title: Simultaneous acquisition of (99m)Tc- and (123)I-labeled radiotracers using a preclinical SPECT scanner with CZT detectors.
abstract: OBJECTIVE
  Simultaneous acquisition of (99m)Tc and (123)I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Wellness Promotion Science Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan. kobayasi@mhs.mp.kanazawa-u.ac.jp.
authors.forename: Masato
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Clinical Research Department, The Medical and Pharmacological Research Center Foundation, Hakui, Japan.|Division of Nuclear Medicine, Department of Radiology, Saitama Medical University Hospital, Saitama, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Matsunari
authors.affiliation: Department of Radioisotope Medicine, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan.
authors.forename: Kodai
authors.initials: K
authors.lastname: Nishi
authors.affiliation: Graduate School of Medicine, Division of Health Sciences, Osaka University, Osaka, Japan.
authors.forename: Asuka
authors.initials: A
authors.lastname: Mizutani
authors.affiliation: Clinical Research Department, The Medical and Pharmacological Research Center Foundation, Hakui, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Miyazaki
authors.affiliation: Wellness Promotion Science Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ogai
authors.affiliation: Wellness Promotion Science Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan.
authors.forename: Jyunko
authors.initials: J
authors.lastname: Sugama
authors.affiliation: Division of Tracer Kinetics, Advanced Science Research Center, Kanazawa University, Kanazawa, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shiba
authors.affiliation: School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kawai
authors.affiliation: School of Medical Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Kinuya
mesh_terms: D000818:Animals; D002104:Cadmium; D007091:Image Processing, Computer-Assisted; D007457:Iodine Radioisotopes; D007553:Isotope Labeling; D051379:Mice; D011849:Radioactive Tracers; D051381:Rats; D017208:Rats, Wistar; D012666:Semiconductors; D013667:Technetium; D013691:Tellurium; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation*; D015032:Zinc
chemical_list: C474490:CdZnTe; D007457:Iodine Radioisotopes; D011849:Radioactive Tracers; D002104:Cadmium; D013667:Technetium; D015032:Zinc; D013691:Tellurium
keywords: 123I; 99mTc; Cadmium zinc telluride; Dual tracer; Small animal SPECT scanner