Image Degradation Reduction Technique for PET Developed

Researchers at the University of Eastern Finland recently developed a novel technique that reduces image degradation caused by respiratory motion during a PET scan. The new technique presented in the PhD thesis of Tuomas Koivumäki, MSc (Tech.), is based on bioimpedance measurement and allows for 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.

In the future, the new 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 study found that when synchronizing images on the basis of bioimpedance, it was possible to discern smaller details. Motion compensation also significantly influenced the parameters measured from the images. Bioimpedance measurement offers a straightforward technique for acquiring the data needed for motion compensation. Furthermore, the technique can be easily integrated into EKG measurement, which is widely used to monitor heart function during the scan.

In techniques based on bioimpedance measurement, a very weak electrical current is passed through the patient's chest, and changes in the resulting voltage are measured. The voltage has been observed to change according to the patient's breathing and cardiac function. Earlier, bioimpedance measurements have been used to assess, for example, body composition, fluid accumulations in lungs, and indicators of cardiac function.

The study focused on the feasibility of bioimpedance-based measurement techniques for respiratory and cardiac motion compensation in PET imaging. The study first used computational models and test subjects to determine an optimized bioimpedance measurement configuration for simultaneous measurement of respiratory and cardiac gating signals. The second phase of the study focused on analyzing whether bioimpedance techniques can be used to reduce respiration-related degradation of PET images.

Degraded image quality caused by respiratory motion has been reported to affect PET scanning performed to detect cancer and heart conditions in particular. At worst, image degradation may lead to a wrong diagnosis and inadequate or unnecessary treatment.

The results were originally published in Medical & Biological Engineering & Computing, Physiological Measurement, and Physics in Medicine and Biology.
— SOURCE: University of Eastern Finland