Duke University

Siemens Medical Solutions Usa, Inc.

Siemens Healthcare Gmbh

Elizabeth R Jenista

Raymond J Kim

Wolfgang Gerhard Rehwald

Enn-Ling Chen

David C Wendell

Han W Kim

A method for correcting image inhomogeneity includes acquiring a non-normalized image and a reference image using receiver coils. A high-signal mask and a low-signal mask are created. Each pixel in the high-signal mask is set to a predetermined integer value if the reference image pixel at the same specific location has a value above a threshold value. Each pixel in the low-signal mask is set to the predetermined integer value if the reference image pixel at the same specific location has a value below or equal to the threshold value. A coil normalization map is created by smoothing the reference image with filters. Then, an iterative procedure is performed to update the coil normalization map using the high-signal mask and the low-signal mask. Following the iterative procedure, the non-normalized image is divided by the current coil normalization map to yield a normalized image.

Magnetic resonance imaging coil normalization by using a reference image

A magnetic resonance imaging system and method are provided for improved phase-sensitive magnetic resonance imaging of tissues affected by cardiovascular pulsatile motion. A magnetically-prepared image dataset and corresponding reference image dataset (for phase sensitivity) are obtained within the duration of a single cardiac cycle. The paired datasets can be single-shot or segmented datasets and a navigator sequence can optionally be provided with each paired dataset. The system and method take advantage of the shape symmetry of the cardiac cycle to acquire the paired dataset in a shorter time interval, thereby reducing misregistration artifacts. The magnetic preparation can include inversion recovery pulses, FIDDLE sequences, other magnetic preparation sequences, or combinations thereof. The reference dataset can be acquired at a lower resolution than the corresponding magnetically-prepared dataset without compromising image quality.

Systems and methods for phase-sensitive inversion recovery MR imaging with reduced sensitivity to cardiac motion

Magnetic resonance imaging (MRI) systems and methods for determining and adjusting TI using single-line acquisition and automatic compartment detection. A method includes positioning a readout line of the MRI scanner through a compartment of interest of a region of interest in a subject. The method includes inverting magnetization within the readout line by playing an inversion pulse; and reading out data along the readout line after play of the inversion pulse. The method also includes determining a T1 value for each pixel along the readout line; determining the pixels that belong to first and second portions within the compartment of interest; determining a T1 value of each of the first and second portions by averaging the pixels within each portion; and determining an inversion time based on the determined T1 values such that the compartment of interest has a desired magnetization in an image to be acquired.

Magnetic resonance imaging (MRI) systems and methods for determining and adjusting inversion time (TI) using single-line acquisition and automatic compartment detection

Magnetic resonance imaging (MRI) acquisition and reconstruction techniques that invert MR signals of selected frequencies without the application of inversion RF pulses are disclosed. An example method comprises acquisition of at least one MR image representative dataset and an associated phase reference dataset, and classifies anatomical material into a first component representing anatomical material having a first range of resonance frequencies associated with a first range of phase differences between the MR image representative dataset and the reference image dataset and a second component representing anatomical material having a second range of resonance frequencies associated with a second range of phase differences between the MR image representative dataset and the reference image dataset. The method assigns different visual attributes to first and second components derived using phase differences between the MR image representative dataset and the reference image dataset and displays an image.

Systems and methods for virtual frequency selective inversion in magnetic resonance

A virtual frequency selective inversion (VFSI) method receives at least one MR image representative dataset and an associated phase reference dataset, and classifies anatomical material into a first component representing anatomical material having a first range of resonance frequencies associated with a first range of phase differences between the MR image representative dataset and the associated phase reference image dataset, and a second component representing anatomical material having a second range of resonance frequencies associated with a second range of phase differences between the MR image representative dataset and the associated phase reference image dataset. The method assigns different visual attributes to first and second components derived using phase differences between the MR image representative dataset and the reference image dataset and displays an image.

System for reconstruction of virtual frequency selective inversion MR images

An MR system acquires, over multiple heart cycles, image datasets representing multiple image slices of an anatomical region of interest of a patient. In the device, an RF signal generator and a magnetic field gradient generator provides an RF pulse and magnetic field gradient sequence for RF signal excitation of the region of interest and for acquiring RF data following the signal excitation. The sequence comprises, a first sequence occurring substantially immediately after the acquisition of image data using a readout magnetic field gradient. The first sequence includes an RF pulse with a predetermined flip angle followed by a magnetic field gradient pulse for reducing field magnetization to substantially zero. The first sequence is preceded by a dummy acquisition sequence comprising the elements of the first sequence except substantially without acquisition of data.

System for suppression of artifacts in MR imaging

An MR imaging system independently manipulates a fat and a water component of MR signals used for generating image data. An RF signal generator and a magnetic field gradient generator provide an RF pulse and magnetic field gradient sequence for acquisition of an MR signal discriminating between anatomical objects based on longitudinal relaxation time (T1). The sequence comprises, a first pulse sequence for selectively inverting a water component of the MR signal substantially exclusively of fat, a first time delay adjustable to discriminate between different anatomical elements, a second pulse sequence having a resonant frequency selected to invert a fat component of the MR signal substantially exclusively of water and a data acquisition magnetic field gradient for acquisition of the MR signal. An image shows enhanced visualization of discriminated anatomical elements.

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Durham, NC, United States of America

Elizabeth R Jenista