Picker International, Inc.

Koninklijke Philips Corporation N.v.

Philips Medical Systems (cleveland), Inc.

James A Halamek

Mark J Loncar

Kecheng Liu

Rao P Gullapalli

Christopher K Anand

Heidi A Schlitt

C Michael Steckner

A region of interest of a subject is disposed in an imaging region ( ) of a magnetic resonance imaging apparatus. A contrast material ( ) is injected into the subject. An operator initiates a series of fast scan imaging sequences to track the position for entry of the contrast material, into the region of interest. A trajectory through a k-space is selected for the fast scan imaging sequences that both generates data lines for the fast scan images and oversamples a common data point ( ). A peak intensity of the oversampled common point ( ) indicates that the bolus of contrast agent ( ) has arrived. A sequence controller ( ) initiates a diagnostic imaging sequence ( ). The operator views the fast scan image and has the option to abort the diagnostic sequence ( ) if the fast scan image does not verify that the contrast agent has arrived in the region of interest. The system continues to taking fast scan images until the arrival of the bolus of contrast agent has been verified.

Focused point oversampling for temporally and spatially resolving dynamic studies

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 method (100) of automatically tuning a radio frequency transmitter (24) and receiver (38) in a magnetic resonance imaging apparatus to an optimum frequency includes generating and acquiring (104) a magnetic resonance signal. The magnetic resonance signal is transformed to the frequency domain and spectral magnitude of the signal is computed (106). A center of gravity interpolation is performed (110) on the spectral magnitude to obtain a desired frequency sampling. A model function is generated based upon a strength of a main magnetic field which has peaks separated by the same separation as that for fat and water signals. The spectral magnitude is correlated (112) with the model function and a peak having the greatest magnitude is located therefrom. The location of a species peak along the spectral magnitude is estimated (114) from empirically derived information, the strength of the main magnetic field and the location of the correlation peak. A region of the spectral magnitude to be examined is defined (116) from empirically derived information, and a peak within this region is located (118) which is nearest the estimated location. Ultimately, the frequency of the radio frequency transmitter and receiver is set (122) to align with the peak located within the region that is nearest the estimated location.

Automatic frequency tuning for MR scanners

A subject's respiratory cycle is monitored (70) and analyzed (74) to determine a probability table (76). The probability table is continuously updated to provide a dynamic indication of the center between most stationary and most moving halves or other characteristic points within the respiratory cycle. At the beginning of each repeat time (TR), as resonance is excited (40), the output of the respiratory monitor is checked (80) and a determination is made (82) whether the patient is currently in the most stationary half or the most moving half of the respiratory cycle. Data lines generated in one half of the respiratory cycle are phase-encoded (84, 88) to generate a data line in each of a plurality of segments of k-space on one side of the central, zero phase-encoding point. Echoes occurring during the other half of the respiratory cycle are phase-encoded to generate data lines in segments of k-space on an opposite side of the central phase-encode angle. This process is repeated until a complete data set is generated with data lines generated during the stationary half of the respiratory cycle on one side of k-space and data lines generated during the half of the respiratory cycle with more motion on the other side. These data lines are then reconstructed into an image representation.

Growing community of inventors

Independence, OH, United States of America

James A Halamek