• 치과방사선
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• 제20권2호
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• pp.187-198
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• 1990

Examinations of the temporomandibular joints were performed on a 1.5 Tesla magnetic resonance (MR) system. An MR surface receiver coil 3 inch in diameter was placed on plastic frame, the patient's head being placed in the frame so that the coil was pressed against the temporal region. In taking advantage of the magnetic resonance imaging that has been studied briskly till now, author obtained the images of parasagittal and paracoronal planes about the temporomandibular joint by using MPGR (Multi-Planar Gradient Recalled), GRASS (Gradient Recalled Acquisition in the Steady State), and CSMEMP (Contiguous Slice Multiple Echo, Multi-Planar), that differ from the Spin Echo pulse sequence which the previous authors used. Five subjects with no symptoms of temporomandibular joint pain and dysfunction were studied. The plane images obtained by these methods were compared with those by Spin Echo pulse sequence. The results were as follows: 1. The optimal repetition times (TR) and echo times (TE) for T.M.J. image were; a. 400 msec and 18 msec in PMGR pulse sequence. b. 40 msec and 12 msec in GRASS pulse sequence. c. 700 msec and 30 msec in CSMEMP pulse sequence. d. 500 msec and 20 msec in Spin Echo pulse sequence. 2. When the MPGR pulse sequence was using, T2-weighted image was obtained in very short time. On the image of the paracoronal plane by GRASS pulse sequence, meniscus showed the moderate signal intensity, and the meniscus and its anteromedial, posterolateral attachments were observed definitely with gray color. 4. The signal intensity of Spin Echo pulse sequence was equal to that of CSMEMP pulse sequence, but the image by CSMEMP pulse sequence showed relatively lower level in its resolution.

• 대한의용생체공학회:의공학회지
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• 제19권3호
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• pp.233-242
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• 1998

본 논문에서는 척추 자기공명영상에 대하여 자동적으로 질환에 관련된 특징 벡터들을 추출하고 디스크 질환을 인식하는 방법을 제안하였다. 척추 자기공명영상은 절단면에 따라 시상 단면 영상과 축 단면 영상으로 나누어 진다. 두가지 영상에서 질환에 관련된 특징 벡터를 추출하여 질환의 유무와 종류를 인식하는데 사용하였다. 시상 단면 영상에서는 각 부위에 해당하는 영역의 동질성을 이용하여 디스크 부분을 추출한 후 영역레이블링 과정을 통해 전체적인 크기와 돌출 정도를 구해서 질환을 나타내는 특징으로 이용하였다. 축 단면 영상에서는 템플릿 정합을 이용하여 디스크 영역을 찾고 경계선을 추출하기 위해 세기와 방향성을 고려한 연산자를 사용했다. 경계선의 모양을 분석해서 디스크 돌출 정도에 관한 수치를 얻었다. 이렇게 얻은 특징벡터들은 유사한 질환을 가진 환자의 영상을 찾기 위한 의료 영상 데이터 베이스에 사용될 수 있으며, 많은 양의 영상에서 질환이 나타나 있는 것을 일차적으로 선별하여 전문의에게 제공하는데 이용될 수 있을 것으로 예상한다.

• 한국방사선학회논문지
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• 제15권7호
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• pp.975-982
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• 2021

본 연구는 체내의 식도용 스텐트와 일플란트에 많이 사용되는 티타늄 성분의 금속성 물질을 사용하여 구리와 black metal, polyester로 구성된 머리카락 보다 가늘게 제작된 mesh로 시험관을 부분적으로 RF를 차폐하여 주변에 위치한 자기공명영상용 팬텀에 미치는 영향을 평가하고자 하였다. 3T Achieva X-series의 Cardiac Coil을 사용하여 TR 500 ms, TE 20 ms, NEX 1, slice thickness 5 mm의 Spin Echo T1강조영상에서 field of view(FOV)에 따른 자기공명영상을 분석하였다. FOV 304 mm × 304 mm에서는 발생하지 않았던 aliasing artifact가 발생하지 않았지만 250 mm × 250 mm 과 170 mm × 170 mm에서는 발생되었다. FOV 170 mm × 170 mm에서 mesh를 사용하지 않은 경우는 SNR이 78.23으로 가장 낮았으며, mesh를 가운데 세워 분리한 경우에는 215.05, mesh로 완전히 차폐한 경우에는 366.44로 높게 측정되었다. 또한 mesh로 완전히 감싸고 차폐한 경우에는 aliasing artifact도 제거되었고, 영상의 왼쪽과 가운데, 오른쪽의 신호 대 잡음비가 높으면서 다른 조건과 비교하여 균질한 영상을 획득할 수 있었다. 결론적으로 mesh로 RF를 부분적으로 감싸고 차단하면 aliasing artifact를 제거할 수 있고, 작은 FOV를 사용하여 영상의 해상도와 균질성이 우수한 자기공명영상을 획득할 수 있을 것으로 사료된다.

• Investigative Magnetic Resonance Imaging
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• 제23권3호
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• pp.251-258
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• 2019

Purpose: To assess the feasibility of the use of spin-echo echo-planar imaging (SE-EPI) magnetic resonance elastography (MRE) in livers of children and young adults. Materials and Methods: Patients (${\leq}20$ years old) who underwent 3T SE-EPI MRE were included retrospectively. Subjects were divided into three groups according to the purpose of the liver MRI: suspicion of fatty liver or focal fat deposition in the liver (FAT group), liver fibrosis after receiving a Kasai operation from biliary atresia (BA group), and hepatic iron deposition after receiving chemotherapy or transfusions (IRON group). Technical failure of MRE was defined when a stiffness map showed no pixel value with a confidence index higher than 95%, and the patients were divided as success and failure groups accordingly. Clinical findings including age, gender, weight, height, and body mass index and magnetic resonance imaging results including proton density fat fraction (PDFF), $T2^*$, and MRE values were assessed. Factors affecting failure of MRE were evaluated and the image quality in wave propagation image and stiffness map was evaluated using the appropriate scores. Results: Among total 240 patients (median 15 years, 211 patients in the FAT, 21 patients in the BA, and 8 patients in the IRON groups), technical failure was noted in six patients in the IRON group (6/8 patients, 75%), while there were no failures noted in the FAT and BA groups. These six patients had $T2^*$ values ranging from 0.9 to 3.8 ms. The image quality scores were not significantly different between the FAT and BA groups (P > 0.999), while the scores were significantly lower in the IRON group (P < 0.001). Conclusion: The 3T SE-EPI MRE in children and young adults had a high technical success rate. The technical failure was occurred in children with decreased $T2^*$ value (${\leq}3.8ms$) from iron deposition.

• 대한의용생체공학회:의공학회지
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• 제3권2호
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• pp.119-122
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• 1982

This paper presents the principles of image formation in NMR(Nuclear Magnetic Resonance) tomography. NMR tomographic imaging is a newly emerging, noninvasive, three-dimensional imaging technique. This new technique is an interdisciplinary science which encompasses the latest technologies in electrical, electronics, computers, physics, chemistry, mathematics, and medical sciences.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 1999년도 제4차 추계학술대회 초록집
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• pp.79-79
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• 1999

• Annals of Clinical Neurophysiology
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• 제13권1호
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• pp.48-50
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• 2011

Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystem disorder caused by the expansion of cytosine-thymine-guanine (CTG) repeats in the myotonic dystrophy protein kinase (DMPK) gene. Some literatures indicated that DM1 had incidental CNS lesions such as white matter lesions and diffuse gray matter atrophy. We report a patient with DM1 whose brain magnetic resonance image (MRI) showed multifocal hyperintense lesions and cystic lesion on both frontotemporoparietal lobes.

• 대한관절경학회지
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• 제11권1호
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• pp.50-53
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• 2007

슬관절에서 원판형 연골은 주로 외측에 발생하는 것이 보통이며, 내측 원판형 연골의 경우 보고가 매우 드물다. 저자들은 슬관절 동통을 주소로 내원한 22세 여자에서 자기 공명 영상 및 관절경을 이용하여 내측 원판형 연골 및 수평 파열을 진단하고 관절경하 부분 절제술로 치료하였기에 보고하고자 한다.

• 한국자기공명학회논문지
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• 제2권1호
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• pp.59-65
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• 1998

The correction of image artifacts due to misadjustment in tuning of RF coils (tip angle) and in the RF single sideband spectrometer was investigated using phase cycling of the $\pi$/2 and $\pi$ pulses in spin-echo sequences. A general procedure was developed for the systematic design of phase cycles that select desirable coherence transfer pathways. To analyze a phase cycling sequence, changes in the coherence level and phase factor for each RF pulse in the spin-echo cycle must be determined. Four different phase cycling schemes (FIXED, ALTERNATE, FORWARD, REVERSED) to suppress unwanted signal components such as mirror and ghost images were evaluated using two signal acquisitions. When the receiver phase factor is cycled counter-clockwise (REVERSED), these artifacts are completely removed.

• 대한족부족관절학회지
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• 제7권1호
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• pp.131-134
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• 2003

Most interdigital neuroma can be diagnosed clinically. But, diagnostic local injection method, sonography and magnetic resonance image(MRI) have been used as secondary tests for clinical confirmation or surgery. Recently, there have been active discussions on the method of interdigital neuroma diagnosis for which sonography or MRI is used. For finding out the location or the number of interdigital neuroma particularly in non-typical clinical manifestation or surgery, MRIs, which are exellent in tissue contrast, may be quite helpful. This case had an interdigital neuroma showing non-typical manifestation. MRIs were used for clinical diagnostic confirmation and finding out the location and the number of interdigital neuroma. Thus, the validity along with literary consideration is being reported.