CSF Velocity Imaging via Repeated EPI and Variance Analysis
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Solution Overview
Problem
Conventional magnetic resonance imaging methods, such as the phase shift method, struggle to faithfully image non-cyclical velocity variations of body fluids like cerebrospinal fluid (CSF) due to low correlation with electrocardiogram gating, resulting in average velocity images that are insufficient for dynamic observations and often produce ghost artifacts.
Innovation Solution
An image processing apparatus and method that creates calculation images with velocity components of CSF using repeated imaging, calculates statistics on these images to determine velocity variations, and displays the distribution of these statistics, allowing for accurate visualization of velocity variations without relying on cyclical correlations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the phase shift method is used to observe CSF dynamics, then velocity information can be obtained, but the velocity variations are averaged over long time periods and ghost artifacts appear due to low correlation with electrocardiogram gating
Solution Approach 1:
The patent segments the velocity measurement process by acquiring multiple independent velocity images at different time points rather than averaging over a long continuous period. This allows capturing instantaneous velocity variations while maintaining temporal resolution, preventing the averaging effect that blurs dynamic CSF flow patterns.
Solution Approach 2:
The patent employs periodic imaging acquisition at multiple discrete time points to capture CSF velocity variations. By repeating the imaging process periodically and analyzing velocity changes across these time points, the method captures non-cyclical velocity variations without requiring correlation to the electrocardiogram cycle, thereby eliminating ghost artifacts while preserving measurement accuracy.
2Measurement precision
If echo signals are collected for 128 to 256 R waves to reconstruct one image, then velocity distribution can be obtained, but the observation time becomes too long (2-4 minutes) and velocity fluctuations during collection become large
Solution Approach 1:
The patent applies partial action by acquiring velocity data from fewer R waves (less than 128-256) to reconstruct each velocity image. By using a reduced number of cardiac cycles for each velocity measurement, the observation time is shortened while still obtaining sufficient signal quality. Multiple such partial measurements are then combined to capture velocity variations over time.
Solution Approach 2:
The patent transitions from a static long-duration average velocity measurement to a dynamic series of short-duration velocity measurements taken at multiple time points. This dynamic approach allows capturing velocity variations over time while keeping each individual measurement brief, thereby reducing temporal loss while maintaining measurement precision.
3Device complexity
If the phase shift method assumes strong correlation with electrocardiogram waveform, then image reconstruction is simplified, but it fails to capture non-cyclical velocity variations of CSF
Solution Approach 1:
The patent uses periodic imaging acquisition at multiple discrete time points to capture CSF velocity variations. By repeating the imaging process periodically and analyzing velocity changes across these time points, the method captures non-cyclical velocity variations without requiring correlation to the electrocardiogram cycle.
Solution Approach 2:
The patent changes the imaging parameter from continuous long-duration acquisition to multiple short-duration acquisitions at different time points. This parameter change allows capturing instantaneous velocity variations while maintaining simplified processing, as each individual measurement remains independent and can be processed using standard phase shift methods.
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
This approach enables faithful imaging of CSF velocity variations, providing detailed distribution and dynamics of CSF flow, even when velocity changes are not correlated with electrocardiogram gating, and improves image quality by avoiding average velocity limitations and ghost artifacts.
Implementation Method 1
a phase shift proportional to a velocity is given to an image by applying a flow-encode gradient magnetic field (Gfe) between an excitation pulse (P1 shown in FIG. 14) and an echo signal (P2 shown in FIG. 14)
Implementation Method 2
according to a phase shift method, a gradient echo method is used; and a phase shift proportional to a velocity is given to an image
Data Source
AI summary
A velocity-image creating unit creates a velocity image that indicates a distribution of velocity components with respect to each of a plurality of images obtained by repeating a plurality of number of times Echo Planar Imaging (EPI) that is capable of obtaining velocity components of a Cerebrospinal Fluid (CSF) flowing inside a subject. A velocity-variance image creating unit calculates variance of velocity components along the time sequence by same position on velocity images by using a plurality of created velocity images. A superimposed-image processing unit then superimposes the distribution of the variance of the velocity components according to the velocity-variance image on an average absolute-value image, and an image display unit displays a superimposed image.