Thermal Strain Estimation Using Ultrasound Echo Stretching Algorithm for Temperature Monitoring: Initial Results

Ultrasound emerges as a promising modality for temperature monitoring in thermal therapies, leveraging the favorable parameter of near-linear variation in speed of sound within the temperature range of 25 °C to 50 °C. The spatial variation of speed of sound induces thermal strain in the received ultrasound from that region. Current techniques for thermal strain estimation involve a two-step process, contributing to error propagation and amplification. We propose a single-step technique that directly estimates the thermal strain by range gating regions in reference and desired frames, stretching the RF echo to maximize cross-correlation for precise matching. This iterative process generates a stretch factor map, subsequently scaled to produce an absolute temperature map. The algorithm's performance is assessed on a homogenous tissue mimicking phantom with a curvilinear probe, demonstrating our ability to track temperature changes.