Dynamic Virtual Bolus MRA for Renal-Safe Angiography
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Solution Overview
Problem
Current Magnetic Resonance Angiography (MRA) methods, such as contrast-enhanced MRA, face challenges with timing issues affecting image quality and the use of exogenous contrast agents, which can be contraindicated for patients with renal impairments, while phase-contrast MRA has limited image field-of-view and provides averaged blood flow velocity information.
Innovation Solution
The implementation of Dynamic Virtual Bolus MRA (DVB-MRA) that uses Magnetic Resonance (MR) velocity data to calculate distance traveled and translate it into a bolus signal without injected contrast agents, achieving higher temporal resolution and visualizing pulsatility of blood flow, similar to X-ray contrast angiography, without ionizing radiation or invasive methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contrast enhanced MRA is used to image blood vessels, then image quality can be improved, but timing problems occur and exogenous contrast agents pose risks to patients with renal impairments
Solution Approach 1:
The patent removes the harmful exogenous contrast agent from the MRA process entirely. Instead of using external contrast media, the system employs phase-contrast MRI techniques to encode blood flow velocity information directly in the phase component of MR signals, thereby achieving vessel imaging without substances that could harm renal-impaired patients
Solution Approach 2:
The patent replaces the chemical/physical mechanism of exogenous contrast agents with a magnetic resonance-based velocity encoding mechanism. By using phase-contrast MRI, the system substitutes the need for contrast media with a field-based measurement approach that detects blood flow through phase shifts in MR signals
2Loss of information
If phase-contrast MRA is used to encode blood flow velocity, then velocity information can be obtained, but the image field-of-view is limited and only aggregate information for a single cardiac cycle is provided
Solution Approach 1:
The patent extends the measurement from a single cardiac cycle to continuous monitoring across multiple cardiac cycles. By accumulating phase information over time and integrating velocity data continuously, the system provides ongoing blood flow velocity information rather than isolated snapshots, thereby expanding the effective temporal field-of-view
Solution Approach 2:
The patent adds the time dimension to the spatial field-of-view by implementing multi-cardiac cycle acquisition. Through temporal integration of velocity data and multi-dimensional phase analysis, the system expands the effective imaging volume beyond single-cycle limitations while maintaining velocity encoding capability
3Loss of information
If phase-contrast MRA is triggered using ECG signals to provide aggregate blood flow velocity information, then velocity data can be obtained, but the temporal resolution is insufficient for detailed pulsatility analysis
Solution Approach 1:
The patent segments the blood flow velocity measurement into multiple time points within each cardiac cycle by acquiring phase-contrast data at different temporal phases. This segmentation allows detailed analysis of pulsatility patterns throughout the cardiac cycle rather than providing only aggregate information
Solution Approach 2:
The patent implements periodic acquisition of phase-contrast velocity data synchronized with the cardiac cycle, capturing velocity information at multiple regular intervals throughout each heartbeat. This periodic sampling enables detailed temporal analysis of blood flow pulsatility while maintaining synchronization with cardiac physiology
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
DVB-MRA provides higher temporal resolution, enabling visualization of vessel pulsatility and diagnostic information without exogenous contrast media, allowing for detailed imaging of vasculature with improved image quality and reduced risk for patients with renal impairments.
Implementation Method 1
Magnetic Resonance Angiography (MRA) uses Magnetic Resonance Imaging (MRI) to image blood vessels
Implementation Method 2
Phase-contrast MRA (PC-MRA) is also known and used to encode the velocity of moving blood (of both arteries and veins) in the phase component of the MR signals
Data Source
AI summary
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.