System and method for nuclear magnetic resonance measurement of blood analyte levels
The nuclear magnetic resonance system can include: a set of magnets, a housing, a set of coils (e.g., receive coil, transmit coil, gradient coil, active shim coil, etc.), and a processing system. The nuclear magnetic resonance method can include: applying a pulse sequence, acquiring a signal, and processing the signal (e.g., to determine blood analyte levels).
1. A nuclear magnetic resonance (NMR) system, comprising:
a set of magnets producing a magnetic field over a region of interest within a bore configured to receive a finger of a user, wherein the set of magnets comprises an array of magnets arranged around the bore;
a transmitter;
a receiver comprising a surface coil, wherein a central axis of the surface coil intersects with a pulp of the finger, wherein a width of the bore along a first axis is greater than a height of the bore along a second axis, the second axis perpendicular to the first axis, wherein the first axis is parallel to the central axis of the surface coil, wherein the second axis is perpendicular to a longitudinal axis of the bore; and
a processing system configured to:
using the transmitter, transmit an electromagnetic pulse sequence;
using the receiver, sample a receive signal; and
determine a blood analyte concentration in the finger based on the receive signal.
2. The NMR system of claim 1 , further comprising a sample interface configured to position a surface of the pulp of the finger within a threshold distance of the surface coil.
3. The NMR system of claim 2 , wherein the threshold distance is less than 5 mm.
4. The NMR system of claim 2 , wherein a susceptibility of the sample interface is within 20% of a susceptibility of the finger.
5. The NMR system of claim 1 , wherein the surface coil comprises a loop coil of between 2 and 5 turns.
6. The NMR system of claim 1 , further comprising a set of button shims retained within pockets of a sleeve, wherein the sleeve is positioned within the bore.
7. The NMR system of claim 1 , wherein the region of interest is nonspherical.
8. The NMR system of claim 7 , wherein a length of the region of interest along the central axis of the surface coil is less than a length of the region of interest along an axis perpendicular to the central axis of the surface coil.
9. The NMR system of claim 1 , wherein the blood analyte comprises glucose.