Sensor array for nuclear magnetic resonance imaging systems and method

Inventors

Tiernan, Timothy C. • Ford, John Chetley

Assignees

Radiation Monitoring Devices Inc

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.

Core Innovation

The invention relates to an intravascular/spatial NMR mapping MRI system in which a magnet orient nuclei of a material and a coil excites the oriented nuclei to induce an emission of NMR signals. Instead of locating NMR signal in conventional fashion, an array of magnetoresistive sensors detects at least one of a magnetic field amplitude or a magnetic field phase of the NMR signals. The sensor array is arranged so that sensors occupy array sites to map detected signal locations.

The magnetoresistive sensors detect the NMR signals in quadrature, with each sensor occupying an array site to map detected signal locations. Quadrature detection is used to provide signal localization from field amplitude and/or field phase at the array sites. The sensor array can be scaled with multiple magnet and multi-row sensor configurations, and includes sensor placement for circumferential and/or row placement to acquire spatial information.

The probe concept positions the sensor array on an insertable probe body, including a distal portion with a minimally invasive aperture, and describes an expandable balloon catheter/expandable member configuration for luminal applications. Static field orientation is used to avoid AMR saturation by orienting the sensor-plane with respect to the static magnetic field Bo. The document further describes slice selection using intrinsic static-field gradients in combination with a CPMG pulse sequence, aiming to avoid diffusion loss, and includes concepts for mapping sensor signals into an NMR image and superimposing lesion maps over anatomic images with coordinate tracking.

Claims Coverage

The document contains three independent claims covering a device for NMR mapping of a material using a magnet, an excitation coil, and a magnetoresistive sensor array that detects magnetic field amplitude and/or magnetic field phase in quadrature to map detected signal locations. Across the independent claims, the core inventive pattern is the magnet orientation plus excitation coil plus spatial magnetoresistive sensor array for quadrature NMR signal localization, with further refinements directed to multiple magnets, proximity relationships, and powering the radiofrequency coil by inductive coupling or conductive coupling.

Overall, the independent claims cover an NMR mapping device that combines a magnet for orienting nuclei, a coil for inducing NMR signals, and a spatial array of magnetoresistive sensors detecting at least magnetic field amplitude and/or magnetic field phase. The sensor array is central for quadrature detection and mapping detected signal locations, while additional independent-claim refinements define multi-magnet proximity and define how a radiofrequency coil is powered using either inductive coupling from an external induction coil or conductive coupling via a conductor.

Stated Advantages

Documented Applications