• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.109-113
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• 1997

Purpose: To evaluate the differences of functional imaging patterns between conventional spoiled gradient echo (SPGR) and echo planar imaging (EPI) methods in cerebral motor cortex activation. Materials and Methods: Functional MR imaging of cerebral motor cortex activation was examined on a 1.5T MR unit with SPGR (TRfrE/flip angle=50ms/4Oms/$30^{\circ}$, FOV=300mm, matrix $size=256{\times}256$, slice thickness=5mm) and an interleaved single shot gradient echo EPI (TRfrE/flip angle = 3000ms/40ms/$90^{\circ}$, FOV=300mm, matrix $size=128{\times}128$, slice thickness=5mm) techniques in five male healthy volunteers. A total of 160 images in one slice and 960 images in 6 slices were obtained with SPGR and EPI, respectively. A right finger movement was accomplished with a paradigm of an 8 activation/ 8 rest periods. The cross-correlation was used for a statistical mapping algorithm. We evaluated any differences of the time series and the signal intensity changes between the rest and activation periods obtained with two techniques. Also, the locations and areas of the activation sites were compared between two techniques. Results: The activation sites in the motor cortex were accurately localized with both methods. In the signal intensity changes between the rest and activation periods at the activation regions, no significant differences were found between EPI and SPGR. Signal to noise ratio (SNR) of the time series data was higher in EPI than in SPGR by two folds. Also, larger pixels were distributed over small p-values at the activation sites in EPI. Conclusions: Good quality functional MR imaging of the cerebral motor cortex activation could be obtained with both SPGR and EPI. However, EPI is preferable because it provides more precise information on hemodynamics related to neural activities than SPGR due to high sensitivity.

• Investigative Magnetic Resonance Imaging
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• v.18 no.4
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• pp.332-340
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• 2014

Purpose : A relative increase in deoxyhemoglobin levels in hypoperfused tissue can cause prominent hypointense signals in the draining veins (PHSV) within areas of impaired perfusion in susceptibility-weighted imaging (SWI). The purpose of this study is to evaluate the usefulness of SWI in patients with acute cerebral infarction by evaluating PHSV within areas of impaired perfusion and to investigate the usefulness of PHSV in predicting prognosis of cerebral infarction. Materials and Methods: In 18 patients with acute cerebral infarction who underwent brain MRI with diffusion-weighted imaging and SWI and follow-up brain MRI or CT, we reviewed the presence and location of the PHSV within and adjacent to areas of cerebral infarction qualitatively and measured the signal intensity difference ratio of PHSVs to contralateral normal appearing cortical veins quantitatively on SWI. The relationship between the presence of the PHSV and the change in the extent of infarction in follow-up images was analyzed. Results: Of the 18 patients, 10 patients showed progression of the infarction, and 8 patients showed little change on follow- up imaging. On SWI, of the 10 patients with progression 9 patients showed peripheral PHSV and the newly developed infarctions corresponded well to area with peripheral PHSV on initial SWI. Only one patient without peripheral PHSV showed progression of the infarct. The patients with infarction progression revealed significantly higher presence of peripheral PHSV (p=0.0001) and higher mean signal intensity difference ratio (p=0.006) comparing to the patients with little change. Conclusion: SWI can demonstrate a peripheral PHSV as a marker of penumbra and with this finding we can predict the prognosis of acute infarction. The signal intensity difference of PHSV to brain tissue on SWI can be used in predicting prognosis of acute cerebral infarction.

• The korean journal of orthodontics
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• v.33 no.3 s.98
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• pp.211-222
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• 2003

The purpose of this study was to determine whether there is an association between disk displacement of the Temporomandibular Joint (TMJ) and dentofacial asymmetry In orthodontic patients. The subjects consisted of 60 female orthodontic patients between the ages of 18 and 38 years (mean age 23.3 years) who had visited the Department of Orthodontics at Seoul National University Dental Hospital from January 2000 to April 2002. On the basis of magnetic resonance imaging (MRI) of their bilateral TMJs, the subjects were divided Into four groups'. bilateral normal group (twenty-one persons); disk displacement of right TMJ group (six persons); disk displacement of left TMJ group (nine persons); and disk displacement of both TMJs group (twenty-four persons) Postero-anterior (PA) cephalograms and diagnostic models which had been taken before orthodontic treatment were measured. In the linear measurements, a line connecting the right and left Latero-Orbitale (Lo) represented the horizontal reference line (H). The vertical reference line (V) was constructed as a line bisecting and running perpendicular to H. One-way analysis of variance (ANOVA) was used to test whether the mean values of measurements between groups were significantly different. In addition, Bonferronil's multiple comparison test was performed at a level of 0.05. The results were as follows; 1 In the diagnostic model analysis, the overjet, nght molar relationship, and left molar relationship were significantly different among the four groups. 2. In the PA cephalometric analysis, differences in the right and left vertical position of the lower first molar and Ag were significantly dissimilar among the four groups. 3. If the disk displacement of TMJ was present on one side, the ipsilateral ramus was shorter, resulting in asymmetry in the vertical position of Ag. This study indicated that dentofacial asymmetry might be related to the disk displacement of TMJ.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.129-136
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• 2002

Purpose : To evaluate the usefulness of MRCP in the diagnosis of the variable causes of common bile duct(CBD) dilatation, except stone or tumor Materials and methods : Twenty-six patients(M:F=15:11, mean age; 62 years) with both MRCP and ERCP were included in this study. Dynamic MRCP(n=12) and contrast-enhanced MRI(n=10) of abdomen were also added. Dilatation of CBD, intrahepatic ducts and pancreatic duct was evaluated, including coexistence of intrahepatic ductal stone, pancreatic pseudocyst, and papillary or papillary edema. The criteria of CBD dilatation was over than 7mm(n= 21, without cholecystectomy) or 10 mm(n=5, with cholecystecto-my) in diameter on T2-weighted coronal image. Results : The mean diameter of CBD was 12.7mm without cholecystectomy(9-19 mm) and 13.0 mm with cholecystectomy(10-15mm), respectively(p 〉0.05). Cholangitis(n=11, 42.3%), chronic pancreatitis(n=8, 30.8%), stenosis of distal CBD(n= 6, 23.1%), periampullary diverticulum(n=3, 11.5%), stenosis of ampulla of Vater(n=2, 7.7%), dysfunction of sphincter of Oddi(n=2, 7.7%), acute focal pancreatitis in the pancreatic head(n=2, 7.7%), papillitis(n=1, 3.8%), pseudocyst in the pancre atic head(n = 1, 3.8%), and ascaris in CBD(n=1, 3.8%) were noted. Pancreatic duct dilatation(n=10, 38.5%) and duodenal diverticulum(n=3, 11.5%) were also seen on MRC P. On dynamic MRCP(12 patients), distal CBD was visualized in 2 patients(16.7%), which was not shown on routine MRCP. Only 1 patient(10.0%) showed papillitis with slightly enhancing papilla on contrast-enhanced MRI (10 patients). Conclusion : MRCP was thought to be helpful in the evaluation of the causes of CBD dilatation, not caused by stone or tumor, especially in the cases of stenosis of distal CBD and chronic pancreatitis, dysfunction of sphincter of Oddi on dynamic MRCP and cholangitis and pericholangitic abnormality on contrast-enhanced MRI.

• Korean Journal of Acupuncture
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• v.31 no.1
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• pp.20-32
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• 2014

Objectives : There has been some controversy about the modulatory effects on brain function during acupuncture on each side of the same acupoint. This study was designed to investigate and compare the blood oxygen level-dependent(BOLD) responses of acupuncture on each side of ST36. Methods : Fourteen healthy subjects were recruited for imaging and received acupuncture or placebo stimulations either on the left or on the right acupoint of ST36 in each scan. For the voxel-wise statistical analysis, one sample T-test and the within-subject analysis of variance(ANOVA) test were performed using SPM8 software. Results : This study showed that acupuncture on each side of ST36 showed different BOLD signal patterns. Higher BOLD responses after acupuncture stimulations at the left ST36 compared to the right were observed mainly in the parahippocampal gyrus(BA 28), dorsolateral prefrontal cortex(DLPFC, BA 44), thalamus, culmen and claustrum. We investigated the different neural responses between rest and activation periods of placebo and acupuncture stimulations on each side of ST36. Acupuncture at the right ST36 elicited activation mainly in the insula, supplementary motor area(SMA) and anterior cingulate cortex(ACC), while acupuncture at the left ST36 elicited activation mainly in the insula, primary somatosensory cortex(SI, BA 2) and DLPFC(BA 44). Conclusions : To our knowledge, this is the first reported functional MRI study directly comparing when needling at the right and at the left side of ST36. This study's preliminary results proved to be evidence of acupuncture's different effects when performed on opposite sides of an acupoint.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.104-112
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• 1998

Purpose : To evaluate the clinical utility of diffusion-weighted imaging by analyzing the signal intersity of lesions in patients with various intracranial diseases. Materials and Methods : difusion-weighted MR imaging was prospectively perormed in randomly selected 70 patients with various intracranial idseases. They consisted of 20 patients with acute infarct, 21 patients with chronic infarct of small vessel disease, 14 patients with primary intracranial tumor, three patients with brain metastasis, five patient with brain abscess, five patients with brain abscess, five patients with cerebral hemorrhage, one patient with neurocysticercosis, and one patient with epidermoid cyst. the diffusion-weighted images were obtained immediately after routine T2-weighted imaging on a 1.5T MR unit using single shot spin echo EPI technique with 6500 ms TR, 107ms TE, $128{\times}128$ matrix, 1 number of excitation, $24{\times}24$ field of view, 5-7 mm slice thickness, 2-3 mm inter-slice gap. The diffusion-gradients (b value of ($1000s{\;}/{\;}textrm{mm}^2$)) were applied along three directions(x, y, z). On visual inspection of diffusion-weighted images, the signal intersity of lesions was arbitrarily graded as one of 5 grades. In quantitative assessment, we measured the signal intensity of all the lesions and the contralateral corresponding normal area using round region of interest(ROI), and then calculated the signal intensity ratio of the lesion to the normal brain parenchyma. Results : On visual inspection, markedly hyperintense signals were seen in all cases of acute infarct, brain abscess, epidermoid cyst, and neurocysticercosis in degenerating stage. In all cases of cerebral hematoma, the very high signal internsity was intermingled with low signal intensity. focal very high signal intersity was also seen in a solid portion of the tumor in a patient. the mean signal intensity ratios of all those lesions to the normal brain parenchyma were above 2.5. Gliosis, solid component of brain tumor, brain metastasis, and vasogenic dedma appeared isointense to the normal brain parenchyma in 71%, 64%, 100%, and 67%, respectively ; the mean signal intensity ratios of those lesions to the normal brain parenchyma ranged 1.15 to 1.28 and there was no significant difference among these(p>0.1). Cystic cerebromalacia and necrotic or cystic portions in tumor were markedly or slightly hypointense, and the mean signal intensity ratios were 0.45 and 0.42, respectively. Conclusion : Very high signal intensity of acute infarct, brain abscess, epidermoid cyst, and cystic neurocysticercosis in degenerating stage on diffusion-weighted images may be helpful in differentiating from other diseases that are hypointense or isointense to the normal brain parenchyma. It may be especially useful differentiation of brain abscess from brain tumor with necrotic or cystic portion.

• Journal of the Korean Society of Radiology
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• v.5 no.5
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• pp.289-294
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• 2011

The aim of this study is to evaluate the differences of ejection fraction of left ventricle through the quantitative analysis of diastolic and systolic volumes according to slices selected using cardiac MR imaging. A total of 12 volunteers (7 normal, 1 myocardium bridge, and 4 arrhythmia) underwent cardiac MRI on a MR scanner(Magnetom Trio, Siemens, Germany). Ejection fractions for quantitative analysis were calculated at single slice of center of left ventricle, 3, 5, and 6-7 slices extending from the center of left ventricle. Average values were analyzed for evaluating differences of ejection fraction according to the number of slices selected. Mean value of normal person of ejection fraction were 67.14% at single slice of center of left ventricle, 66.24% at 3 slices, 65.63% at 5 slices, and 65.29% at 6-7 slices. While ejection fraction obtained from a patient with 61.74% at single slice of center of left ventricle, 60.92% at 3 slices, 60.89% at 5 slices, and 61.89% at 6-7 slices. There was no significant differences by the number of slices selected. This study demonstrates that ejection fraction obtained from single slice of center of left ventricle may represent a optimum parameter for cardiac function, instead of the value calculated on the variable slices selected.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4380-4386
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• 2014

This study was conducted to minimize the imaging distortion by reducing the differences in susceptibility between the tissue and air surrounding it while performing a thyroid diffusion imaging procedure. The study group was composed of 23 healthy adults. Thyroids with many distortions near the air, larynx, and trachea were chosen to test and evaluate the diffusion imaging difference between before and after an application of silicon. As a result, there was reduced distortion with silicon application, and the differences decreased from 30% to 10%. According to One-way ANOVA and Duncan's post-hoc test, there were no significant differences between imaging with a silicon application and T2 imaging of the surface area, which was the standard image. In conclusion, this study presented a radical improvement in reducing the distortions in imaging by compensating for an uneven tissue surface near air without affecting the magnetic resonance contrast and complicating the imaging processes.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.599-606
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• 2013

The purpose of this study is to know a clinical usefulness for delineation of articular cartilage compared with 2D TSE-SPIR and 3D FFE-PROSET technique. From January 2013 to september 2013, a total of 30 normal volunteers(12 men and 18 women aged between 35 and 55 years; mean 49.48 years) were studied on a philips 3.0T MRI scanner. As a quantitative analysis, SNRs and CNRs were evaluated by using two methods for delineation of articular cartilage. As a qualitative analysis, image quality was evaluated by special radiological technologist of MRI for image delineation on a three grade. As a results, SNRs and CNRs for articular cartilage were significantly greater for the 3D FFE-PROSET(SNRs: 8.40, 114.02, 9.53, CNRs: 104.49, 139.49) technique compared to 2D TSE-SPIR(SNRs: 4.41, 71.63, 7.34, CNRs: 64.30, 58.41) technique, image quality also was higher for evaluation of 3D FFE-PROSET(2.40) technique(p=0.0021). In conclusion, this study showed that a 3D FFE-PROSET MRI has improved SNRs and CNRs for evaluating of the articular cartilage, these conclusions in the future will be provided useful information in diagnosis of articular cartilage.

• 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.