# Optically tracked freehand swept synthetic aperture ultrasound

> **NIH NIH R03** · UNIVERSITY OF COLORADO · 2022 · $72,179

## Abstract

Project Summary
Ultrasound imaging is a critical tool for applications such as obstetric, abdominal and cardiac care. As a non-
invasive, real-time, and cost-effective method, ultrasound is the preferred tool for many screening and diagnostic
tasks used across the United States and around the world. The proliferation of pocket-sized point of care systems
has furthered ultrasound's reach into all areas of healthcare. However, image quality is often inadequate for
deep targets in difficult-to-image patients. A lack of resolution at depth and significant acoustic clutter (haze or
distortion) lead to non-diagnostic results and high rates of recall or referral to other imaging modalities, increasing
healthcare costs and putting patients at risk.
Resolution directly depends on the size of the transducer, which is limited by ergonomics of the handheld probe
and by system complexity (especially in point of care systems). Targets at large tissue depths also require lower
imaging frequencies, exacerbating the degradation of resolution. This project builds on the previously
demonstrated swept synthetic aperture (SSA) method to better image deep targets. Using precise knowledge of
the position and orientation of the ultrasound array as it is quickly swept over a target, an effective array larger
than the physical footprint can be constructed to improve lateral resolution by several times.
This proposal focuses on the development of a platform for clinical translation of the SSA technique. Technology
that enables a freehand sweep is required to apply SSA imaging to a diversity of body shapes and imaging
targets in clinical and point of care settings. An optical tracking system will by synchronized with the ultrasound
scanner to allow a sonographer to perform a freehand sweep without mechanical constraints. The position and
ultrasound data will be combined with sub-wavelength positional accuracy to achieve images with improved
resolution. The imaging system will be characterized using imaging phantoms to assess improvements in
resolution and detectability of deep targets. Experimental parameters including the maximum sweep speed and
extent as well as practical guidance for the sweep trajectory will be determined using this platform. This freehand
SSA system will enable future assessment of the clinical impact of improved resolution on diagnostic tasks
across several areas of care. It will also serve as a test platform for array- and image-based tracking to make
the image improvements afforded by SSA imaging accessible without the cost or complexity of the external
tracking hardware.

## Key facts

- **NIH application ID:** 10459552
- **Project number:** 5R03EB032090-02
- **Recipient organization:** UNIVERSITY OF COLORADO
- **Principal Investigator:** Nick Bottenus
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $72,179
- **Award type:** 5
- **Project period:** 2021-08-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10459552

## Citation

> US National Institutes of Health, RePORTER application 10459552, Optically tracked freehand swept synthetic aperture ultrasound (5R03EB032090-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10459552. Licensed CC0.

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