HEART IMAGING WITH ADAPTIVE INVERSION TIME

• US 20080242973A1
• Filed: 04/02/2008
• Published: 10/02/2008
• Est. Priority Date: 04/02/2007
• Status: Active Grant

• Current Assignee: Siemens Healthcare GMBH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Warmuth, Carsten
• Granted Patent: US 9,084,553 B2
• Time in Patent Office: Days
• US Class Current: 600/413
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• 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 33/5601 involving use of a contrast agent for contrast manipulation, e.g. a paramagnetic, super-paramagnetic, ferromagnetic or hyperpolarised contrast agent
• CPC Class Codes: G01R 33/5602 by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse
• CPC Class Codes: G01R 33/5607 by reducing the NMR signal of a particular spin species, e.g. of a chemical species for fat suppression, or of a moving spin species for black-blood imaging
• 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 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• 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

Abstract

In a method for acquisition of magnetic resonance images of the heart, MR signals of the heart are acquired using an imaging sequence, wherein the magnetization is inverted by an RF inversion pulse before the acquisition of the MR signals; and of the heart activity is detected, and the point in time of the switching of the RF inversion pulse dependent on the detected heart activity.

Claims

1. A method for acquiring a magnetic resonance image of a heart, comprising the steps of:

acquiring magnetic resonance signals from a heart in a subject by exposing the subject to a magnetic resonance imaging pulse sequence including at least one pulse during which magnetic resonance signals from the heart are acquired, and including emitting an RF inversion pulse that inverts magnetization at least in the heart, at a point in time before said at least one pulse;

detecting cardiac activity of the heart; and

adapting said point in time of said RF inversion pulse dependent on the detected cardiac activity.

2. A method as claimed in claim 1 comprising adapting said point in time to minimize a longitudinal magnetization of the myocardium of the heart during said acquisition of said magnetic resonance signals by varying a time span from said point in time until a beginning of acquisition of said magnetic resonance signals.

3. A method as claimed in claim 1 comprising employing, as said imaging sequence, a segmenting imaging sequence in which data are entered only into a portion of k-space during a cardiac cycle of the heart in the imaging sequence.

4. A method as claimed in claim 1 comprising employing a gradient echo-based imaging sequence as said imaging sequence, with a bipolar gradient as said at least one pulse, and wherein only NRF excitation pulses are switched during a cardiac cycle of the heart.

5. A method as claimed in claim 1 comprising determining a time span TF from a time of said acquisition of magnetic resonance signals until an R-spike of a cardiac cycle of the heart for at least one preceding cardiac cycle, and determining a time span TT from said R-spike of the cardiac cycle until a beginning of position of said magnetic resonance signals, and calculating a time span TD from the R-spike until switching of said RF inversion pulse dependent on TT and TF.

6. A method as claimed in claim 1 comprising calculating a magnetization of blood in the subject at a point in time of acquisition of said magnetic resonance signals.

7. A method as claimed in claim 1 comprising, during said imaging sequence, emitting a plurality of RF excitation pulses each having a flip angle, and varying the respective flip angles of the respective RF pulses to make said magnetic resonance signals substantially constant.

8. A method as claimed in claim 7 comprising emitting N of said RF pulses during a cardiac cycle of the heart, and varying the respective flip angles to give an Nth excitation pulse a flip angle of 90°

, and iteratively calculating the respective flip angles for each preceding excitation pulse from the flip angle of the excitation pulse immediately following.

9. A method as claimed in claim 1 comprising injecting a contrast agent that interacts with the heart before acquiring said magnetic resonance signals.