Cardiac and chest PET: ECG-bioimpedance measurements make up for respiratory motion

A new method of image reconstruction that synchronizes a preset phase of respiration using electrocardiography (ECG) and bioimpedance raises the image quality of PET usually degraded by breathing artifacts, the University of Eastern Finland (UEF) announced Oct. 10.

PhD candidate Tuomas Koivumaki from UEF and Kuopio University Hospital in Kuopio, Finland, and colleagues reconstructed image data based on both respiratory and cardiac gating signals with electrodes mirroring a II limb lead configuration. Static and ECG-gated images were enhanced with added bioimpedance measurements that allowed the researchers to factor in cardiac displacement from the end of inhalation to the end of exhalation. The research has been published in multiple journals, including Medical & Biological Engineering & Computing and Physics in Medicine and Biology.

For this study, researchers evaluated dual gating in cardiac PET of 11 subjects by measuring myocardial wall thickness and ventricular volume. On average, respiratory motion was gauged at 7.6 mm plus or minus 3.3 mm. The researchers found that, with dual gating, the myocardial wall was thinner than in conventional cardiac-gated imaging, about 9.3 mm versus 11.3 mm, respectively, and they also found a slight but statistically significant increase in left-ventricular myocardial volume of about 4 mL.

This suggests that dual-gating enables finer imaging in more precise detail. Contingent on further study and validation, ECG and bioimpedance measurements could provide a means of dual-gated image reconstruction requiring only a single device with conventional ECG equipment.