자기공명영상검사에서 치과 교정용 금속 물질에 의한 인공물(Artifact)의 영향을 평가하기 위해 치과 교정에 사용되는 와이어(Wire)와 브라켓(Bracket)을 재질별로 선택하여 비교 연구하였다. 치과 금속을 넣은 사각 아크릴 용기는 $200{\times}135{\times}120mm$ 크기이며, 영상을 얻기 위하여 두부 코일을 사용하여 $T_2$강조영상, $T_1$강조영상, FLAIR영상을 획득하였다. 획득된 시퀀스별 자기공명영상의 인공물을 평가하기 위하여 Image J 프로그램을 사용하여 인공물의 면적을 측정 비교하였다. 연구에서 치과 교정용 와이어와 브라켓의 인공물이 가장 큰 물질은 Stainless steel로 나타났다. 현재까지는 치과 교정에서 교정을 목적에 두고 금속 물질을 선택하였으나 치과 교정용 금속은 환자의 기능과 미의 특성뿐 아니라 자기공명영상 인공물 생성 여부도 함께 고려해야 한다. 추후 교정용 금속의 선택 및 개발 발전은 치아교정의 목적과 더불어 다른 분야도 고려해야 할 것으로 사료된다.
자기공명영상검사에서 치과 교정용 금속 물질에 의한 인공물(Artifact)의 영향을 평가하기 위해 치과 교정에 사용되는 와이어(Wire)와 브라켓(Bracket)을 재질별로 선택하여 비교 연구하였다. 치과 금속을 넣은 사각 아크릴 용기는 $200{\times}135{\times}120mm$ 크기이며, 영상을 얻기 위하여 두부 코일을 사용하여 $T_2$강조영상, $T_1$강조영상, FLAIR영상을 획득하였다. 획득된 시퀀스별 자기공명영상의 인공물을 평가하기 위하여 Image J 프로그램을 사용하여 인공물의 면적을 측정 비교하였다. 연구에서 치과 교정용 와이어와 브라켓의 인공물이 가장 큰 물질은 Stainless steel로 나타났다. 현재까지는 치과 교정에서 교정을 목적에 두고 금속 물질을 선택하였으나 치과 교정용 금속은 환자의 기능과 미의 특성뿐 아니라 자기공명영상 인공물 생성 여부도 함께 고려해야 한다. 추후 교정용 금속의 선택 및 개발 발전은 치아교정의 목적과 더불어 다른 분야도 고려해야 할 것으로 사료된다.
To evaluate the effects of an artifact by metal material for orthodontics in Magnetic Resonance Image (MRI) examination, wires and brackets used in orthodontics were selected and compared. Using a head coil, a $T_2$-weighted image, $T_1$-weighted image and FLAIR image were obta...
To evaluate the effects of an artifact by metal material for orthodontics in Magnetic Resonance Image (MRI) examination, wires and brackets used in orthodontics were selected and compared. Using a head coil, a $T_2$-weighted image, $T_1$-weighted image and FLAIR image were obtained. With obtained images, the sizes of the artifacts were measured and compared using Image J Program. In the research, the material with the biggest artifact in the wires and brackets for orthodontics was stainless steel wire. In the future, selecting and developing metal for correction should be considered also in other fields along with the purpose of orthodontics.
To evaluate the effects of an artifact by metal material for orthodontics in Magnetic Resonance Image (MRI) examination, wires and brackets used in orthodontics were selected and compared. Using a head coil, a $T_2$-weighted image, $T_1$-weighted image and FLAIR image were obtained. With obtained images, the sizes of the artifacts were measured and compared using Image J Program. In the research, the material with the biggest artifact in the wires and brackets for orthodontics was stainless steel wire. In the future, selecting and developing metal for correction should be considered also in other fields along with the purpose of orthodontics.
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제안 방법
In consideration of the effects of dental metal materials on the head and neck during an MRI, using a head coil, 3 different types of sequence imaging were obtained: T2 weighted imaging (TR 4,990msec, TE 115 msec, flip angle 150°, FOV 190㎜, matrix size 202×256), T1 weighted imaging (TR 443 msec, TE 14 msec, flip angle 90°, FOV 190㎜, matrix size 202×256), Flair (TR 7,900 msec, TE 109 msec, flip angle 150°, FOV 190㎜, matrix size 202×256) (Table 2).
0T). The wires and brackets were put in a square plastic container filled with MRI phantom solution to carry out an MRI examination. The square container used was an acrylic container with a 5-mm-thick cover (200 x 135 x 120 mm3).
Dental wires vary in size and type according to the degree and period of correction. Therefore, the commercialized wires used in the experiment were categorized into composing materials regardless of the maker and the size of the cross-sectional area variation. For the quantitative evaluation of dental wire distortion width in the MRI, the wires used were cut into 10-mm lengths.
) cause distortions. Therefore, this study attempted to investigate the conditions of dental orthodontic fixtures required for MR tests under an assumption that the degree of artifacts could be minimized by dental orthodontic fixtures such as wires and brackets and their materials.
대상 데이터
The biggest reason for the artifacts is metal retainers in dental materials in MRI. In this study, the material with the greatest artifacts in the wires and brackets for orthodontics turned out to be stainless steel alloy. Yet, the most preferred material is stainless steel alloy for metals in orthodontics.
These artifacts cause damage and risk by magnetism in regard to the information about images in most areas around the metal devices. The biggest reason for the artifacts is metal retainers in dental materials in MRI. In this study, the material with the greatest artifacts in the wires and brackets for orthodontics turned out to be stainless steel alloy.
The wires and brackets were put in a square plastic container filled with MRI phantom solution to carry out an MRI examination. The square container used was an acrylic container with a 5-mm-thick cover (200 x 135 x 120 mm3). The experiment was conducted with the wire at 35-mm height from the center.
This study investigated the image artifacts of the wires and brackets using an MRI device (Siemens 1.0T). The wires and brackets were put in a square plastic container filled with MRI phantom solution to carry out an MRI examination.
Orthodontic metal materials can be categorized into wires and brackets, and dental metal materials commercialized for medical purposes have different shape, size, and compositions according to each method, purpose, and time. To evaluate the effects of dental orthodontic fixtures on artifacts in MRI, five types of dental wire and three types of dental brackets currently used in the course of treatment in dental clinics were selected (Table1).
성능/효과
09㎟. The areas measured in the images were expanded by 17.17x for FLAIR imaging, 18.17x for T1 weighted imaging, and 17.63x for T2 weighted imaging, compared to the actually measured cross-sectional area of 12.31㎟ (Table 3).
60㎟. The areas measured in the images were expanded by 221.54x for FLAIR imaging, 286.41x for T1 weighted imaging, and 248.90x for T2 weighted imaging, compared to the actually measured cross-sectional area of 8.79㎟ (Table 3).
05㎟. The areas measured in the images were expanded by 96.05x for FLAIR imaging, 97.51x for T1 weighted imaging, and 96.08x for T2 weighted imaging, compared to the actually measured cross-sectional area of 1.30㎟ (Table 3).
For these reasons, and because of the strength of titanium, the material is used widely as a dental material. this study, it was also confirmed that titanium alloy showed less distortion compared to other metals, and of the 3 sequences, the Flair imaging showed the least distortion. Therefore, nickel titanium wire has the least distortion among the currently used materials in orthodontic wires, and for the brackets, composite brackets showed the least distortion.
후속연구
Radiologists and MRI examiners should be aware of the effects of orthodontic devices in MRI on the head and neck and their impacts on the images. Therefore, it is expected that the results of this study will be used for MRI examination and image diagnosis of patients who were treated with the wires and brackets for orthodontics.
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