Hospitals around the world are competing to purchase the most advanced Magnetic Resonance Imaging (MRI) scanners – to provide the most effective detection, diagnosis, and treatment monitoring for their patients. The medical centers also like to boast that their MRIs are the best – as a marketing tool.
The scanners, which cost millions of dollars apiece and are of vital importance in diagnostic medicine, provide non-invasive imaging that produces detailed, 3-D anatomical images.
MRIs use powerful magnets that produce a strong magnetic field to force protons in the body to align with that field. When a radiofrequency current is then pulsed through the patient, the protons are stimulated and spin out of equilibrium, straining against the pull of the magnetic field.
When the radiofrequency field is turned off, the MRI sensors can detect the energy released as the protons realign with the magnetic field. The time it takes for the protons to realign with the magnetic field, as well as the amount of energy released, changes depending on the environment and the chemical nature of the molecules. Doctors are able to tell the difference among various types of tissues based on these magnetic properties.
The patient lies inside a large, tube-shaped magnet and remains very still during the imaging process so as not to blur the image. Contrast agents may be injected before or during the MRI to increase the speed at which protons realign with the magnetic field. The faster the protons realign, the brighter the image.
MRI scanners
MRI scanners are particularly well suited to image soft tissues of the body. They differ from computed tomography (CT) scans since they do not use the damaging ionizing radiation of X rays. They can differentiate between white matter and gray matter and can also be used to diagnose aneurysms and tumors.
Because MRI does not use X rays or other radiation, it is the imaging device of choice when frequent imaging is required for diagnosis or therapy, especially in the central nervous system; tendons, ligaments, and muscles are seen much more clearly with MRI than with regular X rays and CT scanners. An MRI is often used to scan knee and shoulder injuries.
One of the limitations of conventional MRI devices, however, is that they have trouble detecting metabolites, which have a very low concentration in tissues. Metabolites are small molecules involved in chemical process in the body, many of which serve as clinical markers indicating various health conditions, including malignant tumors, abnormal cell division, cell death, and cellular stress. This induced many research groups to try to find a solution allowing the identification of metabolites in non-invasive imaging scans.
NEW MATERIALS developed by researchers at the Technion-Israel Institute of Technology in Haifa are expected to lead to significant improvements in the quality of MRI scans and expand their usage.
Chemistry Prof. Aharon Blank and his colleague Dr. Itai Katz have just published their findings in the prestigious journal Science Advances under the title “Long-lived enhanced magnetization – A practical metabolic MRI contrast material.” Their work is expected to allow and improve the early diagnosis of various diseases and reduce the need for radiation-intensive tests
The research, supported by the Technion Human Health Initiative (THHI) and the European Research Council (ERC), included contributions from Prof. Boaz Pokroy and Dr. Arad Lang from the Technion’s Faculty of Materials Science and Engineering, who worked on preparing some of the unique nature-inspired materials, and Dr. Benno Meier from Germany’s Karlsruhe Institute of Technology.
Traditionally, the brief enhanced magnetization period of conventional agents limited clinical imaging. Instead, the researchers combined two materials, one having diagnostic-metabolic activity and the other characterized by robust magnetization retention. This combination slows the magnetization decay in the diagnostic metabolic probe that receives continuously replenished magnetization from the companion material.
The team members’ new technique for identifying metabolites in MRI is called MMV (multiple measurement vector). It’s based on a new composition of metabolites characterized by two significant advantages in this context: a dramatic enhancement by about four orders of magnitude of the magnetic resonance signal and the preservation of signal strength for a relatively long time compared to existing metabolites – about 10 minutes instead of just one minute.
The practical implication of the findings is that the new materials will allow tracking metabolites in various tissues over time. Thanks to these new qualities given to MRI scans, such tests could, in certain cases, replace expensive and radiation-intensive tests like PET-CT.
“Our discovery is very exciting for us, as the new method will provide physicians with a broader time window to perform the scan,” Blank said.
“We estimate it will expand the use of radiation-free MRI scans. These materials will improve the capabilities of medical and research teams in early disease diagnosis, tissue characterization, disease progression monitoring, surgery planning, optimal treatment selection, and informed decision-making.”