• Korean Journal of Digital Imaging in Medicine
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• v.15 no.1
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• pp.27-31
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• 2013

Perfusion MR imaging is how to use exogenous and endogenous contrast agent. Exogenous perfusion MRI methods which are dynamic susceptibility contrast using $T2^*$ effect and dynamic contrast-enhanced using T1 weighted image after injection contrast media. An endogenous perfusion MRI method which is arterial spin labeling using arterial blood flow in body. In order to exam perfusion MRI in human, technical access are very important according to disease conditions. For instance, dynamic susceptibility contrast is used in patients with acute stroke because of short exam time, while dynamic susceptibility contrast or dynamic contrast enhancement provides the various perfusion information for patients with tumor, vascular stenosis. Arterial spin labeling is useful for children, women who are expected to be pregnant. In this regard, perfusion MR imaging is required to understanding, and the author would like to share information with clinical users

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.100-106
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• 2000

Purpose : To evaluate the usefulness of cerebral blood flow measurement applied to perfusion weighted image with short-scan time single shot gradient echo-planar technique in measuring cerebral blood volume(rCBV) of normal rabbits. Materials and methods : With 2.1-3.6 kg weighted rabbits, image is acquired when they are in supine position in children positioner. Perfusion weighted image is acquired to 44 seconds per 1 second successively. After 4 seconds later, Gd-DTPA 2ml are injected into int. jugular vein with 2 ml per second and normal saline is also injected after that. Same technique is applied 2 times per 30 minites in same rabbit. After Image is obtained in two part of cerebral cortex at vertex, convexity, in one of basal ganglia with choosing about $3-5{\textrm{mm}^2}$ areas. Curve of signal intensity changes in time sequence is drawn. After this images are transmitted by PC and software IDL, regional cerebral blood volume is measured with imaging processing program made by us. Results : With 22 of 24 rabbits, satisfactory 1-2 signal intensity versus time curve is made. Cerebral blood capacity and contrast media stay time (ST) is measured in two cerebral cortex and basal ganglia refering in parietal cerebral cortex. Mean focal cerebral blood flow capacity ratio in cortex was $0.97{\pm}0.35$ and in basal ganglia, $0.99{\pm}0.37$, mean contrast media stay time in cortex was $9.83{\pm}1.63$ sec and in basal gaiglia, $9.42{\pm}1.14$ sec, but there was no statistically significant difference between two areas ($\rho$=0.05). Conclusion : In cerebral cortex and basal ganglia, there is no difference in mean focal blood volume and mean contrast stay time. Therefore, PWI is useful in cerebral blood flow and early diagnosis, prognosis of cerebral ischemic disease. Hereafter, it is helpful in analysing cerebral blood flow changes with comparison difference in rCBV between normal tissue and ischemic tissue, and that with DWI finding in infarcted patient.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.25-33
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• 2014

Purpose : To investigate whether quantitative parameters derived from Diffusion-weighted magnetic resonance imaging (DW-MRI) correlate with those of Dynamic contrast-enhanced MRI (DCE-MRI). Materials and Methods: Thirteen patients with pathologically or clinically proven bony metastasis who had undergone MRI prior to treatment were included. The voxel size was $1.367{\times}1.367{\times}5mm$. A dominant tumor was selected and the apparent diffusion coefficient (ADC) value and DCE-MRI parameters were obtained by matching voxels. DCE-MRI data were analyzed yielding estimates of $K^{trans}$ (volume transfer constant) and $v_e$. (extravascular extracellular volume fraction). Statistical analysis of ADC, $K^{trans}$, and $v_e$ value was conducted using Pearson correlation analyses. Results: Fifteen lesions in pelvic bones were evaluated. Of these, 11 showed a statistically significant correlation (P<0.05) between ADC and $K^{trans}$. The ADC and $K^{trans}$ were inversely related in 7 lesions and positively related in 4 lesions. This did not depend on the primary cancer or site of metastasis. The ADC and $v_e$ of 9 lesions correlated significantly. Of these, 4 lesions were inversely related and 5 lesions were positively related. Conclusion: Unlike our theoretic hypothesis, there was no consistent correlation between ADC values and $K^{trans}$ or between ADC values and $v_e$ in metastatic bone tumors.

• Investigative Magnetic Resonance Imaging
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• v.11 no.1
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• pp.10-19
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• 2007

Conventional MRI methods using T1-, T2-, diffusion-, perfusion-weighting, and functional imaging rely on characterizing the physical and functional properties of the tissue. In this review, we introduce an imaging modality based on measured the mechanical properties of soft tissue, namely magnetic resonance elastography (MRE). The use of palpation to identify the stiffness of tissue remains a fundamental diagnostic tool. MRE can quantify the stiffness of the tissue thereby providing a objective means to measure the mechanical properties. To accomplish a successful clinical setting using MRE, hardware and software techniques in the area of transducer, pulse sequence, and imaging processing algorithm need to be developed. Transducer, a mechanical vibrator, is the core of MRE application to make wave propagate invivo. For this reason, considerations of the frame of human body, pressure and friction of the interface, and high magnetic field of a MRI system needs to be taken into account when designing a transducer. Given that the wave propagates through human body effectively, developing an appropriate pulse sequence is another important issue in obtaining an optimal image. In this review paper, we introduce the technical aspects needed for MRE experiments and introduce several applications of this new field.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.120-132
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• 2014

Purpose : To compare dynamic susceptibility contrast imaging, diffusion-weighted imaging, and susceptibility-weighted imaging (SWI) for the differentiation of tumor recurrence and delayed radiation therapy (RT)-related changes in patients treated with RT for primary brain tumors. Materials and Methods: We enrolled 24 patients treated with RT for various primary brain tumors, who showed newly appearing enhancing lesions more than one year after completion of RT on follow-up MRI. The enhancing-lesions were confirmed as recurrences (n=14) or RT-changes (n=10). We calculated the mean values of normalized cerebral blood volume (nCBV), apparent diffusion coefficient (ADC), and proportion of dark signal intensity on SWI (proSWI) for the enhancing-lesions. All the values between the two groups were compared using t-test. A multivariable logistic regression model was used to determine the best predictor of differential diagnosis. The cutoff value of the best predictor obtained from receiver-operating characteristic curve analysis was applied to calculate the sensitivity, specificity, and accuracy for the diagnosis. Results: The mean nCBV value was significantly higher in the recurrence group than in the RT-change group (P=.004), and the mean proSWI was significantly lower in the recurrence group (P<.001). However, no significant difference was observed in the mean ADC values between the two groups. A multivariable logistic regression analysis showed that proSWI was the only independent variable for the differentiation; the sensitivity, specificity, and accuracy were 78.6% (11 of 14), 100% (10 of 10), and 87.5% (21 of 24), respectively. Conclusion: The proSWI was the most promising parameter for the differentiation of newly developed enhancing-lesions more than one year after RT completion in brain tumor patients.

• The Korean Journal of Nuclear Medicine
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• v.25 no.1
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• pp.17-26
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• 1991

뇌 혈류의 기능적 영상화는 간질병소의 국소화에 이용되고 있으며 측두엽성간질의 편측화에 여러가지 진단 방법이 이용되고 있으나 만족할만한 결과를 보이지 못하고 있다. 최근 PET또는 SPECT를 이용하여 측두엽성간질에서 발작 간에 측두엽 병소의 대사율 및 혈류의 감소가 나타나며, 이러한 소견은 발작 유발 병소의 편측화에 매우 유용할것이라는 보고들이 있다. 저자들은 측두엽성간질에서 간질 병소를 편측화 하는데에 $^{99m}Tc-HMPAO$ SPECT의 유용성을 평가 하고자 측두엽성간질 31예에서 발작 간의 $^{99m}Tc-HMPAO$ SPECT 소견, 뇌파, 자기 공명 영상 및 전산화 단층 소견을 비교하였다. SPECT 소견에 따른 나이, 병력 기간과 병발시 나이 등의 임상 지수 간에는 유의한 차이가 없었다. 31예의 환자중 23예에서(74.2%) 국소 뇌 혈류 감소를 보였으며 17예(54.8%)에서 측두엽에 관류 감소가 관찰 되었다. 비인두 뇌파 표준 뇌파는 24예(77.4%)에서 측두엽에 편측화를 보였으며 SPECT와 뇌파 양자가 모두 편측화된 경우 일치도는 8/12예 (66.7%) 였다. 16예에서 시행된 전산화 단층 영상은 모두 편측화를 보이지 못했으며 27예에서 시행된 자기 공명 영상에서는 단지 1예에서 편측화를 보였다. 이상의 결과로서 발작 간의 $^{99m}Tc-HMPAO$ SPECT는 측두엽성간질 병소의 편측화에 유용한 보조 검사로 생각된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.84-87
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• 2017

Cerebral hyperperfusion syndrome (CHS) is a rare complication that can occur when conducting stent insertion or endarterectomy in patients with carotid artery stenosis and is known to be caused by various mechanisms when the blood volume abruptly increases. The main clinical symptoms are unilateral headache, hypertension, seizure, and focal neurologic deficit. Subarachnoid hemorrhage and parenchymal hemorrhage may lead to permanent impairment or death in severe cases. CHS can be predicted by using transcranial Doppler, perfusion magnetic resonance imaging, and single photon emission computed tomography. In our case report, a patient developed CHS subsequent to significant venous congestion caused by carotid artery stent insertion. The patient had preexisting, symptomatic bilateral carotid artery stenosis. Venous congestion occurs when the direction of blood flow changes because of increased blood volume in patients with well-developed collateral vessels. We believe that CHS can be predicted from this finding. This study reports the possibility that CHS could be confirmed by cerebral angiography after insertion of the internal carotid stent.

• Journal of radiological science and technology
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• v.26 no.3
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• pp.25-31
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• 2003

This study was performed to evaluate the usefulness of Deconvolution perfusion CT in patients with acute cerebral infarction. Nine patients with acute cerebral infarction underwent conventional CT and cerebral perfusion CT within 23 hours of the onset of symptoms. The perfusion CT scan for each patient was obtained at the levels of basal ganglia and 1cm caudal to the basal ganglia. By special imaging software, perfusion images including cerebral blood volume(CBV), cerebral blood flow(CBF), and mean transit time(MTT) maps were created. The created lesions were evaluated on each perfusion maps by 3 radiolocical technician. MTT delay time was measured in the perfusion defect lesion and symmetric contralateral normal cerebral hemisphere. Lesion sire were measured on each perfusion map and compared with the value obtained by diffusion weighted MR imaging(DWMRI). All perfusion CT maps showed the perfusion defect lesion in all patients. There were remarkable CT delay in perfusion defect lesion. In comparison of lesion size between each perfusion map and DWMRI, the lesion on CBF map was the most closely correlated with the lesion on DWMRI(7/9). The size of perfusion defect lesion on MTT map was larger than that of lesion on DWMRI, suggesting that m map can evaluate the ischemic penumbra. Deconvolution Perfusion CT maps make it possible to evaluate not only ischemic core and ischemic penumbra but also hemodynamic status in perfusion defect area. These results demonstrate that perfusion CT can be useful to the diagnosis and treatment in the patients with acute cerebral ischemic infarction.

• The Korean Journal of Nuclear Medicine
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• v.30 no.1
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• pp.56-64
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• 1996

The purpose of this study was to evaluate the characteristic perfusion changes in patients with Sturge-Weber syndrome by comparison of the findings of brain MR images and perfusion SPECT images. $^{99m}Tc$-HMPAO or $^{99m}Tc$-ECD interictal brain SPECTs were performed on 5 pediatric patients with Sturge-Weber syndrome within 2 weeks after MR imaging. Brain SPECTs of three patients without calcification showed diminished perfusion in the affected area on MR image. A 3 month-old patient without brain atrophy or calcification demonstrated paradoxical hyperperfusion in the affected hemisphere, and follow-up perfusion SPECT revealed decreased perfusion in the same area. The other patient with advanced calcified lesion and atrophy on MR image showed diffusely decreased perfusion in the affected hemisphere, but a focal area of increased perfusion was also noted in the ipsilateral temporal lobe on SPECT. In conclusion, brain perfusion of the affected area of Sturge-Weber syndrome patients was usually diminished, but early or advanced patients may show paradoxical diffuse or focal hyperperfusion in the affected hemisphere. Further studies are needed for better understanding of these perfusion changes and pathophysiology of Sturge-Weber syndrome.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.117-120
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• 2006

Atretic cephalocelces are defined as skin-covered midline subscalp lesions that contain meninges and rest of glial and/or central nervous system tissue. When the straight sinus is absent or rudimentary, the falcine sinus can be recanalized to enable venous drainage. Although the atretic cephalocele or persistent falcine sinus has largely been described in the pediatric population, it is a rarely observed in the adult population. We report a unique case of spontaneously involuted atretic cephalocele coexistent with persistent falcine sinus in an adult. MR images and MR venography were useful for diagnosis and accurate anatomical depiction.