Detection and elimination of wide bandwidth noise in MRI signals

• US 5,525,906 A
• Filed: 07/11/1994
• Issued: 06/11/1996
• Est. Priority Date: 07/11/1994
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Stormont, Robert S., Crawford, Carl R., Eash, Matthew G., DallaPiazza, Dennis G., Small, Daniel S., Pelc, Norbert J., Souza, Steven P.
• Primary Examiner(s): Snow, Walter E.
• Assistant Examiner(s): MAH, RAYMOND
• Application Number:
  US08/273,577
• Time in Patent Office: 701 Days
• Field of Search: 324/322, 324/318, 324/309, 324/307, 324/300, 324/314, 324/316, 128/653.5
• US Class Current: 324/322
• CPC Class Codes: G01R 33/3621 NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
• CPC Class Codes: G01R 33/5608 Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels image data processing or generation, in general G06T

Abstract

An MRI system includes a noise filter which receives each acquired NMR signal during a scan and detects short-duration noise pulses by sensing the signal level in a band of frequencies outside the imaging bandwidth. A blanking circuit suppresses the NMR signal during the time interval each noise pulse is detected to remove the noise pulse prior to image reconstruction.

Claims

1. In an NMR system which acquires an NMR signal having a desired frequency bandwidth, the improvement comprising:

a filter connected to receive the NMR signal and tuned to pass a range of frequencies outside the desired frequency bandwidth;

a detector connected to receive the filtered output signal from the filter, compare its level with the level of a noise reference signal, and produce a noise indication signal when the level of the filtered NMR signal exceeds that of the noise reference signal; and

means for receiving the NMR signal and modifying the NMR signal when the noise indication signal is produced.

2. The improvement as recited in claim 1 in which the filter passes a band of frequencies higher than the desired frequency bandwidth, and a band of frequencies lower than the desired frequency bandwidth.

3. The improvement as recited in claim 1 in which the means for receiving and modifying the NMR signal is a blanking circuit which suppresses the NMR signal during the interval in which the noise indication signal is produced.

4. The improvement as recited in claim 3 which includes a time delay connected to receive the NMR signal and impose a delay thereon prior to application to the blanking circuit.

5. The improvement as recited in claim 1 which includes a counter connected to the detector and being operable to count the number of noise indication signals which are produced.