New Method to Diagnose Early Osteoarthritis

Researchers at Lund University and Harvard Medical School have developed a new technique called dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) which uses an MRI scan to identify the very earliest stages of Osteoarthritis. Osteoarthritis is the most common world wide condition responsible for disability in people around the world, this new imaging technique to discover it early has led researchers to predict that catching it this early can delay the severe effects of the condition or prevent them entirely. The article below details the information of this technique and its global uses.

A new method is set to help clinicians diagnose osteoarthritis at such an early stage that it will be possible to delay the progression of the disease by many years, or maybe even stop it entirely.

The joint disease osteoarthritis is one of our most common chronic diseases and one of the primary causes of disability for people around the world. “Osteoarthritis often attacks the knee and hip joints and breaks down the impact absorbing cartilage found there. For those affected, the progression of the disease usually takes many years, with gradually increasing pain which often leads to disability,” said Carl Siversson, who has just defended his thesis in medical radiation physics at Lund University (Sweden).

One of the difficulties with osteoarthritis has been diagnosing and tracking the disease before symptoms become evident. It has therefore been difficult to change or delay the course of the disease. Several years ago, researchers from Lund University and Harvard Medical School (Boston, MA, USA) developed a method to measure the degree of osteoarthritis using an MRI scanner, even at a very early stage. The method is called dGEMRIC (delayed gadolinium-enhanced MRI of cartilage).

“This was major progress, but one problem was that the measurements could only be performed in a limited part of the cartilage. We have now improved the method so that we can study all the cartilage in the joint at once. We have achieved this by solving the problem of how to correct all the irregularities in the MRI images,” said Mr. Siversson.

The improved technique has now been assessed both on healthy individuals and on individuals with osteoarthritis, and the findings show that the disease can now be monitored in ways that were not previously possible, according to Mr. Siversson. “Now we are continuing our work to make the method easy for doctors to use in their practice. Our hope is that the method will also be significant for future drug development,” he said, who after completing his PhD will continue his research at Harvard Medical School (Boston, MA, USA).

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First Fluorescence-Guided Ovarian Cancer Surgery

The first fluorescence-guided surgery on an ovarian cancer patient was performed using a cancer cell “homing device” and imaging agent created by a Purdue University researcher.

The surgery was one of 10 performed as part of the first phase of a clinical trial to evaluate a new technology to aid surgeons in the removal of malignant tissue from ovarian cancer patients. The method illuminates cancer cells to help surgeons identify and remove smaller tumors that could otherwise be missed.

Philip Low, the Ralph C. Corely Distinguished Professor of Chemistry who invented the technology, said surgeons were able to see clusters of cancer cells as small as one-tenth of a millimeter, as opposed to the earlier average minimal cluster size of 3 millimeters in diameter based on current methods of visual and tactile detection.

“Ovarian cancer is notoriously difficult to see, and this technique allowed surgeons to spot a tumor 30 times smaller than the smallest they could detect using standard techniques,” Low said. “By dramatically improving the detection of the cancer — by literally lighting it up — cancer removal is dramatically improved.”

The technique attaches a fluorescent imaging agent to a modified form of the vitamin folic acid, which acts as a “homing device” to seek out and attach to ovarian cancer cells. Patients are injected with the combination two hours prior to surgery and a special camera system, called a multispectral fluorescence camera, then illuminates the cancer cells and displays their location on a flat-screen monitor next to the patient during surgery.

The surgeons involved in this study reported finding an average of 34 tumor deposits using this technique, compared with an average of seven tumor deposits using visual and tactile observations alone. A paper detailing the study was published online in Nature Medicine.

Gooitzen van Dam, a professor and surgeon at the University of Groningen in The Netherlands where the surgeries took place, said the imaging system fits in well with current surgical practice.

“This system is very easy to use and fits seamlessly in the way surgeons do open and laparoscopic surgery, which is the direction most surgeries are headed in the future,” said van Dam, who is a surgeon in the division of surgical oncology and Bio-Optical Imaging Center at the University of Groningen. “I think this technology will revolutionize surgical vision. I foresee it becoming a new standard in cancer surgery in a very short time.”

Research has shown that the less cancerous tissue that remains, the easier it is for chemotherapy or immunotherapy to work, Low said.

“With ovarian cancer it is clear that the more cancer you can remove, the better the prognosis for the patient,” he said. “This is why we chose to begin with ovarian cancer. It seemed like the best place to start to make a difference in people’s lives.”

By focusing on removal of malignant tissue as opposed to evaluating patient outcome, Low dramatically reduced the amount of time the clinical trial would take to complete.

“What we are really after is a better outcome for patients, but if we had instead designed the clinical trial to evaluate the impact of fluorescence-guided surgery on life expectancy, we would have had to follow patients for years and years,” he said. “By instead evaluating if we can identify and remove more malignant tissue with the aid of fluorescence imaging, we are able to quantify the impact of this novel approach within two hours after surgery. We hope this will allow the technology to be approved for general use in a much shorter time.”

Low and his team are now making arrangements to work with the Mayo Clinic for the next phase of clinical trials.

The technology is based on Low’s discovery that folic acid, or folate, can be used like a Trojan horse to sneak an imaging agent or drug into a cancer cell. Most ovarian cancer cells require large amounts of the vitamin to grow and divide, and special receptors on the cell’s surface grab the vitamin — and whatever is linked to it — and pull it inside. Not all cancer cells express the folate receptor, and a simple test is necessary to determine if a specific patient’s cancer expresses the receptor in large enough quantities for the technique to work, he said.

Ovarian cancer has one of the highest rates of folate receptor expression at about 85 percent. Approximately 80 percent of endometrial, lung and kidney cancers, and 50 percent of breast and colon cancers also express the receptor, he said.

Low also is investigating targeting molecules that could be used to carry attached imaging agents or drugs to forms of cancer that do not have folate receptors.

He next plans to develop a red fluorescent imaging agent that can be seen through the skin and deep into the body. The current agent uses a green dye that had already been through the approval process to be used in patients, but cannot easily be seen when present deep in tissue. Green light uses a relatively short wavelength that limits its ability to pass through the body, whereas the longer wavelengths of a red fluorescent dye can easily be seen through tissue.

“We want to be able to see deeper into the tissue, beyond the surface,” Low said. “Different cancers have tumors with different characteristics, and some branch and wind their way deeper into tissue. We will continue to evolve this technology and make improvements that help cancer patients.”

In addition to Low and van Dam, the paper’s authors include George Themelis, Athanasios Sarantopoulos and Vasilis Ntziachristos of the Institute for Biological and Medical Imaging at the Technical University of Munich in Germany; Lucia Crane, Niels Harlaar, Rick Pleijhuis, Wendy Kelder and Johannes de Jong of the division of surgical oncology of the BioOptical Imaging Center at the University of Groningen; Henriette Arts and Ate van der Zee of the division of gynaecological oncology at the University of Groningen; and Joost Bart of the Department of Pathology and Molecular Biology of the University Medical Center of Groningen.

Low is the chief science officer for Endocyte Inc., a Purdue Research Park-based company that develops receptor-targeted therapeutics for the treatment of cancer and autoimmune diseases. Endocyte holds the license to the folate receptor-targeting technology and is spinning this technology off into a new company called OnTarget.

Ntziachristos led the team at the Technical University of Munich that developed the camera system. A startup company named SurgOptix BV is working to commercialize the camera system.

The clinical trial was funded by Endocyte Inc. and the University Medical Center of Groningen.

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Brain Waves Control the Impact of Noise On Sleep

Researchers from the University of Liège have discovered that sound is processed in the brain during sleep even though our external perception of the environment is largely decreased, what is most interesting is that the way the sound is processed in our brains differs depending on altering brain waves while we sleep. Researchers used a combination of medical imaging techniques in order to track functions of the brain and see which area of the brain processed different noises and to what extent during sleep. The article below details how these techniques were used.

During sleep, our perception of the environment decreases. However the extent to which the human brain responds to surrounding noises during sleep remains unclear. In a study published this week in Proceedings of the National Academy of Sciences (PNAS), researchers from University of Liège (Belgium) used brain imaging to study responses to sounds during sleep.

They show that brain activity in the face of noise is controlled by specific brain waves during sleep. In particular, waves called sleep ‘spindles’ prevent the transmission of sounds to auditory brain regions. Conversely, when sounds are associated with brain waves called ‘K-complexes’, activation of auditory areas is larger. Our perception of the environment is therefore not continuously reduced during sleep, but rather varies throughout sleep under the influence of particular brain waves.

In this study, the research team led by Dr Thanh Dang-Vu and Prof. Pierre Maquet (Cyclotron Research Center, University of Liège) shows that brain activity induced by sounds during sleep closely depends on brain waves that constitute our sleep.

By using functional magnetic resonance imaging (fMRI) combined with electroencephalography (EEG), researchers have evidenced that auditory brain regions remain active in response to sounds during sleep [see image, left panels], except when sounds occur during brain waves called sleep ‘spindles’. The study indeed shows that spindles prevent the transmission of sounds to the auditory cortex [see image, right panels].

Conversely, sounds can induce the production during sleep of brain waves called ‘K-complexes’. The results brought by this new study demonstrate that production of K-complexes by sounds is associated with a larger activation of auditory brain areas. While spindles prevent the transmission of sounds, K-complexes reflect a more important transmission of sounds to the sleeping brain.

The effects of noise on sleep are therefore controlled by specific brain waves. In particular, the human brain is isolated from the environment during sleep spindles, which might allow essential sleep functions to operate such as the consolidation of memory for previously acquired information. These brain waves thus play a crucial role in sleep quality and stability in the face of noise

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New Nanostructured Glass Designed for Imaging and Recording

Researchers in the United Kingdom have developed a new nanostructured glass which contains the potential for new developments in the field of medical imaging and recording. The glass itself is smaller and cheaper to use than current imaging counterparts. Not only can this glass be used as an imaging tool but can also imprint those images directly into the glass thereby creating a visual copy. The article below details this process and exactly what this new nanostructured glass can accomplish.

By Medimaging International staff writers

UK researchers have developed new nanostructured glass optical elements that have potential applications in optical manipulation and should considerably reduce the cost of medical imaging.

In a study published online May 16, 2011, the journal Applied Physics Letters, a team led by Prof. Peter Kazansky from the University of Southampton’s (UK) Optoelectronics Research Center, described how they have used nanostructures to develop new monolithic glass space-variant polarization converters. These millimeter-sized devices generate “whirlpools” of light, thereby enabling precise laser material processing, optical manipulation of atom-sized objects, ultra-high resolution imaging, and potentially, tabletop particle accelerators. They have since found that the technology can be additionally developed for optical recording.

According to the researchers, at sufficient intensities, ultra-short laser pulses can be used to imprint tiny dots (like three-dimensional [3D] pixels) called voxels in glass. Their previous research showed that lasers with fixed polarization produce voxels consisting of a periodic arrangement of ultra-thin (tens of nanometers) planes. By passing polarized light through such a voxel imprinted in silica glass, the researchers observed that it travels differently depending on the polarization orientation of the light. This ‘form birefringence’ phenomenon is the basis of their new polarization converter.

The benefit of this approach over existing methods for microscopy is that it is 20 times less expensive and it is compact. “Before this we had to use a spatial light modulator based on liquid crystal, which cost about GBP 20,000,” said Prof. Kazansky. “Instead, we have just put a tiny device into the optical beam and we get the same result.”

Since publication of the study, the researchers have developed this technology further and adapted it for a five-dimensional optical recording. “We have improved the quality and fabrication time and we have developed this five-dimensional memory, which means that data can be stored on the glass and last forever,” said Martynas Beresna, lead researcher for the project. “No one has ever done this before.”

The researchers are working with the company Altechna (Vilnius, Lithuania) to introduce this technology to the market.

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Near-Infrared Imaging System Used As Pancreatic Cancer Diagnostic

Recently scientists from different Boston area institutions have shown that a new type of medical imaging, called optical coherence tomography (OCT), can be used as a  non-invasive means to diagnose the difference between low and high risk cysts within the pancreas. This new technique will allow doctors to treat potentially life threatening situations easily and with a high degree of accuracy.

A team of researchers from four Boston-area institutions led by Nicusor Iftimia from Physical Sciences, Inc. has demonstrated for the first time that optical coherence tomography (OCT), a high resolution optical imaging technique that works by bouncing near-infrared laser light off biological tissue, can reliably distinguish between pancreatic cysts that are low-risk and high-risk for becoming malignant. Other optical techniques often fail to provide images that are clear enough for doctors to differentiate between the two types.

To test the diagnostic potential of OCT imaging, researchers used the technique to examine surgically removed pancreatic tissue samples from patients with cystic lesions. By identifying unique features of the high-risk cysts that appeared in the OCT scans, the team developed a set of visual criteria to differentiate between high and low risk cysts. They then tested the criteria by comparing OCT diagnoses to those obtained by examining thin slices of the pancreatic tissue under a microscope. Their results, described in the August issue of the Optical Society’s (OSA) open-access journalBiomedical Optics Express, showed that OCT allowed clinicians to reliably differentiate between low-risk and high-risk cysts with a success rate close to that achieved by microscope-assisted examinations of slices of the same samples.

Future studies by the research team will focus on improving imaging resolution to further differentiate between solid lesions and autoimmune pancreatitis, and test this technology in vivo. They recently received FDA approval for testing this technology in human patients by using an OCT probe small enough to be inserted into the pancreas through a biopsy needle, which will be guided into suspect masses in the pancreas by endoscopic ultrasound imaging. A pilot clinical study is planned to start within the next couple of months. If in vivo data will prove reliable differentiation between the two types of cysts, a study in a larger number of patients will be planned, contingent on NIH funding and FDA approval.

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Scientists Develop New Technique To Easily Navigate Brain’s Landmarks

The brain, with its complicated folds and wiring, has consistently been the most troublesome part of the human body to navigate. However, researchers have now come up with a technique that allows the brain to be quickly navigated by “landmarks” in the brain itself. This feat is most impressive because formerly this technique was only available at autopsy. This technique in conjunction with the Human Connectome Project, a project who’s goal it is to map the intricate wiring of the brain, will lead to better understanding of our body and how it is controlled through the brain.

Like explorers mapping a new planet, scientists probing the brain need every type of landmark they can get. Each mountain, river or forest helps scientists find their way through the intricacies of the human brain.

Researchers at Washington University School of Medicine in St. Louis have developed a new technique that provides rapid access to brain landmarks formerly only available at autopsy. Better brain maps will result, speeding efforts to understand how the healthy brain works and potentially aiding in future diagnosis and treatment of brain disorders, the researchers report in the Journal of Neuroscience Aug. 10.

The technique makes it possible for scientists to map myelination, or the degree to which branches of brain cells are covered by a white sheath known as myelin in order to speed up long-distance signaling. It was developed in part through the Human Connectome Project, a $30 million, five-year effort to map the brain’s wiring. That project is headed by Washington University in St. Louis and the University of Minnesota.

“The brain is among the most complex structures known, with approximately 90 billion neurons transmitting information across 150 trillion connections,” says David Van Essen, PhD, Edison Professor and head of the Department of Anatomy and Neurobiology at Washington University. “New perspectives are very helpful for understanding this complexity, and myelin maps will give us important insights into where certain parts of the brain end and others begin.”

Easy access to detailed maps of myelination in humans and animals also will aid efforts to understand how the brain evolved and how it works, according to Van Essen.

Neuroscientists have known for more than a century that myelination levels differ throughout the cerebral cortex, the gray outer layer of the brain where most higher mental functions take place. Until now, though, the only way they could map these differences in detail was to remove the brain after death, slice it and stain it for myelin.

Washington University graduate student Matthew Glasser developed the new technique, which combines data from two types of magnetic resonance imaging (MRI) scans that have been available for years.

“These are standard ways of imaging brain anatomy that scientists and clinicians have used for a long time,” Glasser says. “After developing the new technique, we applied it in a detailed analysis of archived brain scans from healthy adults.”

As in prior studies, Glasser’s results show highest myelination levels in areas involved with early processing of information from the eyes and other sensory organs and control of movement. Many brain cells are packed into these regions, but the connections among the cells are less complex. Scientists suspect that these brain regions rely heavily on what computer scientists call parallel processing: Instead of every cell in the region working together on a single complex problem, multiple separate teams of cells work simultaneously on different parts of the problem.

Areas with less myelin include brain regions linked to speech, reasoning and use of tools. These regions have brain cells that are packed less densely, because individual cells are larger and have more complex connections with neighboring cells.

“It’s been widely hypothesized that each chunk of the cerebral cortex is made up of very uniform information-processing machinery,” Van Essen says. “But we’re now adding to a picture of striking regional differences that are important for understanding how the brain works.”

According to Van Essen, the technique will make it possible for the Connectome project to rapidly map myelination in many different research participants. Data on many subjects, acquired through many different analytical techniques including myelination mapping, will help the resulting maps cover the range of anatomic variation present in humans.

“Our colleagues are clamoring to make use of this approach because it’s so helpful for figuring out where you are in the cortex, and the data are either already there or can be obtained in less than 10 minutes of MRI scanning,” Glasser says.

This research was funded by the National Institutes of Health (NIH).

Read more http://www.sciencedaily.com/releases/2011/08/110809184153.htm

New High-Speed 3-D Imaging Improves Cancer Screenings

Researchers at the Massachusetts Institute of Technology (MIT) have developed a fast 3-d imaging process known as optical coherence tomography (OCT) which can be used to scan the esophagus or colon for early signs of cancer. Traditionally these areas were screened for signs of cancer using basically a small camera on the end of a small tube, however this old technology only allowed medical practitioners to look for cancer on the surface of any tissue they were looking at. With this new 3-d imaging technology OCT scientists are able to not only see what is on the surface but they are also able to peer under the surface of the tissue to find cancer sooner and treat it more quickly. Below the article explains in full detail the specifics of this new system as well as the medical benefits it brings to the field.

ScienceDaily (Aug. 4, 2011) — Researchers at the Massachusetts Institute of Technology (MIT) have developed a new imaging system that enables high-speed, three-dimensional (3-D) imaging of microscopic pre-cancerous changes in the esophagus or colon. The new system, described in the Optical Society’s (OSA) open access journal Biomedical Optics Express, is based on an emerging technology called optical coherence tomography (OCT), which offers a way to see below the surface with 3-D, microscopic detail in ways that traditional screening methods can’t.

Endoscopy is the method of choice for cancer screening of the colon or esophagus. In the procedure, a tiny camera attached to a long thin tube is snaked into the colon or down the throat, giving doctors a relatively non-invasive way to look for abnormalities. But standard endoscopy can only examine the surface of tissues, and thus may miss important changes occurring inside tissue that indicate cancer development.

OCT, which can examine tissue below the surface, is analogous to medical ultrasound imaging except that it uses light instead of sound waves to visualize structures in the body in real time, and with far higher resolution; OCT can visualize structures just a few millionths of a meter in size. Over the past two decades, OCT has become commonplace in ophthalmology, where it is being used to generate images of the retina and to help diagnose and monitor diseases like glaucoma, and has emerging applications in cardiology, where it’s used to examine unstable plaques in blood vessels that can trigger heart attacks.

The new endoscopic OCT imaging system reported by OCT pioneer James G. Fujimoto of MIT and his colleagues, works at record speeds, capturing data at a rate of 980 frames (equivalent to 480,000 axial scans) per second — nearly 10 times faster than previous devices — while imaging microscopic features less than 8 millionths of a meter in size.

At such high speeds and super-fine resolution, the novel system promises to enable 3-D microscopic imaging of pre-cancerous changes in the esophagus or colon and the guidance of endoscopic therapies. Esophageal and colon cancer are diagnosed in more than 1.5 million people worldwide each year, according to the American Cancer Society.

“Ultrahigh-speed imaging is important because it enables the acquisition of large three-dimensional volumetric data sets with micron-scale resolution,” says Fujimoto, a professor of electrical engineering and computer science and senior author of the paper.

“This new system represents a significant advance in real-time, 3-D endoscopic OCT imaging in that it offers the highest volumetric imaging speed in an endoscopic setting, while maintaining a small probe size and a low, safe drive voltage,” says Xingde Li, associate professor at the Whitaker Biomedical Engineering Institute and Department of Biomedical Engineering at Johns Hopkins University, who is not affiliated with the research team.

In OCT imaging, microscopic-scale structural and pathological features are examined by directing a beam of light on a tissue and measuring the magnitude and echo time-delay of backscattered light. Because the amount of light that can be recaptured and analyzed decreases quickly with depth in tissue due to scattering, the technique can generally only be used to visualize sub-surface features to a depth of 1 to 2 millimeters. “However these depths are comparable to those sampled by pinch biopsies and unlike biopsy, information is available in real time,” Fujimoto says. By using miniature fiber optic scanning catheters or probes, either on their own or in combination with standard endoscopes, colonoscopes, or laparoscopes, OCT imaging can be performed inside the body.

In collaboration with clinicians at the VA Boston Healthcare System and Harvard Medical School, the team is investigating endoscopic OCT as a method for guiding excisional biopsy — the removal of tissue for histological examination — to reduce false negative rates and improve diagnostic sensitivity.

“Excisional biopsy is one of the gold standards for the diagnosis of cancer, but is a sampling procedure. If the biopsy is taken in a normal region of tissue and misses the cancer, the biopsy result is negative although the patient still has cancer,” notes Fujimoto, whose team is one of a number of research groups — including at Johns Hopkins University; the University of California, Irvine; Case Western University; and Massachusetts General Hospital — that are actively pursuing the development of smaller, faster endoscopic OCT systems.

Endoscopic OCT requires miniature optical catheters or probes — just a few millimeters in diameter — that can scan an optical beam in two dimensions to generate high-resolution 3-D data sets. Scanning the beam in one transverse direction generates an image in a cross-sectional plane, whereas scanning the beam in two directions generates a stack of cross-sectional images — that is, a 3-D (or volumetric), image.

“This device development is one of the major technical challenges in endoscopic OCT because probes must be small enough so that they can be introduced into the body, but still be able to scan an optical beam at high speeds,” Fujimoto says. “Increasing imaging speeds has also been an important research objective because high-resolution volumetric imaging requires very large amounts of data in order to cover appreciable regions of tissue, so rapid image acquisition rates are a powerful advantage.”

The optical catheter developed by the MIT researchers and their collaborators uses a piezoelectric transducer, a miniature device that bends in response to electrical current, allowing a laser-light emitting optical fiber to be rapidly scanned over the area to be imaged.

So far, the device — which must be further reduced in size, Fujimoto notes, before it can be deployed with the standard endoscopes now used — has only been used in animal models and in samples of human colons that had been removed during surgical procedures; further development and testing of the technology is needed before it can be tested in human patients. “The ultimate clinical utility of new devices must be established by large clinical studies, which assess the ability of the technology to improve diagnoses or therapy,” he says. “This is a much more complex and lengthy task than the initial development of the technology itself.”

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New Fluorescent Protein Safely Allows To See Inside Live Animals

Scientists have developed a safe non-toxic fluorescent protein that, when injected into animals, allows scientists to see inside the animals body using simple medical imaging technology. This practice has been in development for some time but with this new discovery the practice involves using proteins that show under non invasive infra-red light. Infra-red light allows for maximum transparency in mammalian tissues. This new protein so far doesn’t appear to have any side effects on the animal, a rare benefit in the modern medical field. Using this technology will make it easier to monitor tumors and cancer growths in patients without further complicating their deteriorating health with toxic agents and other chemicals used to make the imaging of their internal organs easier.

ScienceDaily (July 26, 2011) — Researchers at Albert Einstein College of Medicine of Yeshiva University have developed the first fluorescent protein that enables scientists to clearly “see” the internal organs of living animals without the need for a scalpel or imaging techniques that can have side effects or increase radiation exposure.

The new probe could prove to be a breakthrough in whole-body imaging — allowing doctors, for example, to noninvasively monitor the growth of tumors in order to assess the effectiveness of anti-cancer therapies. In contrast to other body-scanning techniques, fluorescent-protein imaging does not involve radiation exposure or require the use of contrast agents. The findings are described in the July 17 online edition of Nature Biotechnology.

For the past 20 years, scientists have used a variety of colored fluorescent proteins, derived from jellyfish and corals, to visualize cells and their organelles and molecules. But using fluorescent probes to peer inside live mammals has posed a major challenge. The reason: hemoglobin in an animal’s blood effectively absorbs the blue, green, red and other wavelengths used to stimulate standard fluorescent proteins along with any wavelengths emitted by the proteins when they do light up.

To overcome that roadblock, the laboratory of Vladislav Verkhusha, Ph.D., associate professor of anatomy and structural biology at Einstein and the study’s senior author, engineered a fluorescent protein from a bacterial phytochrome (the pigment that a species of bacteria uses to detect light). This new phytochrome-based fluorescent protein, dubbed iRFP, both absorbs and emits light in the near-infrared portion of the electromagnetic spectrum- the spectral region in which mammalian tissues are nearly transparent.

The researchers targeted their fluorescent protein to the liver — an organ particularly difficult to visualize because of its high blood content. Adenovirus particles containing the gene for iRFP were injected into mice. Once the viruses and their gene cargoes infected liver cells, the infected cells expressed the gene and produced iRFP protein. The mice were then exposed to near-infrared light and it was possible to visualize the resulting emitted fluorescent light using a whole-body imaging device. Fluorescence of the liver in the infected mice was first detected the second day after infection and reached a peak at day five. Additional experiments showed that the iRFP fluorescent protein was nontoxic.

“Our study found that iRFP was far superior to the other fluorescent proteins that reportedly help in visualizing the livers of live animals,” said Grigory Filonov, Ph.D., a postdoctoral fellow in Dr. Verkhusha””s laboratory at Einstein, and the first author of the Nature Biotechnology paper. “iRFP not only produced a far brighter image, with higher contrast than the other fluorescent proteins, but was also very stable over time. We believe it will significantly broaden the potential uses for noninvasive whole-body imaging.”

Dr. Filonov noted that fluorescent-protein imaging involves no radiation risk, which can occur with standard x-rays and computed tomography (CT) scanning. And unlike magnetic resonance imaging (MRI), in which contrasting agents must sometimes be swallowed or injected to make internal body structures more visible, the contrast provided by iRFP is so vibrant that contrasting agents are not needed.

Read more http://www.sciencedaily.com/releases/2011/07/110718101208.htm

PET Imaging May Help Find Alzheimer’s

PET imaging, otherwise known as positron emission tomography, is starting to be used to look for signs of Alzheimer’s disease within a patient’s brain tissue.  Rather than used dated pathological techniques to guess when a patient might suffer the onset of Alzheimer’s, PET imaging can be used to look for traces of damaged brain tissue that is synonymous with Alzheimer’s disease.

ScienceDaily  — The use of positron emission tomography (PET) imaging may help identify findings in brain tissue associated with Alzheimer’s disease (AD), according to two articles published Online First by Archives of Neurology, one of the JAMA/Archives journals.

As scientists seek to understand more about AD and other forms of dementia, they are exploring the use of PET, according to background information in the article. This imaging technique involves the use of radioactive tracers to highlight areas of the brain affected by these conditions. Various teams of researchers are studying the effectiveness of different types of tracers for identifying brain findings associated with these conditions.

In one study, David A. Wolk, M.D., from the Penn Memory Center in Philadelphia, and colleagues, evaluated use of a tracer called fluorine 18-labeled flutemetamol for imaging the brain. The study involved conducting PET scans on seven patients who were given a dose of this substance. All had previously undergone a biopsy for normal pressure hydrocephalus, a progressive condition that includes dementia and can be difficult to distinguish from AD. Researchers found correspondence between readings of the PET scans and evidence of amyloid lesions — the plaque associated with AD — provided by microscopic evaluation of the biopsied tissue.

In another study, Adam S. Fleisher, M.D., from Banner Alzheimer’s Institute in Phoenix, and colleagues, evaluated PET imaging using the tracer florbetapir F 18. The study population included 68 individuals with probable AD, 60 individuals with mild cognitive impairment, and 82 healthy individuals who served as controls. PET scanning was used to monitor activity of the agent being studied. These researchers found differences in the brain uptake of florbetapir F 18, between the three groups, and in the detection of amyloid plaque; the differences may be large enough to help distinguish between the conditions, and between impaired versus unimpaired brains.

The authors of both articles suggest that their results may demonstrate ways in which PET imaging can be used with selected tracers to help identify findings associated with AD. “With the potential emergence of disease-specific interventions for AD,” state Wolk et al, “biomarkers that provide molecular specificity will likely become of greater importance in the differential diagnosis of cognitive impairment in older adults.” Indeed, Fleisher et al write, “Amyloid imaging offers great promise to facilitate the evaluation of patients in a clinical setting.”

Commentary: Amyloid Imaging-Liberal or Conservative? Let the Data Decide

In an editorial accompanying the papers, William J. Jagust, M.D., from the Helen Wills Neuroscience Institute at the University of California, Berkeley, comments on the role of amyloid in AD and the detection of this plaque as “a topic of active investigation.” The articles by Wolk et al and Fleisher et al, he suggests, “continue to advance the field.”

Jagust notes that the study by Fleisher et al attempted to define cutoffs for positive or negative presence of amyloid. “Most clinical imaging methods rely on interpretation, not quantitation,” he states. “Nevertheless, quantitation of these scans has considerable value because it provides a reliable measure that can be compared across laboratories on either a continuous or dichotomous level.”

Jagust also discusses the problem of how to treat “borderline” or “intermediate” results. He notes that the study by Wolk et al found “perfect agreement” between the scans and the biopsied tissue in terms of positive or negative ratings.

Further, Jagust adds, the two studies show that cutoff levels may be distinct from agent to agent. “These are likely to be related to differences in the tracer as well as to differences in the methods already noted,” he says. Nevertheless, points out Jagust, “Another interesting point is how exceptionally well all of these tracers perform in comparison to pathology.”

For more http://www.sciencedaily.com/releases/2011/07/110712192045.htm

Medical Imaging Becoming Safer for Pediatric Patients

The radiologists at Desert Valley Radiology continuously improve the care provided to their patients by the means of scientific research.  New research affecting the country covers coronary computer tomography angiography (CTA) which produces a high quality image and is less invasive for pediatric patients.  This technology will allow children to avoid cardiac catheterization and the radiation that is associated with it.  As well, adult and pediatric patients will be able to undergo the imaging process without anesthesia or sedation.

Although the heart rate of children has typically been too fast for the technology to obtain a proper image, new medication which slows the heart rate, as well as improved scanners have helped this problem.  A thorough study of this medical technology will be presented in Denver, CO on July 14-17 at the Sixth Annual Scientific Meeting of the Society of Cardiovascular Computed Tomography.

For more information on this technology visit: http://www.sciencedaily.com/releases/2011/07/110717122331.htm