Magnetic resonance surgery using heat waves produced with focussed ultrasound

• US 5,291,890 A
• Filed: 08/29/1991
• Issued: 03/08/1994
• Est. Priority Date: 08/29/1991
• Status: Expired due to Term

• Current Assignee: InSightec Ltd.
• Original Assignee: General Electric Company
• Inventors: Anthony, Thomas R., Cline, Harvey E.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): ZELE, KRISTA MICHELLE
• Application Number:
  US07/751,259
• Time in Patent Office: 922 Days
• Field of Search: 128/653.2, 128/653.5, 128/24.1, 128/24 AA, 128/660.03, 128/662.03, 128/662.06, 128/663.01, 128/399, 128/24 EL
• US Class Current: 600/411
• CPC Class Codes: A61B 18/22 the beam being directed along or through a flexible conduit, e.g. an optical fibre; Couplings or hand-pieces therefor
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: G01R 33/4804 Spatially selective measurement of temperature or pH
• CPC Class Codes: G01R 33/56308 Characterization of motion or flow; Dynamic imaging

Abstract

Surgery is performed with pulsed heat means that selectively destroys tissue in a region within a patient. The size of the region destroyed is dependent upon the frequency of the pulses of the pulsed heat means and thermal conductivity of the tissue of the patient. The pulsed heat means can be a coherent optical source that is guided by laser fiber to the tissue to be destroyed. In another embodiment the pulsed heat means is a focussed ultrasound transducer that dissipates ultrasonic energy at a focal point within the region of tissue to be destroyed. A magnetic resonance imaging system employing a temperature sensitive pulse sequence creates an image of the tissue and the region being heated to allow a surgeon to alter the position of the pulsed heat means or vary the pulse frequency.

Claims

1. A magnetic resonance (MR) surgery system that comprises:

a) a pulsed heat means adapted for providing pulsed energy of an intensity and rate to a patient. The pulsed heat means including adjustment means adapted for causing the pulsed heat means to be pulsed at a frequency f and amplitude Q at an application point of a heated region to create the temperature distribution T(r,t) around the application point described by;

space="preserve" listing-type="equation">T(r,t)=[Q/ρ

cExp[-kr]cos(2π

ft-kr )]/r

where Q is the amplitude of heat provided;

ρ

is density of the heated region;

c is specific heat of the heated region; and

k=Sqrt[ω

/2D], where D is the thermal diffusity of the tissue in the heated region;

b) MR compatible positioning means adapted for positioning the pulsed heat means and the application point to cause a selected tissue within the patient to have the desired temperature distribution t(r,t) where r is the radius from the application point and t is time;

c) an MR imaging means adapted for creating fast scan MR images of the temperature distribution T(r,t) around the application point during surgery using a temperature sensitive pulse sequence; and

d) display means adapted for interactively displaying the temperature sensitive images to an operator to allow the operator to control the temperature distribution T(r,t).

2. A magnetic resonance (MR) surgery system that comprises:

a) a pulsed heat means adapted for providing pulsed energy of an intensity and rate to an application point within a patient to establish a desired temperature distribution T(r,t) around the application point. The pulsed heat means comprising;

1. an ultrasonic transducer adapted for generating pulsed ultrasonic energy, and

2. focussing means adapted for focussing the pulsed ultrasonic energy at the application point to create the desired temperature distribution T(r,t) around the application point;

b) MR compatible positioning means adapted for positioning the pulsed heat means and the application point to cause a selected tissue within the patient to have the desired temperature distribution T(r,t) where r is the radius from the application point and t is time;

c) an MR imaging means adapted for creating fast scan MR images of the temperature distribution T(r,t) around the application point during surgery using a temperature sensitive pulse sequence; and

d) display means adapted for interactively displaying the temperature sensitive images to an operator to allow the operator to control the temperature distribution T(r,t).

3. The MR surgery system of claim 2 including a control unit, the MR compatible positioning means being controlled by the control unit adapted for positioning the pulsed heat means to destroy the selected tissue within the patient.

4. A method of performing heat surgery on a patient, as guided by a magnetic resonance (MR) imaging apparatus capable of producing temperature sensitive MR images, comprising the steps of:

a) determining the position of a selected tissue to be destroyed in said patient with said MR imaging apparatus,

b) applying pulsed heat of an amplitude Q at a pulse frequency f to an application point to create the desired temperature distribution T(r,t) around the application point where r is the radius from the application point and t is time by;

5. focussing ultrasonic waves on the application point, andpositioning the application point such that the temperature distribution T(r,t) would be positioned to destroy selected tissue within said patient without substantial injury to adjacent tissue;

c) monitoring the temperature distribution T(r,t) with said MR imaging apparatus; and

d) adjusting the frequency f, the amplitude Q and the location of the application point.