Elastographic characterization of HIFU-induced lesions

The elastographic characterization of high intensity focused ultrasound (HIFU) induced lesions was investigated. The lesions were induced in vitro in 16 excised canine livers, using different treatment intensity levels and exposure times. In each case, the lesion was clearly depicted by the corresponding elastogram, as a hard area embedded in a softer background. The strain contrast of the lesion/background was found to depend on the temperature increase inside the exposed tissue during the treatment. The area of the lesion as it appeared in the elastogram was automatically computed and correlated with the corresponding area in the gross pathology photograph. The estimated areas ranged between approximately 10 mm² and 110 mm². A high correlation between the areas of damage as depicted by the elastogram, and the corresponding areas as measured from the gross pathology photograph was found (r² = 0.93, p-value<0.0004, n = 16). This statistically significant high correlation demonstrates that elastography has the potential to become a reliable and accurate modality for HIFU therapy monitoring.