Background: Ultrasound elastography is emerging as a viable technology for imaging arterial plaques and cardiac infarction, for tumor detection, and for monitoring ablation therapy.

Methods: This noninvasive imaging modality determines the tissue stiffness (i.e., elasticity) from ultrasound speckle tracking of tissue motion, where tissue deformation is induced by a pushing force or some other source of tissue displacement. However, current methods of elastographic image formation are computationally expensive and, consequently, typically limited to offline processing. The utility of ultrasound based monitoring of ablation can be significantly improved by real-time assessment of tissue stiffness to measure the size of the induced lesion.

Results: The computational power and flexibility needed for real-time elasticity measurement suitable for ablation monitoring is provided by customized hardware. Using real-time assessment of lesion formation, the application of RF or ultrasound ablation energy can be adjusted and monitored to optimize treatment and minimize impact to surrounding tissues.

Conclusions: Off-line ultrasound elastography produces a reliable estimate of the lesion size several minutes after the therapy is delivered, whereas real-time ultrasound elastography systems provide additional feedback describing evolution of the lesion throughout the treatment. Trade-offs associated with different elastographic methods for imaging lesions generated by radio-frequency and ultrasound ablation are also discussed.