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화소값의 통계적 분석을 이용한 신속 망막혈관검출기법 연구
남현성(Hyung-Sung Nam),강욱(Uk Kang),서종모(Jong-Mo Seo),이해영(Hae-Young Lee),篠田啓(Kei Shinoda),곽상인(Sang-In Kwarg) 대한검안학회 2012 Annals of optometry and contact lens Vol.11 No.1
목적: 디지털 안저사진에서 망막혈관의 직경을 신속히 측정하기 위하여, 화소값을 통계적으로 분석하여 망막 혈관을 검출하여 보았다. 대상과 방법: 정상인 디지털 안저사진에서 적색 화소값을 이용한 영상 전처리를 통해 시신경유두를 분획하였다. 이후 이 정보를 활용하여 녹색 화소값에 대하여 시신경유두중심으로부터 시신경유두직경의 2배에서 3배 사이를 관심영역으로 정한 후, 5화소 간격의 동심원을 그리고 동심원상에서의 화소값을 얻었다. 평편화와 3차 스플라인 곡선 추정으로 혈관을 제외한 망막영역의 화소 추세를 구하고, 원래 화소값과의 차이를 구하여 최종적인 화소값 분포를 얻었다. 이것으로부터 평균과 표준편차를 구하고, 84%, 95%, 97.5%의 화소를 포함하는 역치에서 혈관이 구분되는지를 전문가의 판독과 비교하여 보았다. 결과: 97.5% 역치에서는 망막 정맥을, 95% 역치에서는 망막 정맥과 중심반사가 명확한 동맥을, 84%역치에서는 모세혈관 이상의 망막 혈관들을 대부분 검출할 수가 있었다. 망막정맥직경은 97.5% 역치에서, 망막동맥직경은 84% 역치에서 구한 것이 전문가의 판독과 잘 일치하였다. 결론: 기존의 복잡한 혈관추적 기법 대신 단순 통계 기법을 활용하여도 매우 의미있는 결과를 빠르게 얻을 수 있었다. Purpose: In fundus photographs, pixel data were statistically analyzed in order to detect retinal vessel rapidly. Methods: Red channel data was used to detect the optic nerve head (ONH) and make the region of interest (ROI). ROI was established between the circle of radius 2RONH and the circle of radius 3RONH when ONH has radius RONH. After that, intensity profiles along each concentric circle can be obtained in the ROI by using green channel data. Each concentric circle has radius from 2RONH to 3RONH at 5 pixel intervals. Local maximum data were derived from each intensity profile, and data smoothing and cubic spline interpolation were utilized to acquire trend lines. Using these intensity profiles and trend lines, the pixel distribution information was derived by subtracting each intensity profile from the corresponding trend line. Mean and standard deviation (SD) values were calculated for each new intensity profile, and three threshold values (1.96, 1.65 and 1.00 SD from the mean) were used. Segmentation results were analyzed by two retina specialists. Results: Several venules were detected at the threshold 97.5%, venules and clear arterioles were detected at the the threshold 95%, and most venules & arterioles were detected at the threshold 84%. The diameters of the retinal vessels were corresponded with physician s interpretation for venules at the threshold 97.5%, and for arterioles at the threshold 84%. Conclusions: Meaningful result was derived with the fast and simple statistical method which is different from existing complicated vessel tracking algorithms. It would be possible to measure the blood vessel diameter more accurately with the arteriole/venule classification and the compensation of vascular direction.
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박정현,정호경,곽상인,유영석,Jung Hyun Park,Ho Kyung Chung,Sang In Kwarg,Young Suk Yu 대한안과학회 2006 대한안과학회지 Vol.47 No.12
Purpose: To report four cases of spontaneous regression of retinoblastoma. Methods: The clinical courses of two patients were retrospectively investigated: a patient who has been diagnosed with bilateral retinoblastoma and has survived more than six years after his parents refused treatment and a patient with bilateral retinal lesions who has survived nine years whose sister was treated for unilateral retinoblastoma. Results: A nine-year-old girl, diagnosed with bilateral retinoblastoma when she was three months old, remained well for nine years after her parents refused to seek treatment. The right eye had three retinal masses that had regressed, and the left eye showed signs of phthisis and was enucleated for a cosmetic purpose. Microscopic examination of the left eye showed a mass, which consisted mostly of fibroblasts and ground substance and a few retinoblasts without mitotic figures. A six-year-old boy with a family history of retinoblastoma presented with regressed retinal masses in both of his eyes at the first funduscopic examination. The retinal lesions showed no change until his ninth year. Conclusions: Two cases of spontaneous regression of bilateral retinoblastoma were observed. No distant metastasis was detected during long-term follow-up. The retinal lesions were similar to regressed masses after treatment.
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