Posts tagged diffusion tensor imaging

Posts tagged diffusion tensor imaging
Do you obsess over your appearance? Your brain might be wired abnormally
Body dysmorphic disorder is a disabling but often misunderstood psychiatric condition in which people perceive themselves to be disfigured and ugly, even though they look normal to others. New research at UCLA shows that these individuals have abnormalities in the underlying connections in their brains.
Dr. Jamie Feusner, the study’s senior author and a UCLA associate professor of psychiatry, and his colleagues report that individuals with BDD have, in essence, global “bad wiring” in their brains — that is, there are abnormal network-wiring patterns across the brain as a whole.
And in line with earlier UCLA research showing that people with BDD process visual information abnormally, the study discovered abnormal connections between regions of the brain involved in visual and emotional processing.
The findings, published in the May edition of the journal Neuropsychopharmacology, suggest that these patterns in the brain may relate to impaired information processing.
"We found a strong correlation between low efficiency of connections across the whole brain and the severity of BDD," Feusner said. "The less efficient patients’ brain connections, the worse the symptoms, particularly for compulsive behaviors, such as checking mirrors."
People suffering from BDD tend to fixate on minute details, such as a single blemish on their face or body, rather than viewing themselves in their entirety. They become so distressed with their appearance that they often can’t lead normal lives, are fearful of leaving their homes and occasionally even commit suicide. Patients frequently have to be hospitalized. BDD affects approximately 2 percent of the population and is more prevalent than schizophrenia or bipolar disorder. Despite its prevalence and severity, scientists know relatively little about the neurobiology of BDD.
In the current study, Feusner and his colleagues performed brain scans of 14 adults diagnosed with BDD and 16 healthy controls. The goal of the study was to map the brain’s connections to examine how the white-matter networks are organized. White matter is made up of nerve cells that carry impulses from one part of the brain to another.
To do this, they used a sensitive form of brain imaging called diffusion tensor imaging, or DTI. DTI is a variant of magnetic resonance imaging that can measure the structural integrity of the brain’s white matter. From these scans, they were able to create whole brain “maps” of reconstructed white-matter tracks. Next, they used a form of advanced analysis called graph theory to characterize the patterns of connections throughout the brains of people with BDD and then compared them with those of healthy controls.
The researchers found people with BDD had a pattern of abnormally high network “clustering” across the entire brain. This suggests that these individuals may have imbalances in how they process “local” or detailed information. The researchers also discovered specific abnormal connections between areas involved in processing visual input and those involved in recognizing emotions.
"How their brain regions are connected in order to communicate about what they see and how they feel is disturbed," said Feusner, who also directs the Adult Obsessive-Compulsive Disorder Program and the Body Dysmorphic Disorder Research Program at UCLA.
"Their brains seem to be fine-tuned to be very sensitive to process minute details, but this pattern may not allow their brains to be well-synchronized across regions with different functions," he said. "This could affect how they perceive their physical appearance and may also result in them getting caught up in the details of other thoughts and cognitive processes."
The study, Feusner noted, advances the understanding of BDD by providing evidence that the “hard wiring” of patients’ brain networks is abnormal.
"These abnormal brain networks could relate to how they perceive, feel and behave," he said. "This is significant because it could possibly lead to us being able to identify early on if someone is predisposed to developing this problem."

Personalized Brain Mapping Technique Preserves Function Following Brain Tumor Surgery
Neurosurgeons can visualize important pathways in the brain using an imaging technique called diffusion tensor imaging (DTI), to better adapt brain tumor surgeries and preserve language, visual and motor function while removing cancerous tissue. In the latest issue of Neurosurgical Focus, researchers from the Perelman School of Medicine at the University of Pennsylvania review research showing that this ability to visualize relevant white matter tracts during glioma resection surgeries can improve accuracy and, in some groups, significantly extend survival (median survival of 21.2 months) compared to cases where DTI was not used (median survival of 14 months).
"We can view the brain from the inside out now, with 3D images detailing connectivity within the brain, making a virtual intraoperative map," said senior author Steven Brem, MD, professor of Neurosurgery, chief of the Division of Neurosurgical Oncology and co-director of the Penn Brain Tumor Center. "Penn is at the forefront of a major shift in the field - we now have such detail about each individual’s brain tumor - combining diffusion tensor imaging and advanced imaging with the entire personalized diagnostics analysis available for all brain tumor patients at Penn Medicine."
Diffusion tensor imaging (DTI) provides a rendering of axon pathways, by tracking water molecules in the brain as they travel in a direction parallel to axonal fibers, in a 3D model known as “the diffusion tensor.” The diffusion tensor directly represents the direction of water and indirectly represents the orientation of white matter fibers. The colorful images, captured as part of an 8 minute sequence during an MRI, show representations of clusters of axon fibers, where each color indicates a direction of travel, and offer a glimpse of the interwoven communication superhighways of the brain.
"The DTI images can be overlaid with structural and functional MRI images, providing a hybrid map showing topography layered with a road map," said Neurosurgery resident Kalil Abdullah, MD, lead author of the paper. "This rendering gives us increased clarity to visualize important white matter tracts in the brain and adapt our surgical approaches to each person’s case. Rather than focusing on solely taking the tumor out, we can avoid damage to healthy tissue and preserve important pathways responsible for speech, vision and motor function."
Relying heavily on the expertise of radiologists who process and analyze the DTI images, including Ronald L. Wolf, MD, PhD, associate professor of Radiology at Penn, the research on DTI is being translated into clinical practice to guide surgical procedures. Further research efforts are targeted at defining language deficits before surgery and following-up post-operatively to determine any changes or improvements following treatment based on the use of DTI.
Working collaboratively with colleagues in Penn’s departments of Neurosurgery, Neurology, Radiology, Radiation Oncology, Nursing, Pathology and Laboratory Medicine and the Abramson Cancer Center, the Penn Brain Tumor Center combines the latest imaging, biomarker and genetic tumor testing to provide a personalized treatment plan for all types of brain cancers. Brain tumors are among the first areas of interest for Penn’s Center for Personalized Diagnostics (CPD), a joint initiative by Penn Medicine’s Department of Pathology and Laboratory Medicine and the Abramson Cancer Center, which integrates Molecular Genetics, Pathology Informatics, and Genomic Pathology for individualized patient diagnoses and to elucidate cancer treatment options for physicians.
(Image: Swedish Research)
Pig brain models provide insights into human cognitive development
A mutual curiosity about patterns of growth and development in pig brains has brought two University of Illinois research groups together. Animal scientists Rod Johnson and Ryan Dilger have developed a model of the pig brain that they plan to use to answer important questions about human brain development.
“It is important to characterize the normal brain growth trajectory from the neonatal period to sexual maturity,” said Johnson.
“Until we know how the brain grows, we don’t know what is going to change,” added Dilger.
In cooperation with the Beckman Institute, they performed MRI scans on the brains of 16 piglets, starting at the age of 2 weeks, then at 4 weeks, and then at 4-week intervals up to 24 weeks.
“We have world-class people at the Beckman Institute who are pushing and developing the next generation of neuroimaging technology, so we’re able to connect with them and take advantage of their expertise,” said Johnson.
Matt Conrad, a student in Johnson’s lab, used three-dimensional visualization software on over 200 images to manually segment each region on three planes. The software put the information together into a three-dimensional image of the pig brain. This is used to determine the volume of the different structures.
When the piglets were at Beckman for their imaging sessions, Dilger performed other tests, including diffusion tensor imaging (DTI), which shows how neural tracks develop, allowing the exploration of brain complexity and of how neurons form. It was also possible to measure neurochemicals, including creatine and acetylcholine, in the brain, which provides a unique insight into brain metabolism.
The end result of this work is what they call the deformable pig brain atlas.
“We are taking 16 pigs and averaging them, so it’s more representative of all pigs,” said Dilger. “You can then apply it to any individual pig to see how it’s different.”
“It’s called a deformable brain atlas because the software takes information from an individual and deforms it until it fits the template, and then you know how much it had to be deformed to fit,” Johnson explained. “So from that, you can tell whether a brain region is larger or smaller compared to the average.”
Johnson and Dilger said that the goal is to develop a tool for pigs that is equivalent to what is available for the mouse brain and make it publicly available. But they don’t want to stop with tool development.
“We want to use this to address important questions,” Johnson said.
One research direction being pursued in Johnson’s lab is to induce viral pneumonia in piglets at the point in the post-natal period when the brain is undergoing massive growth to see how it alters brain growth and development. They are also looking at effects of prenatal infections in the mother to see if that alters the trajectory of normal brain growth in the offspring. The risk for behavioral disorders and reduced stress resilience is increased by pre- and post-natal infection, but the developmental origins are poorly understood.
Dilger’s group is interested in the effects of early-life nutrition on the brain. They are looking at the effects of specific fatty acids as primary structural components of the human brain and cerebral cortex, and at choline, a nutrient that is important for DNA production and normal functioning of neurons.
“Choline deficiency has been tied to cognitive deficits in the mouse and human, and we’re developing a pig model to study the direct effects choline deficiency has on brain structure and function,” Dilger said. “Many women of child-bearing age may not be receiving enough choline in their diets, and recent evidence suggests this may ultimately affect learning and memory ability in their children. Luckily, choline can be found in common foods, especially eggs and meat products, including bacon.”
Computer Model May Help Athletes and Soldiers Avoid Brain Damage and Concussions
Concussions can occur in sports and in combat, but health experts do not know precisely which jolts, collisions and awkward head movements during these activities pose the greatest risks to the brain. To find out, Johns Hopkins engineers have developed a powerful new computer-based process that helps identify the dangerous conditions that lead to concussion-related brain injuries. This approach could lead to new medical treatment options and some sports rule changes to reduce brain trauma among players.
The research comes at a time when greater attention is being paid to assessing and preventing the head injuries sustained by both soldiers and athletes. Some kinds of head injuries are difficult to see with standard diagnostic imaging but can have serious long-term consequences. Concussions, once dismissed as a short-term nuisance, have more recently been linked to serious brain disorders.
“Concussion-related injuries can develop even when nothing has physically touched the head, and no damage is apparent on the skin,” said K. T. Ramesh, the Alonzo G. Decker Jr. Professor of Science and Engineering who led the research at Johns Hopkins. “Think about a soldier who is knocked down by the blast wave of an explosion, or a football player reeling after a major collision. The person may show some loss of cognitive function, but you may not immediately see anything in a CT-scan or MRI that tells you exactly where and how much damage has been done to the brain. You don’t know what happened to the brain, so how do you figure out how to treat the patient?”
To help doctors answer this question, Ramesh led a team that used a powerful technique called diffusion tensor imaging, together with a computer model of the head, to identify injured axons, which are tiny but important fibers that carry information from one brain cell to another. These axons are concentrated in a kind of brain tissue known as “white matter,” and they appear to be injured during the so-called mild traumatic brain injury associated with concussions. Ramesh’s team has shown that the axons are injured most easily by strong rotations of the head, and the researchers’ process can calculate which parts of the brain are most likely to be injured during a specific event.
The team described its new technique in the Jan. 8 edition of the Journal of Neurotrauma. The lead author, Rika M. Wright, played a major role in the research while completing her doctoral studies in Johns Hopkins’ Whiting School of Engineering, supervised by Ramesh. Wright is now a postdoctoral research fellow at Carnegie Mellon University. Ramesh is continuing to conduct research using the technique at Johns Hopkins with support from the National Institutes of Health.
Beyond its use in evaluating combat and sports-related injuries, the work could have wider applications, such as detecting axonal damage among patients who have received head injuries in vehicle accidents or serious falls. “This is the kind of injury that may take weeks to manifest,” Ramesh said. “By the time you assess the symptoms, it may be too late for some kinds of treatment to be helpful. But if you can tell right away what happened to the brain and where the injury is likely to have occurred, you may be able to get a crucial head-start on the treatment.”

Veterans with mild traumatic brain injury have brain abnormalities
Mild traumatic brain injury (TBI), including concussion, is one of the most common types of neurological disorder, affecting approximately 1.3 million Americans annually.
It has received more attention recently because of its frequency and impact among two groups of patients: professional athletes, especially football players; and soldiers returning from mid-east conflicts with blast-related TBI. An estimated 10 to 20 percent of the more than 2 million U.S. soldiers deployed in Iraq or Afghanistan have experienced TBI.
A recent study by psychiatrists from the Iowa City VA Medical Center and University of Iowa Health Care finds that soldiers returning from Iraq and Afghanistan with mild TBI have measurable abnormalities in the white matter of their brains when compared to returning veterans who have not experienced TBI. These abnormalities appear to be related to the severity of the injury and are related to cognitive deficits. The findings were published online in December in the American Journal of Psychiatry.
By exploring parts of the brain that trigger during periods of daydreaming and mind-wandering, neuroscientists from Western University have made a significant breakthrough in understanding what physically happens in the brain to cause vegetative state and other so-called “disorders of consciousness.”
Vegetative state and related disorders such as the minimally conscious state are amongst the least understood conditions in modern medicine because there is no particular type of brain damage that is known to cause them. This lack of knowledge leads to an alarmingly high level of misdiagnosis.
In support of the study titled, “A role for the default mode network in the bases of disorders of consciousness,” Davinia Fernandez-Espejo, a post doctoral fellow at Western’s Brain and Mind Institute, utilized a technique called diffusion tensor imaging tractography to investigate more than 50 patients suffering from varying degrees of brain injury.
This state-of-the-art magnetic resonance imaging (MRI) technique allows researchers to virtually reconstruct the pathways that connect different parts of the brain in the patients while detecting subtle differences in their brain damage.
Specifically, Fernandez-Espejo was able to show that in vegetative state patients, a group of brain regions known as the default mode network that are known to activate during periods of daydreaming and mind-wandering were significantly disconnected, relative to healthy individuals.
"These findings are a first step towards identifying biomarkers that will help us to improve diagnosis and to find possible therapies for these patients" says Fernandez-Espejo. "But they also give us new information about how the healthy brain generates consciousness."
(Source: communications.uwo.ca)
Brain scans have revealed distinctive features in the brain structure of karate experts that are associated with how well they performed in a test of punching ability.
Researchers from Imperial College London and UCL looked for differences in brain structure between 12 karate practitioners with a black belt rank and an average of 13.8 years’ karate experience, and 12 people of similar age who exercised regularly but did not have any martial arts experience.
Dr Ed Roberts, from the Department of Medicine at Imperial College London, who led the study, explained: "The karate black belts were able to repeatedly coordinate their punching action with a level of coordination that novices can’t produce. We think that ability might be related to fine-tuning of neural connections in the cerebellum, allowing them to synchronise their arm and trunk movements very accurately."
The scans used in this study, called diffusion tensor imaging (DTI), detected structural differences in the white matter of parts of the brain called the cerebellum and the primary motor cortex, which are known to be involved in controlling movement. The differences measured by DTI in the cerebellum correlated with the synchronicity of the subjects’ wrist and shoulder movements when punching.
The DTI signal also correlated with the age at which karate experts began training and their total experience of the discipline. These findings suggest that the structural differences in the brain are related to the black belts’ punching ability.
(Image credit: Adam J. Merton on Flickr)