Nuclear Medicine and Molecular Imaging

The Korean Society of Nuclear Medicine (대한핵의학회)
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Effects of Attenuation and Scatter Corrections in Cat Brain PET Images Using microPET R4 Scanner

MicroPET R4 스캐너에서 획득한 고양이 뇌 PET 영상의 감쇠 및 산란보정 효과

  • Kim, Jin-Su (Department of Nuclear Medicine, Seoul National University College of Medicine) ;
  • Lee, Jae-Sung (Department of Nuclear Medicine, Seoul National University College of Medicine) ;
  • Lee, Jong-Jin (Department of Nuclear Medicine, Seoul National University College of Medicine) ;
  • Lee, Byeong-Il (Department of Nuclear Medicine, Seoul National University College of Medicine) ;
  • Park, Min-Hyun (Department of Otolaryngology Head and Neck Surgery, Seoul National University College of Medicine) ;
  • Lee, Hyo-Jeong (Department of Otolaryngology Head and Neck Surgery, Seoul National University College of Medicine) ;
  • Oh, Seung-Ha (Department of Otolaryngology Head and Neck Surgery, Seoul National University College of Medicine) ;
  • Kim, Kyeong-Min (Research Institute of Nuclear Medicine, Korea Institute of Radiology & Medical Sciences) ;
  • Cheon, Gi-Jeong (Department of Nuclear Medicine, Korea Institute of Radiology & Medical Sciences) ;
  • Lim, Sang-Moo (Department of Nuclear Medicine, Korea Institute of Radiology & Medical Sciences) ;
  • Chung, June-Key (Department of Nuclear Medicine, Seoul National University College of Medicine) ;
  • Lee, Myung-Chul (Department of Nuclear Medicine, Seoul National University College of Medicine) ;
  • Lee, Dong-Soo (Department of Nuclear Medicine, Seoul National University College of Medicine)
  • 김진수 (서울대학교 의과대학 핵의학교실) ;
  • 이재성 (서울대학교 의과대학 핵의학교실) ;
  • 이종진 (서울대학교 의과대학 핵의학교실) ;
  • 이병일 (서울대학교 의과대학 핵의학교실) ;
  • 박민현 (서울대학교 의과대학 이비인후과학교실) ;
  • 이효정 (서울대학교 의과대학 이비인후과학교실) ;
  • 오승하 (서울대학교 의과대학 이비인후과학교실) ;
  • 김경민 (원자력의학원 방사선의학연구센터 핵의학연구실) ;
  • 천기정 (원자력의학원 핵의학과) ;
  • 임상무 (원자력의학원 핵의학과) ;
  • 정준기 (서울대학교 의과대학 핵의학교실) ;
  • 이명철 (서울대학교 의과대학 핵의학교실) ;
  • 이동수 (서울대학교 의과대학 핵의학교실)
  • Published : 2006.02.28
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Abstract

Purpose: The aim of this study was to examine the effects of attenuation correction (AC) and scatter correction (SC) on the quantification of PET count rates. Materials and Methods: To assess the effects of AC and SC $^{18}F$-FDG PET images of phantom and cat brain were acquired using microPET R4 scanner. Thirty-minute transmission images using $^{68}Ge$ source and emission images after injection of FDG were acquired. PET images were reconstructed using 2D OSEM. AC and SC were applied. Regional count rates were measured using ROIs drawn on cerebral cortex including frontal, parietal, and latral temporal lobes and deep gray matter including head of caudate nucleus, putamen and thalamus for pre- and post-AC and SC images. The count rates were then normalized with the injected dose per body weight. To assess the effects of AC, count ratio of "deep gray matter/cerebral cortex" was calculated. To assess the effects of SC, ROIs were also drawn on the gray matter (GM) and white matter (WM), and contrast between them ((GM-WM)/GM was measured. Results: After the AC, count ratio of "deep gray matter/cerebral cortex" was increased by $17{\pm}7%$. After the SC, contrast was also increased by $12{\pm}3%$. Conclusion: Relative count of deep gray matter and contrast between gray and white matters were increased after AC and SC, suggesting that the AC would be critical for the quantitative analysis of cat brain PET data.

목적 : 이 연구에서는 고양이 뇌 PET 영상을 감쇠, 산란 보정 후 정량 평가하여 감쇠, 산란보정의 필요성에 대하여 연구하였다. 대상 및 방법 : 감쇠, 산란보정의 영향을 평가하기 위하여 microPET R4 스캐너를 이용하여 팬텀과 5마리 고양이의 $^{18}F$-FDG PET 스캔을 얻었다. $^{68}Ge$ 선원을 이용하여 30분 동안 투과영상을 얻은 후 FDG를 정맥주사한 다음 방출 영상을 얻었다. PET 영상은 OSEM을 이용하여 영상을 재구성하였고, 감쇠, 산란보정을 하였다. 전두엽, 두정엽 외측 측두엽 등을 포함하는 대뇌피질 영역과 꼬리핵머리, 조가비핵, 시상을 포함하는 심부피질 영역에 관심영역을 그린 다음 감쇠, 산란보정 전, 후의 계수를 측정하였다. 각각의 계수는 방사선원 투여량과 중량으로 정규화하였다. 감쇠보정의 영향을 평가하기 위하여 "심부피질/대뇌피질"의 비를 계산하였다. 산란보정의 영향을 평가하기 위하여 회백질과 백질에 관심영역을 그린 다음 "(회백질-백질)/회백질"의 비를 구하여 대조도를 계산하였다. 결과: 감쇠보정 후, "심부피질/대뇌피질"의 비는 $17{\pm}7%$ 증가하였다. 산란보정 후, "(회백질-백질)/회백질"의 비는 $12{\pm}3%$ 증가하였다. 결론: 감쇠보정 후 "심부피질/대뇌피질"의 계수비가 증가하였고, 산란보정 후 회백질과 백질 사이의 대조도가 증가하였다. 이는 고양이 뇌 PET 영상 획득 및 정량화를 할 때 감쇠보정이 특히 중요함을 반영한다.

Keywords

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