A/Prof Chan Ling Ling (right) studying the MRI images with Septian Hartono (left) and Ms Lee Weiling, Senior Radiographer, SGH.
An emerging new Magnetic Resonance Imaging (MRI) method aims to improve the diagnosis of dementia and Parkinson’s in Singapore. Associate Professor Chan Ling Ling, senior consultant radiologist & clinician scientist, Singapore General Hospital, explains the science behind the new MRI technique, how her team’s research benefits Asians and its potential to harness the power of artificial intelligence.
MRI scans have been available in Singapore for years. How does your research advance this imaging technique?
MRI scans have provided radiation-free diagnostic images for more than 30 years, but we are still discovering new diagnostic uses. They are particularly good for imaging the brain because they can depict brain structures with exquisite image contrast. MRI uses a strong magnetic field and radiofrequency waves to produce images of our body. The challenge for researchers is to know which brain structures to examine to help with diagnosis, design radio wave signals that generate the best contrast to visualise those structures, write software to translate the imaging data into brain images, and obtain quantitative information from the structures examined for diagnosis and monitoring of disease progression.
One of our current areas of interest is white matter myelin, a sheath surrounding nerve cells which enables rapid signal transmission and hence vital for proper nerve and brain function. We hypothesise that different myelin changes occur in Alzheimer’s disease and vascular dementia, two sub-types of dementia. We believe that a new emerging MRI method called Myelin Water Imaging could help diagnose and differentiate these two sub-types of dementia, so that patients can receive the most appropriate care for their condition.
What is the difference between Alzheimer’s disease and vascular dementia?
These are the two most common types of dementia in Singapore, but the causes and treatments are different.
Alzheimer’s disease is caused by a build-up of protein plaques at nerve junctions in the brain. This disrupts the nerve signals resulting in problems with memory, language, reasoning and activities of daily living. This currently affects around 40,000 people in Singapore and the number is expected to grow with our ageing population. While there is no cure for this progressive illness, there are drugs that can help to reduce the symptoms in the early and mid-stages of the disease.
In vascular dementia, the walls of the small blood vessels in the brain thicken and become rigid. This reduces blood flow, damaging brain cells and causing cognitive decline. Asians are genetically more prone to this small vessel disease, and high blood pressure and diabetes increase the risk. In Singapore, 50% of adults over 50 years have high blood pressure and one in nine Singaporeans aged 18 to 69 years has diabetes, so this form of dementia is of growing concern. The good news is that early diagnosis can slow down the progression of vascular dementia through medication and healthy lifestyle habits to lower blood pressure and blood sugar levels to normal limits.
However, the diagnosis of dementia is often not so clear-cut and the majority of elderly patients have a mix of both Alzheimer’s and vascular dementia. Being able to quantify the proportion of Alzheimer’s and vascular dementia in a patient could help guide patient management.
What stage is your research currently at?
Myelin Water Imaging is a novel, advanced MRI technique that is still in the research phase, so it is not yet ready to be rolled out as a ‘plug and play’ diagnostic tool. Researchers at University of British Columbia (UBC) in Vancouver, Canada and Seoul National University (SNU), South Korea, recently developed this technique to allow non-invasive measurement of myelin in the brain. We are now collaborating with these international partners and testing this technique on some of our MRI scanners within SingHealth. Septian Hartono, a medical physicist at the National Neuroscience Institute, has implemented the technique from UBC & SNU which includes the software to produce a myelin map from the raw images so that radiologists can measure changes in the myelin content. We plan to conduct MRI brain scans on a total of 1,000 volunteers which include healthy adults and patients with Alzheimer’s, vascular dementia or Parkinsonism.
For example, Parkinson’s is traditionally considered a movement disorder caused by a lack of dopamine and characterised by the triad of slowness, stiffness and tremors, or “Parkinsonism”. However, different motor sub-types and non-motor health issues such as cognitive impairment are increasingly known to be associated with the disease and atypical Parkinsonism. Researchers have observed regional patterns of white matter myelin changes in the brain which are associated with distinct symptom patterns in Parkinson’s disease. We also hope to find myelin differences in regional white matter that could aid in differentiating motor sub-types of Parkinson’s disease and atypical Parkinsonism. This could impact the treatment that is prescribed for the patient.
What is the potential for your research?
This research project will form the basis of a much-needed resource: a database of Asian MRI brain scans. Imaging databases currently exist in the West but studies have shown differences in brains between Caucasians and Asians.
Once we have built a large database, we can harness the power of deep learning and artificial intelligence to form accurate models for disease predictions for our patients. Deep learning is mostly untapped in the current clinical scene and will develop into an important tool in the future, aiding in quick and unbiased diagnosis and prognosis for our patients.
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