1Department of Radiology, Gunma Prefectural College of Health Sciences, Maebashi, Japan
2Department of Ragiological Technology, Gunma Cardiovascular Center, Maebashi, Japan
3Department of Diagnostic Radiology and Nuclear Medicine, Gunma Cardiovascular Center, Maebashi, Japan
4Department of Ragiological Technology, National Kyusyu Medical Center, Fukuoka, Japan
5Department of Ragiological Technology, Red Cross Maebashi Hospital, Maebashi, Japan
Objective(s): Use of a positron emission tomography (PET)/single-photon emission computed tomography (SPECT) system facilitates the simultaneous acquisition of images with fluorine-18 fluorodeoxyglucose (18F-FDG) and technetium (99mTc)-tetrofosmin. However, 18F has a short half-life, and 511 keV Compton-scattered photons are detected in the 99mTc energy window. Therefore, in this study, we aimed to investigate the consequences of these facts. Methods: The crosstalk correction for images in the 99mTc energy window involved the dual energy window (DEW) subtraction method. In phantom studies, changes in the count of uniform parts in a phantom (due to attenuation from decay), signal detectability in the hot-rod part of the phantom, and the defect contrast ratio in a cardiac phantom were examined. Results: For 18F-FDG in the step-and-shoot mode, nearly a 9% difference was observed in the count of projection data between the start and end positions of acquisition in the uniform part of the phantom. Based on the findings, the detectability of 12 mm hot rods was relatively poor. In the continuous acquisition mode, the count difference was corrected, and detectability of the hot rods was improved. The crosstalk from 18F to the 99mTc energy window was approximately 13%. In the cardiac phantom, the defect contrast in 99mTc images from simultaneous dual-radionuclide acquisition was improved by approximately 9% after DEW correction; the contrast after correction was similar to acquisition with 99mTc alone. Conclusion: Based on the findings, the continuous mode is useful for 18F-FDG acquisition, and DEW crosstalk correction is necessary for 99mTc-tetrofosmin imaging.
1. Japan Radioisotope Association. The Present State of Nuclear Medicine Practice in Japan—A Report of the 7th Nationwide Survey in 2012. Radioisotopes. 2013;62(8):545-608.
2. Coleman RE, Laymon CM, Turkington TG. FDG imaging of lung nodules: a phantom study comparing SPECT, camera-based PET, and delicated PET. Radiology. 1999;210(3):823-8.
3. van Lingen A, Huijgens PC, Visser FC, Ossenkoppele GJ, Hoekstra OS, Martens HJ, et al. Performance characteristics of a 511-keV collimator for imaging positron emitters with a standard gamma-camera. Eur J Nucl Med. 1992;19(5):315-21.
4. Fukuchi K, Katafuchi T, Fukushima K, Shimotsu Y, Toba M, Hayashida K, et al. Estimation of myocardial perfusion and viability using simultaneous 99mTc- Tetrofosmin--FDG collimated SPECT. J Nucl Med. 2000;41(8): 1318-23.
5. Pagnanelli RA, Hanson MW, Turkington T, Coleman RE, Borges-Neto S. Gated 99mTc-Tetrofosmin and 18F-FDG studies: a comparison of single-acquisition and separate-acquisition protocols. J Nucl Med Technol. 2002;30(4):175-8.
6. Hudson HM, Larkin RS. Accelerated image reconstruction using ordered subsets of projection data. IEEE Trans Med Imaging. 1994;13(4):601-9.
7. Takahashi Y, Murase K, Mochizuki T, Higashino H, Sugawara Y, Kinda A. Evaluation of the number of SPECT projections in the ordered subsets-expectation maximization image reconstruction method. Ann Nucl Med. 2003;17(7):525-30.
8. Takahashi Y, Matsuki H, Mochizuki T. Basic study of continuous repetitive data acquisition using a phantom. Kaku Igaku. 1996;33(12):1363-9.
9. Kubo A, Nakamura K, Hashimoto J, Sammiya T, Iwanaga S, Hashimoto S, et al. Phase I clinical traial of a new myocardial imaging agent, 99mTc- PPN1011. Kaku Igaku. 1992;29(10):1165-76.
11. Kanda Y. Investigation of the freely available easy-to-use software ‘EZR’ for medical statistics. Bone Marrow Transplant. 2013;48(3):452-8.
12. Stoll HP, Hellwig N, Alexander C, Ozbek C, Schieffer H, Oberhausen E. Myocardial metabolic imaging by means of fluorine-18 deoxyglucose/technetium- 99m sestamibi dual-isotope single-photon emission tomography. Eur J Nucl Med. 1994;21(10):1085-93.
13. Takahashi Y, Miyagawa M, Nishiyama Y, Ishimura H, Mochizuki T. Dual radioisotopes simultaneous SPECT of 99mTc-tetrofosmin and 123I-BMIPP using a semiconductor detector. Asia Oceania J Nucl Med Biol. 2015;3(1):43-9.