• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.388-391
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• 2011

A lesion that is hyperintense on diffusion-weighted imaging (DWI) and hypointense on the apparent diffusion coefficient (ADC) map is a characteristic magnetic resonance imaging (MRI) finding in acute ischemic infarction. In some cases, however, these findings can persist for a few months after infarct onset. It is thought that these finding reflect the different evolution speeds of the infarcted tissue. We report a patient with a right middle cerebral artery territory infarction with persistent hyperintensity on DWI and hypointensity on the ADC map for over 8 months. To our knowledge, this is the most persistent case of hyperintensity lesion on DWI and the serial MRI images of this patient provide important information on the evolution of infarcted tissue.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.272-276
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• 1996

1948년 Harvard 대학의 Purcell교수와 Stanford 대학의 Bloch교수가 핵자기 공명(Nuclear Magnetic Resonance : NMR) 현상을 발견한 이래로 NMR은 물질의 분자단위에서 화학적, 물리학적 성질을 밝혀내는 탁월한 방법으로 널리 이용되어 왔다. NMR 현상을 이용한 영상촬영법(Magnetic Resonance Imaging, MRI)은 1970년대초 Lauterber와 Damadian 교수가 처음 영상을 얻을 수 있다는 가능성을 제시한 이후 급속한 발전을 하여 1980년대 초에는 Moore와 Holland에 의해 의학분야에 응용 가능할 정도의 영상이 얻어졌다. 1980년대 중반부터 상용화 되었으며 최근 그 기법도 NMR현상과 연관된 파라미터인 $T_{1}$, $T_{2}$는 물론 혈류의 속도, 자화율, 확산(Diffusion), Perfusion의 영상기법을 비롯해 혈관조영술(MR Angiography), 뇌기능영상(Functional Imaging)등 과거에는 상상도 할 수 없었던 다양한 영상기법 개발되었다. 여기서는 먼저 MRI의 원리를 설명한 후 MRI의 여러 촬영기법들과 그 응용에 관해 설명하겠다.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.282-292
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• 1994

Brain perfusion SPECT shows typical regional perfusion abnormalities in Alzheimer's disease(AD) and is useful for its diagnosis. However, there is also arguement that these patterns show significant overlap with other causes, and the accuracy for SPECT in differentiating AD has shown conflicting results. We postulate that the variation in re-ported results are partly due to a difference in patient or control selection with special reference to the mixture of ischemic cerebral disease in the studied population. To deter-mine the effect of ischemic lesions and the nature of control subjects on SPECT studies for AD, we performed $^{99m}Tc$-HMPAO single photon emission computed tomography (SPECT) in 11 probable AD patients with a low (<4) Hachinski ischemic score and 12 non-demented age matched controls. Magnetic resonance imaging(MRI) disclosed ischemic cerebral lesions in 27% (3/11) of the PAD group and 25% (3/12) of the control group. Regional perfusion indices were quantitated from the SPECT images as follows and the distribution of perfusion indices from both groups were compared. This was repeated with controls after excluding those with significant ischemic lesions by MRI : regional perfusion index = average regional count/average cerebellar count All PAD patients showed perfusion abnormality in SPECT. However, 53% (10/12) of controls also showed perfusion at-normalities, and no pattern could reliably differentiate the two groups. After excluding controls with significant cerebral ischemia, the difference in temporal and parietal perfusion index was increased. A decreased tempore-parietal and any parietal or temporal per-fusion index had a sensitivity of 18% and 36% in detecting AD, respectively. When using a separate group of normal age mathced controls, the indices showed an even more difference in the temporal and parietal lobes and the sensitivity of a decreased tempore-parietal and any parietal or temporal perfusion index had a sensitivity of 36% and 55% in detecting AD, respectively. Thus, the type of control with special reference to the pres-once of ischemic cerebral lesions contribute significantly to the accuracy of perfusion SPECT in diagnosing AD. This nay have particular importance in the diagnosis of AD in populations where the prevalance of cerebrovascular disease is high.

• Clinical and Experimental Pediatrics
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• v.63 no.3
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• pp.88-95
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• 2020

Accurate localization of the seizure onset zone is important for better seizure outcomes and preventing deficits following epilepsy surgery. Recent advances in neuroimaging techniques have increased our understanding of the underlying etiology and improved our ability to noninvasively identify the seizure onset zone. Using epilepsy-specific magnetic resonance imaging (MRI) protocols, structural MRI allows better detection of the seizure onset zone, particularly when it is interpreted by experienced neuroradiologists. Ultra-high-field imaging and postprocessing analysis with automated machine learning algorithms can detect subtle structural abnormalities in MRI-negative patients. Tractography derived from diffusion tensor imaging can delineate white matter connections associated with epilepsy or eloquent function, thus, preventing deficits after epilepsy surgery. Arterial spin-labeling perfusion MRI, simultaneous electroencephalography (EEG)-functional MRI (fMRI), and magnetoencephalography (MEG) are noinvasive imaging modalities that can be used to localize the epileptogenic foci and assist in planning epilepsy surgery with positron emission tomography, ictal single-photon emission computed tomography, and intracranial EEG monitoring. MEG and fMRI can localize and lateralize the area of the cortex that is essential for language, motor, and memory function and identify its relationship with planned surgical resection sites to reduce the risk of neurological impairments. These advanced structural and functional imaging modalities can be combined with postprocessing methods to better understand the epileptic network and obtain valuable clinical information for predicting long-term outcomes in pediatric epilepsy.

• The Korean Journal of Nuclear Medicine
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• v.37 no.4
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• pp.229-234
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• 2003

Purpose: Since the prognosis of measles encephalitis is poor, early diagnosis and proper management are very important to improve clinical outcomes. We compared Tc-99m ECD brain SPECT (SPECT) with MR imaging (MRI) for the detection of acute measles encephalitis. Materials and Methods: Eleven patients(M : F=4 : 7, age range 18 months-14 yrs) with acute measles encephalitis were enrolled in this studies. All of them underwent both MRI and SPECT. The results of SPECT were scored from 0 (normal) to 3 (most severe defect) according to perfusion state. We compared two image modalities for the detection of brain abnormality in acute measles encephalitis. Results: Seven of 11 patients (63.6%) revealed high signal intensity in the white matter on T2WI of MRI, on the other hand all patients (100%) showed hypoperfusion on SPECT. Severe perfusion deficits above score 2 were located with decreasing frequencies in the frontal lobe (81.8%), temporal lobe (72.7%), occipital lobe (27.3%), basal ganglia (27.3%), and parietal lobe (9.1%). Conclusion: We conclude that SPECT is more useful than MRI for the detection of brain involvement in patients with acute measles encephalitis.

• Korean Journal of Radiology
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• v.20 no.6
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• pp.985-996
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• 2019

Objective: To determine the correlation between cerebral blood flow (CBF) on arterial spin labeling (ASL) MRI and the degree of postoperative revascularization assessed on digital subtraction angiography in children with moyamoya disease (MMD). Materials and Methods: Twenty-one children (9 boys and 12 girls; mean age, 8.4 ± 3.6 years; age range, 3-16 years) with MMD who underwent both pseudocontinuous ASL MRI at 1.5T and catheter angiography before and after superficial temporal artery encephaloduroarteriosynangiosis were included in this retrospective study. The degree of revascularization in the middle cerebral artery (MCA) territory was evaluated on external carotid angiography and was graded on a 3-point scale. On ASL CBF maps, regions of interest were manually drawn over the MCA territory of the operated side at the level of the centrum semi-ovale and over the cerebellum. The normalized CBF (nCBF) was calculated by dividing the CBF of the MCA territory by the CBF of the cerebellum. Changes in nCBFs were calculated by subtracting the preoperative nCBF values from the postoperative nCBF values. The correlation between nCBF changes measured with ASL and the revascularization grade from direct angiography was evaluated. Results: The nCBF value on the operated side increased after the operation (p = 0.001). The higher the degree of revascularization, the greater the nCBF change was: poor revascularization (grade 1), -0.043 ± 0.212; fair revascularization (grade 2), 0.345 ± 0.176; good revascularization (grade 3), 0.453 ± 0.182 (p = 0.005, Jockheere-Terpstra test). The interobserver agreement was excellent for the measured CBF values of the three readers (0.91-0.97). Conclusion: The nCBF values of the MCA territory obtained from ASL MRI increased after the revascularization procedure in children with MMD, and the degree of nCBF change showed a significant correlation with the degree of collateral formation evaluated via catheter angiography.

• 대한핵의학회:학술대회논문집
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• 1999.11a
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• pp.40.2-40.2
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• 1999

• Proceedings of the KSMRM Conference
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• 2005.09a
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• pp.45-46
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• 2005

• Proceedings of the KSMRM Conference
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• 2006.11a
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• pp.42-42
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• 2006

• Proceedings of the KSMRM Conference
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• 1999.11a
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• pp.103-103
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• 1999