3/29/2023 0 Comments Small buildings for coppercube 5![]() ![]() Using liquid nitrogen (N 2) would simplify by far the cryogenics requirements, but would limit the relaxation time to few tens of minutes 14, 21. The latter would compromise the possibility to employ a permanent magnet with the required magnetic field value and homogeneity to obtain a sufficiently long relaxation time of the HP sample and investigate its state with NMR, respectively. Nevertheless, these Dewars are usually of large dimensions (60–100 L), they require special transportation, and have limited access to the He vessel from the top. One could use a liquid He Dewar supplied by the local cryogenics’ provider and equip it with a permanent magnet 18. These two promising techniques are fundamentally different, but they share a common feature: after extraction from the polarizer, liquid helium (He) temperature and a magnetic field in the tesla range are required to store and transport a HP solid sample at conditions that guarantee a hours long relaxation time of the carbon nuclei 21, 22. ![]() To physically separate carbon nuclei from the polarizing agents by playing with radicals and 13C-labelled molecules with different solubility, or by grafting the radicals inside purpose synthesized porous polymers that can absorb a solution containing the substrate of interest 18– 20. So far, two approaches have been pursued: Making hyperpolarization transportable entails, at the moment of extraction of the HP sample from the dDNP polarizer, the drastic reduction or elimination of the nuclear spins relaxation due to the same paramagnetic polarizing agents used, in the first place, to create the hyperpolarized state upon microwave irradiation 11, 12. Lifting this restriction, making hyperpolarization transportable and disconnecting the production site of the HP molecules from the site of use, would represent a significant step forward. Currently, should you be willing to equip an MRI facility with hyperpolarization, the only way is to place on site costly and technically demanding hardware (i.e. A main drawback is that differently from PET, the current benchmark to investigate hypo and hyper metabolism in the clinic 9, HP molecules prepared employing traditional polarizing agents cannot be transported far away from the production site without losing their high spin order and thus their increased NMR sensitivity 10. One of the reasons why broad consensus among clinicians is still missing lies in the technical complexity that characterize hyperpolarization via dDNP 6– 8. Nevertheless, the methodology struggles to enter everyday clinical practice. Its unmatched capability to investigate cellular metabolism in real time, by injecting hyperpolarized (HP) 13C-labelled molecules, has the potential to revolutionize diagnostic radiology enabling precision medicine and personalized healthcare 2– 5. ![]() Invented in 2003, dissolution Dynamic Nuclear Polarization (dDNP) 1 is undoubtedly the most versatile among the hyperpolarization techniques to increase NMR sensitivity in the liquid state. Should transportable hyperpolarization via DNP become a reality, we herein provide important details to make it possible. In this paper, we detail the theoretical and practical construction of a hyperpolarized samples transportation device small enough to fit in a car and able to hold a sample at 4.2 K for almost 8 h despite the presence of a cryogenically-demanding purpose-built probe that provides enough magnetic field upon insertion of the sample and NMR quality homogeneity at storage position. To bridge the technical gap with PET and provide MRI facilities with hours long relaxing hyperpolarized compounds at controlled conditions, a new generation of low cost/small footprint liquid He cryostats equipped with a magnetically enforced cryogenic probe is needed. The main reason for that is the lack of adequate hardware, strategy, and control on most of the crucial parameters. Nevertheless, so far, all attempts of transport have been limited to a very small scale and to the level of proof-of-principle experiments. Two different methods have been developed that allow “freezing” of the nuclear spin state prior to samples extraction from the polarizer. Since some years, research groups are working to make hyperpolarization transportable. Because of the minute-long hyperpolarization lifetime after dissolution, one of the reasons lies in the need and consequent complexities of having the machine that generates the hyperpolarization (i.e. Despite the clear path towards personalized medicine that dDNP is paving as an alternative and/or complement to Positron Emission Tomography (PET), the technique struggles to enter everyday clinical practice. As of today, dissolution Dynamic Nuclear Polarization (dDNP) is the only clinically available hyperpolarization technique for 13C-MRI. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |