Comparison of 18F-BF4 and 99mTc-TcO4 Uptake in Thyroid Tissues with Various NIS Expression or Under Different Pharmacological Treatment

• Main Authors: Lin Ting-Yu, 林庭羽
• Other Authors: Liou Nien-Hsien
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/74417139951453579102

碩士 === 國防醫學院 === 生物及解剖學研究所 === 101 === The thyroid gland with Na+/I- symporter (NIS) expression can uptake radioiodine and tetra-hedral complex such as TcO4, and thus, allows its function assessed by these radionuclides. Recently BF4, another NIS substrate, is investigated for the potential use as thyroid imaging in PET. We propose to compare 18F-BF4 and 99mTc-TcO4 uptake in thyroid tissues with various NIS expression. In this study, male SD rats were used throughout the experiments. Intervening reagents including perchlorate, thyroid-stimulating hormone (TSH) and methimazole (MMI) were used to alter NIS expression. After 99mTc-TcO4 and 18F-BF4 1mCi, i.p., PET and gamma camera were utilized for animal imaging. After imaging, 18F-BF4 ex vivo uptake was assayed by tissue counts using gamma counter normalized by tissue weight. The results showed that similar time-activity curves with a stable thyroid/Neck ratio at 40 min post injection and similar bio-distribution (accumulated in stomach and thyroid while excretion from genitourinary route). In normal thyroid functional status, 18F-BF4 PET and 99mTc-TcO4 scintigrapghy demonstrated fairly equivalent imaging contrast (neck muscle as background). From the imaging analysis, the perchlorate treatment led to reduced thyroid uptake of both 18F-BF4 than in 99mTc-TcO4 while the former one showed more decreased as compared to the controls. By either TSH or MMI treatment, the enhanced tracer uptake shown on 18F-BF4 and 99mTc-TcO4 imaging were evident and the former one was higher than the latter. In conclusion, 18F-BF4 PET seems able to demonstrate more pronounced change than 99mTc-TcO4 imaging to detect subsequent thyroid tracer uptake as NIS alteration is modulated pharmacologically. It might suggest that 18F-BF4 PET can be more sensitive to detect the subtle change of NIS function. With a fair imaging contrast, 18F-BF4 could be an alternative for 99mTc-TcO4 to measure thyroid functional status in conjunction with the use of PET and further clinical correlation is warranted.