• Journal of Korean Neurosurgical Society
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• v.30 no.4
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• pp.472-478
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• 2001

Objectives : The authors present a retrospective analysis of 100 consecutive adult patients harboring craniopharyngiomas who underwent microsurgical resection between 1981 and 1999 to assess the long-term outcome of surgical treatment and to determine the most optimal management strategy. Methods : The extent of surgical removal was divided into four categories ; GTR(gross total removal), RSTR(radical subtotal removal), STR(subtotal removal),and PR(partial removal). The median follow-up period was 50 months(4-198). CT scan and/or MR imaging and hormonal status were evaluated to the last follow-up. Results : Visual disturbance was the most common presentation, which was improved in 42 cases and aggravated in 19 cases following the operation. Hypopituitarism was detected in 56 patients preoperatively, 82 during the immediate postoperative period, and 76 at the last follow-up. Improvement of pituitary function was not observed in any of these patients. Twenty of 100 patients showed recurrence at the mean of 27 months(3 to 196). The median progression-free survival(PFS) time of all patients was 145 months and 5-year PFS rate was 74%. Five-year PFS rate of GTR or RSTR group(71%) was significantly higher than that of STR or PR group(30%)(p=0.01). Postoperative radiation therapy significantly prolonged the PFS from 94 months in non-radiation group to 182 months(p=0.002). However, there was no statistical difference in number of patients who required hormonal replacement therapy between radiation and non-radiation group. Conclusion : Visual disturbance can be improved by early diagnosis and surgical decompression. GTR or RSTR in selected patients is considered a proper surgical strategy. Post-operative radiation therapy for residual tumors must be considered, although the ideal timing of radiation therapy is to be determined.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.558-574
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• 2014

The number of fatty liver patients is sharply growing due to the rapid increase in the incidence of metabolic syndrome, which can lead to diseases such as abdominal obesity, hypertension, diabetes, and hyperlipidemia. Early diagnosis requires examinations using magnetic resonance imaging (MRI), wherein quantitative analyses are implemented through a professional water-fat separation method in many cases, as the intensity values of the areas of interest and non-interest are considerably similar or the same. However, such separation method generates inaccurate results in high magnetic fields, where the inhomogeneity of the fields increases. To overcome the limits of such conventional fat quantification methods, this paper proposes a field map estimation method that is effective in high magnetic fields. This method generates field maps through echo images that are obtained using the existing IDEAL sequences, and considers the wrapping degree of the field maps. Then clustering is performed to separate calibration areas, the least square fits based on the region growing method schema of the separated calibration areas, and the histograms are adjusted to separate the water from the fats. In experiment results, our proposed method had a superior fat detection rate of an average of 86.4%, compared to the ideal method with an average of 61.5% and Yu's method with an average of 62.6%. In addition, it was confirmed that the proposed method had a more accurate water detection rate of 98.4% on the average than the 88.6% average of the fat saturation method.

• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.130-138
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• 2011

Purpose : To compare fMRIs of visual and auditory word generation tasks, and to evaluate the difference of its activated areas and lateralization according to the mode of stimuli. Materials and Methods : Eight male normal volunteers were included and all were right handed. Functional maps were obtained during auditory and visual word generation tasks in all. Normalized group analysis were performed in each task and the threshold for significance was set at p<0.05. Activated areas in each task were compared visually and statistically. Results : In both tasks, left dominant activations were demonstrated and were more lateralized in visual task. Both frontal lobes (Broca's area, premotor area, and SMA) and left posterior middle temporal gyrus were activated in both tasks. Extensive bilateral temporal activations were noted in auditory task. Both occipital and parietal activations were demonstrated in visual task. Conclusion : Modality independent areas could be interpreted as a core area of language function. Modality specific areas may be associated with processing of stimuli. Visual task induced more lateralized activation and could be a more useful in language study than auditory task.

• Journal of Korean Neurosurgical Society
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• v.40 no.5
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• pp.336-341
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• 2006

Objective : The authors conducted a retrospective study to evaluate the preservation rates of serviceable hearing and to determine its prognostic factors after gamma knife stereotactic radiosurgery[GK SRS] in the patient with vestibular schwannomas. Methods : Between December 1997 and March 2005, 54 patients with a sporadic vestibular schwannoma and serviceable hearing [Gardner Robertson grade I-II] were enrolled in this study. Electronic database of medical records and radiological examinations before and after GK SRS were investigated to the last follow up. The mean marginal dose was $12.3{\pm}0.7Gy$. The mean maximum dose delivered to the tumor center was 24.7Gy [$22{\sim}30Gy$]. The median tumor volume was 2cc [$0.1{\sim}9.1cc$]. The median follow-up period of magnetic resonance[MR] imaging was 31 months [$6{\sim}99\;months$], and the mean follow-up period of audiometry was 24 months [$4{\sim}70\;months$]. Results : The tumor control rate was 100% in the patients with the follow up period more than 2 years. The trigeminal and facial nerve preservation rates were 98% and 100%, respectively. Twenty-eight [52%] of the 54 patients preserved serviceable hearing and 16 [30%] patients retained their pre-GK G-R grade level after GK SRS. In the univariate and multivariate analysis, there was no significant prognostic factor in preservation of the serviceable hearing. Conclusion : The hearing preservation rate is still unsatisfactory compared with the results of other cranial nerve preservation and tumor control in the treatment of vestibular schwannoma by GK SRS. More sophisticated strategy during and after GK SRS is necessary to improve long-term hearing preservation.

• Journal of Korean Neurosurgical Society
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• v.30 no.12
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• pp.1399-1405
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• 2001

Objectives : Gliomatosis cerebri is an uncommon primary brain tumor characterized by diffuse neoplastic proliferation of glial cells, with the preservation of the underlying cytoarchitecture. The aim of this study is to evaluate clinical features, outcome of surgical treatment and adjuvant therapy of gliomatosis cerebri. Methods : Between Jan. 1990 and Dec. 2000, 12 patients were diagnosed with gliomatosis cerebri based on characteristic radiological and histological findings. The patients' age ranged from 18 to 77(mean 44) years and the male to female ratio was 7 : 5. Nine patients underwent decompressive surgery and three, biopsy only. Postoperative radiation therapy was given in all cases except three. In addition to radiation therapy, four patients received chemotherapy. The mean duration of follow-up period was 18.8 months. Results : The most common presenting symptom were seizure and motor weakness. The mean duration of symptom was 5.9 months. There was 5 bilateral lesions and tumor involved corpus callosum in 5, basal ganglia-thalamus in 4, and brain stem in 2. There was no operative mortality but four patients died during the follow-up. The mean survival period for 11 patients was 20.5 months from the time of diagnosis. In univariate analysis, the lesion involving corpus callosum, basal ganglia-thalamus and brain stem correlated significantly with the short length of survival(p<0.05). Also, postoperative radiation as a adjuvant therapy prolonged the patient's survival(p<0.05). Conclusions : In the management of gliomatosis cerebri patients, early detection by MR imaging, active management of increased intracranial pressure, decompressive surgical removal and postoperative adjuvant therapy such as radiation is thought to be a good treatment modality.

• Progress in Medical Physics
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• v.19 no.3
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• pp.178-185
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• 2008

Living donor liver transplantation is increasingly performed as an alternative to cadaveric transplantation. Preoperative screening of the donor candidates is very important. The quality, size, and vascular and biliary anatomy of the liver are best assessed with magnetic resonance (MR) imaging or computed tomography (CT). In particular, the volume of the potential graft must be measured to ensure sufficient liver function after surgery. Preoperative liver segmentation has proved useful for measuring the graft volume before living donor liver transplantations in previous studies. In these studies, the liver segments were manually delineated on each image section. The delineated areas were multiplied by the section thickness to obtain volumes and summed to obtain the total volume of the liver segments. This process is tedious and time consuming. To compensate for this problem, automatic segmentation techniques have been proposed with multiplanar CT images. These methods involve the use of sequences of thresholding, morphologic operations (ie, mathematic operations, such as image dilation, erosion, opening, and closing, that are based on shape), and 3D region growing methods. These techniques are complex but require a few computation times. We made a phantom for volume measurement with pig and evaluated actual volume of spleen and liver of phantom. The results represent that our semiautomatic volume measurement algorithm shows a good accuracy and repeatability with actual volume of phantom and possibility for clinical use to assist physician as a measuring tool.

• Investigative Magnetic Resonance Imaging
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• v.12 no.2
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• pp.161-169
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• 2008

Purpose : The aim of this study was to evaluate the usefulness of MRI performed after excisional biopsy to diagnose residual cancer and additional lesions. Materials and Methods : A total of 16 patients who had breast cancer diagnosed by excisional biopsy underwent preoperative breast MRI between March 2005 and August 2007 were included. MRI findings were considered positive for residual cancer if focal, thick, or irregular rim enhancement or adjacent enhancing lesion was identified around the postoperative biopsy cavity. And additional lesions separated from biopsy cavity including multifocal, multicentric, or contralateral lesion were evaluated. We evaluated the diagnostic accuracy of MRI, comparing MRI with histopathologic finding, and the impact of MRI on surgical planning. Results : The sensitivity and specificity of MRI for detecting residual disease considering rim enhancement were 85.7%(6/7) and 55.6%(5/9). Additional lesions including multifocal, multicentric, or contralateral lesion were found in 6 patients. In 7 patients, results of MRI findings changed surgical treatment planning. Conclusion : The pattern of rim enhancement on MRI after excisional biopsy is not differential point to evaluate remnant lesion. But MRI has an important role to help the detection of multifocal or multicentric, or contralateral breast malignancies, resulting in beneficial change in surgical treatment planning.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.58-60
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• 2007

Magnetic Resonance Imaging(MRI) has become a very widely used medical procedur e. Clo.sed and open systems are typically used with static magnetic fields at or below 2 Tesla. BWhole body SAR(specific absorbsion rate) is the value of SAR averaged over the entire body of the patient over any period of 15 minutes. Head SAR is the value of SAR averaged over the head of the patient for any period of 10 minutes. SAR is a measure of the absorption of electromagnetic energy in the body' (typically in watts per kilogram (W/kg)). The normal operating mode comprises values of head SAR not higher than 3 W/kg. The second level controlled operating mode comprises values higher than 3 W/kg. Current FDA guidance limits the SAR in the whole body. including the head to a range of 1.5 to 4.0 W/kg, depending on the patient's clinical condition. SAR, limit restrictions are incorporated in all MRI systems. and domestic' s guidance limits the SAR in a part body. including the head to 3.2w/kg and less. The purpose of this study is to evaluate on change of head SAR in using MRI pulse sequence and to check if exceed 3.2(w/kg) level in domestic a part exposure through measured head SAR. 23 patient's the average head SAR of pulse sequence is that T2WI sagittal is 0.5375. T2WI axial(FSE) is 0.4817, T1WI axial(SE) is, 0.8179. FLAIR axial is 0.4580. GRE axial is 0.0077, Diffusion is 0.0824w/kg. The head SAR exposed per patient was proved 2.3845w/kg less than the international standard. Coefficient of correlation for the relations body weight and SAR or for the relations ETL(echo train length) and SAR is 1 value. Coefficient of correlation for the relations between TR(time to repeat) and SAR is -0.602 value. so SAR increased relative to weight body and ETL. But the relations between TR and SAR is negative definite.

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.113-119
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• 2000

Purpose : To know the possibility of clinical application of MRI using oxygen inhalation as a perfusion MRI Materials and methods : Two healthy volunteers and three patients of one moyamoya disease, one acute infarction and one meningioma were studied using a 1.5 Tesla MRI unit. Oxygen (15 liters/min) mixed with room air was given using face mask from 8 second to 35 second during the study. Images were acquired 25 times (scan time per study were 1.6 seconds) using susceptibility contrast EPI (echo planar image) sequence. Difference maps were acquired by early (study 12-18), and late (study 19-25) O2 inhalation image groups minus pre-O2 inhalation image group (study 3-9) with a Z-score of 0.7-1.0 using VB31C program of Magneton Vision. The resulting perfusion images were created by superimposition of difference maps on corresponding T1 weighted anatomic images. On moyamoya patient, similar perfusion images were acquired after Gd-DTPA injection, and compared with O2 inhalation perfusion images. Results ; The author can get the perfusion images of the brain by oxygen inhalation with susceptibility contrast EPI sequence at the volunteers, and the patient of moyomoya disease, acute infarction and meningioma. On moyamoya patient, perfusion images with O2 inhalation are similar with perfusion images by Gd-DTPA injection. Conclusion 1 This study has demonstrated that the susceptibility contrast EPI by oxygen inhalation can be used as the clinically useful perfusion MRI technique

• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.490-494
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• 2009

A 2-year-old Maltese and a 5-month-old Yorkshire terrier were presented with ataxia. Tetraparesis was observed in a 9-year -old Yorkshire terrier. The localizations of the lesions suggested brain or cervical spinal cord by the neurological examination, and the following images was achieved: radiography, axial images of computed tomography (CT), reconstruction image of CT such as multi-planar reformation(MPR) and 3-dimensional(3D) reconstruction and magnetic resonance imaging (MRI). On radiography, the misalignment between atlas (C1) and axis (C2), absent dens of axis, and increased space between the dorsal arch of C1 and spinous process of C2 were found. The discontinuation between dens and body of C2 was identified through axial CT images, and the fragmentation of dens separated from axis was observed through MPR and 3D image in all case. The hyperintense lesions and the spinal cord compression on T2-weighted MR images were represented in a dog with tetraparesis, the others represented only spinal cord compression. Three dogs were diagnosed as atlantoaxial instability (AAI) by dens fracture of C2. The dog with tetraparesis was euthanized due to guarded prognosis. The others were recovered completely. It is difficult to differentiate dens fracture of C2 from abnormal dens such as agenesis and hypoplasia. We thought that CT is very useful to evaluate the dens of C2 and differentiate the causes of AAI, and the reconstruction images of CT such as MPR and 3D make the translation of the fragmented dens or axis of AAI more precisely evaluate.