MRI Phantoms portfolio

P150322: Improved Phantom for Quantitative Diffusion MRI

Overview: Among numerous magnetic resonance imaging contrast mechanisms, the insights that diffusion-weighted MRI provides into microstructural tissue changes make it an excellent biomarker for detection and evaluation of necrosis, infection, fibrosis and cancer. Yet to realize its true diagnostic potential it is vital to develop quantitative diffusion MRI (q-dMRI) techniques that enable accurate, robust and reproducible measurements of diffusivity (or apparent diffusion coefficient, ADC). This would create tremendous opportunities in tumor characterization and treatment monitoring.

For q-dMRI to become a valid biomarker, validation of its accuracy and reproducibility is critical. Existing and proposed phantoms do not meet all desired criteria. Still needed are phantoms that exhibit desirable MR spectra, diffusion decay profiles and ADC values spanning the entire range of biological tissues under various physiological conditions and environments.

Invention Summary: UW-Madison researchers have developed a q-dMRI phantom with advantageous properties, including single-peak MR spectrum and Gaussian diffusion propagation. By varying the combined concentration of solvent (e.g., acetone) and solute (e.g., deuterium oxide or diacetyl), the diffusivity of the solution can be controlled to fall within a range of values found in a variety of biological tissues in different physiological conditions and environments.

Under temperature-controlled conditions (for example, submerging the phantom in an ice-water bath) the phantom can reproducibly exhibit ADC values that cover the entire physiological range. Furthermore, different types of paramagnetic salts may be added into the mixture to control T1 and T2 relaxation of the phantom.

Applications:

• Controlled testing and quality assurance of q-dMRI techniques
• Quantitative diffusion imaging protocols are most commonly used for treatment monitoring and staging of metastatic cancer.

Key Benefits:

• Exhibits single-peak MR spectrum
• Gaussian diffusion propagation
• Can reproducibly exhibit ADC values across wide physiological range

P150328: Improved Phantom for Iron and Fat Quantification MRI

Overview: The ability to quantify fat concentration in the body has become increasingly important given the rise in obesity and related comorbidities. Likewise, the ability to quantify iron concentration is important for monitoring patients receiving treatment for hemochromatosis (an iron overload disorder) as well as routine blood transfusions (i.e., hemosiderosis).

Since fat and iron often coexist in organs such as the liver, pancreas and bone marrow, MRI-based quantification techniques have developed rapidly over the past decade to meet this challenge. Validating these techniques using MR phantoms is a critical prerequisite to their widespread clinical translation. However, current phantom designs for fat and iron do not accurately replicate the signal behavior observed in vivo and therefore are not reliable.

Invention Summary: UW-Madison researchers have designed a phantom that accurately reflects in vivo MRI signal behavior in the presence of both fat and iron. The key innovation is that the new phantom is constructed using a lipid emulsion substrate with superparamagnetic iron oxide (SPIO) particles that are proportionately larger than the fat particles, such that the field from those particles encompasses the entirety of the fat signals.

Applications:

• Quality assurance/calibration phantom for MR systems, specifically for fat-iron quantification imaging protocols

Key Benefits:

• More accurate and reliable
• Constructed with commercially available materials
• Designed to achieve a wide range of fat and iron concentrations

Stage of Development: Initial experiments have demonstrated that the larger microspheres result in single R*2 signal decay behavior that closely mimics that of water and fat in vivo.

Included IP

• P150322US01 (PAT)
• P150328US01 (PAT)