Dynamic sequence respiratory gated perfusion pulmonary SPECT without external tracking device
The purpose of this study was to develop and evaluate a new method for respiratory gated pulmonary perfusion SPECT (RGPS) based on dynamic acquisition without using an external tracking device (ETD) or list-mode data acquisition.
In the phantom study, our method used a dynamic sequence technique, which was specified by sequences of 50-ms acquisition during 30 s per view of SPECT instead of using an ETD. For this purpose, we created a computer program that identified respiratory phases by calculating the center of activity (COA) in each dynamic frame image. We compared RGPS using the dynamic sequence acquisition (RGPS-DS) and RGPS using ETD (RGPS-ETD) in phantom studies employing a cylinder phantom filled with technetium-99m solution attached to an instrument providing a simple harmonic motion. In the patient study, RGPS-DS was applied to data collected from 3 patients during a routine study of Tc-MAA pulmonary perfusion SPECT.
In the phantom study, the calculation of COA indicated a good agreement between RGPS-DS and RGPS-ETD. With an oscillatory phantom movement amplitude of 30 mm, the amplitudes determined by RGPS-DS and RGPS-ETD (28.36 and 27.58 mm, respectively) were identical on considering a pixel size of 4.66 mm for reconstructed SPECT images. In the patient study, applicability of our method to patient data was demonstrated.
We have showed the feasibility of our method to obtain RGPS without ETD, and conclude that RGPS-DS may be an innovative and efficient technique in respiratory gated pulmonary perfusion SPECT. Further studies with a larger number of patients should demonstrate the accuracy of our method.
KeywordsRespiration tracking device SPECT Lung Dynamic acquisition
The authors thank Prof. Tetsuo Ito, Prof. Nobuyuki Sugiura, Dr. Norio Tsuchiya, and Dr. Yoshihiro Komeya for scientific advice, and Hideo Morimoto, Hiroshi Takada, Ryou Inoue, Yuko Shintani, Shuhei Yoshida, and Toshiaki Kurokawa for assistance in data acquisition.
Conflict of interest
The authors declare that they have no conflict of interest and source of funding.
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