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

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

Purpose ¹⁸F-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, ¹⁸F-FDG is highly uptake in both tumor tissue and normal brain tissue. The purpose of study is to evaluate comparison of contrasts in ¹⁸F-FDOPA Brain PET/CT and ¹⁸F-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 350 mm2 at the center of the tumor and cerebellum in 12 patients (51.4 ± 12.8 yrs) who ¹⁸F-FDG Brain PET/CT and ¹⁸F-FDOPA Brain PET/CT were examined more than once each. The SUVmax was measured, and the SUVmax 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. ± 10.3 yrs). SPSS 21 was used to compare T/C ratio of ¹⁸F-FDOPA and T/C ratio of ¹⁸F-FDG. Results The T/C ratio of ¹⁸F-FDOPA Brain PET/CT was higher than the T/C ratio of ¹⁸F-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 SUVmax and T/C ratio, the peak point of SUVmax was 5.6 ± 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 SUVmax 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, ¹⁸F-FDOPA Brain PET/CT is effective when reading the image, because the T/C ratio of ¹⁸F-FDOPA Brain PET/CT was higher than T/C ratio of ¹⁸F-FDG Brain PET/CT. In addition, in the case of ¹⁸F-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 ¹⁸F-FDOPA Brain PET/CT. Also, we can help physician to accurate reading using additional scan data.