Volumetric imaging using single chip integrated CMUT-on-CMOS IVUS array

Abstract

Designing a mechanically flexible catheter based volumetric ultrasonic imaging device for intravascular and intracardiac imaging is challenging due to small transducer area and limited number of cables. With a few parallel channels, synthetic phased array processing is necessary to acquire data from a large number of transducer elements. This increases the data collection time and hence reduces frame rate and causes artifacts due to tissue-transducer motion. Some of these drawbacks can be resolved by different array designs offered by CMUT-on-CMOS approach. We recently implemented a 2.1-mm diameter single chip 10 MHz dual ring CMUT-on-CMOS array for forward looking ICE with 64-transmit and 56-receive elements along with associated electronics. These volumetric arrays have the small element size required by high operating frequencies and achieve sub mm resolution, but the system would be susceptible to motion artifacts. To enable real time imaging with high SNR, we designed novel arrays consisting of multiple defocused annular rings for transmit aperture and a single ring receive array. The annular transmit rings are utilized to act as a high power element by focusing to a virtual ring shaped line behind the aperture. In this case, image reconstruction is performed by only receive beamforming, reducing total required firing steps from 896 to 14 with a trade-off in image resolution. The SNR of system is improved more than 5 dB for the same frequency and frame rate as compared to the dual ring array, which can be utilized to achieve the same resolution by increasing the operating frequency.

Design, modeling and characterization of a 35MHz 1-D CMUT phased array

“…Especially when integrated with electronics on the same silicon chip, CMUTs can overcome the electrical interconnect issue [8]. Based on these capabilities, CMUT annular arrays and CMUT-on-CMOS dual ring arrays operating in the 20-60MHz range have been fabricated [9][10]. In addition, single chip high frequency analog beamforming electronics have been demonstrated [11].…”

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

“…We recently realized a single-chip volumetric imaging system using monolithic CMUT-on-CMOS integration where dual-ring CMUT arrays were fabricated directly on top of pre-processed custom designed CMOS wafers and presented some initial results in conferences [21, 22]. Here, we present the design, testing and quantitative characterization of the overall single-chip front-end system suitable for volumetric IVUS and ICE imaging.…”

Real-time imaging system using a 12-MHz forward-looking catheter with single chip CMUT-on-CMOS array

“…Forward looking 2D imaging arrays have the potential to visualize the true 3D volumetric views of the heart in real time. This provides better anatomic information, diagnosing severely occluded arteries, placement and utilizing the guidewire and additional interventional tools during the procedure [4][5][6].…”