A Study on analysis of contrasts and variation in SUV with the passage of uptake time in 18F-FDOPA Brain PET/CT

18F-FDOPA Brain PET/CT 검사의 영상 대조도 분석 및 섭취 시간에 따른 SUV변화 고찰

  • Seo, Kang rok (Department of Nuclear Medicine, Asan medical Center) ;
  • Lee, Jeong eun (Department of Nuclear Medicine, Asan medical Center) ;
  • Ko, Hyun soo (Department of Nuclear Medicine, Asan medical Center) ;
  • Ryu, Jae kwang (Department of Nuclear Medicine, Asan medical Center) ;
  • Nam, Ki pyo (Department of Nuclear Medicine, Asan medical Center)
  • Received : 2019.02.28
  • Accepted : 2019.03.02
  • Published : 2019.04.27

Abstract

Purpose $^{18}F$-FDOPA using amino acid is particularly attractive for imaging of brain tumors because of the high uptake in tumor tissue and the low uptake in normal brain tissue. But, on the other hand, $^{18}F$-FDG is highly uptake in both tumor tissue and normal brain tissue. The purpose of study is to evaluate comparison of contrasts in $^{18}F$-FDOPA Brain PET/CT and $^{18}F$-FDG Brain PET/CT and to find out optimal scan time by analysis of variation in SUV with the passage of uptake time. Materials and Methods A region of interest of approximately $350mm^2$ at the center of the tumor and cerebellum in 12 patients ($51.4{\pm}12.8yrs$) who $^{18}F$-FDG Brain PET/CT and $^{18}F$-FDOPA Brain PET/CT were examined more than once each. The $SUV_{max}$ was measured, and the $SUV_{max}$ ratio (T/C ratio) of the tumor cerebellum was calculated. In the analysis of SUV, T/C ratio was calculated for each frame after dividing into 15 frames of 2 minutes each using List mode data in 25 patients ($49.{\pm}10.3yrs$). SPSS 21 was used to compare T/C ratio of $^{18}F$-FDOPA and T/C ratio of $^{18}F$-FDG. Results The T/C ratio of $^{18}F$-FDOPA Brain PET/CT was higher than the T/C ratio of $^{18}F$-FDG Brain, and show a significant difference according to a paired t-test(t=-5.214, p=0.000). As a result of analyzing changes in $SUV_{max}$ and T/C ratio, the peak point of $SUV_{max}$ was $5.6{\pm}2.9$ and appeared in the fourth frame (6 to 8 minutes), and the peak of T/C ratio also appeared in the fourth frame (6 to 8 minutes). Taking this into consideration and comparing the existing 10 to 30 minutes image and 6 to 26 minutes image, the $SUV_{max}$ and T/C ratio increased by 0.2 and 0.1 each, compared to the 10 to 30 minutes image for 6 to 26 minutes image. Conclusion From this study, $^{18}F$-FDOPA Brain PET/CT is effective when reading the image, because the T/C ratio of $^{18}F$-FDOPA Brain PET/CT was higher than T/C ratio of $^{18}F$-FDG Brain PET/CT. In addition, in the case of $^{18}F$-FDOPA Brain PET/CT, there was no difference between the existing 10 to 30 minutes image and 6 to 26 minutes image. Through continuous research, we can find possibility of shortening examination time in $^{18}F$-FDOPA Brain PET/CT. Also, we can help physician to accurate reading using additional scan data.

$^{18}F$-FDOPA는 뇌 종양의 아미노산 대사를 추적하는 방사성 의약품이다. 본 연구의 목적은 뇌 종양의 아미노산 대사를 영상화 하여 악성 종양을 진단하는 $^{18}F$-FDOPA와 포도당 대사를 통한 $^{18}F$-FDG의 Brain PET/CT 검사 영상의 대조도 분석을 통해 병변의 검출 능력을 비교하고, $^{18}F$-FDOPA Brain PET/CT 검사에서 섭취 시간에 따른 SUV의 변화를 분석하여 최적의 영상 획득 시간을 알아보기 위함이다. $^{18}F$-FDOPA 와 $^{18}F$-FDG 두 영상에서 종양(Tumor)과 소뇌(Cerebellum)의 중심에 각각 약 $350mm^2$의 관심 영역을 설정하여 $SUV_{max}$를 측정하였고, 종양과 소뇌의 $SUV_{max}$ 비율(T/C ratio)을 산출하였고, $^{18}F$-FDOPA 투여 직후 30분 동안 획득한 리스트 수집 방식 데이터(List mode data)를 활용해 2분씩 15프레임으로 나눈 뒤 각 프레임 별로 종양과 소뇌 중심에 $SUV_{max}$를 측정하여 위와 동일한 방법으로 T/C ratio를 산출하여 분석하였다. 종양의 평균 $SUV_{max}$를 비교해 본 결과, $^{18}F$-FDOPA Brain PET/CT 검사에서 $4.2{\pm}0.8$, $^{18}F$-FDG Brain PET/CT 검사에서는 $5.6{\pm}0.7$ 이었다. 또한, T/C ratio는 $^{18}F$-FDOPA 검사에서 $2.1{\pm}0.7$, $^{18}F$-FDG 검사에서는 $1.1{\pm}0.4$ 이었으며, $^{18}F$-FDOPA의 $SUV_{max}$$^{18}F$-FDG보다 낮지만 T/C ratio는 높게 나타나 종양 구별 능력이 더욱 뛰어난 것을 알 수 있었다(t=-5.214, p=0.000). $^{18}F$-FDOPA의 섭취 시간에 따른 $SUV_{max}$와 T/C ratio를 분석한 결과, $SUV_{max}$와 T/C ratio의 Peak는 모두 6~8분에서 나타났다. 이를 토대로 본원에서 $^{18}F$-FDOPA Brain PET/CT 검사에서 활용하는 10~30분의 영상과 Peak가 나타나기 시작한 6~26분의 영상을 비교한 결과 SUV와 T/C ratio가 각각 0.2, 0.1 증가하였다. 추후 지속적인 연구를 통해 검사 소요시간의 단축 가능성과 추가적인 스캔 정보 활용을 통한 정확한 진단에도 도움이 될 것으로 사료된다.

Keywords

References

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