Phantom for diffusion MRI imaging
Inventors
Horkay, Ferenc • Pierpaoli, Carlo • Basser, Peter J.
Assignees
US Department of Health and Human Services
Publication Number
US-10078124-B2
Publication Date
2018-09-18
Expiration Date
2030-01-26
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Abstract
A phantom calibration body (12) for calibrating diffusion MRI device (16) that mimics a material such as a mammalian tissue is disclosed. The phantom calibration body (12) includes a homogeneous aqueous solution (30) that contains a mixture of low molecular-weight and high molecular-weight polymers housed in a container (14) that is placed in the diffusion MRI device (16) for obtaining one or more diffusion MRI images of the phantom calibration body (12). A measure of diffusivity is calculated for each of the one or more diffusion MRI images in order to calibrate the diffusion MRI device. Methods of using the phantom calibration body (12) to calibrate diffusion MRI device (16) are also disclosed.
Core Innovation
The invention provides a phantom calibration body for calibrating diffusion MRI devices that mimics materials such as mammalian tissue. The phantom calibration body includes a homogeneous aqueous solution containing a mixture of low molecular-weight and high molecular-weight polymers housed in a container, designed to have a diffusivity and viscosity that essentially match those of the target material. The diffusivity is controlled by the combined concentration of the polymers, while the viscosity is adjusted by the mixing ratio of the high to low molecular-weight polymers to minimize vibrations and convection artifacts during imaging.
The phantom calibration body solves problems present in prior art calibration bodies that were unstable, flammable, toxic, non-transportable, vibration-sensitive, or anisotropic in diffusion characteristics. Existing calibration bodies also failed to sufficiently mimic tissue diffusivity due to ineffective additives. The invention addresses these shortcomings by providing a stable, non-toxic, non-flammable, homogenous, and isotropic diffusion phantom with controllable diffusivity and viscosity parameters suitable for precise, accurate, and repeatable calibration of diffusion MRI devices.
Claims Coverage
The patent contains independent claims directed to a system and methods for diffusion MRI calibration using a phantom calibration body with specified polymer composition and physical properties. Three independent claims outline the system and methods related to generating diffusion imaging data and calculating diffusivity measurements for calibration purposes.
Phantom calibration body with polymer mixture for diffusion MRI system
A system comprising a phantom calibration body made of a homogeneous aqueous solution of polyvinyl pyrrolidone having a molecular weight distribution mean of 5 to 1000 kDa. The solution has diffusivity essentially the same as target mammalian tissue and viscosity ranging from about 102 cSt to 106 cSt. The system includes a diffusion MRI device configured to scan the phantom and store diffusion imaging data on one or more processors.
Method of diffusion MRI using the phantom calibration body
Providing the system with the phantom calibration body, placing the phantom in the diffusion MRI device, obtaining diffusion imaging data by scanning, and calculating a diffusivity measurement indicative of water diffusivity of the solution. The calculation is provided back to the MRI device by at least one processor for calibration. This method includes performing the calibration as part of routine maintenance, troubleshooting, quality assurance/control, or prototype assessment.
Method of diffusion MRI calibration with polymer phantom
Providing a phantom calibration body composed of a homogeneous aqueous solution of polyvinyl pyrrolidone with a molecular weight distribution mean of 5 to 1000 kDa, having tissue-mimicking diffusivity and viscosity between about 102 and 106 cSt; placing it in the diffusion MRI device; obtaining diffusion imaging data stored on processors; and calculating diffusivity measurements provided back to the MRI device for calibration, including routine maintenance and quality control uses.
The independent claims focus on the creation and use of a polymer-based homogeneous aqueous solution phantom with specific molecular weight distribution and physical properties to mimic target tissue diffusivity, enabling accurate calibration of diffusion MRI devices through imaging data acquisition and diffusivity calculation.
Stated Advantages
The phantom is stable, non-flammable, non-toxic, transportable, and vibration dampening with isotropic diffusion properties.
It provides precisely controllable and reproducible water diffusivity matching that of biological tissues for accurate MRI calibration.
The solution viscosity minimizes convection and vibration artifacts improving measurement accuracy.
The phantom can be used for routine maintenance, quality assurance/control, troubleshooting, and prototype performance assessment of diffusion MRI devices.
The phantom also serves as a resolution phantom due to known container dimensions, allowing calibration of spatial image resolution and distortion.
Documented Applications
Routine maintenance of institutional diffusion MRI devices by technicians or equipment vendors.
Quality assurance and quality control during manufacturing, shipment, installation, repair, and periodic recalibration of diffusion MRI devices.
Performance assessment and design refinement during manufacturing or development of prototype diffusion MRI devices.
Calibration of diffusion MRI image spatial resolution and distortion using dimensional comparisons of known container geometry.
Calibration and validation of diffusion tensor MRI and higher order diffusion MRI methods, including diffusion tensor imaging (DTI), diffusion spectrum imaging (DSI), Q-ball imaging, composite hindered and restricted model of diffusion (CHARMED), AxCaliber, SHORE, and pulsed-field gradient methods.
Calibration of combined diffusion MRI and image resolution quality assurance processes in radiological departments and longitudinal or multi-subject studies.
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