Vessel enhancement filtering in magnetic resonance angiography

• US 5,644,646 A
• Filed: 08/05/1994
• Issued: 07/01/1997
• Est. Priority Date: 08/05/1994
• Status: Expired due to Term

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Du, Yiping, Parker, Dennis L.
• Primary Examiner(s): Couso, Jose L.
• Assistant Examiner(s): Do, Anh Hong
• Application Number:
  US08/286,523
• Time in Patent Office: 1,061 Days
• Field of Search: 382/108, 382/128, 382/130, 382/132, 324/309, 324/312, 324/308, 128/696, 128/653.3, 128/713
• US Class Current: 382/128
• CPC Class Codes: G06T 2200/04 involving 3D image data
• CPC Class Codes: G06T 2207/10088 Magnetic resonance imaging [MRI]
• CPC Class Codes: G06T 2207/20056 Discrete and fast Fourier transform, [DFT, FFT]
• CPC Class Codes: G06T 2207/30101 Blood vessel; Artery; Vein; Vascular
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/94 based on local image properties, e.g. for local contrast enhancement

Abstract

An MRI system includes an MR cylinder, a radio frequency (RF) coil (or antenna), preliminary processing circuitry, and a computer processing system. The RF receiver produces an electrical signal to the preliminary processing circuitry representative of the sensed magnetic field. The preliminary processing circuitry provides a measurement data signal S (which is in the frequency domain) to the computer processing system, which includes a computer processor and a memory. The computer processor stores measurement data signal S as a data matrix M₂ in a larger data matrix M₃ that contains zero values in memory locations surrounding data matrix M₂. This is referred to as zero-padding. The computer processor performs (zero-padded) Fourier transformation on data matrix M₃ to produce an interpolated image data matrix I_D. Interpolated image data matrix I_D is processed through enhancement filtering to provide an enhanced image data matrix I_E that has improved visibility of vessels. The filtering may be performed by a variety of filters including a max-min SD filter or a cross-section filter.

Claims

1. A system for enhancing lines in images produced from data that represent a structure of anatomy of a subject and that are produced in a magnetic resonance imaging (MRI) device, the system comprising:

a detector that detects signals composed of energy passing through and modified by the structure of anatomy and that produces detection signals reflective of the detected modified energy signals;

preprocessing circuitry that receives the detection signals and provides preprocessed signals in response thereto; and

processing circuitry that receives the preprocessed signals and performs a transformation thereon to provide an interpolated image data matrix I_D and that performs a max-min second difference (SD) line enhancing filtering process on the interpolated image data matrix I_D to provide an enhanced image data matrix I_E in which lines are enhanced.

2. The system of claim 1 in which the filtering process is of the form SD_ij =2f(i)-f(i-1)-f(i+1), where f(i) is the image intensity at point i, and f(i-1) and f(i+1) are the image intensity at the neighboring points of f(i) along direction j.

3. The system of claim 1 in which the filtering process is applied in thirteen directions around every image point.

4. The system of claim 1 in which the filtering process determines the difference between the maximum SD and the maximum of zero and the minimum SD.

5. The system of claim 1 in which the filtering process is performed in a hardware filter.

6. The system of claim 1 in which the transformation is a zero-padded Fourier transformation.

7. The system of claim 6 in which intermediate processes are performed on the preprocessed data signals prior to the zero-padded Fourier transformation.

8. A system for enhancing lines in images produced from data that represent a structure of anatomy of a subject, the system comprising:

a detector that detects signals composed of energy passing through and modified by the structure of anatomy and that produces detection signals reflective of the detected modified energy signals;

preprocessing circuitry that receives the detection signals and provides a preprocessed signals in response thereto; and

processing circuitry that receives the preprocessed signals and performs a zero-padded transformation thereon to provide interpolated image data and that performs a line enhancing filtering process on the interpolated image data to provide enhanced image data in which lines are enhanced.

9. The system of claim 8 in which the line enhancing filtering process is a second difference (SD) filtering process.

10. The system of claim 9 in which the second difference (SD) filtering process is a non-linear filtering process.

11. The system of claim 9 in which the second difference (SD) filtering process is a max-min SD filtering process.

12. The system of claim 9 in which the second difference (SD) filtering process is a cross-section filtering process.

13. The system of claim 10 in which the non-linear filtering process includes a second difference (SD) operation of the form SD_ij =2f(i)-f(i-1)-f(i+1), where f(i) is the image intensity at point i, and f(i-1) and f(i+1) are the image intensity at the neighboring points of f(i) along direction j.

14. The system of claim 11 in which the max-min SD filtering process determines the difference between the maximum SD and the maximum of zero and the minimum SD.

15. The system of claim 8 in which the line enhancing filtering process is performed in a hardware filter.

16. A processing system for enhancing lines in images produced from data that represent a structure of anatomy of a subject and that is detected from signals composed of energy passing through and modified by the structure of anatomy and that is preprocessed to produce preprocessed signals, the computer processing system comprising:

a receiving port for receiving the preprocessed signals;

memory in which the preprocessed signals are zero-padded; and

processing circuitry that performs a transformation on the preprocessed signals to produce transformed image data and that performs a multi-directional second difference (SD) line enhancing filtering process on the transformed image data to provide enhanced image data in which lines are enhanced.

17. The system of claim 16 in which processing circuitry includes a hardware filter to perform the line enhancing filtering process.

18. The system of claim 16 in which the transformation is a Fourier transformation.

19. A system for enhancing lines in images produced from data that represent a structure of anatomy of a subject and that are produced in a magnetic resonance imaging (MRI) device, the system comprising:

a detector that detects signals composed of energy passing through and modified by the structure of anatomy and that produces detection signals reflective of the detected modified energy signals;

preprocessing circuitry that receives the detection signals and provides preprocessed signals in response thereto; and

processing circuitry that receives the preprocessed signals and performs a transformation thereon to provide an interpolated image data matrix I_D and that performs a multi-directional second difference (SD) line enhancing filtering process on the interpolated image data matrix I_D to provide an enhanced image data matrix I_E in which lines are enhanced.

20. The system of claim 19 in which the filtering process is a max-min SD filtering process.

21. The system of claim 19 in which the filtering process is a cross-section filtering process.

22. The system of claim 19 in which the transformation is a zero-padded Fourier transformation.

23. The system of claim 19 in which the filtering process is of the form SD_ij =2f(i) -f(i-1)-f(i+1), where f(i) is the image intensity at point i, and f(i-1) and f(i+1) are the image intensity at the neighboring points of f(i) along direction j.

24. A system for enhancing lines in images produced from data that represent a structure of anatomy of a subject and that are produced in a magnetic resonance imaging (MRI) device, the system comprising:

a detector that detects signals composed of energy passing through and modified by the structure of anatomy and that produces detection signals reflective of the detected modified energy signals;

preprocessing circuitry that receives the detection signals and provides preprocessed signals in response thereto; and

a computer processor system that receives the preprocessed signals and performs a transformation thereon to provide an interpolated image data matrix I_D and that performs a cross-sectional line enhancing filtering process on the interpolated image data matrix I_D to provide an enhanced image data matrix I_E in which lines are enhanced.