Microbeamformer-aware layout optimization of a 2D intracardiac echocardiography array for grating-lobe suppression

Three-dimensional intracardiac echocardiography (ICE) has emerged as a promising imaging modality for interventional cardiology. However, catheter-based 2D ICE probes are subject to strict vascular-access constraints, which limit the transducer aperture and independent channel count, leading to spatial undersampling and pronounced grating-lobe (GL) artifacts. This work investigates microbeamformer-aware array-layout optimization for GL suppression in 2D ICE arrays. Using a hybrid analog-digital microbeamformer architecture, the proposed design maps 768 array elements to 64 system channels while retaining the intended transmit focus. Under manufacturable kerf constraints, simulated annealing is used to optimize the element spacing along the elevational direction. With a minimum kerf width of 0.015 mm, the maximum GL level at a focal distance of 50 mm and a common steering angle of θ=φ=45° is reduced from -16.04 dB to -20.97 dB, with the main-lobe full width at half maximum nearly unchanged. Along the evaluated common-angle steering path, θ=φ=0°-45°, the GL reduction increases from 3.15 to 4.93 dB and is accompanied by a 5.60-6.90 dB increase in the maximum near-focus sidelobe level. Numerical phantom imaging simulations further demonstrate reduced GL-related artifacts, with the artifact-to-background contrast ratio decreased by up to 6.98 dB. As an exploratory, layout-preserving alternative to kerf optimization, nonuniform subaperture grouping reduces the maximum GL by 4.07 dB at θ=φ=45° without changing the physical element positions. These results demonstrate the potential of microbeamformer-aware layout optimization for balancing channel reduction, structured GL suppression, and fabrication constraints in miniaturized 2D ICE arrays.