Anomalous Ultrasonic Attenuation of Agarose Hydrogel

An anomaly in ultrasound attenuation of agarose hydrogel studied over a temperature range of 283 K to 311 K, is observed. Anomalous ultrasound attenuation occurs at ~290 K. A theoretical model has been worked out to explain the anomaly. A differential scanning calorimetry (DSC) study shows an endothermic peak at ~290 K, indicating phase transition when scanned over a temperature range of 282 to 330 K at different heating rates. The investigation helps identify the range of temperature over which a gelatin/agar-based phantom may be used in mimicking tissues. This effect may also be explored in temperature imaging.