Tag: MRI

Significant White Matter Changes in Autism Revealed by MRI

Significant alterations in the brain’s white matter in adolescents with autism spectrum disorder (ASD). Credit: RSNA and researcher, Clara Weber

Using specialised MRI, researchers found significant changes in the microstructure of the brain’s white matter, especially in the corpus callosum in adolescents and young adults with autism spectrum disorder (ASD) compared to controls. This research will be presented next week at the annual meeting of the Radiological Society of North America (RSNA).

“One in 68 children in the U.S. is affected by ASD, but high variety in symptom manifestation and severity make it hard to recognise the condition early and monitor treatment response,” explained Clara Weber, postgraduate research fellow at Yale University School of Medicine. “We aim to find neuroimaging biomarkers that can potentially facilitate diagnosis and therapy planning.”

Researchers reviewed diffusion tensor imaging (DTI) brain scans from a large dataset of patients between the age of six months and 50 years. DTI is an MRI technique that measures connectivity in the brain by detecting how water moves along its white matter tracts. Water molecules diffuse differently through the brain, depending on the integrity, architecture and presence of barriers in tissue.

“If you think of gray matter as the computer, white matter is like the cables,” Weber said. “DTI helps us assess how connected and intact those cables are.”

For the study, clinical and DTI data from 583 patients from four existing studies of distinct patient populations were analysed: infants (median age 7 months), toddlers (median age 32 months), adolescents, and young adults.

“One of the strengths of our study is that we looked at a wide range of age groups, not just school-aged children,” Weber said.

To assess the influences of age and ASD diagnosis on white matter microstructure, the research team created fractional anisotropy, mean diffusivity and radial diffusivity maps using data from the four studies.

Fractional anisotropy is the extent water diffusion is restricted to just one direction. A value of zero means that diffusion is unrestricted in all directions, while one means that diffusion is unidirectional. Mean diffusivity is the overall mobility of water molecules, indicating how densely cells are packed together. Radial diffusivity is the extent water diffuses perpendicular to a white matter tract.

“When white matter integrity is disrupted, we see more water diffusing perpendicularly, which translates to a higher radial diffusivity,” Weber said.

The key finding of the analysis was reduced fractional anisotropy within the anterior/middle tracts of the corpus callosum in adolescent and young adult ASD patients compared to individuals in the control group. The corpus callosum is a thick bundle of nerve fibers that connects and allows the two sides of the brain to communicate. Corresponding increases in ASD-related mean diffusivity and radial diffusivity were found in young adults.

“In adolescents, we saw a significant influence of autism,” Weber said. “In adults, the effect was even more pronounced. Our results support the idea of impaired brain connectivity in autism, especially in tracts that connect both hemispheres.”

Compared to controls, no reduction in fractional anisotropy was seen in the same tracts in toddlers and infants with ASD.

The researchers hope the findings can help improve early diagnosis of ASD and provide potential objective biomarkers to monitor treatment response.

“We need to find more objective biomarkers for the disorder that can be applied in clinical practice,” Weber said.

Source: EurekAlert!

MRI Clear Cell Likelihood Score Matches Renal Carcinoma Growth

Photo by MART PRODUCTION from Pexels

According to a new study, the MRI-derived standardised non-invasive clear cell likelihood score (ccLS) is correlated with the growth rate of small renal masses (cT1a, <4 cm) and could help guide personalised management.

The study was published in the American Roentgen Ray Society’s American Journal of Roentgenology. Extracted from clinical reports, “the ccLS scores the likelihood that the small renal mass represents clear cell renal cell carcinoma, from 1 (very unlikely) to 5 (very likely),” explained corresponding author Ivan Pedrosa from the University of Texas Southwestern Medical Center at Dallas. “Small renal masses with lower ccLS may be considered for active surveillance, whereas small renal masses with higher ccLS may warrant earlier intervention.”

The team’s retrospective study included consecutive small renal masses assigned a ccLS on clinical MRI exams performed from June 2016 to November 2019. Tumour size measurements were obtained from available prior and follow-up cross-sectional imaging examinations, up to June 2020.

Among 389 small renal masses in 339 patients (198 men, 141 women; median age, 65 years) on active surveillance that were assigned a ccLS on clinical MRI examinations, those with ccLS4-5 grew significantly faster (9% diameter, 29% volume yearly) than those with ccLS1-2 (5% diameter, p<.001; 16% volume, p<.001) or ccLS3 (4% diameter, p<.001; 15% volume, p<.001).

With a lack of validated imaging markers to characterise biologic aggressiveness of small renal masses hindering medical decision making, “growth is associated with ccLS in small renal masses,” the authors reiterated, “with higher ccLS correlating with faster growth.”

Source: EurekAlert!

Earlier, Improved MRI Detects ‘Broken-heart’ Syndrome

A new study from Karolinska Institutet in Sweden suggests that early magnetic resonance imaging (MRI) of the heart can greatly increase the rate of diagnosis of broken-heart syndrome, which can happen when there is no obvious cause in the coronary artery. 

Myocardial infarction is typically caused by a blockage of the coronary artery by a blood clot. However, in up to 10% of all myocardial infarctions, no obvious cause in the coronary artery is found, and so the working diagnosis MINOCA (myocardial infarction with non-obstructive coronary arteries) is given, which can subsequently lead to one of several diagnoses.

Most of these patients are women, many of whom are diagnosed with takotsubo cardiomyopathy (broken-heart syndrome), characterised by reduced heart function that is likely stress-related, presenting the same symptoms as a standard heart attack.

“Around 80 to 90% of broken-heart sufferers are women, and the disease is associated with mental stress,” said principal investigator Per Tornvall, senior physician and professor at the Department of Clinical Science and Education, Stockholm South General Hospital, Karolinska Institutet. “There also seems to be a link to hypersensitivity towards stress caused by low estrogen levels. Unfortunately, research on the investigation and treatment of myocardial infarction is often done on men, while female heart disease is less studied.”

In a prior study with 150 patients, cardiovascular magnetic resonance (CMR) is often done when examining patients with MINOCA. CMR conducted approximately 10 days after onset can result in a diagnosis in under half the patients, normally takotsubo or myocarditis (inflammation of the heart muscle), Now, the same researchers have tested a new, more sensitive CMR technique two to four days after onset on a comparable group of 148 patients. They found that 77% of the patients could be diagnosed: 35% of takotsubo and 17% of myocardial inflammation, compared with 19 and 7%, respectively, in the first study.

“We don’t know how much effect the improved CMR technique has, but the results suggest that with early examination more patients can get a correct diagnosis and therefore the right treatment,” says Professor Tornvall. “The next step is for us to develop the CMR examination with pharmacological stress of the heart. This will enable us to study the smallest of the blood vessels and hopefully find a cause for the 23% who received no diagnosis.”

Source: Medical Xpress

Journal information: Peder Sörensson et al. Early Comprehensive Cardiovascular Magnetic Resonance Imaging in Patients With Myocardial Infarction With Nonobstructive Coronary Arteries, JACC: Cardiovascular Imaging (2021). DOI: 10.1016/j.jcmg.2021.02.021