Optimizing circular ring arrays for forward- looking IVUS imaging

Abstract

Forward-looking (FL) catheter-based imaging systems are highly desirable for guiding interventions in intravascular ultrasound (IVUS) applications. One of the main challenges of array based FL-IVUS systems is the large channel count which results in increased system complexity. Synthetic phased array processing with reduced firing count simplifies the front-end and hence can enable 3-D real-time imaging. Recently, we have investigated dual-ring arrays suitable for IVUS imaging, where the two concentric circular arrays are used separately as transmit (Tx) and receive (Rx) arrays. In this study, we present different optimized array designs based on dual and single circular rings that are suitable for synthetic phased array processing with reduced number of firings. To obtain optimal firing set that produces low side lobes in the wide-band response, we use simulated annealing algorithm. In the simulations we use 1.2 mm diameter array configurations with 64 Tx and 58 Rx elements, center frequency of 20 MHz and fractional bandwidth of 50% and 80%. The results show that optimized dual ring arrays provide 8 dB improvements in peak near side lobe level with no widening in main lobe width when compared with full and other sparse coarrays.

A Column-Row-Parallel ASIC architecture for 3D wearable / portable medical ultrasonic imaging

“…The miniaturized imaging system is mounted onto the tip of a catheter, which provides minimally invasive diagnosis, interventions or treatments in medical procedures [73][74][75][76]. Currently the more commonly used ultrasound systems for intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) are side-looking ones, while forward-looking ones are gaining more popularity because they offers complimentary information.…”

“…Although dedicated annular ring arrays are available by custom fabrication [75,76], a generalpurpose 2D array with the proposed Column-Row-Parallel architecture can achieve similar results [77,78]. The full 2D array provides even more flexibility, since more rings can be formed within the regular 2D aperture.…”

Single-chip CMUT-on-CMOS front-end system for real-time volumetric IVUS and ICE imaging

“…Dual-ring annular CMUT arrays with separate Tx and Rx rings enable separate optimization of Tx and Rx element geometry and electronics for higher SNR with negligible loss in resolution [18–20]. For successful realization of FL-IVUS imaging catheters with small sized elements, close integration of front-end electronics and the transducer array within the catheter is very critical.…”

PMN-PT single-crystal high-frequency kerfless phased array

“…SL probes may also use circular arrays mounted along the circumference of the catheter to enable electronic scanning of the cross-sectional area without mechanical artifacts caused by rotating transducers [6]. A major disadvantage of these SL probes is the lack of forward-looking (FL) capability to provide a view of the path or structures in front of the catheter, which is helpful in guiding interventions, especially in the case of chronic total occlusions [7]. Although single-element-transducer-based systems in which the transducer is mounted on a rotating cam assembly have been realized for FL-IVUS, these systems require a complex mechanism with complicated beam alignment and calibration protocols [8]–[10].…”

“…To construct miniature high-frequency array transducers, capacitive micromachined ultrasonic transducers (CMUTs) were also studied extensively. Because the array size can be minimized easily with IC technology with CMUTs, researchers have put forth great effort in developing forward-looking circular arrays for intravascular imaging [7], [16]–[18]. These devices have very complex configurations that utilize a sparse array approach.…”