Abstract: A non-invasive method of determining a temperature distribution in a targeted tissue volume treated with thermal therapy involves determining a baseline perfusion characteristic of the targeted tissue volume. A temperature distribution is calculated in the targeted tissue volume based on the baseline perfusion characteristic of the tissue, a microwave power input and a coolant temperature input. A perfusion characteristic of the targeted tissue volume is iteratively adjusted based on the calculated temperature distribution, and the temperature distribution is iteratively recalculated based on the adjusted perfusion characteristic, the microwave power input and the coolant temperature input throughout the thermal therapy.

Abstract: A thermal therapy catheter includes a catheter shaft having an outer surface that is insertable into the body lumen. The catheter shaft carries an energy-emitting element. A multi-lobe balloon is positioned around the outer surface of the catheter shaft adjacent to the energy-emitting element, with opposing ends of the multi-lobe balloon being sealingly connected to the catheter shaft to form a chamber between the multi-lobe balloon and the outer surface of the catheter shaft. Fluid is circulated between the outer surface of the catheter shaft and the multi-lobe balloon in a defined fluid flow path to firmly contact the wall of the body lumen and thereby cool the body lumen tissue while thermally treating targeted tissue at a depth from the body lumen wall.

Abstract: A method and apparatus for reducing restenosis of a stenotic region of a blood vessel after performing a dilatation angioplasty treatment is disclosed. The method includes radiating microwave energy from a microwave antenna to kill a medial tissue layer of the blood vessel in the stenotic region. The radiation is applied during or after inflation of dilatation balloon to permanently dilate the stenotic region. When radiation is applied during dilatation of the stenotic region, the dilatation balloon forms a seal against the inner wall surface of the blood vessel to exclude blood in the vessel from contacting the stenotic region. The method preferably further includes cooling the blood circulating in the blood vessel about a shaft of the catheter with cooling fluid circulating within cooling lumens of the catheter and cooling an inner wall surface of the blood vessel in the stenotic region during the application of radiation to the medial cell layer.

Abstract: A thermal therapy catheter includes a catheter shaft having an outer surface that is insertable into the body lumen. The catheter shaft carries an energy-emitting element. A multi-lobe balloon is positioned around the outer surface of the catheter shaft adjacent to the energy-emitting element, with opposing ends of the multi-lobe balloon being sealingly connected to the catheter shaft to form a chamber between the multi-lobe balloon and the outer surface of the catheter shaft. A fluid is circulated between the outer surface of the catheter shaft and the multi-lobe balloon in a defined fluid flow path to firmly contact the wall of the body lumen and thereby conductively cool the body lumen tissue while thermally treating targeted tissue at a depth from the body lumen wall.

Abstract: A thermal therapy method includes inserting a microwave antenna-containing applicator into a body cavity such as a urethra adjacent a targeted tissue region such as a prostate, energizing the microwave antenna, and circulating coolant between the microwave antenna and a wall of the body cavity. The therapy is controlled by decreasing a temperature of the coolant and continually adjusting coolant temperature based on other parameters. The applicator is maintained at a predetermined temperature set point by adjusting a power level provided to the microwave antenna. In one embodiment involving treatment of the prostate, rectal temperature is monitored and, upon sensing a rectal temperature that exceeds a predetermined threshold, the temperature of the coolant is increased to force a reduction in power provided to the microwave antenna to maintain the applicator at the predetermined temperature set point.

Abstract: A microwave energy delivery system for microwave thermal therapy includes an antenna and a transmission line connected to the antenna. A microwave generating source includes a generator connected to the transmission line and a dual directional coupler for detecting forward power delivered to the antenna and reverse power reflected from the antenna with low uncertainty.

Abstract: A catheter shaft carries a coaxial cable, the terminal end of which contains a dipole antenna with opposing first and second helical elements. The first and second helical elements originate from a common connection to an outer conductor of the coaxial cable. The first and second helical elements are formed by winding flat wire around an outer insulator of the coaxial cable near a terminal end of the coaxial cable. A variable, controllable impedance is connected between an inner conductor of the coaxial cable and a point on the second helical element where the resistive component of the antenna's impedance matches the characteristic impedance of the coaxial cable. The impedance match minimizes reflective losses of the antenna, thereby maximizing power transferred to the antenna. The antenna has an effective electrical length which is equal to one-half the wavelength of the radiation emitted, independent of the physical length of the antenna.

Abstract: A device for prostate treatment is inserted into a prostatic portion of an urethra and connected to an energy source. Energy is delivered to the prostate from the device. The amount of energy emitted to prostatic tissue adjacent to a bladder is greater than that emitted to prostatic tissue distant from the bladder.

Abstract: A catheter shaft carries a coaxial cable, the terminal end of which contains a dipole antenna with opposing first and second helical elements. The first and second helical elements originate from a common connection to an outer conductor of the coaxial cable. The first and second helical elements are formed by winding flat wire around an outer insulator of the coaxial cable near a terminal end of the coaxial cable. A variable, controllable impedance is connected between an inner conductor of the coaxial cable and a point on the second helical element where the resistive component of the antenna's impedance matches the characteristic impedance of the coaxial cable. The impedance match minimizes reflective losses of the antenna, thereby maximizing power transferred to the antenna. The antenna has an effective electrical length which is equal to one-half the wavelength of the radiation emitted, independent of the physical length of the antenna.

Abstract: An intraurethral, Foley-type catheter shaft contains a microwave antenna capable of generating a cylindrically symmetrical thermal pattern, within which temperatures are capable of exceeding 45.degree. C. The antenna, which is positioned within the shaft, is surrounded by means within the shaft for absorbing thermal energy conducted by the tissue and asymmetrically absorbing electromagnetic energy emitted by the antenna--a greater amount of electromagnetic energy being absorbed on one side of the shafts. This asymmetrical absorption alters the thermal pattern generated by the microwave antenna, making it cylindrically asymmetrical, which effectively focuses microwave thermal therapy toward undesirous benign tumorous tissue growth of a prostate anterior and lateral to the urethra, and away from healthy tissue posterior to the urethra.

Abstract: An intraurethral, Foley-type catheter shaft contains a microwave antenna capable of generating a cylindrically symmetrical thermal pattern, within which temperatures are capable of exceeding 45.degree. C. The antenna, which is positioned within the shaft, is surrounded by means within the shaft for absorbing thermal energy conducted by the tissue and asymmetrically absorbing electromagnetic energy emitted by the antenna--a greater amount of electromagnetic energy being absorbed on one side of the shaft. This asymmetrical absorption alters the thermal pattern generated by the microwave antenna, making it cylindrically asymmetrical, which effectively focuses microwave thermal therapy toward undesirous benign tumorous tissue growth of a prostate anterior and lateral to the urethra, and away from healthy tissue posterior to the urethra.

Abstract: A method of prostate treatment includes the step of inserting into a prostatic portion of urethra an energy emitting device that is connected to an energy source. Energy is delivered to the prostate from the energy emitting device. The amount of energy emitted to prostatic tissue adjacent to a bladder is greater than that emitted to prostatic tissue distant from the bladder.

Abstract: A method of applying microwave energy to cardiac tissue uses a catheter adapted for insertion into a cardiac chamber and which includes a microwave antenna, a cooling lumen structure, and an inflatable cooling balloon. Necrosing levels of microwave energy are delivered from the microwave antenna to diseased cardiac tissue spaced from the catheter. Tissues immediately surrounding the catheter are cooled and microwave energy emitted by the antenna is selectively absorbed by the cooling lumen structure surrounding the antenna. The cooling balloon of the catheter is positioned adjacent the antenna and partially surrounds the cooling lumen structure on one side of the catheter to provide additional cooling capability and additional microwave energy absorption on the side of the catheter opposite the diseased cardiac tissue to prevent unwanted heating of blood within the cardiac chamber.

Abstract: A method for treating an individual with diseased prostatic tissue, such as benign prostatic hyperplasia, includes inserting a catheter into a urethra to position a microwave antenna located within the catheter adjacent a prostatic region of the urethra. A microwave antenna is then driven within a power range for applying microwave energy substantially continuously to prostatic tissue to heat the prostatic tissue surrounding the microwave antenna at a temperature and for a time period sufficient to cause necrosis of the prostatic tissue.

Abstract: A microwave antenna is insertable into a cardiovascular catheter and is formed from a coaxial cable including an inner conductor and an inner insulator with the inner insulator having a reduced diameter portion adjacent a distal end of the catheter. An antenna coil portion of the microwave antenna is disposed about the reduced diameter portion and has a first section, a second section, and a point intermediate to the first and second sections. The intermediate point is electrically connected to an outer conductor of the coaxial cable. An impedance matching means is connected to the inner conductor and to the second section of the antenna coil portion.

Abstract: An intraurethral, Foley-type catheter shaft contains a microwave antenna capable of generating a cylindrically symmetrical thermal pattern, within which temperatures are capable of exceeding 45.degree. C. The antenna, which is positioned within the shaft, is surrounded by means within the shaft for absorbing thermal energy conducted by the tissue and asymmetrically absorbing electromagnetic energy emitted by the antenna--a greater amount of electromagnetic energy being absorbed on one side of the shaft. This asymmetrical absorption alters the thermal pattern generated by the microwave antenna, making it cylindrically asymmetrical, which effectively focuses microwave thermal therapy toward undesirous benign tumorous tissue growth of a prostate anterior and lateral to the urethra, and away from healthy tissue posterior to the urethra.

Abstract: A method for treating an individual with benign prostate hyperplasia is disclosed. The method includes inserting a catheter into a urethra so as to position an energy emitting element located within the catheter adjacent a prostatic region of the urethra. A fluid is circulated within the catheter until the fluid stabilizes at a prechilled temperature. An energy emitting element is then energized sufficient to heat prostatic tissue surrounding the energy emitting element.

Abstract: An intraurethral, Foley-type catheter shaft contains a microwave antenna capable of generating a cylindrically symmetrical thermal pattern, within which temperatures are capable of exceeding 45.degree. C. The antenna, which is positioned within the shaft, is surrounded by means within the shaft for absorbing thermal energy conducted by the tissue and asymmetrically absorbing electromagnetic energy emitted by the antenna--a greater amount of electromagnetic energy being absorbed on one side of the shaft. This asymmetrical absorption alters the thermal pattern generated by the microwave antenna, making it cylindrically asymmetrical, which effectively focuses microwave thermal therapy toward undesirous benign tumorous tissue growth of a prostate anterior and lateral to the urethra, and away from healthy tissue posterior to the urethra.

Abstract: An intraurethral, Foley-type catheter shaft contains a microwave antenna capable of generating a cylindrically symmetrical thermal pattern, within which temperatures are capable of exceeding 45.degree. C. The antenna, which is positioned within the shaft, is surrounded by means within the shaft for absorbing thermal energy conducted by the tissue and asymmetrically absorbing electromagnetic energy emitted by the antenna--a greater amount of electromagnetic energy being absorbed on one side of the shaft. This asymmetrical absorption alters the thermal pattern generated by the microwave antenna, making it cylindrically asymmetrical, which effectively focuses microwave thermal therapy toward undesirous benign tumorous tissue growth of a prostate anterior and lateral to the urethra, and away from healthy tissue posterior to the urethra.

Abstract: An intraurethral, Foley-type catheter shaft contains a microwave antenna capable of generating a cylindrically symmetrical thermal pattern, within which temperatures are capable of exceeding 45.degree. C. The antenna, which is positioned within the shaft, is surrounded by means within the shaft for absorbing thermal energy conducted by the tissue and asymmetrically absorbing electromagnetic energy emitted by the antenna--a greater amount of electromagnetic energy being absorbed on one side of the shaft. This asymmetrical absorption alters the thermal pattern generated by the microwave antenna, making it cylindrically asymmetrical, which effectively focuses microwave thermal therapy toward undesirous benign tumorous tissue growth of a prostate anterior and lateral to the urethra, and away from healthy tissue posterior to the urethra.