement, disc deformity, joint effusion and obscurity of the TPA in 68, 73, 28 and 27 joints, respectively. Of the 68 TMJs with disc displacement, anterior disc displacement without reduction (ADDWR) was seen most frequently (47/68). CBCT imaging found 65 TMJs were characterized by the presence of osseous abnormalities and were significantly associated with disc deformity and ADDWR (P < 0.05). There was no statistically significant association between the presence of joint effusion and obscurity of TPA and TMJ osseous abnormalities.

Conclusions

TMD patients with confirmed ADDWR or disc deformity on MRI are at risk of having osseous abnormalities in the TMJ and further examination with CBCT is recommended.     

High-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T: comparison of surface coil and volume coil

PURPOSE: To evaluate high-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T using a surface coil (SC) or volume coil (VC). MATERIALS AND METHODS: MRI was obtained from nine volunteers in the supine position with a 3-inch SC and in prone position with a transmit-receiver wrist VC at 3 T. Coronal two-dimensional-gradient echo (2D-GRE) images (TR/TE/FA = 500 msec/15 msec/40 degrees , 1 mm slice-thickness, 60 mm field of view [FOV], 192 x 256 matrix) and coronal 3D-GRE images (TR/TE/FA = 33 msec/15 msec/10 degrees , 0.8 mm slice-thickness, 80 mm FOV, 256 x 256 matrix) were used. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the TFCC and surrounding structures were measured. For qualitative measurement, visualization of TFCC and intercarpal ligaments was graded. RESULTS: SNR of TFCC, cartilage, and bone marrow on 2D-GRE with SC/VC was as follows: 5.3/5.3 (TFCC), 16.5/14.4 (cartilage), and 3.61/3.96 (bone marrow). 3D-GRE showed similar SNR. Cartilage-TFCC/cartilage-bone marrow CNR were 11.1/12.8 (SC-2D-GRE), 8.8/10.5 (VC-2D-GRE), 14.1/15.5 (SC-3D-GRE), and 11.9/15.0 (VC-3D-GRE). Quantitative values were not significantly different between SC and VC. Visualization of TFCC and intercarpal ligament with SC was superior to that with VC. All structures show higher scores with 3D-GRE imaging compared to 2D-GRE imaging. CONCLUSION: SC may provide superior qualitative and quantitative results and can be an alternative in case of difficulty in prone position at 3T.     

MRI evaluation of TMJ internal derangement: Degree of anterior disc displacement correlated with other TMJ soft tissue and osseous abnormalities

Objective

To evaluate the relationship between anterior disc displacement (ADD) degree and other temporomandibular joint (TMJ) soft tissues and osseous abnormalities in symptomatic TMJ dysfunction based on magnetic resonance imaging findings.

Patients and methods

MR images of 106 TMJs in 53 patients, presented with symptomatic TMJ dysfunction were included. Degree of ADD was detected and its relationship to joint effusion, retrodiscal layer integrity, thickness of lateral pterygoid muscle (LPM) attachments, degenerative changes and condylar position and translation as well as clinical manifestations was studied.

Results

Compared with normal disc position, risk of joint effusion and degenerative changes were significantly increased with increased degree of ADD (p < 0.05). LPM attachment thickening and retrodiscal layer abnormalities are significantly associated with an advanced degree of ADD (p < 0.05). Risk of ADD is significantly increased with posterior position of the condyle within the fossa.

Conclusion

There is a direct relationship between the ADD degree and other TMJ soft tissues and bone abnormalities as well as the severity of clinical manifestations, so early MRI detection and reporting of ADD degree and other MRI findings might help clinicians in full assessment and determining strategy of management of TMJ dysfunction.     

Web-based calibration of observers using MRI of the temporomandibular joint

Objectives

Research diagnostic criteria for temporomandibular disorders (RDC/TMDs) were proposed in 1992 with the aim of standardizing and testing methods for diagnosing TMDs. RDC/TMDs have so far been lacking standardized methods for imaging and criteria for imaging diagnosis of disorders of the temporomandibular joint (TMJ). Criteria for disorders of the TMJ have recently been proposed for MRI. The aim of this study was to publish MR images of the TMJ on the web and to test the agreement of five observers using the criteria.

Methods

20 cases of MRI of the TMJ were published on the web together with the criteria. The MR images were taken in closed and open mouth positions, and sagittal and coronal views. Five observers diagnosed disc position, disc shape, joint effusion and loose calcified bodies in the TMJ.

Results

In all cases except one, three or more observers agreed upon the diagnosis. All agreed on whether a loose calcified body was present or not. The second best agreement was obtained for disc position in the sagittal view, where all observers agreed in 16 of the 20 cases. For disc position in the coronal view and the evaluation of the disc shape, observer agreement was lower.

Conclusion

Criteria were useful in order to standardize and simplify evaluation and thereby probably increase the diagnostic outcome among different observers for MRI of the TMJ. We recommend that the criteria be used internationally to facilitate comparisons between different studies.     

Subtle pathology detection with multidetector row coronal and sagittal CT reformations in acute head trauma

We sought to analyze retrospectively the advantages of coronal and sagittal reformations obtained with multidetector row computed tomography (CT) in patients with acute head trauma. Multidetector 16-section CT was performed in 200 patients (110 male and 90 female; age range, 3–87 years; mean age, 45 years) with acute head trauma. Scans were performed sequentially, and axial 5-mm-thick slices were obtained from base of skull to vertex. The source data set was reformatted in coronal and sagittal planes, with 2-mm-thick sections at 2-mm intervals. Images were analyzed retrospectively by two independent, blinded readers. The final diagnosis was determined by clinical follow-up. CT imaging abnormalities were detected in 55 out of 200 patients who were scanned for head trauma. Acute traumatic intracranial abnormality was detected on axial scans in 45 patients. Subtle findings were confirmed on coronal and sagittal CT reformations in ten cases, and these were undetected initially on axial CT. Coronal and sagittal reformations confirmed subtle findings in 18.2% (10/55) of the cases (P = 0.001). Indeterminate neuroimaging findings confirmed by coronal and sagittal CT head reformations include tentorial and interhemispheric fissure subdural hemorrhage, subarachnoid hemorrhage, and inferior frontal and temporal lobe contusions. Coronal and sagittal CT head reformations improve the sensitivity and diagnostic confidence in the clinical setting of acute trauma. Overall, coronal and sagittal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal structures and in the diagnosis of acute abnormality.     

Changes in condylar mobility and radiographic alterations after treatment in patients with non-reducing disc displacement of the temporomandibular joint

OBJECTIVES: The purpose of this study was to examine changes in condylar mobility and morphological changes in the affected condyles after treatment in patients with non-reducing disc displacement of the temporomandibular joint (TMJ). METHODS: Changes in condylar mobility and morphological changes of the condyle were examined radiographically in 55 patients who were diagnosed as having non-reducing disc displacement of the unilateral TMJ and had received pumping with injection of sodium hyaluronate. In all patients, standardized lateral oblique transcranial radiographs and panoramic jaw tomograms were taken both at initial visit and at 12 months or more follow-up (mean 28.1 months after treatment; range 12-104 months). 42 joints in 21 persons with no current or previous TMJ symptoms served as a control. RESULTS: Clinical signs and symptoms improved after treatment in the patients. Condylar mobility significantly increased after treatment in patients (P<0.001), although it did not reach levels of the control group. Frequency of radiographic changes of the condyle significantly increased after treatment (P<0.005). In most of the patients, no or only mild changes were observed. Frequency of changes of the condyle in patients at follow-up was significantly greater than that in controls (P<0.001). CONCLUSIONS: In the patients, condylar mobility increased in the subsequent course after treatment. However, bony changes of the condyle appeared more frequently. Long term-follow-up after treatment on bony changes of the condyle seems to be necessary in patients with non-reducing disc displacement of the TMJ.     

Knee joint hyaline cartilage defects: a comparative study of MR and anatomic sections.

The value of routinely used MR sequences in the detection of focal changes of femorotibial articular cartilage was studied. T1-weighted, proton density, and T2-weighted SE as well as gradient echo images were acquired in 20 cadaveric knees (56-88 years old, mean 73.8 years). Three hundred five coronal and sagittal (3 mm) anatomic sections were prepared, and 82 areas of cartilage defects were identified. Initially, in an unblinded fashion, correlation of MR scans and anatomic sections was performed. Fifty-nine lesions (72.0%) were detectable on T1-weighted images, 57 (70.0%) with meniscal windowing, 49 (60.0%) on proton density images, 56 (68.3%) on T2-weighted images, and 54 (65.9%) on gradient echo images. Sixty-eight (83.0%) were visible on at least one type of imaging sequence. Most defects presented as a focus of abnormal signal. Subsequently, images of a subset of 35 pathologic and 35 normal cartilage surfaces were blindly evaluated by two osteoradiology fellows. Sensitivity was 71.4% for the detection of focal cartilage changes, specificity was 68.6%, and accuracy was 70.0%. We conclude that the value of those MR sequences that are routinely used in the analysis of internal derangements of the knee in the detection of focal defects of the hyaline cartilage is limited.     

Coronal radiographs and videofluoroscopy improve the diagnostic quality of temporomandibular joint arthrography

Detection of mediolateral displacement of the temporomandibular joint (TMJ) meniscus and evaluation of the reducibility of this displacement are necessary because surgery is indicated when the displacement is irreducible. During TMJ arthrography, the routine sagittal study does not allow detection of this type of meniscal displacement. In a prospective study of 158 TMJ arthrograms in 83 patients, coronal radiographs were obtained and videofluoroscopy was performed (in addition to routine sagittal films and fluoroscopy) to detect mediolateral shift of the meniscus and to evaluate the reducibility of this displacement. Both upper and lower joint spaces were opacified. Coronal and lateral radiographs were obtained with the mouth open and closed. On coronal images, in 79 cases (50%) the meniscus was shifted medially, in 22 cases (14%) laterally, and in 57 cases (36%) it was in the normal position. In 90 (89%) of the 101 abnormal cases, anterior displacement was associated with a mediolateral shift. In 59 cases (58%), the mediolateral shift was irreducible. Coronal and lateral views and fluoroscopy were reviewed separately by two observers, whose conclusions were identical for all cases. In 32 (54%) of the 59 joints with irreducible mediolateral displacement, surgery was performed. For all of these, comparison of radiologic data with surgical findings indicated that coronal views and videofluoroscopy were diagnostic, whereas mediolateral displacements were not detectable on routine sagittal studies.     

New scans from old: digital reformatting knee MRI

Purpose: To determine the accuracy of cartilage volume and bone areas measured from a 3D knee MRI sequence reformatted in different planes.Methods: MRI of 16 adult subjects (9 females, 7 males, age range 45–68 years) were acquired in the sagittal plane using a 3D T1-weighted fat suppressed spoiled gradient echo sequence. Medial and lateral tibial cartilage volumes were determined by processing images acquired in the sagittal plane and from the same image data reformatted in the coronal plane. Tibial plateau areas were determined by processing images acquired in the sagittal plane and reformatted in the axial plane.Results: Cartilage volumes calculated from the original sagittal acquisition and data reformatted into the coronal plane were similar. The average over- or under-estimation of the lateral and medial cartilage volume from the reformatted coronal scans compared to the sagittal sequences was 4.6% and 9.8% respectively. Similar medial and lateral tibial plateau areas were obtained when the sagittal data was reformatted in the axial plane. The average over- and under-estimate of lateral and medial tibial plateau areas from the reformatted axial scans compared to the originally acquired sagittal sequences was 6.5% and 6.8% respectively.Conclusion: Knee data acquired via MRI in one plane can be reformatted into different planes, providing comparable cartilage volumes and bone areas. As different planes through the knee may provide better visualization of different joint structures, this method may be useful clinically and as a research tool, while avoiding the cost associated with the prolonged scanning times associated with acquiring multiple planes.