Noise suppression methods and apparatus

Abstract

According to some aspects, a method of suppressing noise in an environment of a magnetic resonance imaging system is provided. The method comprising estimating a transfer function based on multiple calibration measurements obtained from the environment by at least one primary coil and at least one auxiliary sensor, respectively, estimating noise present in a magnetic resonance signal received by the at least one primary coil based at least in part on the transfer function, and suppressing noise in the magnetic resonance signal using the noise estimate.

What is claimed is: 
     
         1 - 27 . (canceled) 
     
     
         28 . A method of suppressing noise in an environment of a magnetic resonance imaging system, the method comprising:
 receiving a magnetic resonance signal using a first primary coil;   receiving a noise signal using a first auxiliary sensor;   estimating noise present in the magnetic resonance signal by applying a transform to the noise signal received by the first auxiliary sensor to obtain a noise estimate, wherein the transform applied to the noise signal comprises a respective plurality of parameters for each of a plurality of frequencies of the transform, the transform being previously obtained based at least in part on a plurality of calibration measurements obtained using the first primary coil and the first auxiliary sensor; and   suppressing noise in the magnetic resonance signal using the noise estimate.   
     
     
         29 . The method of  claim 28 , wherein the respective plurality of parameters comprises, for each of the plurality of frequencies, at least one of a respective amplitude or a respective phase. 
     
     
         30 . The method of  claim 28 , wherein the respective plurality of parameters comprises a respective amplitude and phase for each of the plurality of frequencies. 
     
     
         31 . The method of  claim 28 , wherein the plurality of frequencies is a plurality of frequency bins. 
     
     
         32 . The method of  claim 28 , wherein the transform was previously obtained by estimating the respective plurality of parameters based on a first plurality of calibration signals obtained by the first primary coil and a second plurality of calibration signals obtained by the first auxiliary sensor. 
     
     
         33 . The method of  claim 32 , wherein each of the first plurality of calibration signals and the second plurality of calibration signals comprises multiple values. 
     
     
         34 . The method of  claim 28 , wherein the plurality of calibration measurements is indicative of multiple values for each of the plurality of frequencies. 
     
     
         35 . The method of  claim 28 , wherein the plurality of calibration measurements comprises a first plurality of calibration signals obtained using the first primary coil and a second plurality of calibration signals obtained using the first auxiliary sensor. 
     
     
         36 . The method of  claim 35 , wherein a discrete Fourier transform of the first plurality of calibration signals provides multiple values for each of the plurality of frequencies. 
     
     
         37 . The method of  claim 35 , wherein the first plurality of calibration signals comprises a first calibration signal comprising a first plurality values obtained at a respective plurality of times. 
     
     
         38 . The method of  claim 35 , wherein the respective plurality of parameters comprises a respective amplitude and phase for each of the plurality of frequencies, and wherein the method further comprises obtaining the transform at least in part by estimating the respective amplitude and phase of the transform for each of the plurality of frequencies based on the first plurality of calibration signals obtained by the first primary coil and the second plurality of calibration signals obtained by the first auxiliary sensor. 
     
     
         39 . The method of  claim 35 , wherein each of the first plurality of calibration signals is obtained substantially at a same time as a respective one of the second plurality of calibration signals. 
     
     
         40 . The method of  claim 28 , wherein the first primary coil is arranged within a field of view of the magnetic resonance imaging system to detect magnetic resonance signals produced by a sample when positioned within the field of view, and wherein the first auxiliary sensor comprises at least one auxiliary coil arranged outside the field of view. 
     
     
         41 . The method of  claim 28 , wherein the noise signal is received by the first auxiliary coil substantially at a same time as the first primary coil receiving the magnetic resonance signal. 
     
     
         42 . The method of  claim 28 , wherein the magnetic resonance system is a low-field magnetic resonance imaging system configured to generate a B 0  field of 0.2 T or less. 
     
     
         43 . The method of  claim 42 , wherein the low-field magnetic resonance imaging system is configured to generate a B 0  field of 0.1 T or less. 
     
     
         44 . A magnetic resonance imaging (MRI) system comprising:
 a first primary coil;   a first auxiliary sensor; and   at least one controller configured to:
 receive a magnetic resonance signal via the first primary coil; 
 receive a noise signal via the first auxiliary sensor; 
 estimate noise present in the magnetic resonance signal received by the first primary coil by applying a transform to the noise signal received by the first auxiliary sensor to obtain a noise estimate, wherein the transform applied to the noise signal comprises a respective plurality of parameters for each of a plurality of frequency bins of the transform, the transform being previously obtained based at least in part on a plurality of calibration measurements obtained via the first primary coil and the first auxiliary sensor; and 
 suppress noise in the magnetic resonance signal using the noise estimate. 
   
     
     
         45 . The MRI system of  claim 44 , wherein the plurality of calibration measurements comprises a first plurality of calibration signals obtained via the first primary coil, the first plurality of calibration signals being indicative of multiple values for each of the plurality of frequency bins. 
     
     
         46 . The MRI system of  claim 44 , wherein the respective plurality of parameters comprises a respective amplitude and phase for each of the plurality of frequency bins. 
     
     
         47 . The MRI system of  claim 44 , wherein the magnetic resonance system is a low-field magnetic resonance imaging system configured to generate a B 0  field of 0.2 T or less.