Sensor Array for Nuclear Magnetic Resonance Imaging Systems and Method

Abstract

The present invention generally provides improved devices, systems, and methods for measuring materials with NMR and/or MRI. Exemplary embodiments provide a sensor array for NMR mapping of the material. For example tissue can be measured with the sensor array mounted on a probe body having a distal portion which can be inserted through a minimally invasive aperture. While many tissues can be measured and/or diagnosed, one exemplary embodiment includes a probe adapted for insertion into a lumen of a blood vessel. The sensor array can provide improved spatial resolution of tissue and/or tissue structures positioned near the sensor array to diagnose potentially life threatening diseases, for example a fibrous cap covering a vulnerable plaque. In specific embodiments, the sensors are attached to an expandable member, for example a balloon, which can be inflated to urge the probe sensors radially outward to position the sensors near the tissue structures.

1 . A probe for measuring a tissue, the probe comprising:
 a body having a proximal portion and a distal portion insertable into a minimally invasive aperture; and   an array of sensors sensitive to at least one of a magnetic field amplitude or a magnetic field phase, each sensor occupying an array site to map an NMR signal from an associated measurement region of the tissue.   
   
   
       2 . The probe of  claim 1  wherein the sensors are arranged in rows. 
   
   
       3 . The probe of  claim 2  wherein the distal portion of the body has an axis extending toward a distal end of the body, and the rows extend axially along the probe. 
   
   
       4 . The probe of  claim 3  wherein each sensor has a field of view and each row has an angular orientation arranged to separate the field of view of each sensor in a first row from the field of view of each sensor in a second row. 
   
   
       5 . The probe of  claim 1  wherein the distal portion of the body has an axis extending toward a distal end of the body, and the probe is adapted to fit within a tissue structure as the probe is advanced along the axis. 
   
   
       6 . The probe of  claim 5  wherein the sensors are positioned circumferentially around the axis. 
   
   
       7 . The probe of  claim 1  wherein the probe body comprises flexible substrate having a printed circuit etched thereon, the circuit connected with the sensors, the distal portion of the probe body adapted to deform to place the sensors in proximity with a tissue structure. 
   
   
       8 . The probe of  claim 7  wherein the probe body comprises an expandable balloon to deform the distal portion and place the sensors in proximity with the tissue structure. 
   
   
       9 . The probe of  claim 1  wherein the probe body is adapted for insertion into a vaginal, rectal, bronchial, urethral or esophageal body cavity. 
   
   
       10 . The probe of  claim 1  wherein the distal portion of the probe body is disposed on a distal end of a catheter, the probe adapted to measure a blood vessel. 
   
   
       11 . The probe of  claim 1  wherein the tissue comprises skin and the probe is adapted to lie on a surface of the skin. 
   
   
       12 . The probe of  claim 1  wherein the distal portion of the body comprises a tube to drain fluid from the tissue. 
   
   
       13 . A method of forming an NMR image of a material, the method comprising:
 orienting nuclei of the material with a magnet;   exciting the oriented nuclei of the material with a coil to induce an emission of NMR signals;   measuring at least one of a magnetic field amplitude or a magnetic field phase of the NMR signals from the material with a plurality of magnetoresistive sensors, each sensor occupying an array site on a probe; and   mapping the signal from each sensor to a location in the image substantially dependent on the site on the probe.   
   
   
       14 . The method of  claim 13  further comprising:
 spatially encoding the NMR signals to provide a depth of the signal from each sensor; and   mapping the signal measured with each sensor to the location in the image in correlation with the signal depth and sensor position on the probe.   
   
   
       15 . The method of  claim 13  wherein the material comprises a tissue with a structure, the method further comprising conforming the array to the tissue structure to position the sensors near the tissue structure. 
   
   
       16 . The method of  claim 13  wherein the material comprises a tissue with a structure, the method comprising inflating an expandable member to radially urge the sensors toward the tissue structure.