Automatic phase determination for retrospectively gated cardiac CT

Abstract

The recent improvements in CT detector and gantry technology in combination with new heart rate adaptive cone beam reconstruction algorithms enable the visualization of the heart in three dimensions at high spatial resolution. However, the finite temporal resolution still impedes the artifact-free reconstruction of the heart at any arbitrary phase of the cardiac cycle. Cardiac phases must be found during which the heart is quasistationary to obtain outmost image quality. It is challenging to find these phases due to intercycle and patient-to-patient variability. Electrocardiogram (ECG) information does not always represent the heart motion with an adequate accuracy. In this publication, a simple and efficient image-based technique is introduced which is able to deliver stable cardiac phases in an automatic and patient-specific way. From low-resolution four-dimensional data sets, the most stable phases are derived by calculating the object similarity between subsequent phases in the cardiac cycle. Patient-specific information about the object motion can be determined and resolved spatially. This information is used to perform optimized high-resolution reconstructions at phases of little motion. Results based on a simulation study and three real patient data sets are presented. The projection data were generated using a 16-slice cone beam CT system in low-pitch helical mode with parallel ECG recording.

Automatic selection of optimal systolic and diastolic reconstruction windows for dual-source CT coronary angiography

“…However, this difference grew with increasing heart rates. A similar approach also using a motion-map algorithm has been developed by another group [12]. Hoffmann et al presented clinical results using this approach with data acquired with a 16-slice CT scanner [13].…”

Segmentation and motion estimation of stent grafts in abdominal aortic aneurysms

“…ECG gating is extensively used in cardiac exams [2,120,85], especially for the assessment of coronary arteries [32,18,46]. The goal in most of these studies is to limit the effect of motion rather than to examine the motion itself for which the technique can also be utilized.…”

Motion Calculations on Stent Grafts in AAA

“…ECG-gated CT is extensively used in cardiac exams (Albers et al, 2003;Manzke et al, 2004;Williamson et al, 2008), especially for the assessment of coronary arteries (Chartrand-Lefebvre et al, 2007;Dewey et al, 2008;Greuter et al, 2005). The goal in most of these studies is to limit the effect of motion rather than to examine the motion itself for which the technique can also be utilized.…”