Method for non-invasive quantification of organ fat using magnetic resonance approach

A method for non-invasive quantification of organ fat using a magnetic resonance approach, comprising the following steps:

• step I, constructing a detection system:
• constructing a system for non-invasive quantification of the organ fat based on a low-field nuclear magnetic resonance using an external computer, a radio frequency subsystem, and a portable magnet module, wherein
• the radio frequency subsystem comprises a low-field nuclear magnetic resonance spectrometer, a power amplifier, one or more pre-amplifiers, a transmit/receive switching module, and a radio frequency coil;
• the low-field nuclear magnetic resonance spectrometer provides one-way transmit and gate control signal to the power amplifier and a transmit/receive switching gate signal to the transmit/receive switching module;
• the power amplifier is connected to the transmit/receive switching module after amplifying a transmitted signal, and the transmit/receive switching module is configured to switch the radio frequency subsystem between a transmitting state and a receiving state;
• in the transmitting state, the radio frequency coil is configured to transmit radio frequency pulses;
• in the receiving state, the radio frequency coil is configured to receive a echo signal generated after an organ fat detection target region is excited;
• the low-field nuclear magnetic resonance spectrometer is connected to an external computer which controls operations of magnetic resonance pulse sequence command, and transmits the received echo signal back to the external computer through a data transmission interface;
• and the external computer further comprises a data processing module to analyze and process data from low-field nuclear magnetic resonance, and a display module to display results with diagnostic values;
• step II, attaching to a detection region:
• closely attach a probe to a human body surface adjacent to the organ fat detection target region for non-invasive quantification of organ fat, wherein the probe comprises a magnet and the radio frequency coil;
• step III, system startup:
• clicking a system start button to run the system for the non-invasive quantification of the organ fat;
• step IV, acquiring data, wherein (1) the low-field nuclear magnetic resonance spectrometer transmit the radio frequency pulses to the organ fat detection target region through the radio frequency coil, excites the nuclear spins of the organ fat detection target region, receives echo signal generated from the organ fat detection target region, and performs timing control on transmission and reception, and the pulse sequences comprise at least a Carr-Purcell-Meiboom-Gill sequence with a fixed or random echo spacing and a Carr-Purcell-Meiboom-Gill sequence with a fixed or random excitation flip angle,
• (2) in at least one setting of the RF coil, the pulse sequence comprises one or more magnetization preparation modules to enhance contrast, and each of the one or more magnetization preparation modules comprises inversion recovery, saturation recovery, spectrally selective pulses, T2 preparation pulses, diffusion preparation pulses, and velocity-selective saturation pulses, and
• (3) using two-step phase cycling with a 0 phase excitation pulse, a 90 phase refocusing pulse and a 0 phase receiver, plus a 0 phase excitation pulse, a −90 phase refocusing pulse and a 0 phase receiver to remove or reduce ringing signal from the echo signal;
• step V, analyzing the data:
• processing echo data and calculating tissue parameters by running an internal processor of the low-field nuclear magnetic resonance spectrometer and programming or running a result analysis software of the external computer, wherein the tissue parameters comprise at least proton density fat fraction;
• performing both a data filtering method and a curve fitting method based on a tissue model;
• the curve fitting method based on the tissue model is achieved by performing a model-constrained multi-exponential fitting on the echo signal, comparing signal attenuation curves at different echo spacing, or matching a measured signal with a simulated signal generated;
• and
• step VI, performing horizontal data analysis:
• combined with information of other patients from other tests, records or imaging studies, performing analysis to form the method for the non-invasive quantification of the organ fat based on the magnetic resonance approach.