Magnetic resonance imaging apparatus and magnetic resonance imaging method

• US 9,687,171 B2
• Filed: 08/11/2009
• Issued: 06/27/2017
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Inventors: Kitane, Shinichi
• Primary Examiner(s): LAURITZEN, AMANDA L
• Application Number:
  US12/538,957
• Publication Number:
  US 20100041982A1
• Time in Patent Office: 2,877 Days
• Field of Search: 600301, 600407, 600410, 600413, 600419, 600428, 600437, 600448, 600454, 600455, 600456, 600458, 600468, 324306, 324307, 324309, 324313
• CPC Class Codes: A61B 5/0037 Performing a preliminary scan, e.g. a prescan for identifying a region of interest
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0263 using NMR
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: G01R 33/20 involving magnetic resonance medical aspects A61B5/055; magnetic resonance gyrometers G01C19/60
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR
• CPC Class Codes: G01R 33/3415 comprising arrays of sub-coils , i.e. phased-array coils with flexible receiver channels
• CPC Class Codes: G01R 33/44 using nuclear magnetic resonance [NMR] G01R33/24, G01R33/62 take precedence
• CPC Class Codes: G01R 33/483 with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy
• CPC Class Codes: G01R 33/54 Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
• CPC Class Codes: G01R 33/56 Image enhancement or correction, e.g. subtraction or averaging techniques , e.g. improvement of signal-to-noise ratio and resolution
• CPC Class Codes: G01R 33/56316 involving phase contrast techniques
• CPC Class Codes: G01R 33/5635 Angiography, e.g. contrast-enhanced angiography [CE-MRA] or time-of-flight angiography [TOF-MRA]
• CPC Class Codes: G01R 33/5673 Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker
• CPC Class Codes: G01R 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

A magnetic resonance imaging apparatus includes a trigger generating unit, a blood flow image generating unit and a control unit. The trigger generating unit acquires blood flow information of an object and generates a trigger based on the blood flow information. The blood flow image generating unit acquires imaging data with using the trigger and generates blood flow image data. The control unit controls so as to repeatedly perform a probe sequence for acquiring the blood flow information and an imaging sequence for acquiring the imaging data alternately.

Claims

1. A magnetic resonance imaging (MRI) apparatus comprising:

static and gradient magnetic field generators, at least one radio frequency (RF) coil configured to be coupled to an imaging volume, RF transmitter and receiver circuits coupled to the RF coil and at least one programmable computer connected to control said gradient magnetic field generator, said RF transmitter and receiver circuits, the at least one programmable computer being configured to

provide a probe sequence and acquire blood flow information of an object within an imaging scan to acquire magnetic resonance signals from the object and to generate a trigger for an imaging sequence, also within said imaging scan, using the blood flow information acquired in the probe sequence, wherein a data acquisition region of the probe sequence is set to a local region including at least a target blood vessel, and the blood flow information is acquired from magnetic resonance signals obtained from the target blood vessel;

acquire imaging data from the object during said imaging sequence initiated by the trigger and to generate blood flow image data using the acquired imaging data; and

repeatedly and alternately perform, during said imaging scan, (a) said probe sequence acquiring the blood flow information and (b) the imaging sequence acquiring the imaging data,

wherein the local region to which the probe sequence is applied is located downstream of a region to which the imaging sequence is applied.

2. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

a signal from blood flow in a target blood vessel, and an absolute value of intensity of the signal or a luminance value of image data generated from the signal as the blood flow information.

3. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

a velocity of blood flow in a target blood vessel as the blood flow information.

4. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire a temporal phase shift amount of a signal from blood flow in a target blood vessel as the blood flow information.

5. The magnetic resonance imaging apparatus of claim 4, wherein the at least one programmable computer being further configured to acquire

a difference in phase between a signal corresponding to each time phase and a reference signal as the temporal phase shift amount.

6. The magnetic resonance imaging apparatus of claim 4, wherein the at least one programmable computer being further configured to acquire

a difference in phase between signals adjacent to each other in time as the temporal phase shift amount.

7. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

the blood flow information by NMR RF (nuclear magnetic resonance radio frequency) excitation of a local region including a target blood vessel at a downstream side of a region for acquiring the imaging data.

8. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

a velocity of blood flow in a target blood vessel as the blood flow information by NMR RF (nuclear magnetic resonance radio frequency) excitation of a local region including the target blood vessel with a sequence using a phase contrast MRI method.

9. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to generate

the trigger when it is determined that the blood flow information is within a range specified by preset thresholds.

10. A magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

k-space data corresponding to one line passing through a center of k-space by NMR RF (nuclear magnetic resonance radio frequency) excitation of a local region including a target blood vessel with a sequence of a field echo or a spin echo type and to generate the trigger is generated when it is determined that the blood flow information is within a range specified by preset thresholds, the threshold values being obtained from the k-space data.

11. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to

(a) generate a trigger for a first imaging sequence to be performed in a period when the blood flow information is within a local maximal range specified by preset thresholds and (b) generate a trigger for a second imaging sequence to be performed in a period when the blood flow information is within a local minimal range specified by further preset thresholds, and

generate the blood flow image data by subtraction processing between first imaging data acquired by the first imaging sequence and second imaging data acquired by the second imaging sequence.

12. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

the magnetic resonance signals repeatedly at a predetermined interval and the trigger is generated only when it is determined that the blood flow information is within a range specified by preset thresholds obtained from the magnetic resonance signals.

13. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

the magnetic resonance signals repeatedly until it is determined that the blood flow information is within a range specified by preset thresholds and the trigger is generated when it is determined that the blood flow information is within the range based on the magnetic resonance signals.

14. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to generate

the blood flow image data as T2 weighted image data by acquiring the imaging data with a non-contrast-enhanced three dimensional MRI scan using a spin echo type imaging sequence.

15. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

the imaging data using a steady state free precession MRI sequence.

16. The magnetic resonance imaging apparatus of claim 1, wherein the at least one programmable computer being further configured to acquire

saturated blood signals flowing into an imaging section as the imaging data using a field echo type MRI sequence wherein a saturation pulse is applied to a target blood flow and using an inflow effect of a time of flight method without using contrast medium.

17. A magnetic resonance imaging (MRI) method comprising:

operating an MRI system including static and gradient magnetic field generators, at least one radio frequency (RF) coil configured to be coupled to an imaging volume, RF transmitter and receiver circuits coupled to the RF coil and at least one programmed computer to

(a) acquire blood flow information of an object by acquiring magnetic resonance signals from the object and generating a trigger, for an imaging sequence during an imaging scan that includes both the probe sequence and the imaging sequence, using the blood flow information acquired in the probe sequence, wherein a data acquisition region of the probe sequence is set to a local region including at least a target blood vessel, and the blood flow information is acquired from magnetic resonance signals obtained from the target blood vessel;

(b) acquire imaging data from the object during said imaging sequence initiated by the trigger and generate blood flow image data using the acquired imaging data; and

(c) repeatedly and alternately perform, during said imaging scan, (a) the probe sequence acquiring the blood flow information and (b) the imaging sequence acquiring the imaging data,

wherein the local region to which the probe sequence is applied is located downstream of a region to which the imaging sequence is applied.