CONTROLLED HIGH EFFICIENCY LESION FORMATION USING HIGH INTENSITY ULTRASOUND
An ultrasound system used for both imaging and delivery high intensity ultrasound energy therapy to treatment sites and a method for treating tumors and other undesired tissue within a patient's body with an ultrasound device. The ultrasound device has an ultrasound transducer array disposed on a distal end of an elongate, relatively thin shaft. In one form of the invention, the transducer array is disposed within a liquid-filled elastomeric material that more effectively couples ultrasound energy into the tumor, that is directly contacted with the device. Using the device in a continuous wave mode, a necrotic zone of tissue having a desired size and shape (e.g., a necrotic volume selected to interrupt a blood supply to a tumor) can be created by controlling at least one of the f-number, duration, intensity, and direction of the ultrasound energy administered. This method speeds the therapy and avoids continuously pausing to enable intervening normal tissue to cool.
1 . A method for administering an ultrasonic therapy to a target, comprising the steps of:
(a) providing an ultrasonic transducer that emits a focused high energy ultrasonic energy when energized;
(b) positioning the ultrasonic transducer to focus it at an imaged target;
(c) directing the ultrasonic transducer toward a desired focal point within the target;
(d) energizing the ultrasonic transducer so that it emits the focused high energy ultrasonic energy at the desired focal point, causing heating of a portion of the target disposed at the desired focal point;
(e) creating a positive feedback process between the ultrasound transducer and the target; and
(f) utilizing an imaging technique to monitor the degree of tissue injury caused by the heating.
2 . The method of claim 1 , wherein the heating creates a lesion and wherein a desired shape and size of the lesion are selected so that formation of the lesion substantially deprives the target of a blood supply, causing the ultimate destruction of the target.
3 . The method of claim 1 , wherein the heating creates a lesion and wherein a desired shape and size of the lesion are selected to cause heating of a blood vessel.
4 . The method of claim 1 , wherein the target is a blood vessel.
5 . The ultrasonic system of claim 1 , wherein said high intensity ultrasonic energy is configured to heat tissue between the transducer and focal point to a temperature of 50° C. or more.
6 . The ultrasonic system of claim 1 , wherein the heating creates a lesion wherein the lesion has a volume of about 4.5 cubic centimeters.
7 . The method of claim 1 , wherein the target is a prostate.
8 . The method of claim 7 , wherein imaging and therapy are interleaved in time to monitor the ultrasonic therapy.
9 . The method of claim 7 , further comprising the step of administering ultrasound contrast prior to administering the ultrasound therapy.
10 . The method of claim 9 , further comprising inducing cavitation to further increase tissue injury.
11 . The method of claim 9 , further comprising the step of monitoring the formation of cavitation with the imaging.
12 . The method of claim 7 , further comprising alternating between ultrasound therapy and ultrasound imaging to generate a plurality of ultrasound image frames during treatment.