A system and method for dynamically adjusting the energy of HIFU signals delivered to a patient, and/or to aid in visualizing the likely degree and location of HIFU effects on patient tissue. The system transmits a HIFU signal into a patient and receives echoes therefrom. The echo signals are analyzed to determine the energy of the signals in a first range, such as at one or more harmonics and/or sub-harmonics of the fundamental frequency of the HIFU signal, and energy of the echo signals in a second range such as at the fundamental frequency of the HIFU signal. Based on the comparison, the energy and/or focus of the HIFU signals delivered to the patient is adjusted. An image of the compared echo signal powers in two or more frequency ranges may also be displayed for a user or used to adjust the focus point of the HIFU signals.