Methemoglobin MRI Contrast for Leak-Free Vascular Imaging
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Solution Overview
Problem
Existing MRI contrast agents like gadolinium suffer from leakage across vascular walls, slow dissipation, allergic reactions, and unclear long-term effects, while devices like Minimax Plus Oxygeneration Systems require large blood volumes, making them impractical for small aliquots.
Innovation Solution
Using nitric oxide or sodium nitrite to convert hemoglobin to methemoglobin in a patient's blood, either in vitro or in vivo, to create a safe and effective MRI contrast agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gadolinium is used as an MRI contrast agent, then image contrast is improved, but vascular leakage occurs limiting proper vascular imaging
Solution Approach 1:
The invention changes the chemical composition parameter of the contrast agent from gadolinium-based compounds to methemoglobin-based compounds. Methemoglobin provides similar or enhanced MRI contrast while maintaining vascular wall integrity, as it is naturally contained within red blood cells and does not leak across vascular walls.
Solution Approach 2:
The invention uses the patient's own blood (autologous blood) as the source of hemoglobin, which is then converted to methemoglobin. This eliminates the need for expensive, potentially toxic gadolinium compounds while using a biocompatible, naturally occurring substance that is rapidly cleared from the body.
2Measurement precision
If gadolinium is used as an MRI contrast agent, then image contrast is improved, but dissipation is slow causing problems with serial scans
Solution Approach 1:
The invention changes the metabolic clearance parameter by using methemoglobin, which is naturally processed by the body's reticuloendothelial system. Methemoglobin is rapidly reduced back to hemoglobin and cleared from the body, enabling serial scans within hours rather than days, while maintaining excellent contrast during the imaging window.
3Measurement precision
If gadolinium is used as an MRI contrast agent, then image contrast is improved, but allergic reactions occur in some individuals
Solution Approach 1:
The invention uses the patient's own blood as the contrast agent source, eliminating exposure to exogenous gadolinium compounds that can cause allergic reactions. The autologous methemoglobin is biocompatible and eliminates the risk of hypersensitivity reactions while providing sufficient contrast for imaging.
Solution Approach 2:
The invention employs the patient's own hemoglobin molecules, converted to methemoglobin, as the contrast agent. This self-service approach uses the body's natural substances rather than external contrast agents, eliminating allergic reactions while maintaining imaging effectiveness.
4Measurement precision
If Minimax Plus Oxygeneration Systems are used to diffuse gas into blood, then contrast agent is produced, but large amounts of blood are required making small aliquots impracticable
Solution Approach 1:
The invention applies local treatment by introducing nitric oxide or sodium nitrite directly into a small aliquot of blood sample to convert hemoglobin to methemoglobin. This localized conversion allows sufficient contrast agent production from minimal blood volumes (microliters to milliliters) rather than requiring large blood volumes processed through entire-blood oxygenation systems.
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
Methemoglobin provides enhanced image contrast without vascular leakage, rapid dissipation, and reduces the risk of adverse reactions, enabling accurate imaging of vascular systems and other regions with minimal blood volume.
Implementation Method 1
Blood is exposed to a formation agent, such as nitric oxide with a gas-permeable membrane filter, or direct exposure to sodium nitrite, to produce blood that has a higher concentration of methemoglobin
Implementation Method 2
Blood is exposed to a formation agent, such as nitric oxide with a gas-permeable membrane filter
Data Source
AI summary
The present invention relates to the use of a formation agent, such as nitric oxide or sodium nitrite to produce methemoglobin as an alternative MRI contrast agent. The formation agent can be infused using either a respiratory system or a delivery mechanism. One embodiment of this invention relates to systems and methods for producing an image of an internal region with a magnetic resonance scanning system. Blood is drawn from the patient. The blood is exposed to formation agent through a delivery system, to produce blood that has a higher saturation of methemoglobin. Where in vitro techniques are used the treated blood is injected back into the patient. The patient is scanned in the magnetic resonance scanner. These systems and methods can be used to produce images of regions which may not otherwise be possible with other contrasting agents. For example, an accurate vascular brain MRI may not be as informative if the patient is injected with an existing contrasting agent. In addition, an alternate embodiment of the invention relates to internally exposing the blood to the formation agent by placing the gas-permeable membrane along a particular blood pathway or intravenous sodium nitrite.