• Investigative Magnetic Resonance Imaging
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• 제20권1호
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• pp.44-52
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• 2016

Purpose: To quantitatively and qualitatively compare fat-suppressed MRI quality using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with that using frequency selective fat-suppression (FSFS) T2- and postcontrast T1-weighted fast spin-echo images of the head and neck at 3T. Materials and Methods: The study was approved by our Institutional Review Board. Prospective MR image analysis was performed in 36 individuals at a single-center. Axial fat suppressed T2- and postcontrast T1-weighted images with IDEAL and FSFS were compared. Visual assessment was performed by two independent readers with respect to; 1) metallic artifacts around oral cavity, 2) susceptibility artifacts around upper airway, paranasal sinus, and head-neck junction, 3) homogeneity of fat suppression, 4) image sharpness, 5) tissue contrast of pathologies and lymph nodes. The signal-to-noise ratios (SNR) for each image sequence were assessed. Results: Both IDEAL fat suppressed T2- and T1-weighted images significantly reduced artifacts around airway, paranasal sinus, and head-neck junction, and significantly improved homogeneous fat suppression in compared to those using FSFS (P < 0.05 for all). IDEAL significantly decreased artifacts around oral cavity on T2-weighted images (P < 0.05, respectively) and improved sharpness, lesion-to-tissue, and lymph node-to-tissue contrast on T1-weighted images (P < 0.05 for all). The mean SNRs were significantly improved on both T1- and T2-weighted IDEAL images (P < 0.05 for all). Conclusion: IDEAL technique improves image quality in the head and neck by reducing artifacts with homogeneous fat suppression, while maintaining a high SNR.

• 대한의생명과학회지
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• 제10권2호
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• pp.115-120
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• 2004

To investigate the correlation between the magnetic resonance imaging (MRI) of cerebral fat embolism that is induced by injecting oleic acid into 10 cats, and a pathologic diagnosis. Using a microcatheter, 30 ${mu}ell$ of oleic acid was injected into the internal carotid artery of 10 cats. MR T2-weighted image (T2WI), diffusion-weighted image (DWI) and Gadolinium-enhanced T1-weighted image (Gd-enhanced T1WI) were obtained after 30 minutes and 2 hours of embolization. After 30 minutes of the embolization, lesions of very high signal intensity were detected by T2WI in 6 cats, and of slightly high signal intensity in 2 cats; in the remaining 2 cats, signal intensity was normal. DWI showed lesions of very high intensity in 9 cats and of slightly high intensity in one cat. According to the findings of light microscopic examination, infarcted lesions mainly involved the gray matter, but also some white matter. A magnetic resonance imaging diagnosis for cerebral fat embolism that was induced by oleic acid through the internal carotid artery in cats showed high signal intensity on the T2WI and the DWI within an initial 2 hours, and with a well enhancement on the Gd-enhanced T1WI. Considering cellular edema, cerebrovascular injury and extracellular space widening, we assumed pathologically that cytotoxic and vasogenic edema exists at the same time.

• 디지털콘텐츠학회 논문지
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• 제11권1호
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• pp.73-78
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• 2010

PROPELLER 확산강조영상기법이 금속에 의해 발생한 magnetic susceptibility artifact를 제거 할 수 있는지를 알아보고자 하였다. 뇌 MRI를 촬영한 환자 중에서 치아에 금속성 이물질을 가지고 있는 환자 20명을 대상으로 3.0T MR scanner를 이용하여 b value 0, 1000 s/mm2을 기준으로 에코 평면확산강조영상, PROPELLER 확산강조영상과 각각의 ADC map영상을 획득한 후 양쪽 측두엽, 뇌교, 안와등 네 부위에서 발생한 magnetic susceptibility artifact의 발생률을 비교 하였다.에코평면 확산강조영상 기법에서 금속물질이 있는 경우 magnetic susceptibility artifact가 발생되어 진단에 큰 제한점을 두었지만 PROPELLER 확산강조영상기법은 magnetic susceptibility artifact를 감소함으로써 임상적으로 정확한 진단에 도움이 될 것으로 생각된다.

• 대한디지털의료영상학회논문지
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• 제11권2호
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• pp.51-57
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• 2009

The purpose of this study would evaluate if having clinical effects on diffusion image with quantitative analysis through ADC values of brain's normal tissue and lesions before and after contrast injections using a 3.0T. From November in 2007 until December in 2008, a total of 32 patient was performed on 3.0T(Signa Excite, GE Medical System, USA) with the normal or lesions in the patient who requests diffusion weighted image with 8channel head coil. The pulse sequence was used with spin echo EPI(TR: 10000msec, TE: 72.2 msec, Matrix: 128*128, FOV: 240 mm, NEX: 1, diffusion direction: 3, b-value: 1000). Measurement results of ADC values on lesions, CSF, white matter, gray matter, lesions after contrast injection were measured less 75% than before contrast injection, infarction: 100%, CSF: 78%(high), white matter: 71.4%(low), gray matter: 50%(high, low). The results of paired t-test on the deference of ADC values which statically is significant in three(lesions, CSF, white matter)regions except for white matter(p<0.05). Quantitative analysis of lesions, CSF, white matter, gray matter have difference on all regions. ADC values were low in lesions and white matter, normal CSF after contrast injection commonly is high than before contrast injection, ADC values which white matter were high and low (50:50) after contrast injection. 3.0T diffusion weighted image clinically supposed that performing DWI examination after contrast injection was not desirable because of having effects on brain tissue.

• 한국콘텐츠학회논문지
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• 제10권9호
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• pp.302-308
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• 2010

자기공명영상에서는 체내 금속물에 의한 강자성 인공물(Ferromagnetic artifact)이 발생하여 많은 영상의 왜곡을 초래 한다. 본 연구는 T1 강조영상의 자장 세기와 시퀀스에 따른 수술시 인체 내에 사용되는 금속물의 왜곡을 분석하여 영상 왜곡을 최소화 할 수 있는 시퀀스와 금속물의 종류를 알아보았다. SIEMENS사의 1.5T와 3.0T를 이용하였고, Ti+Al, Stainless, Nitinol 금속물을 팬텀 내에 각각 위치시켜 시퀀스별 SE(Spin Echo), TSE(Turbo Spin Echo), VIBE, Flash T1 강조영상을 획득하였다. 획득된 영상을 통해서 금속물질 주변에서 발생하는 영상의 왜곡 정도를 비교 및 분석하였다. 실험결과 임상에서 사용되는 모든 금속물에서 강자성 허상이 발생 하였는데, 그 중 TSE 시퀀스와 Nitinol 금속물에서 가장 작은 아티팩트가 발생하였다. TSE 시퀀스와 Nitinol이 사용된 1.5T 영상에서 면적 0.97 cm2, 장축 0.76 cm, 단축0.72 cm로 왜곡 정도가 가장 작게 나타났다. 그러므로 금속을 체내에 삽입한 환자의 검사를 위해서 3.0T 보다 1.5T 자기공명영상 장비를 사용하고, TSE 시퀀스를 사용하는 것이 T1 강조영상을 얻는데 가장 적합하다고 사료된다.

• 대한의생명과학회지
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• 제11권1호
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• pp.31-36
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• 2005

To evaluate the magnetic resonance imaging and electron microscopic findings of the hyperacute stage of cerebral fat embolism in cats and the time needed for the development of vasogenic edema. Magnetic resonance imaging was performed at 30 minutes (group 1, n=9) and at 30 minutes and 1, 2, 4, and 6 hours after embolization with triolein (group 2, n= 10). As a control for group 2, the same acquisition was obtained after embolization with polyvinyl alcohol particles (group 3, n=5). Electron microscopic examination was done in all cats. In group 1, the lesions were iso- or slightly hyperintense on T2-weighted (T2W) and diffusion-weighted (DWIs) images, hypointense on the apparent diffusion coefficient (ADC) map image, and markedly enhanced on the gadolinium-enhanced T1-weighted images (Gd-T1WIs). In group 2 at 30 minutes, the lesions were similar to those in group 1. Thereafter, the lesions became more hyperintense on T2WIs and DWIs and more hypoinfense on the ADC map image. In group 3, the lesions showed mild hyperintensity on T2WIs at 6 hours but hypointensity on the ADC map image from 30 minutes, with a tendency toward a greater decrease over time. Electron microscopic findings revealed discontinuity of the capillary endothelial wall, perivascular and interstitial edema, and swelling of glial and neuronal cells in groups 1 and 2. The lesions were hyperintense on T2WIs and DWIs, hypointense on the ADC map image, and enhanced on Gd-T1WIs. On electron microscopy, the lesions showed cytotoxic and vasogenic edema with disruption of the blood-brain barrier.

• 방사선산업학회지
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• 제10권4호
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• pp.227-230
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• 2016

DWI of biological effects are independent of magnetic field strength in various regions. High field strength, however, does affect the signal to noise ratio (SNR) and artifacts of diffusion weighted imaging (DWI) images, which ultimately will influence the quantitative of diffusion imaging. In this study, the effects of field strength on DWI are reviewed. The effects of the diseases also are discussed. Comparing DWI in cerebellum, WM, GM, Hyperacute region measurements both as a function of field strength (1.5T and 3.0T). Overall, the SNR of the DWI roughly doubled going from 1.5 T to 3.0 T. In summary, DWI studies at 3.0 T is provided significantly improved DWI measurements relative to studies at 1.5T.

• Journal of Yeungnam Medical Science
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• 제27권2호
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• pp.105-112
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• 2010

병리조직학적으로 고환림프종으로 확진된 예들의 초음파검사 및 자기공명영상을 후향적으로 분석하여 다른 고환종양과 구분할 수 있는 소견이 있는지를 알아보기 위하여 본 연구를 시행하였다. 수술적 절제에 의해 확진된 7예와 초음파-유도하 조직생검으로 확진된 1예 등 총 8예를 대상으로 하였다. 종괴의 크기와 위치, 고환 이외에 침범된 장기를 조사하였고, 초음파검사에서는 종괴의 모양과 경계, 종괴 내부의 에코, 균일도와 함께 색도플러검사에서의 혈관분포상태를 조사하였다. 자기공명영상이 시행된 4예를 대상으로 종괴의 모양과 경계, 균일도, T1-및 T2-강조영상에서의 신호강도 및 조영증강 여부와 시간에 따른 조영증강의 변화를 조사하였다. 고환에 국한되어 있었던 경우는 2예에 불과하였고, 4예는 정삭을, 4예는 대동맥주위림프절을 침범하고 있었다. 초음파검사에서 종양의 외연은 6예에서 평활하였고 종괴의 에코는 7예에서 정상 고환 보다 저에코로 보였다. 4예는 균일하였고, 3예는 전반적으로는 균일하였으나 약간 불균일한 부분을 포함하고 있었고, 1예는 불균일하였다. 8예 모두에서 주변의 정상 조직보다는 현저하게 혈관분포상태 (vascularity)가 증가되어 있었다. 자기공명영상 T1-강조영상에서는 정상 고환과 유사한 신호강도로, T2-강조영상에서는 현저한 저신호강도로 관찰되었고 대체로 균일하였다. 조영 후 검사에서는 4예 모두 정상 고환 조직보다는 저신호강도로, 약하게, 균일하게 조영증강되었는데, 역동적 조영증강 검사가 시행된 1예에서는 시간이 감에 따라 점차 조영증강이 증가되는 소견을 관찰할 수 있었다. 이상의 결과를 토대로 50세 이상의 나이가 많은 환자에서 고환 종괴가 관찰되고, 초음파 검사에서 균일한 저에코로, 자기공명영상 T2-강조영상에서 균일한 저신호강도로 관찰될 때에는 고환림프종의 가능성을 가장 먼저 고려하여야할 것으로 생각한다.

• Investigative Magnetic Resonance Imaging
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• 제19권3호
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• pp.146-152
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• 2015

Purpose: The purpose of this study was to evaluate the associated brain parenchymal abnormalities of developmental venous anomalies (DVA) with susceptibility-weighted image (SWI). Materials and Methods: Between January 2012 and June 2013, 2356 patients underwent brain MR examinations with contrast enhancement. We retrospectively reviewed their MR examinations and data were collected as per the following criteria: incidence, locations, and associated parenchymal signal abnormalities of DVAs on T2-weighted image, fluid-attenuated inversion recovery (FLAIR), and SWI. Contrast enhanced T1-weighted image was used to diagnose DVA. Results: Of the 2356 patients examined, 57 DVAs were detected in 57 patients (2.4%); 47 (82.4%) were in either lobe of the supratentorial brain, 9 (15.7%) were in the cerebellum, and 1 (1.7%) was in the pons. Of the 57 DVAs identified, 20 (35.1%) had associated parenchymal abnormalities in the drainage area. Among the 20 DVAs which had associated parenchymal abnormalities, 13 showed hemorrhagic foci on SWI, and 7 demonstrated only increased parenchymal signal abnormalities on T2-weighted and FLAIR images. In 5 of the 13 patients (38.5%) who had hemorrhagic foci, the hemorrhagic lesions were demonstrated only on SWI. Conclusion: The overall incidence of DVAs was 2.4%. Parenchymal abnormalities were associated with DVAs in 35.1% of the cases. On SWI, hemorrhage was detected in 22.8% of DVAs. Thus, we conclude that SWI might give a potential for understanding of the pathophysiology of parenchymal abnormalities in DVAs.

• Investigative Magnetic Resonance Imaging
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• 제6권1호
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• pp.21-27
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• 2002

목적: 뇌실질내 혈종의 시기별 확산강조영상 소견을 알아보고자 하였다. 대상 및 방법: 임상적으로 뇌출혈의 시기가 분명한 환자 17명을 대상으로 하였다. 확산강조영상은 1.5 tesla 자기공명영상 기기를 이용하였으며, b 값은 세 방향 모두 $1000{\;}sec/\textrm{mm}^2$으로 하였다. 출혈 시기는 12시간 이하인 초급성기 5예, 3일 이하인 급성기 4예, 3주이하의 아급성기 4예, 3주 이후의 만성기 4예였다. 확산강조영상에서 혈종의 중심부와 주변부의 신호강도를 뇌실질 신호와 비교하여 bright, high, iso, low, dark 신호로 분류하여 분석하였으며, 각 시기의 T2강조영상과 T1강조영상에서의 신호강도와 비교 관찰하였다. 결과: 확산강조영상에서 초급성기 혈종의 중심부와 주면부는 각각 high와 dark신호를 보였고, 급성기는 중심부와 주변부가 각각 dark와 high-bright 신호강도를 보였다. 아급성기와 만성기는 중심부와 주변부가 high-bright와 dark 신호강도를 보였다. 시간 경과에 따른 혈종의 신호 변화는 전체적으로 T2강조영상에서의 신호 변화와 비슷하나, T2강조영상에 비해 빠르고 현저한 신호 변화를 보였다. 결론: 뇌실질내 혈종은 확산강조 자기공명영상에서 중심부와 주변부의 신호강도가 시기별로 특징적으로 변하며 중심부는 초급성기, 아급성기와 만성기에 high-bright신호를, 급성기에는 dark 신호를 보였고, 주변부는 초급성기, 아급성기와 만성기에 dark 신호를, 급성기에는 high-bright 신호를 보였다.