Development of Ultrasound Transducers for Gating the Acquisition of Computed Tomography Coronary Angiography (CTCA)

Cardiovascular disease (CVD) accounts for 30% of deaths. The gold standard for diagnosing coronary artery disease (CAD) is catheter-based coronary angiography, which is expensive and invasive. Computed tomography coronary angiography (CTCA) represents an attractive alternative because it is noninvasive and computed tomography is widely available. However, CTCA is subject to cardiac motion and thus must be gated to acquire images during the quiescent phase of the cardiac cycle. Gating based on mechanical motion using ultrasound has been demonstrated to improve CTCA imaging performance relative to electrocardiogram (ECG) gating. However, most ultrasound transducers produce streak artifacts in the CT image. In order to address this problem, single element and linear array CT-compatible transducers were designed and fabricated with the goal of achieving acceptable imaging performance for gating while maintaining X-ray compatibility for prospective gating of CT acquisitions using ultrasound imaging data. The developed transducers were radiographically and acoustically tested and were used to acquire images both in tissue-mimicking phantoms and
_in
vivo
in a healthy volunteer. These results have identified alternative passive materials that can be used in low frequency transducers to improve CT compatibility with >15 cm penetration depth and similar imaging performance to transducers with standard, non-CT-compatible materials.