• Journal of Biomedical Engineering Research
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• v.36 no.5
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• pp.169-176
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• 2015

Implantable closed-loop epilepsy controllers require ideally both accurate epileptic seizure detection and low power consumption. On-chip oscillators can be used in implantable devices because they consume less power than other oscillators such as crystal oscillators. In this study, we investigated the tolerable error range of a lower power on-chip oscillator without losing the accuracy of seizure detection. We used 24 ictal and 14 interictal intracranial electroencephalographic segments recorded from epilepsy surgery patients. The performance variations with respect to oscillator frequency errors were estimated in terms of specificity, modified sensitivity, and detection timing difference of seizure onset using Generic Osorio Frei Algorithm. The frequency errors of on-chip oscillators were set at ${\pm}10%$ as the worst case. Our results showed that an oscillator error of ${\pm}10%$ affected both specificity and modified sensitivity by less than 3%. In addition, seizure onsets were detected with errors earlier or later than without errors and the average detection timing difference varied within less than 0.5 s range. The results suggest that on-chip oscillators could be useful for low-power implantable devices without error compensation circuitry requiring significant additional power. These findings could help the design of closed-loop systems with a seizure detector and automated stimulators for intractable epilepsy patients.

• The Korean Journal of Nuclear Medicine
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• v.34 no.3
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• pp.169-182
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• 2000

Purpose: To investigate the various ictal perfusion patterns and find the relationships between clinical factors and different perfusion patterns. Materials and Methods: Interictal and ictal SPECT and SPECT subtraction were performed in 61 patients with partial epilepsy. Both positive images showing ictal hyperperfusion and negative images revealing ictal hypoperfusion were obtained by SPECT subtraction The ictal perfusion patterns of subtracted SPECT were classified into focal hyperperfusion, hyperperfusion-plus, combined hyperperfusion-hypoperfusion, and focal hypoperfusion only. Results: The concordance rates with epileptic focus were 91.8% in combined analysis of ictal hyperperfusion and hypoperfusion images of subtracted SPECT, 85.2% in hyperperfusion images only of subtracted SPECT, and 68.9% in conventional ictal SPECT analysis. Ictal hypoperfusion occurred less frequently in temporal lobe epilepsy (TLE) than extratemporal lobe epilepsy. Mesial temporal hyperperfusion alone was seen only in mesial TLE while lateral temporal hyperperfusion alone was observed only in neocortical TLE. Hippocampal sclerosis had much lower incidence of ictal hypoperfusion than any other pathology. Some patients showed ictal hypoperfusion at epileptic focus with ictal hyperperfusion in the neighboring brain regions where ictal discharges propagated. Conclusion: Hypoperfusion as well as hyperperfusion in ictal SPECT should be considered for localizing epileptic focus. Although the mechanism of ictal hypoperfusion could be an intra-ictal early exhaustion of seizure focus or a steal phenomenon by the propagation of ictal discharges to adjacent brain areas, further study is needed to elucidate it.

• Clinical and Experimental Pediatrics
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• v.52 no.7
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• pp.804-810
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• 2009

Purpose : We investigated whether ictal single-photon emission computed tomography (SPECT) with prolonged injection of technetium-99m (99mTc) ethyl cysteinate dimer during repeated spasms can localize the epileptogenic foci in children with infantile spasms. Methods : Fourteen children with infantile spasms (11 boys, 3 girls; mean age, $2.2{\pm}1.3$ years) were examined. When a cluster of spasms was detected during video electroencephalography (EEG) monitoring, $^{99m}Tc$ ethyl cysteinate dimer was slowly and continuously injected for 2 minutes to determine the presence of ictal SPECT. For 7 children, the ictal and interictal SPECT images were visually analyzed, while for the remaining 7 children, the SPECT images were analyzed using the subtraction ictal SPECT coregistered to magnetic resonance imaging (MRI) (SISCOM) technique. Subsequently, we analyzed the association between the ictal SPECT findings and those of other diagnostic modalities such as EEG, MRI, and positron emission tomography (PET). Results : Increase in cerebral blood flow on ictal SPECT involved the epileptogenic foci in 10 cases6 cases analyzed by visual assessment and 4 analyzed by the SISCOM technique. The ictal SPECT and video-EEG findings showed moderate agreement (Kappa=0.57; 95% confidence interval, 0.18-0.96). Conclusion : Ictal SPECT with prolonged injection of a tracer could provide supplementary information to localize the epileptogenic foci in infantile spasms.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.4
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• pp.388-393
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• 2016

Epilepsy, characterized by enduring the predisposition to generate epileptic seizures, was conceptually defined in 2005 as a disorder of the brain. According to the international league against epilepsy in 2014 that there is a high risk of recurrence within 10 years. The existence of interictal epileptiform discharges (IEDs) at the Electroencephalography (EEG) is an important risk factor for a possible recurrence of seizures, disproving that the seizures may increase. The purpose of this study was to analyze the correlation between recurrent seizures and epilepsy EEG findings in patients with IEDs, which was carried out to serve as the basis for the EEG to predict the prognosis of patients with epilepsy. This study included 432 adults older than 20 years of age who care for patients with epilepsy at Seoul National University Hospital, between June 2007 and December 2010. The results showed no difference between men and women in the EEG epilepsy disease, but there was a difference between various age groups. Correlation analysis showed a negative correlation between recurrence of seizures and age; it showed a positive correlation between recurrence and IEDs. In addition, age was associated with a predictive power of 10.9% and IEDs showed a predictive power of 15% on recurrent seizures. Therefore, EEG is considered as a very important test in epilepsy diagnosis. Therefore, further studies are necessary on the relationship between seizure recurrence and EEG.

• Clinical and Experimental Pediatrics
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• v.50 no.9
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• pp.896-900
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• 2007

Purpose : The aim of this study was to investigate the speech problems in benign rolandic epilepsy (BRE) according to the seizure focus in EEG and semiology. Methods : Twenty three patients [right origin (13 patients) or left side (10 patients)] who met the BRE criteria by International League Against Epilepsy (ILAE) were prospectively enrolled. We excluded the patients who had abnormal MRI or showed both side spikes in EEG. Computerized Speech Lab was used to assess the speech characteristics of the patients. Results : The error pattern of laryngeal articulation in BRE was exclusively substitution of stop consonants, these errors showed more frequent in the left group (16.0% vs 25.5%). Voice onset time (VOT) of stop consonants and Total duration (TD) of word in both groups were prolonged than normal control group, especially in left group (P<0.05). The first formant of vowel /o/ and second formant of /e/ were significantly decreased in left group (P<0.05). The right group scored wider on pitch range ($192.9{\pm}54.0Hz$) and energy range in spontaneous speech ($14.2{\pm}6.4db$) than the left group ($233.3{\pm}12.5Hz$, $19.4{\pm}9.3db$, respectively, P>0.05). Duration of counting (5 to 9) in left group slower than right group ($8.6{\pm}1.7$ vs $7.9{\pm}1.8sec$). Conclusion : Our data suggested that interictal spikes and seizures in either centrotemporal sides, especially left side group, may induce speech problems. We recommend the logopedic and phoniatric evaluations of speech in BRE patients.

• Clinical and Experimental Pediatrics
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• v.55 no.2
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• pp.63-67
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• 2012

A 4-year-old girl with Panayiotopoulos syndrome presented with a history of 4 prolonged autonomic seizures. The clinical features of her seizures included, in order of occurrence, blank staring, pallor, vomiting, hemi-clonic movement on the right side, and unresponsiveness. A brain magnetic resonance imaging (MRI) showed a slightly high $T_2$ signal in the left hippocampus. Interictal electoencephalogram revealed spikes in the occipital area of the left hemisphere. We analyzed the current-source distribution of the spikes to examine the relationship between the current source and the high $T_2$ signal. The current source of the occipital spikes was not only distributed in the occipital area of both cerebral hemispheres, but also extended to the posterior temporal area of the left hemisphere. These findings suggest that the left temporal lobe may be one of the hyperexcitable areas and form part of the epileptogenic area in this patient. We hypothesized that the high $T_2$ signal in the left hippocampus of our patient may not have been an incidental lesion, but instead may be related to the underlying electroclinical diagnosis of Panayiotopoulos syndrome, and particularly seizure. This notion is important because an abnormal $T_2$ signal in the hippocampus may represent an acute stage of hippocampal injury, although there is no previous report of hippocampal pathology in Panayiotopoulos syndrome. Therefore, long-term observation and serial follow-up MRIs may be needed to confirm the clinical significance of the $T_2$ signal change in the hippocampus of this patient.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.107-118
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• 2007

Background : It is well known that non-rapid eye movement(NREM) sleep activates the occurrence of interictal epileptiform discharges(IED) in many epileptic syndromes. We performed this study to assess the effect of NREM sleep on IED in epileptic patients with organic brain lesions. Materials and Methods : We analyzed awake and sleep electroencephalopathy(EEG) recorded simultaneously after partial sleep deprivation in 50 patients. We calculated the awake and sleep spike index (ASI and SSI, spikes/epoch), and the percentage increase of ASI and SSI during sleep. Results : In the 50 patients, the IEDs were recorded exclusively during the awake state in 1 (2%) patient, and during the sleep state in 13(26%) patients. The SSI was higher in 44 (88%) patients, and the ASI was higher in 5 (10%) patients. The mean ASI and the SSI in patients with organic brain lesions were $0.058{\pm}0.121$ and $0.148{\pm}0.187$, and it was $0.081{\pm}0.150$ and $0.174{\pm}0.226$ in patients without organic brain lesions. There were significant increases in the spike index (P<0.05) during NREM sleep in both groups (n=36), but no significant difference in the percent increase of spike index (P>0.05). Conclusion : The IEDs were activated significantly during NREM sleep both in patients with and without organic brain lesions, but there were no differences in the degree of activation in both groups. The activating effect of NREM sleep was not correlated with clinical factors such as, frequent nocturnal seizures, frequent generalized tonic clonic seizures, type of epilepsy and taking anticonvulsants. We conclude that the routine EEG used to evaluate epileptiform discharges in epileptic patients should include sleep recordings after partial sleep deprivation.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.463-468
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• 1996

본 연구는 간질 병소의 국소화에 있어 발작기 및 발작간 뇌스캔의 정확도를 알아보고 발작기 뇌 스캔에서 나타나는 간질 확산이 정확한 간질 병소를 국소화 하는데 어떠한 영향을 미치는가에 대하여 알아보고자 하였다. 15명의 복잡 부분 발작 환자를 대상으로 하였으며, 간질 병소의 최종적인 국소화는 두피 및 발작 뇌파, 피질 뇌파, 자기 공명 영상, 임상양상 및 병리 소견을 종합한 근거로 하였다. 발작기 뇌스캔은 뇌파상 발작 중 또는 환자가 aura를 호소할 때 Tc-99m HMPAO 20mCi(740 MBq)를 정맥주입후 시행하였으며 발작간 뇌스캔은 발작기 뇌스캔 후 3일 이내 임상적으로 발작 증상이 없는 기간에 시행하였다. 간질 병소는 우측 측두엽이 8예, 좌측 측두엽이 6예, 측두엽 이외의 기원이 1예 였다. 발작기 뇌스캔상, 모두 11예(73.3 %)에서 단발성 또는 다발성 섭취 증가가 간질 병소 및 간질확산 부위에서 관찰되었으며, 간질 병소에만 국한된 섭취 증가는 4예(26.7%)에 불과 하였다. 발작간 뇌스캔에는 모두 11예(73.3 %)에서 간질 병소에만 섭취가 감소되었다. 자기 공명 영상에서는 8예(53.3 %)에서 hippocampal sclerosis를 포함한 간질 병소가 확인되었다. 본 연구로 복잡 부분 발작 환자에서, 간질 확산이 발작기 뇌 스캔 중 자주 관찰됨을 알 수 있었으며, 이러한 간질 확산에 따른 다발성 방사능 섭취가 발작기 뇌스캔상, 간질 병소의 국소화에있어 한계가 있음을 결론 내릴 수 있었다.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.469-475
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• 1996

목 적 : 측두엽 간질 환자의 발작간 뇌 스캔에서 관찰되는 측두엽 혈류 감소와 같은 쪽 시상 혈류 감소 소견의 빈도를 알아보고 이러한 소견이 간질 병소 국소화에 미치는 유용성에 대해 알아보고자 한다. 대상 및 방법 : Tc-99m-ECD를 이용하여 발작간 뇌 스캔을 시행한 67명의 측두엽 간질 환자에서 편측 측두엽과 같은 쪽 시상에 혈류 감소를 보인 12명의 환자를 대상으로 하였다. 간질 병소는 표면 뇌파 검사, 발작시 뇌파 검사, 심부 뇌파 검사, 자기 공명 영상 그리고 임상적 소견을 종합하여 국소화 하였다. 결 과 : 편측 측두엽과 같은 쪽 시상에 혈류 감소는 18%의 환자에서 관찰되었다. 7명의 환자는 왼쪽 측두엽과 시상에 혈류 감소를 보였다. 이들 7명중 4명은 자기공명영상 소견상 왼쪽 내측 측두엽 경화 소견을 보였다. 5명의 환자는 오른쪽 측두엽과 시상에 혈류 감소를 보였다. 이들 5명중 4 명은 자기공명영상 소견상 오른쪽 내측 측두엽 경화 소견을 보였다. 결 론 : 발작간 뇌 스캔상 관찰되는 편측 측두엽과 같은 쪽 시상의 혈류 감소 소견은 측두엽과 시상사이의 상호 연결에 의한 해리 현상으로 부분 발작의 병태 생리와 밀접한 연관이 있으리라 생각한다. 또한 이러한 소견은 간질 병소 국소화에 도움이 되리라 생각한다.

• Progress in Medical Physics
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• v.14 no.1
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• pp.34-42
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• 2003

In medical imaging, three-dimensional (3D) display using Virtual Reality Modeling Language (VRML) as a portable file format can give intuitive information more efficiently on the World Wide Web (WWW). The web-based 3D visualization of functional images combined with anatomical images has not studied much in systematic ways. The goal of this study was to achieve a simultaneous observation of 3D anatomic and functional models with planar images on the WWW, providing their locational information in 3D space with a measuring implement using VRML. MRI and ictal-interictal SPECT images were obtained from one epileptic patient. Subtraction ictal SPECT co-registered to MRI (SISCOM) was performed to improve identification of a seizure focus. SISCOM image volumes were held by thresholds above one standard deviation (1-SD) and two standard deviations (2-SD). SISCOM foci and boundaries of gray matter, white matter, and cerebrospinal fluid (CSF) in the MRI volume were segmented and rendered to VRML polygonal surfaces by marching cube algorithm. Line profiles of x and y-axis that represent real lengths on an image were acquired and their maximum lengths were the same as 211.67 mm. The real size vs. the rendered VRML surface size was approximately the ratio of 1 to 605.9. A VRML measuring tool was made and merged with previous VRML surfaces. User interface tools were embedded with Java Script routines to display MRI planar images as cross sections of 3D surface models and to set transparencies of 3D surface models. When transparencies of 3D surface models were properly controlled, a fused display of the brain geometry with 3D distributions of focal activated regions provided intuitively spatial correlations among three 3D surface models. The epileptic seizure focus was in the right temporal lobe of the brain. The real position of the seizure focus could be verified by the VRML measuring tool and the anatomy corresponding to the seizure focus could be confirmed by MRI planar images crossing 3D surface models. The VRML application developed in this study may have several advantages. Firstly, 3D fused display and control of anatomic and functional image were achieved on the m. Secondly, the vector analysis of a 3D surface model was defined by the VRML measuring tool based on the real size. Finally, the anatomy corresponding to the seizure focus was intuitively detected by correlations with MRI images. Our web based visualization of 3-D fusion image and its localization will be a help to online research and education in diagnostic radiology, therapeutic radiology, and surgery applications.