Koninklijke Philips Corporation N.v.

Philips Medical Systems (cleveland), Inc.

Christopher K Anand

Michael R Thompson

Dee H Wu

Paul M Margosian

Wayne R Dannels

Francis H Bearden

James A Halamek

C Michael Steckner

A dose of a contrast agent ( ) is administered to the patient ( ). A magnetic resonance is excited by an RF pulse ( ) in a region of interest of the patient ( ). An echo-planar imaging (EPI) readout waveform is implemented a preselected duration after the excitation to generate T or T * weighted data. During the preselected duration, another echo planar readout waveform is implemented to generate T or proton density weighted data. The data is reconstructed ( ) to generate a T or T * weighted image and a T weighted image. The T and T or T * weighted images are combined ( ) to generate a contrast enhanced image.

Multiple contrast echo-planar imaging for contrast-enhanced imaging

To generate a magnetic resonance angiograph, a patient is injected with a contrast-enhancing agent ( ). An ellipsoidal central portion of k-space ( ) and a first surrounding region ( ) are continuously sampled ( ). A portion of each central data set ( ) is reconstructed ( ) into a low-resolution volume and maximum-intensity-projected ( ) onto a line. The maximum intensity projection ( ) is processed ( ) in order to detect the arrival of the contrast enhancing bolus within a volume of interest. Upon detection of the arrival of the bolus, the acquisition of a high-resolution magnetic resonance angiograph is triggered ( ) in which higher phase encode portions ( ) of k-space are sampled. The central data set ( ) along with the higher phase encode views ( ) are reconstructed ( ) into a high-resolution magnetic resonance angiogram. The present technique allows for substantially zero latency between the detection of the contrast-enhancing agent bolus and the acquisition of the magnetic resonance angiogram.

Contrast-enhanced MRA including an effective zero-latency method of bolus detection

A subject is disposed in an imaging region ( ) of a magnetic resonance imaging apparatus. An operator submits a series of user preferences to the apparatus. A gradient optimizer ( ) generates a gradient waveform that is optimal for the imaging procedure based on the user submitted specifications and the apparatus hardware specifications. The optimizer ( ) accesses a memory that stores ideal gradient waveform models. The model that best fits the user specifications is selected and digitized ( ). The digitized waveform is then convolved ( ) with a band-limited kernel ( ) that represents a frequency spectrum ( ) of a gradient amplifier ( ), producing a gradient waveform ( ) that is smooth and does not exceed the capabilities of the amplifier. This optimized waveform is used in an imaging process including a collected data reconstruction portion of the process.

Band-limited gradient waveforms

A subject is disposed in an imaging region ( ) of a magnetic resonance imaging apparatus. An operator designates a steady-state imaging sequence and a sequence controller ( ) coordinates a gradient field controller ( ) and an RF pulse controller ( ) to generate the desired sequence. The gradient controller applies gradients that define a closed trajectory through k-space that starts at an origin point and follows a closed path to an end point. An analyzer ( ) analyzes data sampled at the beginning and end points. A gradient offset processor ( ) signals the sequence controller to apply additional gradients until the analyzer determines that the end point coincides with the origin point. A scaling circuit ( ) scales data sampled between the origin and end points for various anomalies in the steady-state magnetization, reconstructing scaled data into at least one image representation.

Steady-state imaging sequence

A three-dimensional fast spin echo (FSE) scan is performed by stepping ( ) through a plurality of phase encode k-space views from a computed view list ( ). The view list is computed such that (i) magnetic resonance echoes having a selected image contrast are encoded in the center of k-space, (ii) adjacent data lines in k-space have similar contrast, and (iii) common planes of data lines in k-space are completed at regular intervals. As each data line is read, it is Fourier transformed ( ) and stored ( ) within a fast-access memory ( ). Once a plane of data lines is acquired, it is Fourier transformed ( ) along a second direction using a plurality of parallel processors ( ). The twice-transformed data is stored ( ) in conventional memory ( ). Once all of the phase encode views on the view list are acquired, a final Fourier transform ( ) along a third direction is performed ( ), rendering a volumetric image representation. The method of data acquisition uses fewer memory buffers and takes less time than conventional methods.

Time and memory optimized method of acquiring and reconstructing multi-shot 3D MRI data

A non-rectangular central kernel ( ) of magnetic resonance image data is collected and stored in an acquired data memory ( ). A non-rectangular peripheral portion ( ) of magnetic resonance image data adjacent the central kernel ( ) is collected and stored in the acquired data memory ( ). A phase correction data value set ( ) is generated from at least a portion of the central and peripheral data value sets. A synthetic conjugately symmetric data set ( ) is generated ( ) from the peripheral data set and phase corrected ( ) using the phase correction data value set ( ). Unsampled corners of k-space are zero filled. The central, peripheral, and conjugately symmetric data sets are combined ( ) to form a combined data set. The combined data'set is Fourier transformed ( ) to form an intermediate image representation ( ), which may be exported for display ( ) or used for a further iteration. In this manner, a significant amount of data in a central region of k-space that contributes most strongly to the resultant image is collected while significantly reducing data acquisition time.

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Chesterland, OH, United States of America

Christopher K Anand