Category: neuroimaging

Posted on

T1-weighted MRI

T1-weighted MRI, also known as T1-MRI, is a type of magnetic resonance imaging (MRI) that is used to create detailed images of internal organs, bones, and other structures inside the body. This imaging technique is particularly useful for visualizing soft tissue structures, such as the brain, spinal cord, and muscles, as well as for detecting certain types of tumors and other abnormalities.

The principle behind T1-weighted MRI is based on the behavior of hydrogen atoms, which are present in large quantities in the body’s water and fat molecules. When a person is placed in a magnetic field, the hydrogen atoms align with the field and emit radiofrequency signals, which are then detected by a receiver coil and used to create an image.

One of the key features of T1-weighted MRI is that it can distinguish between different types of tissue based on their water and fat content. For example, fat appears bright on a T1-weighted image, while water appears dark. This makes it possible to clearly see the boundaries between different structures, such as the brain and spinal cord, or the muscles and tendons.

T1-weighted MRI is also useful for identifying certain types of tumors and other abnormalities. Tumors, for example, tend to have a higher water content than the surrounding tissue, which makes them appear darker on a T1-weighted image. Similarly, certain types of cysts and other fluid-filled structures will also appear dark, making them easy to distinguish from surrounding tissue.

Another advantage of T1-weighted MRI is that it does not use ionizing radiation, which is the type of radiation used in x-rays and CT scans. Instead, it relies on a magnetic field and radiofrequency signals, which are considered to be safer than ionizing radiation. This makes T1-weighted MRI an attractive option for people who are at risk for developing cancer, such as children and pregnant women, as well as for those who have already had a lot of radiation exposure.

Despite its many advantages, T1-weighted MRI is not without its limitations. For example, it is not as good at visualizing certain types of bone and other hard tissue, which can make it difficult to detect certain types of fractures and other injuries. Additionally, some patients may find the procedure uncomfortable or claustrophobic, as they need to lie still inside a narrow tube for several minutes while the images are being taken. Some people also cannot receive an MRI due to implanted medical devices or other conditions.

Overall, T1-weighted MRI is a powerful imaging technique that can provide detailed images of internal organs, bones, and other structures inside the body. Its ability to distinguish between different types of tissue based on their water and fat content, as well as its ability to detect certain types of tumors and other abnormalities, make it a valuable tool for healthcare professionals. Its lack of ionizing radiation also makes it a safer option for certain patients, while the limitations of T1-weighted MRI include difficulty in visualizing certain types of bone and other hard tissue and being uncomfortable for certain patients.

Posted on

One in five older adults experience brain network weakening following knee replacement surgery

Gainesville, FL – A new University of Florida study finds that 23 percent of adults age 60 and older who underwent a total knee replacement experienced a decline in activity in at least one region of the brain responsible for specific cognitive functions. Fifteen percent of patients declined across all brain networks the team evaluated.

“In essence, normally synchronized parts of the brain appeared more out of sync after surgery,” said Jared Tanner, Ph.D., the study’s co-lead author and a research assistant professor in the department of clinical and health psychology in the UF College of Public Health and Health Professions, part of UF Health.

Patients who were cognitively weaker before surgery – with worse working memory, slowed mental processing and evidence of brain atrophy as seen in imaging scans – demonstrated the biggest network declines after surgery.

Researchers say they do not yet know if or how patients perceive these network declines. They may contribute to brain “fuzziness” some patients experience right after surgery.

The study, which was published today online ahead of print in the Journal of Alzheimer’s Disease, was conducted to help scientists understand the causes of postsurgical cognitive impairment, which causes memory and thinking problems in about 15 to 30 percent of older adult patients, Tanner said. In most cases, these thinking and memory problems will resolve within six months to a year after surgery.

“Our study builds on 50 years of research into how the aging brain responds to anesthesia and surgery,” Tanner said. “We know older age and cognitive impairment before surgery are risk factors, but the specific causes are not known.”

For the UF study, the team conducted cognitive and brain imaging tests before and after surgery on 48 patients ages 60 and older undergoing a knee replacement. Results were compared with age-matched adults who have knee osteoarthritis, but did not have surgery.

The researchers used resting state functional MRI to look at patterns of blood flow in the brain while patients were lying still. Imaging data helped researchers understand how blood flow changes affected connections across brain networks that are responsible for functions such as memories of oneself and others, determining what outside stimuli deserve further attention, and working memory.

Participants who did not have surgery did not demonstrate any changes across the two brain scans, but 23 percent of participants who had knee replacement surgery showed large declines in connectivity in at least one brain network when tested 48 hours after surgery.

“It was surprising to observe such significant effects of orthopedic surgery on the human brain,” said Haiqing Huang, Ph.D., the study’s other lead author, a data manager at the University of Pittsburgh’s Brain Aging & Cognitive Health Lab and a graduate of the biomedical engineering program at the UF Herbert Wertheim College of Engineering.

The investigators say more research is needed to learn if the brain network changes persist.

“Our goals include investigating if patients who have this brain change after surgery continue to show this change later in their recovery, say at three months or one year after the surgery,” said Catherine Price, Ph.D., the study’s senior author and a UF associate professor of clinical and health psychology and anesthesiology.

People with concerns about their attention or memory should discuss them with their surgical team, Tanner said. At UF Health, neuropsychologists and anesthesiologists have established what is believed to be the first clinical service to identify older adults who may be at risk of developing cognitive problems after surgery so that health care providers can intervene to lessen the impact.

“We strongly believe clinicians need to consider preoperative memory and attention abilities in their patients,” said Price, also the co-director of the Perioperative Cognitive and Anesthesia Network, or PeCAN, service. “Across the nation, however, cognition is not routinely assessed prior to surgery.”

There are also actions patients can take on their own, based on previous studies of healthy aging.

“The brain is resilient and there are things we can do to help protect our brains before and after surgery,” Tanner said. “Exercise, following a Mediterranean-style diet (primarily vegetables, fruits and whole grains), remaining mentally and socially active and otherwise striving to stay as healthy as possible – all might help patients’ brains cope with surgery better,” Tanner said.

—

Mingzhou Ding, Ph.D., of the J. Crayton Pruitt Family department of biomedical engineering in the Herbert Wertheim College of Engineering, served as the study’s other senior author. The project is part of a larger investigation involving Thomas Mareci, Ph.D., of the department of biochemistry and molecular biology in the College of Medicine and the Evelyn F. and William L. McKnight Brain Institute; Hari Parvataneni, M.D., of the department of orthopaedics and rehabilitation in the College of Medicine; Ilona Schmalfuss, M.D., of the department of radiology in the College of Medicine; Mark Rice, M.D., and Cynthia Garvan, Ph.D., of the department of anesthesiology in the College of Medicine; and Ann Horgas, Ph.D., of the department of biobehavioral nursing science in the College of Nursing. The research was supported by funding from the National Institutes of Health.

Press release source.

Reference

Huang H, Tanner J, Parvataneni H, Rice M, Horgas A, Ding M, Price C (2018) Impact of Total Knee Arthroplasty with General Anesthesia on Brain Networks: Cognitive Efficiency and Ventricular Volume Predict Functional Connectivity Decline in Older Adults. J Alzheimers Dis 62, 319-333.

Posted on

Memory Problems in Some With Parkinson’s Disease

From a recent news release by Jill Pease at the University of Florida.

Using a combination of neuropsychological testing and brain imaging, University of Florida researchers have discovered that in a group of recently-diagnosed patients with Parkinson’s disease, about one quarter have significant memory problems.

Parkinson’s disease is commonly known as a movement disorder that leads to tremors and muscle rigidity, but there is growing recognition of cognitive problems associated with the disease. One of the most common is slower thinking speed that causes patients to have trouble quickly retrieving information. The UF study identifies a subset of patients who have a different kind of cognitive issue — memory problems, or difficulty learning and retaining new information.

The findings were published July 24 in the journal PLOS ONE.

“While a large proportion of people with Parkinson’s will experience slower thinking speed, which may make them less quick to speak or have difficulty doing two things at once, we now know that there are a subset of individuals with Parkinson’s disease who have memory problems,” said Catherine Price, Ph.D., the study’s senior author and an associate professor in the UF College of Public Health and Health Professions’ department of clinical and health psychology, part of UF Health. “It is important to recognize which people have issues with learning and memory so we can improve diagnostic accuracy and determine if they would benefit from certain pharmaceutical or behavioral interventions.”

For the UF study, 40 people in the early stages of Parkinson’s disease and 40 healthy older adults completed neuropsychological assessments and verbal memory tests.

About half the participants with Parkinson’s disease struggled with an aspect of memory, such as learning and retaining information, or recalling verbal information, said lead author Jared Tanner, Ph.D., an assistant research professor in the UF department of clinical and health psychology who conducted the study as part of his dissertation research for a UF doctoral degree in clinical psychology.

“And then half of those participants, or nearly one quarter of all participants with Parkinson’s, were really having a difficult time consistently with their memory, enough that it would be noticeable to other people,” said Tanner, adding that researchers were encouraged by the fact that most participants in the initial stages of Parkinson’s were not having significant memory problems.

All participants received brain scans, which used new imaging techniques that allowed the scientists to navigate the pathways of white matter fibers, the tissue through which messages travel across the brain. The methodology was developed by the research group ofThomas Mareci, Ph.D., a professor of biochemistry and molecular biology in the UF College of Medicine, and is described in a paper published July 14 in PLOS ONE.

Experts have theorized that cognitive problems in Parkinson’s are caused by a shortage of the brain chemical dopamine, which is responsible for patients’ motor issues. But with the help of imaging, the UF researchers were able to spot changes in the brain’s gray and white matter that appear unrelated to dopamine loss and are specific to those patients with Parkinson’s who have memory problems.

“Not only is gray matter important for memory, in Parkinson’s disease white matter connections between the temporal lobe and a region in the posterior portion of the brain called the retrosplenial cortex were particularly important in the recall of verbal information,” Tanner said. “People with Parkinson’s disease who had stronger connections between these areas of the brain did better at remembering information.”

Tanner’s study is part of a larger research project supported by a $2.1 million grant from the National Institute of Neurological Disorders and Stroke of the National Institutes of Health. Researchers led by Price are using imaging and cognitive testing to determine profiles for the cognitive problems that most commonly affect patients with Parkinson’s. The information gleaned from the research could help clinicians foreshadow the type of cognitive impairment a patient may experience over time, if any, and tailor treatment plans accordingly.

Posted on

Art of Neuroimaging

Check out more images on my neuroimaging site.

Posted on

Video Introduction to the Cingulum

I posted this on my neuroimaging blog and thought I should post it here too. This is a video I put together about the cingulum, a prominent white matter fiber track in the brain that is involved in emotion, attention, memory, among many other functions. All images except one from Gray’s Anatomy (the anatomy book, not the T.V. show) were created by me using some fairly advanced imaging techniques. If you are interested about some of the techniques, read my neuroimaging blog.

Posted on

New Neuroimaging Website

I’ve started an online structural neuroimaging guide for users of Mac OS X. The site can be found here. I am just beginning with it so there is not much information there yet but I hope to slowly expand it and make it a good resource for things related to neuroimaging, particularly structural MRI (including diffusion weighted images). My primary interests are with neuroimaging, neuroanatomy, and neuropsychology; I spend the bulk of my research time doing one of my favorite things – dealing with methods of neuroimaging analysis. While my role is not as technical as some of our collaborators, I enjoy the process of processing MRIs. In the process I have learned a great deal about imaging and wanted to put together a series of guides that will allow others, especially students and novices, to conduct their own analyses. There is a lot of very useful information out there but it is not consolidated into any one locale. One thing I plan on doing is consolidating much of the information into one place and making it easy to follow.

Posted on

Leukoaraiosis and Lacunes – A Very Brief Overview

As people age, it is common for their brain white matter to change. These changes often appear as bright white spots on T2-weighted MR scans. These areas or spots of hyperintensity (i.e., white matter hyperintensities {WMH}) are also called leukoaraiosis (LA). Researchers are still investigating the exact nature and pathology of these abnormalities but our understanding of them is increasing. They most often seem to start around the lateral ventricles and spread from there, although it is possible to have punctate WMH throughout the brain white matter (i.e., WMH that are not connected to other regions). WMH on brain MRIs represent rarefaction of the white matter, including swelling, demyelination, and damage, although the exact nature and combination of the white matter changes is not known. These WMH can interfere with normal cognitive functioning, including processing speed, attention, inhibition, as well as global executive functioning (although these claims are still being investigated).

Other damage to white matter includes lacunes, which are little holes in the brain, much like the holes in Swiss cheese. They are caused by mini infarcts, or strokes, or other processes. Most of the time they are due to “silent strokes”, or strokes that are small enough that the person does not have any noticeable stroke symptoms. These lacunes can have similar impact on cognition as WMH. Both WMH and lacunes are related to vascular risk factors, such as hyper- or hypo-tension, diabetes, etc.

Posted on

Moral Development and the Brain

Moral reasoning is the ability a person has to reason in and through social, ethical, and emotional situations. One component of moral reasoning is moral behavior, which is the intentional and voluntary acting in a prosocial manner (Walker, 2004). Moral behavior and reasoning are the foundation for “many human social and cultural institutions such as family structures, legal and political government systems that affect the lives of virtually every person” (Eslinger, Flaherty-Craig, & Benton, 2004, p. 100). Often situations in life are morally ambiguous and involve a choice between two actions that both have consequences that may or may not be in opposition to each other. Some researchers, such as Lawrence Kohlberg, believe that people will reason through these situations at varying levels or stages, with some in a very concrete and egotistic manner and others in an abstract and universal manner.

Lawrence Kohlberg was the first researcher to come up with a major testable theory of moral development. He formulated six stages of development, with most adults reaching stage four, a few five, and very few stage six. The first two stages are at the pre-conventional level (typically self-centered and concrete reasoning), stages three and four are at the conventional level (recognition of social norms and laws), and the last two stages at the post-conventional level (recognition of universal rights and responsibilities). While Kohlberg’s theory of moral development is a stage model, the progression through the stages is not necessarily viewed as invariant. This means that people reach them at different rates and do not always reason at a particular stage with any given dilemma. There is significant variability within and between people in moral reasoning abilities. Most research focuses on between-person variability.

Continue reading “Moral Development and the Brain”

Posted on

MedINRIA MRI Visualization and Processing

I just ran across a site that has a few medical imaging software packages. One of them is MedINRIA.

“MedINRIA aims at providing to clinicians state-of-the-art algorithms dedicated to medical image processing and visualization. Efforts have been made to simplify the user interface, while keeping high-level algorithms. Each application is called a module, and can be loaded dynamically from a single main window. MedINRIA is available for Microsoft Windows XP/Vista, Linux Fedora Core, MacOSX, and is fully multithreaded.”

Link to a description and download.

MedINRIA screenshot

I have not tried the software yet – my MRI analysis software is FSL – but this software looks promising. Plus it runs natively on Windows, Linux (Fedora Core), and Mac OS X (FSL only runs natively in OS X and Linux – it’s a little tricky to run in Windows). Not that running in Windows is necessarily a perk – our preferred MRI processing workstation is a Mac – but many people are using Windows. If I get around to installing the software, I’ll post a review of it later. I’m always looking to user-friendly ways to analyze MRI data. Best of all, like FSL, it is free. It is based, in part, on the open-source and excellent ITK and VTK packages.

Posted on

The beginnings of functional neuroimaging

Angelo MossoAngelo Mosso was an Italian physiologist, interested in many things but among them, blood flow and blood pressure in humans. He was born in Turin in 1846 to a father who was a carpenter by trade. Showing great promise in school, Mosso was able to attend the University of Turin and study the natural sciences. Always the consummate and prodigious researcher, over the course of his career he published more than 200 articles and books. Mosso’s work helped lay the foundation for many important (and modern) neuroscientific research methods, such as fMRI and the polygraph.

Mosso demonstrated in the late 1800s an increase in brain blood vessel pulsation as people thought about things. He interpreted this to mean that blood flow increased to the brain when people had thoughts. This particular study was one of the first (documented) functional neuroimaging (of sorts) studies. Both fMRI and PET are based on the idea that increased blood flow to the brain is associated with changes in cognition. It’s doubtful that he could have imagined how influential this research would be.

Visit this site for a longer biography of Mosso.

Proudly powered by WordPress