Kobayashi Masato, Matsunari Ichiro, Nishi Kodai, Mizutani Asuka, Miyazaki Yoshiharu, Ogai Kazuhiro, Sugama Jyunko, Shiba Kazuhiro, Kawai Keiichi, Kinuya Seigo
Wellness Promotion Science Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan.
Clinical Research Department, The Medical and Pharmacological Research Center Foundation, Hakui, Japan.
Ann Nucl Med. 2016 May;30(4):263-71. doi: 10.1007/s12149-015-1055-6. Epub 2016 Jan 8.
Simultaneous acquisition of (99m)Tc and (123)I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors.
10-ml cylindrical syringes contained about 37 MBq (99m)Tc-tetrofosmin ((99m)Tc-TF) or 37 MBq (123)I-15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid ((123)I-BMIPP) were used to assess the relationship between these SPECT radioactive counts and radioactivity. Two 10-ml syringes contained 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP to assess the influence of (99m)Tc upscatter and (123)I downscatter, respectively. A rat-sized cylindrical phantom also contained both 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. The two 10-ml syringes and phantom were scanned using a pinhole collimator for rats. Myocardial infarction model rats were examined using 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. Two 1-ml syringes contained 105 MBq (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) and 35 MBq (123)I-labeled N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane ((123)I-FP-CIT). The two 1-ml syringes were scanned using a pinhole collimator for mice. Normal mice were examined using 105 MBq (99m)Tc-HMPAO and 35 MBq (123)I-FP-CIT.
The relationship between SPECT radioactive counts and radioactivity was excellent. Downscatter contamination of (123)I-BMIPP exhibited fewer radioactive counts for 300 MBq (99m)Tc-TF without scatter correction (SC) in 125-150 keV. There was no upscatter contamination of (99m)Tc-TF in 150-175 keV. In the rat-sized phantom, the radioactive count ratio decreased to 4.0 % for 300 MBq (99m)Tc-TF without SC in 125-150 keV. In the rats, myocardial images and radioactive counts of (99m)Tc-TF with the dual tracer were identical to those of the (99m)Tc-TF single injection. Downscatter contamination of (123)I-FP-CIT was 4.2 % without SC in 125-150 keV. In the first injection of (99m)Tc-HMPAO and second injection of (123)I-FP-CIT, brain images and radioactive counts of (99m)Tc-HMPAO with the dual tracer in normal mice also were the similar to those of the (99m)Tc-HMPAO single injection. In the first injection of (123)I-FP-CIT and second injection of (99m)Tc-HMPAO, the brain images and radioactive counts with the dual tracer were not much different from those of the (123)I-FP-CIT single injection.
Dual-tracer imaging of (99m)Tc- and (123)I-labeled radiotracers is feasible in a preclinical SPECT scanner with CZT detector. When higher radioactivity of (99m)Tc-labeled radiotracers relative to (123)I-labeled radiotracers is applied, correction methods are not necessarily required for the quantification of (99m)Tc- and (123)I-labeled radiotracers when using a preclinical SPECT scanner with CZT detector.
使用基于碲化镉锌（CZT）探测器的临床前SPECT扫描仪评估同时采集（99m）Tc和（123）I的情况。
使用装有约37 MBq（99m）Tc - 替曲膦（（99m）Tc - TF）或37 MBq（123）I - 15 - （对碘苯基）-3R，S - 甲基十五烷酸（（123）I - BMIPP）的10 ml圆柱形注射器来评估这些SPECT放射性计数与放射性之间的关系。两个10 ml注射器分别装有100或300 MBq（99m）Tc - TF和100 MBq（123）I - BMIPP，以分别评估（99m）Tc向上散射和（123）I向下散射的影响。一个大鼠尺寸的圆柱形体模也装有100或300 MBq（99m）Tc - TF和100 MBq（123）I - BMIPP。使用大鼠针孔准直器对两个10 ml注射器和体模进行扫描。使用300 MBq（99m）Tc - TF和100 MBq（123）I - BMIPP对心肌梗死模型大鼠进行检查。两个1 ml注射器分别装有105 MBq（99m）Tc标记的六甲基丙烯胺肟（（99m）Tc - HMPAO）和35 MBq（123）I标记的N - ω - 氟丙基 - 2β - 甲氧基羰基 - 3β - （4 - 碘苯基）去甲托烷（（123）I - FP - CIT）。使用小鼠针孔准直器对两个1 ml注射器进行扫描。使用105 MBq（99m）Tc - HMPAO和35 MBq（123）I - FP - CIT对正常小鼠进行检查。
SPECT放射性计数与放射性之间的关系良好。在125 - 150 keV下，对于300 MBq（99m）Tc - TF且无散射校正（SC）时，（123）I - BMIPP的向下散射污染表现为放射性计数较少。在150 - 175 keV下，（99m）Tc - TF没有向上散射污染。在大鼠尺寸的体模中，对于300 MBq（99m）Tc - TF且在125 - 150 keV下无SC时，放射性计数率降至4.0%。在大鼠中，双示踪剂的（99m）Tc - TF心肌图像和放射性计数与（99m）Tc - TF单次注射时相同。在125 - 150 keV下，无SC时（123）I - FP - CIT的向下散射污染为4.2%。在正常小鼠中，第一次注射（99m）Tc - HMPAO和第二次注射（123）I - FP - CIT时，双示踪剂的（99m）Tc - HMPAO脑图像和放射性计数也与（99m）Tc - HMPAO单次注射时相似。在第一次注射（123）I - FP - CIT和第二次注射（99m）Tc - HMPAO时，双示踪剂的脑图像和放射性计数与（123）I - FP - CIT单次注射时没有太大差异。
在具有CZT探测器的临床前SPECT扫描仪中，（99m）Tc和（123）I标记的放射性示踪剂的双示踪剂成像可行。当应用相对于（123）I标记的放射性示踪剂具有更高放射性的（99m）Tc标记的放射性示踪剂时，在使用具有CZT探测器的临床前SPECT扫描仪对（99m）Tc和（123）I标记的放射性示踪剂进行定量时不一定需要校正方法。
