US 12,440,119 B2
Stimulated-echo imaging for EPRI
Howard J. Halpern, Chicago, IL (US); and Boris Epel, Chicago, IL (US)
Filed by Howard J. Halpern, Chicago, IL (US); and Boris Epel, Chicago, IL (US)
Filed on Feb. 21, 2025, as Appl. No. 19/059,955.
Application 19/059,955 is a division of application No. 18/127,538, filed on Mar. 28, 2023, granted, now 12,232,858.
Prior Publication US 2025/0204804 A1, Jun. 26, 2025
Int. Cl. A61B 5/055 (2006.01); G01R 33/341 (2006.01); G01R 33/36 (2006.01); G01R 33/60 (2006.01); G01V 3/10 (2006.01)
CPC A61B 5/055 (2013.01) [G01R 33/341 (2013.01); G01R 33/3607 (2013.01); G01R 33/3621 (2013.01); G01R 33/60 (2013.01); G01V 3/104 (2013.01)] 21 Claims
OG exemplary drawing
 
1. An apparatus for stimulated-echo (SE) electron paramagnetic resonance imaging (EPRI) of a volume of animal tissue in vivo in an animal, the apparatus comprising:
a magnetic-field generator configured to generate a substantially static magnetic field in the volume of animal tissue;
a set of transmit coils, wherein the set of transmit coils generates an excitation magnetic field in the volume of animal tissue in response to an applied electrical signal;
a set of receive coils, wherein the set of receive coils generates a sensed electrical signal in response to a sensed magnetic field in the volume of animal tissue, wherein the set of receive coils is configured to detect electron paramagnetic resonance signals in the volume of animal tissue;
a pulsed-RF driver circuit, operatively coupled to an RF signal source and to the set of transmit coils, that drives a plurality of pulse sets, each pulse set including: a first π/2 pulse that includes a plurality of cycles of RF, followed by a fixed amount of time τ and then a second π/2 pulse that includes a plurality of cycles of RF followed by a waiting time T and thereafter a third π/2 pulse that includes a plurality of cycles of RF in the direction generally orthogonal to the substantially static magnetic field in the volume of animal tissue from a surface of the animal next to the volume of animal tissue;
an RF receiver circuit operatively coupled to the set of receive coils to receive the sensed electrical signal from the set of receive coils and to generate a received electrical signal, wherein the transmitted pulse sets are of magnitudes and durations configured such that after the first two π/2 pulses the magnetization is stored along the longitudinal z-axis where it remains during the waiting time T, wherein the waiting time T is varied allowing the magnetization to decay with T1e and wherein the third π/2 pulse rotates the z-component back into the transverse xy-plane where it gives rise to a stimulated echo at the fixed amount of time τ after the third π/2 pulse to measure electron T1e spin-lattice relaxation information from the volume of tissue in order to measure oxygen in the volume of tissue; and
an image-generation unit operatively coupled to the RF receiver circuit and configured to process the received electrical signal and to generate image data based on the received electrical signal.