Posts tagged medical imaging
Articles and news from the latest research reports.
A safer approach for diagnostic medical imaging
Medical imaging is at the forefront of diagnostics today, with imaging techniques like MRI (magnetic resonance imaging), CT (computerized tomography), scanning, and NMR (nuclear magnetic resonance) increasing steeply over the last two decades. However, persisting problems of image resolution and quality still limit these techniques because of the nature of living tissue. A solution is hyperpolarization, which involves injecting the patient with substances that can increase imaging quality by following the distribution and fate of specific molecules in the body but that can be harmful or potentially toxic to the patient. A team of scientists from EPFL, CNRS, ENS and CPE Lyon and ETH Zürich has developed a new generation of hyperpolarization agents that can be used to dramatically enhance the signal intensity of imaged body tissues without presenting any danger to the patient. Their work is published in PNAS.
The team of scientists coordinated by Lyndon Emsley – who is currently Professor at EPFL and ENS Lyon – has developed a new generation of hyperpolarizing agents that are both effective and safe for the patient. The substances, called HYPSOs, were developed by the teams of Christophe Copéret at ETH Zurich and Chloé Thieuleux at CPE-Lyon. The HYPSOs come in the form of a fine, white, porous powder that contains the “tracking” molecules to be hyperpolarized. The HYPSO powder is made up of mesoporous silica (silicon dioxide), which is the major component of sand and is commonly used in nanotechnology.
The silica powder used for the HYPSOs consists of particles, containing pore channels. It has been designed in such a way that the surface of each pore channel can be evenly covered with molecules known as ‘organic radicals’. The radicals are homogeneously distributed, and are able to induce polarization around them. “Controlling the radical distribution was a ‘tour de force’ never achieved in the past, which made the HYPSO materials ideal for this application,” says Christophe Copéret. The pore channels are then filled with a solution of the “tracking” molecules to be hyperpolarized, which act as markers for the imaging – e.g. pyruvate, which is important in the production of energy in cells.
Using novel instruments and methods developed by Sami Jannin at EPFL, the HYPSO sample is hyperpolarized with microwaves in a magnetic field at a very low temperature. The magnetic moments of the atoms are forced to align through a process called “dynamic nuclear polarization”, which transfers the spin energy of the free radicals’ electrons to the markers’ nuclei. The electronic spin magnetism of the hyperpolarizing agent acts on the marker molecule, aligning, or “polarizing”, the nuclei of its atoms.
Hot water is then used to melt and flush the substrate out of the powder. Because of the equipment and conditions needed, the process generally takes place in a room adjacent to the imaging facility. The substrate is then ready to be injected through a long tube into the patient inside the medical imaging device. The entire process only lasts about ten seconds.
Two scans are performed, one with and one without the hyperpolarized agent. When the two images are compared, it is possible to observe the distribution of the hyperpolarized marker in the patient’s body, which, depending on the medical context, can be indicative of disease. For example, accumulation of pyruvate in the prostate could be an early indication of prostate cancer.
The researchers have tested the efficiency of the HYPSOs method on several imaging markers, including pyruvate, acetate, fumarate, pure water, and a simple peptide. Because the HYPSOs is physically retained during dissolution, the technique yields pure solutions of hyperpolarized markers, free of any contaminant. The protocol is therefore simpler and potentially safer for the patient, while its dramatic efficiency on signal quality forecasts the use of this new generation of hyperpolarized agents with a broad range of molecules. As Sami Jannin points out: “We have now received queries of scientists from abroad who are eager to boost their research with this new technology. Amongst other plans, we are very excited about testing these materials in vivo”.
(Source: actu.epfl.ch)
Wireless signals could transform brain trauma diagnostics
New technology developed at the University of California, Berkeley, is using wireless signals to provide real-time, non-invasive diagnoses of brain swelling or bleeding.
The device analyzes data from low energy electromagnetic waves that are similar to those used to transmit radio and mobile signals. The technology, described in the May 14 issue of the journal PLOS ONE, could potentially become a cost-effective tool for medical diagnostics and to triage injuries in areas where access to medical care, especially medical imaging, is limited.
The researchers tested a prototype in a small-scale pilot study of healthy adults and brain trauma patients admitted to a military hospital for the Mexican Army. The results from the healthy participants were clearly distinguishable from the patients with brain damage, and data for bleeding was distinct from data for swelling.
Boris Rubinsky, Professor of the Graduate School at UC Berkeley’s Department of Mechanical Engineering, led the research team along with César A. González, a professor in Mexico at the Instituto Politécnico Nacional, Escuela Superior de Medicina (National Polytechnic Institute’s Superior School of Medicine).
“There are large populations in Mexico and the world that do not have adequate access to advanced medical imaging, either because it is too costly or the facilities are far away,” said González. “This technology is inexpensive, it can be used in economically disadvantaged parts of the world and in rural areas that lack industrial infrastructure, and it may substantially reduce the cost and change the paradigm of medical diagnostics. We have also shown that the technology could be combined with cell phones for remote diagnostics.”
Rubinsky noted that symptoms of serious head injuries and brain damage are not always immediately obvious, and for treatment, time is of the essence. For example, the administration of clot-busting medication for certain types of strokes must be given within three hours of the onset of symptoms.
“Some people might delay traveling to a hospital to get examined because it is an hour or more away, or because it is exceedingly expensive,” said Rubinsky. “If people had access to an affordable device that could indicate whether there is brain damage or not, they could then make an informed decision about making that trip to a facility to get prompt treatment, which is especially important for head injuries.”
The researchers took advantage of the characteristic changes in tissue composition and structure in brain injuries. For brain edemas, swelling results from an increase in fluid in the tissue. For brain hematomas, internal bleeding causes the buildup of blood in certain regions of the brain. Because fluid conducts electricity differently than brain tissue, it is possible to measure changes in electromagnetic properties. Computer algorithms interpret the changes to determine the likelihood of injury.
The study involved 46 healthy adults, ages 18 to 48, and eight patients with brain damage, ages 27 to 70.
The engineers fashioned two coils into a helmet-like device that was fitted over the heads of the study participants. One coil acted as a radio emitter and the other served as the receiver. Electromagnetic signals were broadcast through the brain from the emitter to the receiver.
“We have adjusted the coils so that if the brain works perfectly, we have a clean signal,” said Rubinsky. “Whenever there are interferences in the functioning of the brain, we detect them as changes in the received signal. We can tell from the changes, or ‘noises,’ what the brain injury is.”
Rubinsky noted that the waves are extremely weak, and are comparable to standing in a room with the radio or television turned on.
The device’s diagnoses for the brain trauma patients in the study matched the results obtained from conventional computerized tomography (CT) scans.
The tests also revealed some insights into the aging brain.
“With an increase in age, the average electromagnetic transmission signature of a normal human brain changes and approaches that of younger patients with a severe medical condition of hematoma in the brain,” said González. “This suggests the potential for the device to be used as an indication for the health of the brain in older patients in a similar way in which measurements of blood pressure, ECG, cholesterol or other health markers are used for diagnostic of human health conditions.”
New algorithm can analyze information from medical images to identify diseased areas of the brain and connections with other regions.
Disorders such as schizophrenia can originate in certain regions of the brain and then spread out to affect connected areas. Identifying these regions of the brain, and how they affect the other areas they communicate with, would allow drug companies to develop better treatments and could ultimately help doctors make a diagnosis. But interpreting the vast amounts of data produced by brain scans to identify these connecting regions has so far proved impossible.
Now, researchers in the Computer Science and Artificial Intelligence Laboratory at MIT have developed an algorithm that can analyze information from medical images to identify diseased areas of the brain and their connections with other regions.
The MIT researchers will present the work next month at the International Conference on Medical Image Computing and Computer Assisted Intervention in Nice, France.
An open platform revolutionizes biomedical-image processing
Ignacio Arganda, a young researcher from San Sebastián de los Reyes (Madrid) working for the Massachusetts Institute of Technology (MIT) is one of the driving forces behind Fiji, an open source platform that allows for application sharing as a way of improving biomedical-image processing. Arganda explains to SINC that Fiji, which has enjoyed the voluntary collaboration of some 20 developers from all over the world, has become a de facto standard that assists laboratories and microscope companies in their development of more precise products.
Ignacio Arganda is a postdoctoral researcher at the Laboratory of Computational Neuroscience of the Massachusetts Institute of Technology (MIT). Along with a group of researchers he implemented Fiji, a platform that allows for applications to be shared in order to improve and advance in the processing and analysis of biomedical imaging. “All of this in open source,” outlines Arganda.
The platform was built from a previous one, ImageJ, which was well known in the industry at the time. ImageJ was not an open source platform but it was publicly accessible. According to Arganda, it had the advantage that any person working in medical imaging could easily create small software applications to resolve their particular problems and then incorporate it into the platform by means of a plug-in (an application which is linked to another providing a new or specific function).
Nonetheless, the researcher adds that this platform became too chaotic with applications of all kinds, some of which were not related to biomedical-imaging. It also began being used to handle astronomical images, in video tracking, etc. “There was a significant lack of control and structure,” he says.
Therefore, “in a spontaneous manner and without any help” this group of researchers decided to create the new open source platform that could put order to that already in place, reusing what was of interest and useful in their work.
"We created a webpage organised like Wikipedia where people could contribute and use their knowledge to help others. To our surprise, it became very popular," he ensures. According to Ignacio Aranda, Fiji currently has 127,000 unique visits (20,000 each month).
(Source: eurekalert.org)