TDRA Standardized Clinical Cognition MRI Protocol
Scientist Explains with Dr. Sandra Black
January 6, 2022
As part of the process of determining a dementia diagnosis, physicians commonly order magnetic resonance imaging (MRI), which is a scan that reveals fine details of the brain. Until the development of the TDRA Standardized Clinical Cognition MRI Protocol, there was no agreed-upon MRI protocol used for the diagnosis of dementia across TDRA partner sites. To maximize the benefit to patients, a standardized protocol was developed to ensure that high-quality imaging is being acquired across all TDRA sites.
What is it?
The TDRA Standardized Clinical Cognition MRI Protocol explains how to acquire a standard set of MRI brain images for patients being investigated for dementia. An MRI scanner can take many types of brain image. The protocol provides a series of instructions that can be programmed into the MRI machine, allowing the technician doing the scan to specify the optimal series of images to capture. The resulting set of MRI images shows various patterns of brain changes that occur in aging and in various types of dementia.
Implementing this protocol ensures that standards for imaging are met at each site so that dementia specialists are provided with a consistent level of information to inform their decision-making. The protocol will be used by each of the clinical dementia imaging sites in the TDRA, including Sunnybrook, the University Health Network (UHN), and Unity Health Toronto (UHT).
How does it work?
The images captured using the standardized protocol contain information about whether a person’s brain shows evidence of any of the known causes of dementia. The two leading causes of dementia are Alzheimer’s disease (AD) and cerebrovascular disease, or ‘vascular dementia’. Neurodegenerative disorders (e.g., AD) show patterns of shrinkage in different parts of the brain. For example, the hub for memory formation (affected in AD), or shrinkage of frontal lobes seen in a rarer condition called Frontotemporal Degeneration. Neurovascular diseases (e.g., vascular dementia) show injury affecting the brain’s blood vessels and brain tissue, such as stroke due to bleeding or blockage of an artery. The protocol is important because it allows doctors to visualize these major processes that can lead to brain loss contributing to dementia.
Additionally, there are certain comorbid conditions that commonly occur with dementia. A comorbid condition is an additional secondary disease that a person may have. Some of these ‘comorbidities’ cause visible impacts on the brain, and the MRI images in the protocol can help to capture this important information.
Some of the images are used qualitatively, meaning one looks for certain characteristics or features in the brain. For example, microbleeds (small leakage of blood cells into the brain) or strokes, including injury to brain tissues due to disrupted blood/oxygen flow to the area or larger brain bleeds. The images can also be measured quantitatively. Different brain compartments or specific regions can be measured in cubic centimeters, which can then benefit from new machine learning methods that can generate regional brain volumes very quickly. For example, the size and shape of the hippocampus, the brain’s memory hub, can now be generated in 90 seconds, whereas it used to take several hours to trace this tiny vital structure. Together, all the features examined are referred to as ‘imaging biomarkers’.
Biomarkers are critical to the ongoing understanding of the process of how a person develops dementia. There are many factors that can impact this process (e.g., genetics, lifestyle, modifiable risk-factors). As such, we need the best possible view of what is going on in a person’s brain to begin to tease apart the different disease-causing processes.
How was it developed?
The TDRA met with stakeholders across each site to learn their standard of care and needs. Then, a basic set of necessary protocols was agreed upon and implemented. The protocol was informed by other existing initiatives like the Canadian Dementia Imaging Protocol (CDIP), the Alzheimer’s Disease Neuroimaging Initiative (ADNI), and locally by the Sunnybrook Dementia Study protocol that has been used for >25 years.
Why is it important?
The TDRA Standardized Clinical Cognition MRI Protocol is like a gold standard set of instructions for clinicians to use. Requesting this protocol ensures that clinicians get an informative set of MRI images in half an hour, which will provide relevant information to assist with diagnosis and tracking disease progression. Without efforts like this, imaging protocols can vary widely from site to site, and may not include the various images needed to better understand the possible diagnostic considerations. The standardized protocol will help to drive clinical care forward and potentially improve diagnosis, outcomes, and treatment options for people living with dementia.
The standardized protocol will also improve translation of research findings. If the same MRI images are acquired across various sites, then findings from multi-site studies can be compared and combined. This will drive the underlying science forward, as well.
Next Steps?
The standardized protocol is now in place at participating TDRA sites. From here, the protocol will be monitored for use, quality, and appropriateness.
The overall goal is to use such standardized MRI protocols at sites across Toronto, Ontario, and Canada, which are in line with developments in other countries, in order to enable machine learning and ‘big data’ analysis. Hopefully, this will help the clinical-scientific community to understand and alleviate the heavy burden of dementia worldwide.
Read TDRA's statement about the protocol
Special thanks to Dr. Joel Ramirez and Christopher Scott for their contributions to this article.
