• Title, Summary, Keyword: T1 강조영상

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T1-, T2-weighted, and FLAIR Imaging: Clinical Application (T1, T2강조영상, FLAIR영상의 임상 적용)

  • Kim, Jae-Hyoung
    • Investigative Magnetic Resonance Imaging
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    • v.13 no.1
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    • pp.9-14
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    • 2009
  • T1-, and T2-weighted imagings and FLAIR (fluid attenuated inversion recovery) imaging are fundamental imaging methods in the brain. T1-weighted imaging is a spin-echo sequence with short TR and short TE and produces the tissue contrast by different T1 relaxation times. In other words, short TR maximizes the difference of the longituidinal magnetization recovery between the tissues. T2-weighted imaging is a spin-echo sequence with long TR and long TE and produces the tissue contrast by different T2 relaxation times. Long TE maximizes the difference of the transverse magnetization decay between the tissues. FLAIR is an inversion recovery sequence using 180 degree inversion pulse. 2500 msec of inversion time is applied to suppress the CSF signal.

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Chemical Saturation Breath-hold Fast MR Imaging for characterization of Regional Fatty Changes in Liver (화학적 포화 호흡정지 급속 자기공명영상에서 국소적 간지방병변의 특성화)

  • 김동국;유정식;김태훈;오세정;김지형
    • Investigative Magnetic Resonance Imaging
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    • v.1 no.1
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    • pp.135-141
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    • 1997
  • Purpose: To assess the usefulness of breath-hold fast MR imaging of liver with fat suppression (FS) by application of chemical saturation technique in the diagnosis of regional fatty changes suspected in sonography. Materials and Methods: Thirteen patients who had focal lesions with diffuse, homogeneous signal changes after FS through chemical saturation technique without additional changes of imaging parameter during MR imaging of liver were selected. T1-weighted fast low-angle shot and T2-weighted turbo spin-echo sequences were obtained with or without FS during each single breath-holding session. Subjective changes of signal intensity between the pre-FS and the FS images were compared with the sonographic findings in each lesion. Results: Seven lesions of decreased signal intensity after FS on T1 or T2-weighted images, including three lesions only at FS T1 images, were regarded as focal fat infiltration. All seven lesions had compatible sonographic findings as homogenously echogenic areas. Another six lesions of subjectively increased signal intensity including two lesions only at FS T2 images were regarded as focal fat sparing. All six lesions had sonographic findings as homogenous echo poor areas suggesting focal fat sparing. In cases regarded as fat infiltration, score changes were more prominent at FS T1 images than FS T2 images(p=0.0002). In cases regarded as fat sparing, score changes were more prominent at FS T2 images than FS T1 images(p=0.042). Conclusion: Breath-hold fast T1 and T2-weighted MR imaging with and without chemical saturation pre-pulse may be sufficient for characterization of regional fatty changes in the differential diagnosis of focal hepatic lesion found at sonography.

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Anthracofibrosis Mimicking Lung Cancer on CT: MR Imaging Findings (CT상 폐암과 유사하게 보이는 기관지 탄분 섬유화증의 자기공명영상 소견)

  • 류대식;이덕희;정승문;최수정;박성빈;박만수;강길현
    • Investigative Magnetic Resonance Imaging
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    • v.5 no.1
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    • pp.18-23
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    • 2001
  • Purpose : To describe the MRI findings in the bronchial anthracofibrosis mimicking lung cancer on CT examination. Materials and methods : Ten patients, who showed CT findings mimicking lung cancer, were selected among fifty patients of bronchial anthracofibrosis proven by bronchoscopic biopsy, consisting of two men and eight women, ranging in age from 58 to 79 years old faverage age, 68 years old). CT scan and MRI were performed in all patients (n=10). Percutaneous lung biopsy on mass was performed in one patient. MRI findings were analyzed with the emphasis on the signal intensity of the mass (n=4), collapsed lung (n=4) and Iymph node (n=10) on axial T1 and T2-weighted images by two radiologists in consensus. No contrast enhancement was used in all cases. Results : CT scan revealed mass (n=4), atelectasis with obstructive pneumonia(n=4) and bronchial wall thickening(n=2). All patients showed enlarged medistinal Iymph nodes(n=10). The mass showed low signal intensity on T1WI and T2WI (n =4). The collapsed lung in patients with atelectasis indicated intermediate signal intensity on T1WI and low signal intensity on T2WI (n= 4). Nine patients showed low sisnal intensity of Iymph node on T1WI and T2WI, except one patient who showed central high signal intensity with peripheral rim of low signal intensity in right lower paratracheal llmph node on T2WI. Conclusion : Low signal intensity of a mass, collapsed lung, and lymph nodes on T2WI in anthracofibrosis patients may be helpful in differentiation of the lesion from lung cancer.

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T1-weighted FLAIR MR Imaging for the Evaluation of Enhancing Brain Tumors: Comparison with Spin Echo Imaging (조영증강을 보이는 뇌종양의 평가에 있어 T1강조 FLAIR 영상과 스핀에코 MR 영상의 비교)

  • Jeong, Boseul;Choi, Dae Seob;Shin, Hwa Seon;Choi, Hye Young;Park, Mi Jung;Jeon, Kyung Nyeo;Na, Jae Beom;Chung, Sung Hoon
    • Investigative Magnetic Resonance Imaging
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    • v.18 no.2
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    • pp.151-156
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    • 2014
  • Purpose : Spin-echo (SE) technique is most commonly used pulse sequence for T1-weighted MR imaging. T1-weighted fluid-attenuated inversion recovery (T1FLAIR) is a relatively new pulse sequence and it provides higher tissue contrast between the gray matter (GM) and white matter (WM) of the brain than T1-weighted SE (T1SE) sequence. However, there has been controversy for the evaluation of enhancing brain tumors with T1FLAIR compared to T1SE. The purpose of this study was to compare T1FLAIR and T1SE sequences for the evaluation of enhancing intracranial tumors. Materials and Methods: Fifty-two patients with enhancing brain tumors were evaluated with contrast-enhanced (CE) T1SE and T1FLAIR imaging. Eight quantitative criteria were calculated: lesion-to-WM contrast ratio (CR) and contrast-to-noise ratio (CNR), lesion-to-GM CR and CNR, lesion-to-CSF CR and CNR, and WM-to-GM CR and CNR. For qualitative evaluation, two radiologists assessed lesion conspicuity on CE T1SE and T1FLAIR sequences with three-scale: 1, T1SE superior; 2, sequence equal; T1FLAIR superior. Results: Seventy-nine tumors (31 primaries, 48 metastases) were assessed. For quantitative measurement, the T1FLAIR lesion-to-GM, lesion-to-CSF, WM-to-GM CR and CNR values were comparable and statistically superior to those of the T1SE images (p < 0.001 in all). However, lesion-to-WM CR and CNR were similar on both two sequences without statistically significant difference (p = 0.661, 0.662, respectively). For qualitative evaluation, both radiologists assessed that T1FLAIR images were superior to T1SE images for the evaluation of lesion conspicuity. Conclusion: For the evaluation of enhancing intracranial tumors, T1FLAIR sequence was superior or comparable to T1SE sequence.

이중 경사 자장 에코와 일반 경사 자장 에코 펄스열로부터의 $\Delta{R}_1$$\Delta{R}_2$에 대한 컴퓨터 가상 실험

  • 김대홍;김은주;서진석
    • Proceedings of the KSMRM Conference
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    • pp.102-102
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    • 2002
  • 목적:$\Delta{R}_1$$\Delta{R}_2\;^{*}$$T_1$, $T_2\;^{*}$로부터 직접 구해야 하지만, 시간 해상도 때문에 각각 $T_1$, $T_2\;^{*}$ 강조영상으로부터 구하는 것이 일반적이다. $T_1$, $T_2\;^{*}$ 강조영상으로부터 얻은 $\Delta{R}_1$$\Delta{R}_2\;^{*}$ 과 이중 경사 자장에코 펄스열로부터 얻은 $\Delta{R}_1$$\Delta{R}_2\;^{*}$ 를 컴퓨터 가상 실험을 통해서 비교한다. 강조 영상의 신호 세기만으로는 정확한 관류 정보를 얻을 수 없음을 보이고자 한다. 대상 및 방법: 알려진 $\Delta{R}_1$$\Delta{R}_2\;^{*}$ 값을 이용하여 강조영상으로부터 구할 수 있는 $\DeltaR_1$$\Delta{R}_2\;^{*}$ 을 농도에 따라서 가상실험으로 구하고, 이 값과 이중 경사 자장 에코 펄스열로부터 구할 수 있는 $\Delta{R}_1$$\Delta{R}_2\;^{*}$를 가상실험으로 구해서 비교한다.

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Imaging Studies in Mouse Brain Using Clinical 3T MRI Scanner (임상용 3T MRI를 이용한 마우스 뇌의 영상)

  • Lim, Soo-Mee;Park, Eun-Mi
    • Progress in Medical Physics
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    • v.21 no.4
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    • pp.348-353
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    • 2010
  • The purpose of this study was to explore the potentials of a clinical 3T MRI in mouse brains and technical adaptation and optimization. T1-weighted images (T1WI), T2-weighted images (T2WI), FLAIR (Fluid Attenuated Inversion Recovery) images, Gadolinium enhanced T1-weighted images (Gd-T1WI), Diffusion weighted images (DWI) were acquired in brain of 2 mice (weight 20~25 g) with cerebral infarction by occlusion of right middle cerebral artery, 1 hour, 24 hours, 72 hours after infarction and 1 normal mouse brain using clinical 3T MRI scanner. We analyzed differentiation of striatum, ventricle, cerebral cortex, and possibility of detection of acute cerebral infarction. We could differentiate the striatum, ventricle, cerebral cortex on T2WI and on DWI, FLAIR, T1WI, the differentiation of each anatomy of brain was not definite, but acute cerebral infarction was detected on DWI of 1 hour, 24 hours, 72 hours after infarction and on T2WI, FLAIR of 24 hours, 72 hours after infarction. Clinical 3T MRI can be used in differentiation of anatomy of mouse brains and DWI can be helpul in detection of acute cerebral infarction in acute phase. With technical adaptation and optimization clinical 3T MRI can be useful tool for provide preclinical and clinical small animal studies.

Metal Artifact Caused by Magnetic Field Strength and Sequence on T1WI-MRI (자기공명영상에서 자장세기와 시퀀스에 따른 아티팩트 변화)

  • Ko, Seong-Jin
    • The Journal of the Korea Contents Association
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    • v.10 no.9
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    • pp.302-308
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    • 2010
  • In MRI, the Ferromagnetic artifact is generated by the metalization within in which the before inspection removal is impossible and the distortion of an image is brought. The distortion measure according to the steel for each sequence of T1 image and magnetic field intensity are analyzed and minimized method is looked into. We used SIEMENS 1.5T and 3.0T MRI for experiment equipment. First, it places within the Phantom making a metalization(Ti+Al, Stainless, Nitinol) on 1.5T, 3.0T MRI and the T1 weighted image for each Sequence is acquired. The distortion of an image and about adjacent portion change of the metal material were compared through the obtained image, we analyzed. In all metalizations, a distortion was generated and a distortion was few in particularly, and Titanium-Aluminium alloy. And the extent of a distortion was worse image in the Turbo spin Echo. The use of the Titanium-Aluminium alloy the inserted in an internal material of the metalization is recommend. and, equipment of 1.5T the patient inserting a metal in an internal is used in an inspection than equipment of 3.0T. Also, the sequence is suitable when it obtains the optimum T1 weighted image of an impersonate to use the Turbo spin Echo.

Usefulness of the Technique of Collecting Signals by Selecting Elements from RF Receive Phase Array Coil in Magnetic Resonance Imaging (자기공명영상검사 시 Array coil에서 element를 선택하여 신호를 수집하는 기법의 유용성)

  • Choi, Kwan-Woo;Son, Soon-Yong
    • The Journal of the Korea Contents Association
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    • v.18 no.6
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    • pp.461-466
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    • 2018
  • In this study, we investigated the signal intensity changes by activating all and partially selected coil elements as a way to increase the SNR in a single region MR imaging. Two cylindrical fluid phantoms were placed side by side in a phase array coil and MRI scans were repeated by turning on the entire elements and selected elements. As a result, on both of the T1 and T2 weighted images signal intensities were significantly increased by 5.49% and 14.64%, respectively. In conclusion, if only a single region was to be imaged, selecting appropriate elements and collecting signals only from them could easily improve image qualities and signal intensities.

The Value of Additional Cervicothoracic Spine Sagittal T2-weighted Images Included in Routine Lumbar Spine MR Imaging (요추 MR영상에 포함된 경흉추 시상T2강조영상의 효용성 평가)

  • Seo, Jiwoon;Park, So Young;Lee, Joon Woo;Lee, Guen Young;Kang, Heung Sik
    • Investigative Magnetic Resonance Imaging
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    • v.17 no.2
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    • pp.91-100
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    • 2013
  • Purpose : To evaluate the usefulness of cervicothoracic spine sagittal T2-weighted images (CT SAG T2WIs) included in routine lumbar spine MRI. Materials and Methods: Institutional review board approval was obtained and informed consents were waived for this retrospective study. The study group comprised 2,113 patients who underwent lumbar spine MRI from January 2005 to December 2005. CT SAG T2WIs were added in the routine lumbar spine MRIs. Radiologic reports were reviewed retrospectively for pathologic lesions on CT SAG T2WIs by one radiologist. Information of additional cervical or thoracic spine MRI and/or CT for further evaluation of positive findings on CT SAG T2WIs and their treatment were collected by retrospectively reviewing medical records. Results: The CT SAG T2WIs revealed 142 pathologic lesions in 139 (6.58%) of the 2,113 patients. They were easily obtained without positional change in a scan time of less than 2 minutes. Additional cervical or thoracic spine MRI and/or CT for positive findings on CT SAG T2WIs were performed in 13 patients. Seven patients underwent surgical treatment. Conclusion: CT SAG T2WIs included in routine lumbar spine MRI were useful in finding the pathologic lesions in cervicothoracic spine for the patients who assumed to have lesions in lumbar spine.

3T MR Spin Echo T1 Weighted Image at Optimization of Flip Angle (3T MR 스핀에코 T1강조영상에서 적정의 숙임각)

  • Bae, Sung-Jin;Lim, Chung-Hwang
    • Journal of radiological science and technology
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    • v.32 no.2
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    • pp.177-182
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    • 2009
  • Purpose : This study presents the optimization of flip angle (FA) to obtain higher contrast to noise ratio (CNR) and lower specific absorption rate (SAR). Materials and Method : T1-weighted images of the cerebrum of brain were obtained from 50$^\circ$ to 130$^\circ$ FA with 10$^\circ$ interval. Signal to noise ratios (SNRs) were calculated for white matter (WM), gray matter (GM), and background noise. The proper FA was analyzed by T-test statistics and Kruskal-wallis analysis using R1 = 1- exp ($\frac{-TR}{T1}$) and Ernst angle cos $\theta$ = exp ($\frac{-TR}{T1}$). Results : The SNR of WM at 130$^\circ$ FA is approximately 1.6 times higher than the SNR of WM at 50$^\circ$. The SNR of GM at 130$^\circ$ FA is approximately 1.9 times higher than the SNR of GM at 50$^\circ$. Although the SNRs of WM and GM showed similar trends with the change of FA values, the slowdown point of decrease after linear fitting were different. While the SNR of WM started decreasing at 120$^\circ$ FA, the SNR of GM started decreasing at less than 110$^\circ$. The highest SNRs of WM and GM were obtained at 130$^\circ$ FA. The highest CNRs, however, were obtained at 80$^\circ$ FA. Conclusion : Although SNR increased with the change of FA values from 50$^\circ$ to 130$^\circ$ at 3T SE T1WI, CNR was higher at 80$^\circ$ FA than at the usually used 90$^\circ$ FA. In addition, the SAR was decreased by using smaller FA. The CNR can be increased by using this optimized FA at 3T MR SE T1WI.

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