RU2673992C1 - Method for estimating dysfunction of temporomandibular joints by means of magnetic resonance imaging in real-time - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to dentistry, and can be used in assessing dysfunction of the temporomandibular joints (TMJ) using magnetic resonance imaging (MRI). To do this, MRI is performed on a device with a magnetic induction of 1.5 T with a standard 16-channel matrix receiving-transmitting coil for the head. T1-weighted images (T1WI) and T2-weighted images (T2WI) are obtained with the mouth open and closed. After a static scan protocol in the closed mouth position, an assessment of the lateral displacement of the intra-articular disc is performed, for which an oblique coronal T2BI is performed, which is positioned parallel to the mandible branch and perpendicular to the meniscus. Then a study is performed with the mouth open, fixing the patient's jaw with the help of a dental bite retractor. Dental bite rotator is a plastic device in the shape of a parallelepiped, the sides of which are represented by flattened platforms for fixing teeth. Selection of the desired length of the device is made before the study based on the degree of mouth opening by the patient. In the process of studying with an open mouth to obtain T2VI, the patient divides the movement from the full opening to the complete closing of the mouth into twenty parts: 10 at the opening and 10 at the closing, the patient performs all movements independently, without instructions from the operator, using the tomograph sounds for the determination of the duration of each movement, corresponding to the duration of each movement less than a second. Total time of scanning in conditions of natural movements with a full opening and then closing the mouth to one joint is up to 10 seconds.

EFFECT: method provides simultaneous visualization of all structures of the TMJ, including the condyle and meniscus, in real time, which allows to obtain an accurate description of the location of the anatomical structures and their relationship with each other during natural chewing.

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Description

The invention relates to medicine, namely to dentistry.

Diseases of the temporomandibular joints (TMJ) are widespread and occur in 25-65% of the population [Hasan MA, Abdelrahman T.E.F. MRI evaluation of TMJ internal derangement: Degree of anterior disc displacement correlated with other TMJ soft tissue and osseous abnormalities. The Egyptian Journal of Radiology and Nuclear Medicine, 2014; 45 (3): 735-744; Yaremenko A.I., Korolev V.O. Minimally invasive surgical techniques for treating diseases of the temporomandibular joint. Review of scientific literature. Bulletin of Novgorod State University 2015; 2 (85): 93-95]. Dysfunction of these joints is the most common condition among this group of disorders and accounts for about 80-90% of the total number of patients [Devaraj S.D., Pradeep D. Internal Derangement of Temporomandibular Joint - a review IOSR. Journal of Dental and Medical Sciences. 2014; 13 (3): 66-73]. Most often, the lesion is characterized by the presence of pain in the joint extending to the area of the eyes and temple, which can be aggravated by wide open mouths and lead to reflex spasm of the masticatory muscles.

TMJ dysfunction is understood to mean a change in the position and shape of the intraarticular disk (meniscus). Objective visualization of joint structures is performed using a number of different research methods. However, the most informative technology is magnetic resonance imaging (MRI). Determining the position of the intraarticular disc during chewing movements allows you to determine the degree of joint dysfunction, which increases the effectiveness of the treatment.

A known method of visualizing the position of the disk using static and dynamic MRI performed using a surface two-sided coil for the study of TMJ (Farghally M.A., Hassan M.A., Barakat KI The accuracy of dynamic Magnetic Resonance Imaging in evaluation of internal derangement of the temporomandibular joint; comparison with arthroscopic findings. The Egyptian Journal of Radiology and Nuclear Medicine Volume 43, Issue 3, September 2012, Pages 429-436 - prototype). The static protocol includes sagittal T1 weighted images (VI), T2VI in the open and closed mouth position. Dynamic research is carried out to obtain images weighted by proton density (PD). The first tomograms are obtained in the closed mouth position, then one block of a special rotary expander 2 mm thick is installed in the premolar-molar region and scanning is performed. Then add two similar blocks, matching each other as a key to the lock, for a gradual maximum opening of the mouth. After each manipulation, a scan is performed. Subsequently, the blocks of the conservator in the reverse order are removed until complete occlusion. The resulting images are loaded into a special program that allows you to view tomograms in CINE mode. Such a study seems to be effective for assessing the position of the disc at various moments of the opening of the mouth, however, it does not show the synchronous movement of the condyle and meniscus in real time and requires considerable duration for obtaining images and subsequent post-processing processing. In addition, the use of a special coil for the TMJ narrows the range of tomographs used, since not all devices are equipped with such additional equipment.

Dynamic research is also known to produce ultrafast T1VI (Beer A, Kolk A, Neff A, Hof N, Treumann T, Rummeny EJ. Cine-MRT des Kiefergelenks im Vergleich zurconellenlen MRT und Achsiographie. RoFo 2004; 176: 506-512) . The examination is carried out using a special surface coil for TMJ. Three tomograms are performed for each movement of the patient’s jaw in 12 seconds, which eliminates the need for rotary expanders. However, the choice of the pulse sequence, the slice thickness and the size of the matrix correspond to poor image quality with poor differentiation of the surrounding soft tissue structures, as well as a significant amount of time spent on a full mouth opening and closing cycle.

It is known to conduct a real-time study on volunteers using an apparatus with magnetic field induction of 3 T and using a surface coil for TMJ to obtain a FLASH pulse sequence in 50 seconds for each joint [Shuo Z., Gersdorff N., Frahm J. Real-Time Magnetic Resonance Imaging of Temporomandibular Joint Dynamics. The Open Medical Imaging Journal, 2011, 5: 1-9]. Such a study allows obtaining high-resolution images, however, the use of the FLASH sequence does not provide high differentiation of tissues, as well as the structures of the bilaminar zone. In addition, a small number of medical institutions are equipped with similar high-tech tomographs.

The technical problem that we were solving was real-time imaging with the synchronous movement of the condyle and meniscus.

Achievable technical result is the simultaneous visualization of all structures of the TMJ (including the condyle and meniscus) in real time, which allows to obtain an accurate description of the location of the anatomical structures and their relationship to each other during natural chewing.

The accuracy of the obtained research results is also due to the obtained T2VI, which have high spatial resolution and excellent differentiation of soft tissues.

The resulting images represent the sequence of motion of the condyle and disc for 10 seconds, which is comparable to the act of natural chewing.

Real-time MRI allows you to evaluate the relative position of intraarticular structures, the synchronism or impaired movement of the condyle and disc.

The developed technique allows you to clearly determine the configuration of the intraarticular disk with obtaining objective data on its movement at all stages of the active movement of the jaw, which in turn allows you to make a correct conclusion about the degree of joint dysfunction.

These aspects of the technical result are achieved through the implementation of the following set of essential features:

Get T1-weighted images (T1VI) and T2-weighted images (T2 VI) with open and closed mouth. Moreover, after the static scanning protocol in the closed mouth position, the lateral displacement of the intraarticular disk is assessed, for which an oblique-coronal T2VI is additionally performed, which is positioned parallel to the branches of the lower jaw and perpendicular to the meniscus. Then, an open-mouth study is performed, fixing the patient’s jaw with a dental bite expander. The dental bite expander is a plastic device in the shape of a parallelepiped, the sides of which are represented by flattened areas for fixing teeth. The selection of the desired length of the device is carried out before the study based on the degree of opening of the patient’s mouth. In the process of an open-mouth study with obtaining T2VI, the patient divides the movement from full opening to complete closing of the mouth into twenty parts: 10 for opening and 10 for closing, while the patient makes all movements independently, without operator's instructions, using sounds to determine the duration of each movement the work of the tomograph corresponding to the duration of each movement is less than a second. The total scan time in natural movements with full opening and then closing the mouth on one joint is up to 10 seconds.

In this case, MRI is performed on a device with a magnetic field induction of 1.5 T, with a standard matrix 16-channel transmitter-receiver coil for the head.

The method is as follows.

Magnetic resonance imaging is performed on an apparatus with a magnetic field induction of 1.5 T. The study does not require special preliminary preparation of the patient. The procedure is carried out using a standard matrix 16-channel transceiver coil for the head. Laying the patient in a supine position, centering the laser beam on the nose bridge.

The examination begins with obtaining locators in three mutually perpendicular planes. The static scanning protocol in the closed mouth position includes T2VI marking in the axial and coronal planes.

Sagittal T2VI positioning is performed according to the obtained tomograms parallel to the lower jaw branch. Similarly, marking T1VI.

To assess the lateral displacement of the intraarticular disk, an oblique-coronal T2VI is performed, which is positioned parallel to the branches of the lower jaw and perpendicular to the meniscus.

To conduct an open-mouth study, dental bite rotary expanders are used, which are plastic devices in the shape of a parallelepiped, the sides are represented by flattened areas for fixing teeth. The selection of the desired device length is made before the study based on the degree of opening of the patient's mouth. Thanks to the bite rotary expander, it is possible to easily fix the jaw in the open state. The scanning protocol is similar to a closed-mouth study.

Real-time evaluation of the position of the disk is carried out to obtain T2VI, which has both high spatial resolution and excellent differentiation of the surrounding soft tissue structures.

The patient is invited to divide the movement from full opening to complete closing of the mouth into twenty parts: 10 for opening and the same amount for closing. Less than a second is allocated for each movement, which corresponds to the loud sound of the tomograph during scanning. That is, the patient makes all the movements on his own, without instructions from the operator, focusing on the work of the tomograph.

Thus, the total scan time with full opening and then closing the mouth on one joint takes up to 10 seconds. This allows you to evaluate the movement of the articular condyle and disc in conditions of natural movements.

Example No. 1

A 40-year-old patient came to the clinic complaining of pain in both TMJs during chewing, as well as a feeling of jamming in the joints.

When conducting an MRI, a displacement of both articular discs in the frontal plane, a change in their shape in the form of a rectangle, and also diffuse changes in the structure were detected. When examining with an open mouth, the right intraarticular disk appears to be wedge-shaped, the left retained a rectangular shape. Evaluation of images in real time allowed us to determine the almost complete immobility of the menisci during movements and the limited displacement of the articular heads of the condyles. Such changes are characteristic of subluxation of both articular discs without reduction.

Example No. 2

A 27-year-old patient came to the clinic complaining of pain in the area of the right TMJ while chewing, as well as the feeling of a “click” on the right. When conducting an MRI, a ventral displacement of the right articular disc in the sagittal plane in the position of habitual occlusion, a deformation of the meniscus shape in the form of a rectangle, was found. The left intraarticular disk had a physiological position, however, an irregular rectangular shape. In an open-mouth study, both menisci were determined at the apex of the articular processes. In real time, the correct movement of the articular condyles was noted, the movement of the articular discs synchronously behind the articular head was monitored. Such changes are characteristic of subluxation of the right articular disc with reduction.

Claims (2)

1. A method for assessing dysfunction of the temporomandibular joints (TMJ) using magnetic resonance imaging (MRI) in real time, including obtaining T1-weighted images (T1VI) and T2-weighted images (T2VI) with open and closed mouth, characterized the fact that after the static scanning protocol in the closed mouth position, the lateral displacement of the intraarticular disk is assessed, for which an oblique-coronal T2VI is additionally performed, which is positioned parallel to the branches of the lower jaw and perpendicular to the sku, then conduct an open-mouth study, fixing the patient’s jaw with a dental bite expander, which is a plastic device in the form of a parallelepiped, the sides of which are represented by flattened areas for fixing the teeth, and the selection of the desired length of the device is carried out before the study, based on the degree of disclosure the patient’s mouth, in the open-mouth study with T2VI, the patient divides the movement from full opening to complete closing of the mouth into two there are ten parts: 10 for opening and 10 for closing, and the patient makes all movements independently, without instructions from the operator, using the sound of the tomograph to determine the duration of each movement, the corresponding duration of each movement is less than a second, the total scanning time under natural movements with full opening and then closing the mouth on one joint is up to 10 s. 2. The method according to p. 1, characterized in that the MRI is performed on a device with a magnetic field induction of 1.5 T, with a standard matrix 16-channel transmitter-receiver coil for the head.