Magnetic resonance imaging apparatus and magnetic resonance imaging method
Inventors
Miyazaki, Mitsue • Chung, Christine
Assignees
Canon Medical Systems Corp • Office of General Counsel of VA • University of California San Diego UCSD
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Publication Number
US-12007458-B2
Publication Date
2024-06-11
Expiration Date
2039-07-08
Abstract
A magnetic resonance imaging apparatus according to an embodiment includes sequence controlling circuitry and processing circuitry. The sequence controlling circuitry acquires a first piece of data by executing a first pulse sequence having a first Echo Time (TE) value, to acquire a second piece of data by executing a second pulse sequence having a second TE value different from the first TE value, and to acquire a third piece of data by executing a third pulse sequence having a third TE value different from the first and the second TE values. The processing circuitry extracts a signal related to water, a signal related to a first fat, and a signal related to a second fat, on the basis of the first piece of data, the second piece of data, and the third piece of data.
Core Innovation
The invention relates to a magnetic resonance imaging apparatus and method that enables the extraction of signals related to water and multiple types of fat from acquired magnetic resonance data. The apparatus includes sequence controlling circuitry configured to acquire three distinct pieces of data by executing three pulse sequences each having different Echo Time (TE) values and a processing circuitry that extracts signals related to water, a first fat, and a second fat based on these data and the chemical shift values of the substances.
The problem addressed is the limitation in existing magnetic resonance imaging methods which typically assume one type of fat for signal extraction and often use single-voxel Magnetic Resonance Spectroscopy (MRS) that lacks spatial resolution. Known methods like the IDEAL method do not account for multiple fat types, such as olefinic fat, and may fail when water signals are absent in a pixel. Therefore, the invention aims to enable the quantification and rendering of signals from multiple fat types and water in two- or three-dimensional images by acquiring data at multiple TE values and appropriately processing the signals.
Claims Coverage
The patent contains multiple independent claims focusing on a magnetic resonance imaging apparatus and method that use three pulse sequences with different TE values and center frequency adjustments to separate signals of water and multiple fats.
Use of three distinct pulse sequences with specially selected TE values
The apparatus and method acquire data using three pulse sequences having mutually different TE values, where the second pulse sequence causes signals of protons of two fats to have phases opposite to each other and the first causes them to be in-phase.
Setting center frequency to correspond to chemical shift of a fat
The pulse sequences are executed such that the center frequency is equal to a frequency corresponding to the chemical shift of a fat, enabling separation of fat signals even in tissues without water.
Processing circuitry calculation based on chemical shifts
Processing extracts signals related to water, first fat, and second fat using the acquired data and known values of chemical shifts of water and the fat types, calculating coefficients related to signal phases based on differences in chemical shifts.
Execution of linked pulse sequences with uniform receiver gain
The three pulse sequences are executed as a linked acquisition while maintaining the same receiver gain level, ensuring comparability of the acquired data.
User input affects pulse sequence settings
Processing circuitry receives user inputs about types of fats and water to be visualized, establishes the settings of pulse sequences accordingly, and controls execution of those sequences.
The claims focus on a magnetic resonance imaging apparatus and method that utilize three pulse sequences with different TE values and set the center frequency to a fat chemical shift to separately extract signals of water and multiple fat types from MR data, with calculations based on chemical shifts, execution of linked sequences with consistent gain, and user-configurable settings.
Stated Advantages
Enables quantification of signals from multiple types of fat, including saturated and unsaturated fats, in two- or three-dimensional images instead of single-voxel MRS.
Allows effective signal extraction in tissues with low or no water content by setting the center frequency to fat rather than water.
Improves the accuracy of fat signal rendering by considering different types of fat separately, overcoming limitations of conventional methods like IDEAL.
Maintains receiver gain at the same level across acquisitions to allow proper comparison of datasets.
Documented Applications
Quantification and imaging of saturated and unsaturated fats such as aliphatic, olefinic, monounsaturated, and polyunsaturated fats in biological tissues like liver, bones, and fat tissues.
Rendering two-dimensional or three-dimensional images that separate water and multiple fat types for enhanced magnetic resonance imaging diagnostics.
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