Retrospective Cardiac Gating with A Prototype Small-Animal X-ray Computed Tomograph

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Preclinical Research

Background:

• Preclinical X-ray CT scanners commonly use CMOS detectors and Tungsten X-ray sources.
• High heart rates in mice (~600 beats/min) pose challenges for cardiac motion artifact reduction in CT imaging.
• Cardiac gating is crucial for in vivo cardiac function studies, minimizing motion-induced blurring.

Purpose of the Study:

• To describe a method for preclinical intrinsic retrospective cardiac-gated CT imaging.
• To advance research on in vivo cardiac function and structure analysis using a novel CT scanner.
• To demonstrate the effectiveness of cardiac gating in a prototype small-animal CT system.

Main Methods:

• Development of the CrumpCAT prototype small-animal X-ray CT scanner.
• Acquisition of numerous projections with short exposure times (~20 ms).
• Retrospective extraction of respiratory and cardiac signals from raw projection data.
• Rejection of projections during the respiratory inspiration phase.
• Division of remaining projections into 12 cardiac phases for independent reconstruction.
• Iterative reconstruction to produce 4D (four-dimensional) volumetric datasets for each cardiac phase.

Main Results:

• The CrumpCAT scanner achieved medium (200 µm) and high (125 µm) resolution imaging.
• Retrospective respiratory and cardiac gating were successfully implemented.
• The cardiac-gating method effectively minimized motion artifacts, enabling detailed cardiac analysis.
• Demonstrated the utility of the cardiac-gating feature through in vivo imaging results.

Conclusions:

• The developed cardiac-gating method is effective for preclinical CT imaging of cardiac function.
• The CrumpCAT prototype facilitates detailed in vivo assessment of cardiac structure and dynamics.
• This technology is relevant for institutions studying small-animal cardiac physiology.