Synchronization of pulmonary scintigraphy by respiratory flow and by impedance plethysmography

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Abstract
Image blurring as a result of patient motion, including organ movement, can cause loss of sensitivity in the detection of disease. The use of gated protocols using external signals to synchronize the acquisition with the motion of the organ of interest may provide a solution. Although such a solution has been implemented in cardiac imaging, the implementation of respiratory gating is more challenging considering the irregular nature of respiratory motion. In this work we investigated the use of two different physiological signals; namely respiratory flow and impedance plethysmography for synchronization of pulmonary scintigraphy with respiratory motion. An acquisition and post-processing signal interface was developed using LabVIEW in order to allow detection and comparison of the two signals for the same patient. Methodology was also developed for the rejection of irregular respiratory cycles based on mean amplitude, overall cycle duration and the cycle inspiration to expiration duration ratio (I/E). Rejection criteria based on tidal volume were also examined using the respiratory flow signal. Our data demonstrate that the two respiratory signals investigated are equivalent with only a phase shift difference present. In the case of respiratory flow, irregular cycles were rejected by setting acceptance limits at 40% and 30% around the mean for the I/E and the amplitude or duration of the cycle respectively. In the case of impedance plethysmography a limit of 50% for all rejection criteria was found to be optimum. Finally, a dynamic acquisition protocol was developed and tested providing synchronized scintigraphic images using both types of recorded respiratory signals.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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