A PhD student at the University of Eastern Finland has presented a technique that reduces image degradation during a PET scan caused by the movement of the patient breathing.
The technique, developed by Tuomas Koivumäki, is based on bioimpedance measurement, whereby a very weak electrical current is passed through the patient's chest and the voltage measured. The voltage has been observed to change according to the patient's breathing and cardiac function, allowing image reconstruction at a specific phase of the patient's breathing pattern. This, in turn, makes it possible to reduce image degradation caused by motion.
PET scanning is routinely used to detect cancer and heart conditions. In the future, the newly developed technique will enable increasingly accurate image acquisition especially during PET scans performed to detect cancers of the chest and upper abdomen, and inflammatory diseases of the heart. The enhanced image quality could potentially improve the reliability of diagnosis and lead to better monitoring of treatments.
The study found that when synchronising images on the basis of bioimpedance, it was possible to discern smaller details. Bioimpedance measurement offers a straightforward technique for acquiring the data needed for motion compensation. Furthermore, the technique can be easily integrated into an electrocardiogram (ECG) measurement, which is widely used to monitor heart function during the scan.
The study first used computational models and test subjects to determine an optimised bioimpedance measurement configuration for simultaneous measurement of respiratory and cardiac gating signals. The second phase of the study focused on analysing whether bioimpedance techniques can be used to reduce respiration-related degradation of PET images.
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