General Electric Company

University of Michigan

General Electric Corporation Gmbh

Thomas K Foo

Matthew A Bernstein

Cecil E Hayes

Kevin Franklin King

Paul Arthur Bottomley

Robert David Darrow

Martin R Prince

Jason Andrew Polzin

Vincent B Ho

Steven D Wolff

Patrick L Le Roux

Paul R Moran

Vivek Prabhakar Vaidya

Xiaodong Tao

Thomas L Chenevert

Tsur Bernstein

Frederick H Epstein

Yoon-Won Kang

Maggie M Fung

Andrew E Arai

Beth E Slayman

Jeffrey A Feinstein

William H Perman

Systems and methods for landmark correction in Magnetic Resonance Imaging (MRI) are provided. One method includes acquiring at least one calibration image or at least one localizer image of an object, identifying in the calibration or localizer images a region of the object as a reference point, wherein the reference point defines a landmark position. The method further includes determining an offset between an initial landmark position and the identified landmark position. The method also includes using the determined offset for MRI.

Systems and methods for landmark correction in magnetic resonance imaging

A system and method is disclosed to combine both a fractional echo (k.sub.x) and a fractional NEX (k.sub.y) to reduce acquisition times and echo times in MR imaging. The method uses both zero-filling and homodyne reconstruction to construct concurrent fractional NEX and fractional echo data in a single image while minimizing any blurring effects. The system includes acquiring partial MRI data in the k.sub.x direction and acquiring partial MRI data in the k.sub.y direction. Once a partial echo and a partial NEX are acquired, the missing data is first zero-filled in the k.sub.x direction and Fourier transformed to acquire a full x direction data set. Next, the data is synthesized in the k.sub.y direction using a homodyne reconstruction technique to acquire a full data set in the k.sub.y direction. The full x,y data set can then be used to reconstruct an MR image with reduced acquisition and echo times. In order to minimize the effects of blurring in the resulting MR image, it is preferable to acquire at least an 80% fractional echo and a 60% fractional NEX. The system can be extended to any number of desirable dimensions.

MRI reconstruction using partial echo and partial NEX data acquisitions

A 3DFT MRA dynamic study is performed using a contrast agent to enhance image contrast. A monitor pulse sequence is performed at a high temporal rate to monitor the magnitude of the NMR signal produced in a monitor region after the contrast agent is injected into the patient. When the monitor signal reaches a threshold value, the patient is signaled and the 3DFT image data set is acquired.

Method for performing magnetic resonance angiography using a contrast

NMR data for imaging perfusion of blood is acquired from a series of slice locations using a cardiac gated NMR pulse sequence. Data for the slice locations are acquired by a corresponding series of data acquisition segments performed during the R--R interval of each cardiac cycle. Selective rf saturation pulses are interleaved with the data acquisition segments to uniformly condition spin magnetization in each slice location.

Acquistion of segmented cardiac gated MRI perfusion images

A fast and computationally efficient system and method is disclosed for detecting and tracking the position of a reference structure in the body using a linear phase shift to minimize motion artifacts in magnetic resonance imaging. In one application, the system and method is used to determine the relative position of the diaphragm in the body in order to synchronize data acquisition to the same relative position with respect to the abdominal and thoracic organs to minimize respiratory motion artifacts. The system and method uses the time domain linear phase shift of the reference structure data in order to determine its spatial positional displacement as a function of the respiratory cycle. The signal from a two-dimensional rectangular or cylindrical column is first Fourier transformed to the image domain, apodized or bandwidth-limited, converted to real, positive values by taking the magnitude of the profile, and then transformed back to the image domain. The relative displacement of a target edge in the image domain is determined from an auto-correlation of the resulting time domain information.

System and method for detecting and tracking reference position changes

A method is provided for acquiring MR image data pertaining to a coronary artery which is in motion between end-diastolic and end-systolic maximum excursion positions, respectively, during a cardiac cycle. The method comprises the step of tracking the location of the artery during the cardiac cycle as the artery moves between the positions of maximum excursion. The method further comprises acquiring MR data at a number of locations during the cardiac cycle in a region lying between the maximum excursion positions, each having the excitation or acquisition scan locations adjusted during the MR scan so as to substantially coincide with the location of said artery at the time of data acquisition.

Method for adjusting MR scan plane over cardiac cycle to track motion of

A method is disclosed to reconstruct multiphase MR images that accurately depict the entire cardiac cycle. A segmented, gradient-recalled-echo sequence is modified to acquire data continuously. Images are retrospectively reconstructed by selecting views from each heartbeat based on cardiac phase rather than the time elapsed from the QRS complex. Cardiac phase is calculated using a model that compensates for beat-to-beat heart rate changes.

Retrospective ordering of segmented MRI cardiac data using cardiac phase

A method is provided for rapidly measuring change in T.sub.2 * in a region of an MR imaging subject, the method employing a double gradient echo sequence with spiral readout. In this technique, two gradient echoes are acquired after a single RF excitation. A first readout trajectory spirals out from the center of k-space, i.e., k.sub.r =0, to some maximum radius, and then a second readout trajectory spirals back towards the center of k-space. A gradient echo is formed each time a k-space trajectory passes through the center of k-space. The signal intensity of the two echoes allows the calculation of the T.sub.2 * values on a pixel by pixel basis. The ability to measure changes in T.sub.2 * allows measurement of change in perfusion to be quantified.

Spiral scanning method for monitoring physiological changes

A fast gradient echo, cardiac gated NMR scan is performed by acquiring groups of views during each cardiac cycle. Each group of views is preceded by an accelerator RF pulse and disdaq pulse sequences to improve T.sub.1 contrast and drive spin magnetization rapidly to dynamic equilibrium.

Fast cardiac gated NMR acquisition with improved T.sub.1 contrast

Flow encoded NMR pulse sequences are employed to acquire data sets from which a set of angiographic images can be reconstructed depicting blood flow at successive phases during the cardiac cycle. The number of angiographic images is increased by selecting views from adjacent data sets to form interpolated data sets that are employed to reconstruct angiographic images depicting blood flow at cardiac phases between the successive phases.

MRA image produced by temporal flow data sharing

Fast NMR pulse sequences are employed to acquire data in a single breath-hold from which a plurality of cardiac phase images are reconstructed. Signals from fat are suppressed by frequency selective RF inversion pulses applied just prior to each group of fast NMR pulse sequences.

Multi-phase fat suppressed MRI cardiac imaging

Fast NMR pulse sequences are employed to acquire data sets from which a set of images can be reconstructed depicting a patient's heart at successive phases during the cardiac cycle. The number of images is increased by selecting views from adjacent data sets to form interpolated data sets that are employed to reconstruct images depicting the patient's heart at cardiac phases between the successive phases.

MRI cardiac image produced by temporal data sharing

An NMR system performs a 3DFT scan using a set of steady-state free precession (SSFP) pulse sequences. A contrast preparation pulse sequence precedes each series of SSFP pulse sequences employed to acquire one plane through the three-dimensional space, and it includes a spectrally selective RF inversion pulse tuned to fat or water. The sequence is repeated without any magnetization recovery delays until all the planes have been acquired.

Fast NMR image acquisition with spectrally selective inversion pulse

T*.sub.2 contrast in images reconstructed from fast NMR pulse sequences is improved by increasing the gradient recalled echo time TE. The pulse repetition time TR is minimized to maintain high temporal resolution by asymmetrically acquiring the echo signal with its peak disposed bear the end of the acquisition window.

Monitoring body functions using fast NMR pulse sequences

An NMR system performs a 2DFT or 3DFT scan using a set of steady-state free precession (SSFP) pulse sequences. A contrast preparation pulse sequence precedes each series of SSFP pulse sequences and it includes a spectrally selective RF inversion pulse timed to water to provide T.sub.1 contrast between tissues having relatively long T.sub.1 times, followed by a spectrally selective RF inversion pulse tuned to suppress the signals from fat.

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Waukesha, WI, United States of America

Thomas K Foo