Fast Retrospectively Gated Quantitative Four-Dimensional (4D) Cardiac Micro Computed Tomography Imaging of Free-Breathing Mice

Abstract

We have developed a high-resolution micro computed tomography method for evaluating the cardiac function and morphology of free-breathing mice in acquisition times shorter than 1 minute.

Intrinsic Gating for Small-Animal Computed Tomography

“…Values determined by self-gated and extrinsically gated CT matched closely with those quoted in the literature. 5,8 Minor differences in the values may derive from different animal sizes, ages, anesthesia states, the physiological conditions under which the animals were tested, and measurement error. 19 -21 Difference (⌬) in the detected values Confidence intervals and individual differences between extrinsically and intrinsically determined parameters are also listed.…”

“…Both prospective [5][6][7] and retrospective 8 -10 methods for respiratory and cardiac gating have been described, and their benefit for image analysis has been demonstrated. [7][8][9][10] Regardless of whether they are retrospective or prospective, all gating methods currently in use in small-animal CT imaging depend on ECG to derive a gating reference signal. In addition, heart movement attributable to respiration must either be suppressed via intubation or detected by a pneumatic cushion and taken into consideration.…”

High-Resolution CT for Small-Animal Imaging Research

“…Alternatively, rapid 3D phenotyping of cardiovascular development in mouse embryos has been achieved by ex vivo micro-CT with iodine staining (Degenhardt et al, 2010). In vivo micro-CT-based cardiac morphological and functional imaging in mice and rats has been reported using both PG and RG approaches (Badea et al, 2005(Badea et al, , 2008cBartling et al, 2007a,b;Detombe et al, 2008;Drangova et al, 2007;Nahrendorf et al, 2007;Song et al, 2007). Using both approaches, quantitative estimates can be made for ejection fraction, stroke volume, and cardiac output on the basis of left ventricle (LV) volume measurements in the 4D (3D þ time) micro-CT data sets.…”

“…In most of the proposed studies, blood pool contrast agents have been used; although with faster scanning available with the flat-panel-based systems (Bartling et al, 2007a,b;Drangova et al, 2007), this may be optional. For example, recently, a method for imaging cardiac perfusion in the mouse has been proposed using a scan protocol that consists of repetitive injections of conventional low-molecular-weight contrast media within several consecutive scans (Sawall et al, 2012).…”

“…Some applications, such as studies of skeletal development (Guldberg et al, 2004), may accept lower resolution but require larger FoV, that is, imaging the whole mouse or rat using the larger field of view offered by flat-panel-based systems (Bartling et al, 2007a,b;Drangova et al, 2007;MissbachGuentner et al, 2007). As an example of bone imaging using micro-CT in Figure 8, we present images from a longitudinal study of bone healing in a model of large lesion in rat femur.…”