Image-guided tissue ablation

Abstract

A method of treating hypertension in a mammal is described, including: by focused sound energy, heating at least one nerve at a surface of a renal artery in a mammal; during the heating and by magnetic resonance imaging, repeatedly determining thermal levels in each of first and second volumetric zones of a region that includes at least a portion of the surface, the second zone being adjacent to the first zone; after determining that an indicium of a thermal level in the first zone exceeds a first threshold, and upon determining that an indicium of a thermal level in the second zone exceeds a second threshold, ceasing the heating of the at least one nerve for at least three months; and as a result of the heating, lowering a blood pressure in the mammal.

What is claimed is: 
     
         1 . A method of treating a mammal, comprising:
 by focused sound energy, heating a target tissue in a mammal;   during the heating and by magnetic resonance imaging, repeatedly determining thermal levels in each of a first volumetric zone and a second volumetric zone within a target region that includes at least a portion of the target tissue and is subject to the heating;   after determining that an indicium of a thermal level in the first zone exceeds a first threshold, and upon determining that an indicium of a thermal level in the second zone exceeds a second threshold, different from the first threshold, ceasing the heating of the target tissue for at least one day.   
     
     
         2 . The method of  claim 1 , wherein the first zone is substantially concentric with the second zone. 
     
     
         3 . The method of  claim 1 , wherein the first zone is overlapping with the second zone. 
     
     
         4 . The method of  claim 1 , wherein the first zone is spaced apart from the second zone. 
     
     
         5 . The method of  claim 1 , wherein the second zone is adjacent to the first zone. 
     
     
         6 . The method of  claim 1 , wherein the magnetic resonance imaging comprises a proton resonance frequency acquisition sequence. 
     
     
         7 . The method of  claim 1 , wherein the heating is ceased for at least four months. 
     
     
         8 . The method of  claim 1 , wherein the heating is ceased for at least six months. 
     
     
         9 . The method of  claim 1 , wherein the heating is ceased for at least 12 months. 
     
     
         10 . The method of  claim 1 , wherein the target tissue comprises a nerve. 
     
     
         11 . A method of treating a mammal, comprising:
 by focused sound energy, heating a first region of target tissue in a mammal;   during the heating and by magnetic resonance imaging, repeatedly determining thermal levels in each of a first volumetric zone and a second volumetric zone within the first region that includes at least a portion of the target tissue and is subject to the heating of the first region;   after determining that an indicium of a thermal level in the first zone exceeds a first threshold, and upon determining that an indicium of a thermal level in the second zone exceeds a second threshold, different from the first threshold, heating a second region of the target tissue by focused sound energy;   during the heating and by magnetic resonance imaging, repeatedly determining thermal levels in each of a third volumetric zone and a fourth volumetric zone of the second region that includes at least a portion of the target tissue and is subject to the heating of the second region;   after determining that an indicium of a thermal level in the third zone exceeds a third threshold, and upon determining that an indicium of a thermal level in the fourth zone exceeds a fourth threshold, different from the third threshold, ceasing the heating of the target tissue for at least one day.   
     
     
         12 . The method of  claim 11 , wherein the third zone is substantially concentric with the fourth zone. 
     
     
         13 . The method of  claim 11 , wherein the third zone is overlapping with the fourth zone. 
     
     
         14 . The method of  claim 11 , wherein the third zone is spaced apart from the fourth zone. 
     
     
         15 . The method of  claim 11 , wherein the second zone is adjacent to the first zone and wherein the fourth zone is adjacent to the third zone. 
     
     
         16 . The method of  claim 11 , wherein the first region and the second region defines a pathway. 
     
     
         17 . The method of  claim 11 , wherein the heating is ceased for at least four months. 
     
     
         18 . The method of  claim 11 , wherein the heating is ceased for at least six months. 
     
     
         19 . The method of  claim 11 , wherein the heating is ceased for at least 12 months. 
     
     
         20 . The method of  claim 11 , wherein the target tissue comprises a nerve.