MR-PET cyclic motion gating and correction

• US 9,535,145 B2
• Filed: 10/29/2008
• Issued: 01/03/2017
• Est. Priority Date: 11/09/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Demeester, Gordon D., Morich, Michael A., Eagan, Timothy P.
• Primary Examiner(s): Patel, Neha
• Application Number:
  US12/740,358
• Publication Number:
  US 20100290683A1
• Time in Patent Office: 2,988 Days
• Field of Search: 382/131
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0035 adapted for acquisition of images from more than one imaging mode, e.g. combining MRI and optical tomography
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/33 specially adapted for cooperation with other devices
• CPC Class Codes: A61B 5/7289 Retrospective gating, i.e. associating measured signals or images with a physiological event after the actual measurement or image acquisition, e.g. by simultaneously recording an additional physiological signal during the measurement or image acquisition
• CPC Class Codes: A61B 5/7292 Prospective gating, i.e. predicting the occurrence of a physiological event for use as a synchronisation signal
• CPC Class Codes: A61B 6/037 Emission tomography
• CPC Class Codes: A61B 6/5247 combining images from an ionising-radiation diagnostic technique and a non-ionising radiation diagnostic technique, e.g. X-ray and ultrasound
• CPC Class Codes: A61B 6/5288 involving retrospective matching to a physiological signal
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: G01R 33/481 MR combined with positron emission tomography [PET] or single photon emission computed tomography [SPECT]
• 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
• 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

In preparation for acquiring PET image data, subject motion models are built based on physiologic signal monitoring and MR data is collected and used for improved PET imaging. The physiologic signal monitoring is also used during PET imaging, and the acquired MR data is used for prospective or retrospective gating of the PET image acquisition, or in the PET reconstruction for improved correction/imaging.

Claims

1. An imaging system, including:

a magnetic resonance (MR) scanner that scans a region of interest in a subject to generate image data of the region of interest during a physiological cycle;

a processor that divides the physiological cycle into a plurality of frames, associates the MR image data to corresponding frames in the physiological cycle, and reconstructs a series of MR images to generate a motion model of the region of interest during the physiological cycle;

a positron emission tomography (PET) scanner that collects PET data from the region of interest during the frames of the physiological cycle;

a PET reconstruction processor that uses the motion model to generate a PET image in one or more reference frames of the physiological cycle; and

a vital signs monitor (VSM) that monitors the physiological cycle in the subject as the MR scanner scans the region of interest;

wherein the processor analyzes the motion model to determine an amount of detected motion in each frame of the cyclic physiological signal, identifies a frame in which a smallest amount of motion occurred during the MR scan, and gates the PET scanner to collect data during the identified frame.

2. The system according to claim 1, wherein the PET scanner collects data from the region of interest as lines of response in list mode, and marks each line of response in accordance with the frame in which it is collected.

3. The system of claim 1, wherein the PET scanner is a time-of-flight (TOF) scanner.

4. The system according to claim 1, wherein the VSM includes at least one of an electrocardiograph to monitor a cardiac cycle in the subject and a respiratory monitor to monitor a respiratory cycle in the subject.

5. The system according to claim 1, wherein the VSM monitors the cyclic physiological signal in the subject during the PET scan.

6. The system according to claim 1, wherein the PET reconstruction processor adjusts PET data collected during a frame other than the reference frame in accordance with the motion model and reconstructs the adjusted PET data into a PET image corresponding to the reference frame.

7. The system according to claim 6, wherein the MR scanner generates navigator sequences that generate MR image data that is reconstructed to indicate at least one of displacement of the region of interest relative to a predefined point, and

rotation of the region of interest relative to a predefined axis.

8. The system according to claim 6, wherein the motion model is a 3D model of the region of interest.

9. The system according to claim 1, wherein the processor includes:

a routine for acquiring the MR image data of the region of interest in a subject;

a routine for monitoring a physiological cycle in the subject during MR data acquisition;

a routine for associating the acquired MR image data with one of a plurality of frames in the physiological cycle;

a routine for generating, from the acquired MR data, a motion model indicative of relative displacement of the region of interest in each frame;

a routine for monitoring a physiological signal in the subject during a PET scan; and

a routine for employing the motion model to infer displacement of the region of interest during each frame of the physiological cycle during the PET scan.

10. An imaging system, including:

a magnetic resonance (MR) scanner that scans a region of interest in a subject to generate images and MR data of the region of interest during a physiological cycle;

a processor that correlates motion during the physiological cycle to the MR images and motion data for the physiological cycle, and characterizes the motion as displacement, relative to a reference position, as a function of time during the physiological cycle;

a positron emission tomography (PET) scanner that collects PET data from the region of interest during the physiological cycle; and

a PET reconstruction processor that uses the motion characterization to generate a PET image at the reference position of the physiological cycle.

11. The system according to claim 10, wherein the motion characterization includes a measurement of motion of selected tissue using an MR spin tagging technique.

12. The system according to claim 10, wherein the processor timestamps the physiological signals acquired during MR and PET scans, and time-registers the physiological signals acquired during the PET scanning to the physiological signals acquired during the MR scan using a correlation function to align the physiologic signals acquired during MR and PET scanning, and wherein the time-stamped physiological signals and registrations are digitally stored to memory.