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Tau Positron Emission Tomography Imaging in Degenerative Parkinsonisms
류철형,조한나,최재용,유영훈,이명식 대한파킨슨병및이상운동질환학회 2018 Journal Of Movement Disorders Vol.11 No.1
In recent years, several radiotracers that selectively bind to pathological tau proteins have been developed. Evidence is emerging that binding patterns of in vivo tau positron emission tomography (PET) studies in Alzheimer’s disease (AD) patients closely resemble the distribution patterns of known neurofibrillary tangle pathology, with the extent of tracer binding reflecting the clinical and pathological progression of AD. In Lewy body diseases (LBD), tau PET imaging has clearly revealed cortical tau burden with a distribution pattern distinct from AD and increased cortical binding within the LBD spectrum. In progressive supranuclear palsy, the globus pallidus and midbrain have shown increased binding most prominently. Tau PET patterns in patients with corticobasal syndrome are characterized by asymmetrical uptake in the motor cortex and underlying white matter, as well as in the basal ganglia. Even in the patients with multiple system atrophy, which is basically a synucleinopathy, 18F-flortaucipir, a widely used tau PET tracer, also binds to the atrophic posterior putamen, possibly due to off-target binding. These distinct patterns of tau-selective radiotracer binding in the various degenerative parkinsonisms suggest its utility as a potential imaging biomarker for the differential diagnosis of parkinsonisms.
복수 특징의 사전 검사에 의한 영상 벡터양자화의 고속 부호화 기법
류철형,나성웅,Ryu Chul-hyung,Ra Sung-woong 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.12C
본 논문에서는 영상 백터 양자화를 위한 새로운 고속 부호화 기법을 제안하는데, 제안 기법은 다차원의 참조 표로 복수 특징의 부분 거리를 사용한다. 복수 특징을 사용하는 기존 기법은 탐색 순서와 연산 과정을 고려할 때 복수 특징을 단계적으로 처리한다. 반면에 제안 기법은 참조 표를 사용하여 복수 특징들을 동시에 활용한다. 본 논문에서는 가용한 수준의 메모리를 위해 테두리 효과를 고려하는 참조 표의 구성 방법과 참조 표의 부분 거리를 활용하며 현재의 탐색을 중지하는 방법을 상세하게 기술한다. 시뮬레이션 결과는 제안 기법의 효율성을 확인시켜 주는데, 부호책 크기가 256일 때 제안 기법은 OHTPDS 기법이나 $M-L_2NP$ 기법 등과 같이 최근에 제안된 기법들이 요구하는 연산량의 $70\%$ 수준까지 연산량을 감소시킨다. 가용한 수준의 전처리와 메모리를 사용함으로써 제안 기법은 전체탐색 기법과 통일한 화질을 유지하면서 전체 탐색 기법이 요구하는 연산량의 $2.2\%$ 이하로 연산량을 감소시킨다. This paper presents a new fast encoding algorithm for image vector quantization that incorporates the partial distances of multiple features with a multidimensional look-up table (LUT). Although the methods which were proposed earlier use the multiple features, they handles the multiple features step by step in terms of searching order and calculating process. On the other hand, the proposed algorithm utilizes these features simultaneously with the LUT. This paper completely describes how to build the LUT with considering the boundary effect for feasible memory cost and how to terminate the current search by utilizing partial distances of the LUT Simulation results confirm the effectiveness of the proposed algorithm. When the codebook size is 256, the computational complexity of the proposed algorithm can be reduced by up to the $70\%$ of the operations required by the recently proposed alternatives such as the ordered Hadamard transform partial distance search (OHTPDS), the modified $L_2-norm$ pyramid ($M-L_2NP$), etc. With feasible preprocessing time and memory cost, the proposed algorithm reduces the computational complexity to below the $2.2\%$ of those required for the exhaustive full search (EFS) algorithm while preserving the same encoding quality as that of the EFS algorithm.
파킨슨병과 다계통위축증 감별 진단에 정량적 18-fluorodeoxyglucose PET의 유용성
류철형,이승엽,유영훈,이명식 대한신경과학회 2006 대한신경과학회지 Vol.24 No.1
Background: Overlapping clinical features of idiopathic Parkinson's disease (IPD) and multiple system atrophy (MSA) make it difficult to conduct an accurate differential diagnosis. We performed a quantitative F18- fluorodeoxyglucose PET (FDG PET) and measured the striatal and cerebellar glucose metabolism to evaluate the efficacy of a FDG PET study in the differential diagnosis between IPD and MSA. Methods: This study included 19 patients with IPD, 28 patients with MSA (MSA-P:MSA-C=19:9) and 12 age matched normal controls. A FDG PET study was performed in all subjects and the original PET image was corrected with the radioactivity curve obtained by repetitive sampling of the radial arterial blood. Results: The measurements of striatal and cerebellar glucose metabolisms of the patients with MSA-P were significantly lower than those of the patients with IPD (P<0.001). However, the measurement of the caudate nucleus provided the most reliable clue for the differential diagnosis between IPD and MSA-P (sensitivity 94.7% and specificity 94.7%). In the patients with MSA-C, the glucose metabolism of the cerebellar vermis (P<0.001), cerebellar cortex (P<0.001) and putamen (P<0.05) was significantly lower than those of the patients with IPD. Conclusions: Quantitative FDG PET is a useful and reliable method in making a differential diagnosis between IPD and MSA.
파킨슨병 환자에서 전극선의 부분 손상으로 인한 심부뇌자극 효과 소실
류철형,장진우,이명식 대한신경과학회 2005 대한신경과학회지 Vol.23 No.6
A patient with Parkinson's disease developed fluctuation in the deep brain stimulation (DBS) effect, an unpleasant left facial paresthesia and the left limb dystonia. Impedance of the right DBS was over 2000 ohm in three proximal contacts. Skull X-ray studies showed partial breakage of right electrode lead below the mastoid process. Partial electrode breakage must be considered when there is a deterioration of the DBS effect, an unexpected side effect of DBS, and an alteration of impedance.