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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session B

Poster G1 - Development of an Experimental Platform to Test Integrated Diffuse Correlation Tomography and Ultrasound Probes for Breast Cancer Imaging

Thursday, October 24, 2024
2:45 PM – 3:45 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Breast cancer remains one of the leading causes of cancer-related deaths worldwide, with treatment efficacy hindered by the lack of precise, non-invasive methods for real-time monitoring. Current techniques are either inaccurate (X-ray mammography) or unsuitable for frequent monitoring due to high costs (MRI) or radioactivity (PET). To address these challenges, our long-term goal is to develop an integrated imaging system combining diffuse correlation tomography (DCT) and ultrasound shear wave elastographic imaging (SWEI), aiming to create a more accessible, cost-effective, and efficient tool for breast cancer treatment monitoring.

As the first step, this project focuses on developing an experimental platform to test and optimize DCT probe for breast imaging. DCT uses near-infrared light to detect the motion of red blood cells, offering a measure of microvascular blood flow in three dimensions, while SWEI assesses tissue stiffness and non-linear biomechanical properties related to structural changes.

The controlled environment enables us to refine DCT measurements, optimize probe designs, and develop scanning strategies, aiming to improve the accuracy and reliability of blood flow measurements in breast tissue, which is crucial for assessing tumor response to therapy. By enhancing our ability to detect and quantify changes in tumor vasculature during treatment, we lay the groundwork for future integration of DCT with SWEI. Ultimately, this multifaceted approach seeks to provide clinicians with a powerful tool for real-time, quantitative assessment of treatment efficacy, enabling more personalized and adaptive treatment strategies in breast cancer care.

Materials and

Methods:  We designed a DCT probe with 4 sources and 4 detectors arranged in a 2.5 cm x 4 cm grid pattern, providing 16 source-detector pairs with separations ranging from 2.5 cm to 3.9 cm. To test this probe, we developed an experimental platform consisting of a liquid tissue phantom and an automated scanning system.

The phantom was constructed using a 20 cm x 20 cm x 20 cm container filled with a liquid mimicking breast tissue optical properties (absorption coefficient = 0.04 cm-1, reduced scattering coefficient = 8 cm-1). A 2-cm diameter tumor-simulating hollow sphere was placed at depths of 2, 3, and 4 cm from the surface to the center of the sphere. The phantom includes tubing connected to a syringe pump, controlling flow rates (0, 1, 3, 5 ml/min) to simulate blood flow changes.

We integrated motorized linear stages with the DCT system using a LabVIEW program, allowing positioning of the probe over a 12 cm x 5 cm region of interest on the phantom surface. Our experimental protocol involved scanning using all four source positions at each of the three tumor depths, testing four different flow rates to simulate varying levels of tumor blood flow.

For data analysis, we calculated the blood flow index (BFI) from the optical data. BFI is a measure of blood flow based on the motion of scattering particles (primarily red blood cells) in the tissue, derived using an analytic solution of the correlation diffusion equation in a homogeneous semi-infinite geometry.

Results, Conclusions, and Discussions: Our experiments with the liquid phantom system have yielded promising results, demonstrating the potential of our experimental platform for testing and optimizing DCT probes for breast imaging. By varying flow rates using the syringe pump, we simulated changes in tumor blood flow and assessed our system's ability to detect these changes at different depths.

Key findings from our experiments include:
1. Detection of flow changes: Our system successfully detected increased BFI values in regions corresponding to the simulated tumor during active pumping, demonstrating the system's ability to identify areas of increased blood flow, which could indicate the presence of a tumor or changes in tumor vasculature.
2. Depth sensitivity: We observed that the system's ability to detect flow changes varied with tumor depth. The contrast between tumor and background BFI values was strongest at 2 cm depth and decreased at 3 cm and 4 cm depths, as expected.
3. Flow rate sensitivity: We observed a correlation between the set flow rates (0, 1, 3, 5 ml/min) and the calculated BFI values, suggesting that our DCT system can quantify relative changes in blood flow.

Our next steps include:
1. Adapting existing DCT reconstruction methods for the specific geometry and optical properties of breast tissue.
2. Optimizing probe design by testing different source-detector configurations to improve depth sensitivity.
3. Refining our scanning strategy to balance comprehensive coverage with practical measurement times.
4. Developing more complex phantom designs that better mimic the heterogeneity of real breast tissue.

The work lays the foundation for translating DCT technology to clinical breast imaging applications. By optimizing probe designs and scanning strategies, we aim to improve the sensitivity and specificity for detecting and characterizing breast tumors. The future integration of DCT with SWEI will provide a multi-parametric assessment of tumor physiology. This combined approach has the potential to offer real-time, quantitative metrics of tumor response to therapy, enabling clinicians to make more informed decisions about treatment efficacy. By providing early indicators of treatment response, this technology could facilitate timely adjustments to treatment plans, potentially improving outcomes and reducing unnecessary side effects for breast cancer patients.

Acknowledgements (Optional):