Evaluation of Simultaneous Dual-radioisotope SPECT Imaging Using 18F-fluorodeoxyglucose and 99mTc-tetrofosmin

Document Type: Original Article

Authors

1 Department of Radiology, Gunma Prefectural College of Health Sciences, Maebashi, Japan

2 Department of Ragiological Technology, Gunma Cardiovascular Center, Maebashi, Japan

3 Department of Diagnostic Radiology and Nuclear Medicine, Gunma Cardiovascular Center, Maebashi, Japan

4 Department of Ragiological Technology, National Kyusyu Medical Center, Fukuoka, Japan

5 Department of Ragiological Technology, Red Cross Maebashi Hospital, Maebashi, Japan

10.7508/aojnmb.2016.02.002

Abstract

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.

Keywords

Main Subjects


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