# 3-D Super-Resolution Ultrasound (SR-US) Imaging with a 2-D Sparse Array

## TL;DR

This paper demonstrates a feasible method for 3D super-resolution ultrasound imaging and velocity mapping using a specially designed 2D sparse array, reducing system complexity and data size while visualizing microvascular structures.

## Contribution

A novel 2D sparse array was designed and used for high frame rate 3D super-resolution ultrasound imaging, enabling detailed microvascular visualization with reduced system complexity.

## Key findings

- Successful 3D super-resolution imaging of microvascular structures.
- Achieved high frame rate volumetric imaging with reduced data size.
- Demonstrated super-resolved velocity mapping in 3D.

## Abstract

High frame rate 3-D ultrasound imaging technology combined with super-resolution processing method can visualize 3-D microvascular structures by overcoming the diffraction limited resolution in every spatial direction. However, 3-D super-resolution ultrasound imaging using a full 2-D array requires a system with large number of independent channels, the design of which might be impractical due to the high cost, complexity, and volume of data produced. In this study, a 2-D sparse array was designed and fabricated with 512 elements chosen from a density-tapered 2-D spiral layout. High frame rate volumetric imaging was performed using two synchronized ULA-OP 256 research scanners. Volumetric images were constructed by coherently compounding 9-angle plane waves acquired in 3 milliseconds at a pulse repetition frequency of 3000 Hz. To allow microbubbles sufficient time to move between consequent compounded volumetric frames, a 7-millisecond delay was introduced after each volume acquisition. This reduced the effective volume acquisition speed to 100 Hz and the total acquired data size by 3.3-fold. Localization-based 3-D super-resolution images of two touching sub-wavelength tubes were generated from 6000 volumes acquired in 60 seconds. In conclusion, this work demonstrates the feasibility of 3D super-resolution imaging and super-resolved velocity mapping using a customized 2D sparse array transducer.