Helical cardiac cone beam reconstruction using retrospective ECG gating

Abstract

In modern computer tomography (CT) systems, the fast rotating gantry and the increased detector width enable 3D imaging of the heart. Cardiac volume CT has a high potential for non-invasive coronary angiography with high spatial resolution and short scan time. Due to the increased detector width, true cone beam reconstruction methods are needed instead of adapted 2D reconstruction schemes. In this paper, the extended cardiac reconstruction method is introduced. It integrates the idea of retrospectively gated cardiac reconstruction for helical data acquisition into a cone beam reconstruction framework. It leads to an efficient and flexible algorithmic scheme for the reconstruction of single- and multi-phase cardiac volume datasets. The method automatically adapts the number of cardiac cycles used for the reconstruction. The cone beam geometry is fully taken into account during the reconstruction process. Within this paper, results are presented on patient datasets which have been acquired using a 16-slice cone beam CT system.

Evaluation of biventricular ejection fraction with ECG-gated 16-slice CT: preliminary findings in acute pulmonary embolism in comparison with radionuclide ventriculography

“…A recent paper [20] has shown that image quality in multi-detector row cardiac CT strongly depends on the choice of the appropriate reconstruction parameters, such as the reconstruction algorithm, reconstruction technique and placement of the reconstruction interval. In our study, the reconstruction technique [21,22] corrects for the cone beam geometry by performing a full 3D filtered back projection which is synchronized with each patient's ECG curve and heart rate by the use of an adaptative multi-segmental reconstruction.…”

Four-dimensional cardiac imaging in living embryos via postacquisition synchronization of nongated slice sequences

“…12 Using specific modifications to conventional MRI pulse sequences, it is also possible to generate and extract a signal that varies in synchrony with the cardiac cycle for later reconstruction. [13][14][15][16] For CT, various methods have been developed, either to recover an imaged volume of the heart in a defined motion state at a single time point 17 or for 4D imaging, by tracking the projection's center of mass. 18 ECG-free algorithms have also been used for US imaging.…”

Algebraic and analytic reconstruction methods for dynamic tomography

“…f a(t) + l ζ dl, (1) where ζ ∈ S 2 is a unit vector in R 3 (S 2 is the unit sphere in R 3 ), a(t) ∈ R 3 is the x-ray source position at time t ∈ T ⊂ R, t is then also the source trajectory parameter in R 3 , see Fig. 1.…”

“…The problem under consideration is the reconstruction of f , or equivalently of f Γ t , from cone-beam measurements Df Γt , see (1), for known deformation functions Γ t , t ∈ T . Our objective is to apply efficient accurate deformation corrections in the reconstruction algorithms.…”

“…Dynamic tomography is a very active area [1], [2]. Movements or deformations of the patient must be taken into account in nuclear medicine, such as SPECT or PET because of long measurement time, but also in CT for fast moving organs such as the heart.…”