Intraluminal magneto sensor system and method of use

• US 8,212,554 B2
• Filed: 05/11/2006
• Issued: 07/03/2012
• Est. Priority Date: 05/11/2005
• Status: Active Grant

• Current Assignee: University of Houston System, Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: University of Houston System, Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Brazdeikis, Audrius, Wosik, Jaroslaw, Cherukuri, Paul, Naghavi, Morteza
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): Allgood, Alesa
• Application Number:
  US11/918,205
• Publication Number:
  US 20090322323A1
• Time in Patent Office: 2,245 Days
• Field of Search: 324/207, 324/244, 324/149, 324/318, 324/423, 324/248, 600/424, 600/409, 600/431, 600/509, 600/421, 600/423, 600/436, 600/407, 600/9, 600/12, 600/13
• US Class Current: 324/244
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence

Abstract

A system (100) including a catheter mounted magneto sensor (114), such as a superconducting quantum interference device (SQUID), and methods using the system are disclosed, where the system and method are designed to detect changes in a magnetic field in a body of interest, such as a patient, to detect changes in a magnetic field in a patient, to identify loci in a target body that accumulate magnetic particles or to identify vulnerable plague in a patient.

Claims

1. A method for identifying loci in an animal including a human that accumulate magnetically active agents comprising the steps of:

inserting an intraluminal magneto sensor system including a catheter and a magneto sensor attached to a distal end of the catheter and positioning the sensor adjacent an area of interest (AOI) of the animal,

administering the magnetically active agents to the animal,

measuring a first magnetic field distribution of the magnetically active agents in the AOI of an animal with the magneto sensor, and

determining an amount of the magnetically active agents in the AOI of the animal from the distribution to determine loci within the AOI having high accumulations of the magnetically active agents relative to other locations in the AOI, where the loci may be associated with ischemia, infarction, injury, inflammation, infection, tumor, bleeding, angiogenesis, abnormally high blood barrier permeability, abnormally high capillary permeability, clot formation, plaque, or vulnerable plaque.

2. The method of claim 1, further comprising the step of:

measuring a second magnetic field distribution in the AOI with the magneto sensor, prior to the administering step,

comparing the first and second magnetic field distributions, and

determining loci within the AOI that have an amount of the magnetically active agents above a threshold value.

3. The method claim 1, wherein the sensor is moveable and the method further comprising the steps of:

moving the magneto sensor to a different AOI of the animal;

repeating steps of administering, measuring, determining, and the moving steps, and

determining loci within AOI distributed along an artery or vein that have an amount of the magnetically active agents above a threshold value.

4. A method for measuring weak magnetic field perturbations due to locally accumulation of a magnetically active agent at loci in an animal including a human comprising the steps of:

i. inserting an intraluminal magneto sensor system including a catheter and a magneto sensor attached to a distal end of the catheter and positioning the sensor adjacent an area of interest (AOI) of the animal into which magnetically active agents were administered,

ii. monitoring cardiac activity electrically or magnetically of the animal;

iii. determining a beginning of a trigger signal interval, t_o by analyzing a cardiac cycle waveform of the animal;

iv. determining a duration, t_d of the trigger signal interval;

v. generating a trigger signal waveform using parameters determined in steps (iii) and (iv);

vi. transmitting the trigger signal waveform to an arbitrary-form signal generator in order to generate an excitation signal waveform of chosen duration at the end of trigger;

vii. transmitting the excitation signal waveform through an excitation coil setup in order to achieve a required polarization of magnetic moments of the magnetically agent;

viii. repeating steps (ii) through (vii);

ix. detecting a biomagnetic signal at the magnetometer;

x. extracting data from the selected interval of the cardiac cycle that equals a length of the excitation signal waveform; and

xi. transforming the data from step (x) into a data form which indicates presence of the agent at the target location.

5. A method for measuring weak magnetic field perturbations due to locally accumulation of a magnetically active agent at loci in an animal including a human comprising the steps of:

i. inserting an intraluminal magneto sensor system including a catheter and a magneto sensor attached to a distal end of the catheter and positioning the sensor adjacent an area of interest (AOI) of the animal into which magnetically active agents were administered,

ii. exciting the AOI with acoustic radiation energy with a dual beam ultrasonic transmitter probe adapted to generate a mechanical vibration of the agents in the AOI at a beat frequency created by an interference of the dual beam ultrasound;

iii. detecting a biomagnetic signal with the magnetometer,

iv. applying a modulation to the AOI to allow phase sensitive detection,

v. localizing loci within the AOI using the probe for data registration, and

vi. transforming the data from step (v) into a data form which indicates a presence of the agent in the loci of the AOI.

6. An intraluminal magneto sensor system comprising:

a catheter;

a thermally insulating housing disposed at a distal end of the catheter, where the housing includes;

a magneto sensor, and

optionally other sensors or components,

a cryogenic fluid circulation assembly including;

a cryogenic fluid inlet conduit attached to the magnetic sensor and optional other

sensors or components for supplying a cryogenic fluid to cool the magnetic sensor

and optional other sensors or components,

a cryogenic fluid outlet conduit for removing the cryogenic fluid, and

a source of cryogenic fluid attached to a inlet conduit,

where the cryogenic fluid circulation assembly cools the magnetic sensor and optional other sensors or components and the thermally insulating housing protects the animal including a human from cryogenic temperatures and where magnetic sensor is adapted to measure loci within an area of interest (AOI) having high accumulations of the magnetically active agents relative to other locations in the AOI and where the loci may be associated with ischemia, infarction, injury, inflammation, infection, tumor, bleeding, angiogenesis, abnormally high blood barrier permeability, abnormally high capillary permeability, clot formation, plaque, or vulnerable plaque.

7. The system of claim 6, wherein the cryogenic fluid is a gas and wherein the magnetic sensor is a SQUID sensor.