• 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 radiological science and technology
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• v.26 no.1
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• pp.71-82
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• 2003

In this paper, I proposed a classifier of liver cirrhotic step using T1-weighted MRI(magnetic resonance imaging) and hierarchical neural network. The data sets for classification of each stage, which were normal, 1type, 2type and 3type, were obtained in Pusan National University Hospital from June 2001 to december 2001. And the number of data was 46. We extracted liver region and nodule region from T1-weighted MR liver image. Then objective interpretation classifier of liver cirrhotic steps in T1-weighted MR liver images. Liver cirrhosis classifier implemented using hierarchical neural network which gray-level analysis and texture feature descriptors to distinguish normal liver and 3 types of liver cirrhosis. Then proposed Neural network classifier teamed through error back-propagation algorithm. A classifying result shows that recognition rate of normal is 100%, 1type is 82.3%, 2type is 86.7%, 3type is 83.7%. The recognition ratio very high, when compared between the result of obtained quantified data to that of doctors decision data and neural network classifier value. If enough data is offered and other parameter is considered, this paper according to we expected that neural network as well as human experts and could be useful as clinical decision support tool for liver cirrhosis patients.

• Annals of Clinical Neurophysiology
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• v.4 no.2
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• pp.114-118
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• 2002

Backgrounds : Carpal tunnel syndrome (CTS) is a common condition that is usually diagnosed by electrophysiologic studies. However, CTS provide limited information to determine the causes of CTS and to choose the treatment method. We evaluated diagnostic sensitivity of MR imaging and treatment decisions by MR imaging in electrodiagnosed CTS. Methods : 14 patients (26 wrists) with electrodiagnosed CTS were studied using MR imaging. In 26 wrists for which axial T1 & T2 weighted images were obtained at 1.5T with a decided wrist coil. Previously described MR imaging of CTS such as increased median nerve signal, flattening of median nerve, reticular bowing, tenosynovitis and space occupying lesions were retrospectively evaluated. Degree of improvement was evaluated by global symptom score (GSS). The GSS rated symptoms from 0 (no symptoms) to 10 (severe) in each of five categories: pain, numbness, paresthesia, weakness/clumsiness, and nocturnal awakening. Subjects' GSS was recorded at baseline, 2 weeks, 1 month, 6 months after treatment. We decided to medical treatment that showed mainly inflammatory sign such as increased median nerve signal, tenosinovitis and to surgical treatment such as space occupying lesion, high canal pressure sign. Results : MR imaging showed that increased median nerve signal were in 20 wrists (77%), flattening of median nerve were in 6 wrists (23%), reticular bowing were in 3 wrists (12%), tenosynovitis were in 8 wrists (32%), decreased canal size in 2 wrists (7.6%), space occupying lesion were in 1 wrist (4%). A good outcome was revealed in 21 wrists by medical treatment that showed mainly increased median nerve signal, tenosynovitis. The mean GSS were 27.7 at baseline, 11.2 at 2 weeks, 11.0 at 6 months in medical treatment group. Another 5 wrist had surgical treatment shown by ganglion and high canal pressure sign such as median nerve flattening, reticular bowing, decreased canal size: 3 wrists had good prognosis, but 2 wrists (one patient) had no significant improvement due to small carpal tunnel size. Conclusions : Our results are in agreement with most previously described MR imaging signs of CTS. MR imaging plays an important role in several cases and especially in the assessment of failure of surgical treatment. Knowledge of MR findings may permit more rational choice of treatment.

• Progress in Medical Physics
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• v.11 no.2
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• pp.109-116
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• 2000

One consideration of radiation delivery in cervical cancer is the complication of critical organs, e.g., bladder and rectum. The absorbed dose of bladder and rectum in HDR intracavitary brachytherapy is measured indirectly with TLD dosimetry A method for the complication reduction of bladder and rectum is suggested. For two-hundred cervical cancer patients, follow-up MRI images were reviewed and distances from cervical central axis to bladder and rectum and vaginal wall thickness were measured. The sealed TLDs were placed upon the gauze packing of the ovoids and the distances to the TLDs from the ovoid center were measured in the simulation film and actual doses of bladder and rectum were calculated. From published data, maximal tolerance doses of bladder and rectum were derived and based on the permissible doses per fraction in HDR brachytherapy the packing thicknesses were determined in both directions. The required minimal packing thicknesses for bladder and rectum were 0.43 and 0.92 cm, respectively. The results were compared with computer calculation using the Meisberger polynomial approach. It is our hope this study can be used for a guideline for users in clinic in estimating critical organ dose in bladder and rectum in HDR brachytherapy in vivo dosimetry.

• Investigative Magnetic Resonance Imaging
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• v.3 no.1
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• pp.78-83
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• 1999

Purpose : To evaluate the language areas activated by fMRI during different reading tasks and to assess the difference of activated areas according to each reading task. Materials and Methods : Functional maps of the language area were obtained during three reading tasks(Korean consonant letter, pseudoword, and word) in nine right-handed volunteers(7 males 2 females). MR examinations were performed at 1.5T scanner with EPI BOLD technique(gradient echo shot EPI, TR/TE 3000/60, flip angle $90^{\circ}$, matrix $64{\times}64$, 5mm thickness, no slice gap). Each task consisted of three resting periods and two activation periods and each period lasted 30 seconds. We used SPM program for the postprocessing of images and signification level was set at p<0.01. Activated areas were topographically analyzed in each stimulus. Results : Significant activated signals were demonstrated in all volunteers. Activated signals were seen in the frontal, temporal, parietal and occipital lobes during reading tasks and they were lateralized to the left hemisphere except occipital lobe. Letter and pseudoword produced stronger activated signals than word, and the activated signals were more lateralized to the left hemisphere in pseudoword reading than in letter reading. Conclusion : Activated signals were induced in the language areas by reading task of letter or wordform. Greater activation of language areas was induced when letter or pseudowords were presented than familiar words.

• Korean Journal of Biological Psychiatry
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• v.10 no.2
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• pp.168-176
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• 2003

Objectives:We investigated the characteristics of P300 generators in obsessive-compulsive disorder(OCD) patients by using voxel-based statistical parametric mapping of current density images. Methods:P300 generators, produced by a rare target tone of 1500Hz under a frequent non-target tone of 1,000Hz, were measured in 15 right-handed OCD patients and 15 controls. Low Resolution Electromagnetic Tomography(LORETA), using a realistic head model of the boundary element method based on individual MRI, was applied to the 128-channel EEG. Statistical parametric mapping(SPM) was applied for the statistical analysis. Results:We found that both groups had the mean current density of P300 in the parietal, temporal and prefrontal lobe. There was a trend for decreased current density in the prefrontal area in OCD patients. The statistical comparison showed current density increase in the supraparietal area, a statistically significant longer P300 latency and a trend for reduced P300 amplitude in OCD patients. Conclusion:It suggests that P300 source of both groups exists in multiple brain regions at the same time. And both groups had no statistically significant differences in the current density of P300 except for increased current density in the supraparietal area in OCD patients. But, considering the statistically significant longer P300 latency, a trend for reduced P300 amplitude and relative mean current density reduction in the prefrontal area in OCD patients, this study suggests that the frontal lobe may have a reduced normal inhibitory process in OCD patients.

• Journal of Korean Neurosurgical Society
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• v.30 no.4
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• pp.451-455
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• 2001

Objectives : There have been several studies documenting the changing level of the conus throughout infancy and childhood, but there is only a little detailed study that documents the range of conus positions in a living adult population, especially in Korean, without spinal deformity. Methods : we made a sequential study of magnetic resonance images of the lumbar spine to determine the variation in position of the conus medullaris in 650 living korean adults population without spinal deformity who checked MRI to identify the cause of low back pain. The study population consisted of patients over the age of 16 years. A T1-weighted, midline, sagittal image was reviewed for identifying the postion of conus. This location was recorded in relation to the upper, middle, or lower third of the adjacent vertebral body or the adjacent intervertebral disc. Results : The study group consisted of 305 men(47%) and 345 women(53%) with a mean age 45.9 years(range, 16-79 years). The conus existed commonly at the middle third of L1(131cases, 20.2%), at the L1-2 intervertebral space(129cases, 19.8%), and the lower third of L1(123cases, 18.9%). The mean position of conus was the lower third of L1(range, middle third of T12 to middle third of L3). Conclusions : The mean position of conus was at the lower third of L1(range, middle third of T12 to middle third of L3). This results was same as that of foreign study. Our results of living korean adult population could allow for safe clinical procedures such as lumbar puncture, spinal anesthesia, and help to explain the differences among observed neurologic injuries from fracture-dislocation at the thoracolumbar junction.

• Journal of Korean Neurosurgical Society
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• v.59 no.6
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• pp.577-583
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• 2016

Objective : The inter-rater reliability of the modified Knosp's classification was measured before the analysis. The clinical validity of the parasellar extension grading system was evaluated by investigating the extents of resection and complication rates among the grades in the endoscopic endonasal transsphenoidal surgery (EETS) for pituitary adenomas. Methods : From November 2008 to August 2015, of the 286 patients who underwent EETS by the senior author, 208 were pituitary adenoma cases (146 non-functioning pituitary adenomas, 10 adrenocorticotropic hormone-secreting adenomas, 31 growth hormone-secreting adenomas, 17 prolactin-secreting adenomas, and 4 thyroid-stimulating hormone-secreting adenomas; 23 microadenomas, 174 macroadenomas, and 11 giant adenomas). Two neurosurgeons and a neuroradiologist independently measured the degree of parasellar extension on the preoperative sellar MRI according to the modified Knosp's classification. Inter-rater reliability was statistically assessed by measuring the intraclass correlation coefficient. The extents of resection were evaluated by comparison of the pre- and post-operative MR images; the neurovascular complications were assessed by reviewing the patients' medical records. The extent of resection was measured in each parasellar extension grade; thereafter, their statistical differences were calculated. Results : The intraclass correlation coefficient value of reliability across the three raters amounted to 0.862. The gross total removal (GTR) rates achieved in each grade were 70.0, 69.8, 62.9, 21.4, 37.5, and 4.3% in Grades 0, 1, 2, 3A, 3B, and 4, respectively. A significant difference in the extent of resection was observed only between Grades 2 and 3A. In addition, significantly higher complication rates were observed in the groups above Grade 3A. Conclusion : Although the modified Knosp's classification system appears to be complex, its inter-rater reliability proves to be excellent. Regarding the clinical validity of the parasellar extension grading system, Grades 3A, 3B, and 4 have a negative predictive value for the GTR rate, with higher complication rates.

• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.155-160
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• 1993

The identification of viable myocardium in patients with coronary artery disease and left ventricular dysfunction is an issue of increasing clinical relavance in the current era of myocardial revascularization. There are at least two forms of reversible myocardial dysfunction. Early reperfusion does not always lead to immediate functional improvement; rather, the return of contractility in tissue salvaged by reperfusion is delayed for hours, days or even weeks, a phenomenon that has been termed "stunned myocardium". Some patients with coronary artery disease show myocardial dysfunction at rest which are associated with reduced perfusion, and which disappear after revascularization; this phenomenon has been termed "hibernating myocardium". Recently, cardiac imaging techniques that evaluate myocardial viability on the basis of perfusion-contraction mismatch and inotropic reserve have gained substantial popularity and clinical success. This review focus on the application of $^{201}TI$ and $^{99m}Tc-MIBI$ to address myocardial viability in patients with hibernating and stunned myocardium. It is clear that 4-hour redistribution images of $^{201}TI$ underestimate ischemia and overestimate scar. Delayed imaging and reinjection imaging have been developed for the assessment of viability. Among many protocols suggested, stress-redistribution-reinjection imaging gained most popularity. Although $^{99m}Tc-MIBI$ could identify myocardial viability, $^{201}TI$ reinjection technique was regarded as superior to it. In conclusion, $^{201}TI$ stress, 4-hr rest redistribution, and reinjection imaging technique may be the most preferable method for evaluation of myocardial viability.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.5
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• pp.462-469
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• 2000

Positron Emission Tomography(PET) is a new diagnostic method that can create functional images of the distribution of positron emitting radionuclides, which when administered intravenously in the body, makes possible anatomical and functional analysis by quantity of biochemical and physiological process. After genetic and biochemical changes in initial stage, malignant tumor undergoes functional changes before undergoing anatomical changes. So, early diagnosis of malignant tumors by functional analysis with PET can be achieved, replacing traditional anatomical analysis, such as computed tomography(CT) and magnetic resonance image(MRI), etc. Similarly, PET can identify malignant tumor without confusion with scar and fibrosis in follow up check. In the Korea Cancer Center Hospital(KCCH) from October 1997 to September 1999, clinical study was performed in 79 cases that underwent 89 times PET evaluation with [18F]-Fluorodeoxyglucose for diagnosis of oral and maxillofacial tumors, and the data was analysed by Bayesian $2{\times}2$ Classification Table. The results were as follows : Evaluation for initial diagnosis with FDG-PET (P<0.005) 1. Agreement rate or accuracy rate is 88.9%. 2. Sensitivity is 95.2%, and specificity 66.7%. 3. Positive predictive rate is 90.9%, and negative predictive rate 80.0%. 4. In consideration of tumor stage, diagnostic rate in less than stage II was 90% and in greater than stage III 100%. 5. In consideration of tumor size, diagnostic rate in less than T2 was 92.3% and in greater than T3 100%. After primary treatment, evaluation for follow up check with FDG-PET (P < 0.001) 1. Agreement rate or accuracy rate is 85.4%. 2. Sensitivity is 87.5%, and specificity 82.4%. 3. Positive predictive rate is 87.5%, and negative predictive rate 82.4%. 4. In 24 recurred cases, 6 had distant metastasis, and 5 of them were diagnosed with FDG-PET, resulting in diagnostic rate of FDG-PET of 83.3%. From the above results, Positron Emission Tomography with [18F]- Fluorodeoxyglucose appears to be more sensitive and accurate for detecting the presence of oral and maxillofacial tumors, and has various clinical applications such as early diagnosis of tumor in initial and follow up check and detection of distant metastasis.