Optimal Contrast of Imaging Characteristics for 4 Dimensional MRI of the Temporomandibular Joint by Examining the Signal Intensity
Namrath ChatchaiyanKaoru KoideMakoto TsuchimochiHajime TanjiEiichiro AsanoHironobu IshiiToshihide SatoMami IshiiA KondoKeishi Ohta
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The purpose of this study was to achieve optimal contrast of imaging characteristics in 4 dimensional MR images of the temporomandibular joint (TMJ) for evaluating the TMJ structures during mandibular movement. Twelve TMJs from six subjects without any TMJ dysfunction were studied. MRI was performed using a 1.5 MR system with an eight-channel phased array coil. The images were acquired using a balanced steady-state free precession (b-SSFP) sequence. The optimal flip angle was determined for differentiation for the main anatomical structures of the TMJ; the posterior band of the articular disc, the retrodiscal tissues, the condylar head, and the lateral pterygoid muscle, by examining the signal intensity (SI-d) of TMJ structures on b-SSFP MR images obtained using various flip angles. Repeated measures two-way analysis of variance (ANOVA) was performed, followed by Bonferroni's multiple comparison analysis. The main anatomical structures of the TMJ had the highest SI-d at flip angles of 30 degrees and 40 degrees, and there were the most significant differences between the SI-d of the articular disc and all other structures at a flip angle of 40 degrees, followed by a flip angle of 30 degrees. These data suggest that a flip angle of approximately 30 degrees to 40 degrees is appropriate for obtaining the optimal contrast of imaging characteristics for 4 Dimensional MR images of the TMJ with b-SSFP sequence.Keywords:
Flip angle
Lateral pterygoid muscle
Intensity
Abstract From this review of the literature it appears that we may draw the following conclusions. The incidence of Class III malocclusions is at most 4.2% (Goose et al. 1957, Ast et al. 1965; Knowles 1966, Thylander and Myrberg 1973). The development of various condyle growth hypotheses have lead us to believe that the condyle behaves in a rather unique manner. The condyle does not appear to be an epiphysis, neither does it behave the same as the cranium. It is a unique cartilaginous structure that cannot grow against intermittent or continuous forces (Copray 1985). The cybernetic model as proposed by Petrovic and co workers (1977) that eloquently describes the condyle to be stimulated by a cybernetic switch that connects to the periodontal ligament also does not seem to have much validity. It appears that the lateral pterygoid muscle and the temporo-mandibular condylar frenum have been ascribed capabilities that do not comply to the results of condylotomy studies. Gorette-Nicaise, Awn, and Dhem (1983) as well as the study by Whetten, and Johnston (1985) have shown that neither the absence of the lateral pterygoid muscle nor the physical volumetric expansion of the airway increases condylar growth. It appears that increase in the pressure applied to the condyle could decrease condyle cell proliferation (Armstrong 1961; Thilander 1963; 1965: Janzen and Bluher 1965; Graber 1969; Petrovic 1972; Graber and Muller 1974; Graber 1975;) with resulting growth attenuation. Accordingly, condylar growth is controlled by physical restraint, the absence which leads to incremental growth. The presence of mechanical pressure of adequate duration and magnitude, thus, should limit growth of the young actively growing condyle.
Lateral pterygoid muscle
Epiphysis
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Abstract Objectives The purpose of this study was to investigate the condylar morphology and position of Koreans using cone-beam computed tomography (CBCT) images. Analyzing the mean values of this study with reference to left and right sides, gender, and age will help to understand the size of the condyle and glenoid fossa, condylar morphology, and temporomandibular joint (TMJ) symmetry for establishing the standard temporomandibular joint structures of Koreans and then design the standard temporomandibular joint prosthesis for Koreans. Results There was no significant result in the condyle size, condyle axis angle, joint space, fossa depth, and mandibular body size between the left and right sides ( p > 0.05). On the other hand, the mediolateral width of the condyle and mandibular body size show significantly different with the gender ( P < 0.05). Also, significant differences were found in condyle size, joint space, fossa depth, and mandibular body size according to age groups ( p < 0.05). Conclusions Condylar position and morphology vary according to side, age, and gender. The results of this study are expected to help in customizing a treatment for the patients who need TMJ reconstruction by predicting the TMJ morphology according to age and gender and design the standard temporomandibular joint prosthesis for the Koreans.
Fossa
Mandible (arthropod mouthpart)
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The aim of the present study was to investigate morphology of temporomandibular joint using cone beam computer tomography. Study included 45 adults (32 females and 13 males). Articular eminence inclination, glenoid fossa width, glenoid fossa depth, condylar mediolateral distance, condylar anteroposterior distance and condylar type were determined for each temporomandibular joint. Since independent samples t-test did not show significant differences between left and right sides for all of observed parameters (p≥0.05), left and right side values were treated as one sample. The determined glenoid fossa depth was 7.11±2.23, glenoid fossa width 19.22±2.58, condylar anteroposterior distance 7.54±1.59, condylar mediolateral distance 17.95±2.81 and articular eminence inclination was 34.59±7.35 degrees. Most of condyles were classified as convex type (32.5%), followed by flattened (23.8%), rounded (11.3%) and angled (10%). Undefined (other type) were classified 22.5% of condyles. Cone beam computer tomography measurements of temporomandibular joint bone structures in present study showed similarities to most of previous research (with different populations studied). Still, the prevalence of different condylar types differs from those obtained by most of previous studies. Interindividual differences in temporomandibular joint morphology are expected.
Fossa
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The purpose of this study was to achieve optimal contrast of imaging characteristics in 4 dimensional MR images of the temporomandibular joint (TMJ) for evaluating the TMJ structures during mandibular movement. Twelve TMJs from six subjects without any TMJ dysfunction were studied. MRI was performed using a 1.5 MR system with an eight-channel phased array coil. The images were acquired using a balanced steady-state free precession (b-SSFP) sequence. The optimal flip angle was determined for differentiation for the main anatomical structures of the TMJ; the posterior band of the articular disc, the retrodiscal tissues, the condylar head, and the lateral pterygoid muscle, by examining the signal intensity (SI-d) of TMJ structures on b-SSFP MR images obtained using various flip angles. Repeated measures two-way analysis of variance (ANOVA) was performed, followed by Bonferroni's multiple comparison analysis. The main anatomical structures of the TMJ had the highest SI-d at flip angles of 30 degrees and 40 degrees, and there were the most significant differences between the SI-d of the articular disc and all other structures at a flip angle of 40 degrees, followed by a flip angle of 30 degrees. These data suggest that a flip angle of approximately 30 degrees to 40 degrees is appropriate for obtaining the optimal contrast of imaging characteristics for 4 Dimensional MR images of the TMJ with b-SSFP sequence.
Flip angle
Lateral pterygoid muscle
Intensity
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Gas in the joint space was observed in three patients with condylar fracture who were referred for CT examinations of the mandible. CT showed that the condylar fractures were non-open fractures. The gas was only observed in the intrajoint capsule of the temporomandibular joint (TMJ). Follow-up CT, 4 days after the initial CT, showed that the gas in the joint space was absorbed in one of three cases. In the non-open condylar fractures, the gas collection in the TMJ was considered to be a vacuum phenomenon due to the intact joint capsule of the TMJ on CT.
Mandible (arthropod mouthpart)
Joint capsule
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Objective To examine whether they may further cause joint ankylosis lateral pterygoid muscles influence condyle morphology in healing process of sagittal fracture of mandibular condyles(SFMC).Methods Twelve healthy adult sheep were included in our study,and all animals were treated with surgery to make condyles fracture on right side of temporomandibular joint.The animals were randomly divided into two groups:the pterygoids of sheep in one group were cut and not able to function.The others in other group were not cut.They were still on internal poles of fractured condyles and their functions remained.We immediately examined whether pterygoid muscles were cut(or not) by MRI after operation.3D computed tomograms(CT) were taken 1,4,12 and 24 weeks after operation.Measure displacement of internal poles of fractured condyles,and changes in internal and external diameters of mandibular condyles.The sheep were put to death 4,12,and 24 weeks after operation.3D CT were taken then.After multiplanar reconstruction,measure related parameters about condyles so as to observe change of condyles.Results The CT scanning showed that changes in internal and external diameters of mandibular condyles were obviously different in two groups(P0.05),that internal poles of fractured condyles were distracted by pterygoid muscles and that influence on condyle morphology after sagittal fracture was more obvious in group where functions of lateral pterygoid were kept.Conclusions The building of this animal model proves that lateral pterygoid muscle does influence condyle morphology after sagittal fracture.This study provide research platform for study of the role of distraction osteogenesis of lateral pterygoid muscle in traumatic ankylosis of temporomandibular joint.
Lateral pterygoid muscle
Pterygoid Muscles
Ankylosis
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Temporomandibular joint (TMJ) is a unique joint. The dimension joint space is determined by the optimal Condylar position. Conventional radiographs cannot exactly show the relationship hence MRI and CT are being used frequently for imaging of TMJ. CBCT has recent advancement into technology especially in this field as helped to analyse the TMJ in more comphrehensive manner. The aim of this study is to assess the position of condyle in TMJ with patients of TMDs. The importance of relationship between condyle and glenoid fossa remains controversial. The CBCT utilizes less radiation and as higher resolution than normal CT. The position of condyle in the glenoid fossa is measured with high accuracy using CBCT technique for reconstruction and imaging of the TMJ. It provides reliable and accurate images. The study was designed to compare the condylar morphology in symptomatic and asymptomatic patients with TMD s.
Fossa
Position (finance)
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Lateral pterygoid muscle
Pterygoid Muscles
Fossa
Temporal muscle
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