mri – Brainy Behavior

January 16, 2023January 16, 2023

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.

February 7, 2018February 26, 2018

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.

April 14, 2009

Video of my brain

I posted a video of my brain on YouTube just to show the quality of MRI scans we have now (and the fun things we can do with post-processing). The scans were done on a 3T Philips Achieva MR scanner. We acquired 2 T1 scans of my brain (160 1mm slices – 1 mm cubed voxel size) then post-processed the DICOMs using FreeSurfer. The skull-stripped output files (in NIFTI format) were then rendered in 3D in OsiriX. I created a fly-through movie of the brain and exported it as an MP4 movie. If you have any questions about the process, feel free to ask.

November 29, 2007November 29, 2007

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.

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