Systems and methods for magnetic resonance angiography
Inventors
Tan, Ek Tsoon • Foo, Thomas Kwok-Fah • Ho, Vincent B.
Assignees
General Electric Co • Uniformed Services University of Health Sciences
Publication Number
US-9014781-B2
Publication Date
2015-04-21
Expiration Date
2032-04-19
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Abstract
Systems and methods for Magnetic Resonance Angiography (MRI) are provided. One method includes obtaining Magnetic Resonance (MR) velocity data and determining a distance map for one or more vessels to define a distance path. The method also includes calculating, using the MR velocity data, at a plurality of time intervals and for a plurality of pixels (i) a distance traveled during a current time interval as a current distance traveled, wherein a total distance traveled is incremented by the current distance traveled and (ii) a bolus signal using a bolus signal profile, the distance path and total distance traveled, wherein a current time interval is incremented by a defined time step.
Core Innovation
The invention provides systems and methods for Magnetic Resonance Angiography (MRA) that use Magnetic Resonance (MR) velocity data to generate dynamic virtual bolus images of vasculature without the use of exogenous contrast agents. The method involves obtaining MR velocity data, determining a distance map for one or more vessels to define a distance path, and calculating at multiple time intervals and for multiple pixels the distance traveled during a current time interval and a bolus signal using a bolus signal profile, the distance path, and total distance traveled. This process is iterated until the bolus signal stabilizes, allowing for imaging that depicts the filling of vessels as a function of time.
The problem being solved addresses limitations of conventional contrast-enhanced MRA (CE-MRA) and phase-contrast MRA (PC-MRA). CE-MRA involves injected contrast agents whose timing is critical, and whose use poses risks for patients with renal impairment. PC-MRA provides only aggregate blood flow velocity information averaged for a single cardiac cycle and is limited by imaging field-of-view. The invention overcomes these issues by enabling high temporal resolution MRA without injected contrast, visualizing the passage of a "virtual" bolus with temporal resolution orders of magnitude greater than CE-MRA, thereby allowing visualization of blood flow pulsatility and providing additional diagnostic information.
Claims Coverage
The patent includes three independent claims directed to a computer readable storage medium, a method, and an MRI system, each incorporating inventive features related to virtual bolus MRA using MR velocity data and distance mapping.
Non-transitory computer readable storage medium for virtual bolus MRA
Includes instructions to obtain MR velocity data, determine a distance map defining a distance path for vessels, calculate at multiple time intervals and pixels the distance traveled and a bolus signal using a bolus signal profile, and display a sequence of images depicting vessel filling over time based on the bolus signal.
Method for Magnetic Resonance Angiography using dynamic virtual bolus
Comprises obtaining MR velocity data, determining a distance map for vessels, integrating on a pixel-by-pixel basis the distance traveled of a dynamic virtual bolus using the MR velocity data over multiple fields-of-view, translating the integrated distance to a bolus signal using a bolus model, and displaying vessel filling as a function of time based on this bolus signal.
MRI system with dynamic virtual bolus MRA module
Includes an imaging portion configured to acquire MR velocity data and a processing portion with a dynamic virtual bolus MRA module configured to determine a distance map for vessels and calculate, over time intervals and pixels, the distance traveled and bolus signal using a bolus signal profile and distance path, incrementing time by defined steps.
The claims collectively cover the inventive integration of MR velocity data and vessel distance mapping to generate dynamic virtual bolus signals, enabling high temporal resolution visualization of blood flow through vessels without contrast agents, applicable as computer instructions, methods, and within MRI systems.
Stated Advantages
Enables Magnetic Resonance Angiography without the need for injected contrast agents, avoiding associated risks and contraindications.
Provides higher temporal resolution imaging than conventional contrast-enhanced MRA, allowing visualization of blood flow pulsatility.
Allows visualization of vessel pulsatility and dynamic blood flow information analogous to real-time contrast bolus passage without ionizing radiation or invasive procedures.
Extends dynamic virtual bolus imaging beyond a single cardiac cycle, producing a continuous time series reflecting blood flow.
Removes time restrictions related to contrast agent transit, enabling acquisition of higher spatial resolution images or improved signal-to-noise ratio.
Documented Applications
Imaging of arteries and veins in various body regions including head and neck arteries, thoracic or abdominal aorta, renal arteries, and peripheral arteries to depict vascular anatomy and blood flow function.
Visualization of arterial and venous blood flow using virtual contrast bolus tracking for diagnostic assessment, including detecting arterial disease via pulsatility.
Use as an alternative or complement to contrast-enhanced imaging, including after administration of contrast agent for other purposes, benefiting signal-to-noise ratio without requiring additional contrast bolus.
Visualization applicable across multiple imaging fields-of-view and suitable for peripheral artery pulsatile angiography and run-off studies.
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