brain health

In our previous blogs, we discussed ASL MRI to image abnormal blood vessels in Moyamoya patients. We looked at a study that compared MRI and PET images of normal and healthy people. In this blog, we will look at the application of ASL MRI on adult Moyamoya patients.

According to the latest study by Dr. Moss Zhao (AHA Postdoctoral Fellow, 2021), ASL MRI can detect impaired blood flow and circulation in Moyamoya patients without any radiation or contrast agents.

In this study, Dr. Zhao’s team enrolled nearly 30 adult Moyamoya patients without acute stroke or tissue infarcts in the brain. They scanned the brain of these patients using the advanced ASL MRI technique (multi-delay ASL) that were tested successfully on normal and healthy people before. Similar to the study designed in the previous blog, Dr. Zhao’s team collected both ASL and PET images from the Moyamoya patients at the same time before these patients underwent their bypass surgery. The results from this study were convincing that ASL can replace PET to characterize the pathophysiology of Moyamoya disease patients. The image in this blog shows the vessel occlusion and its impact on blood flow in a Moyamoya patient.

Another advantage of ASL is the elimination of contrast agents. In many MRI exams, patients need to receive a contrast agent (such as gadolinium) to enhance the image quality. However, the contrast agent can cause side effects and deposit in the brain. Although there is no evidence suggesting its impact on health, we should minimize the use of these contrast agents. In the same study, Dr. Zhao’s team also demonstrated that the advanced ASL can create images without contrast agents and that doctors favored the new ASL technique over the conventional contrast-based imaging method.

Taken together, ASL MRI will become more accessible to radiologists to diagnose Moyamoya disease without causing side effects to patients. The technique will allow safe, affordable, and fast for imaging to identify patients with a higher risk for stroke.

Image source: JCBFM

REFERENCE

https://doi.org/10.1177/0271678X221083471

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In our previous blog, we discussed Moyamoya disease – a cerebrovascular disorder that affects the blood vessels in the brain and disproportionately affects women and Asians. It often begins in childhood and causes the patient to have a high risk of stroke. In this blog, we will discuss the process of how Moyamoya disease is diagnosed using medical imaging.

When a patient presents symptoms of Moyamoya disease such as blurred vision, muscle twitching, and/or weakness of one side of the body, a physician may order an imaging exam including computerized tomography (CT), magnetic resonance imaging (MRI), or digital subtraction angiography (DSA). These scans can show the structure and functions of the brain and whether the blood vessels are occluded (blocked). The scan often takes place for about 30 minutes and the side effects are negligible. A radiologist would interpret the scans and produce a report about the findings based on the images. Depending on the type of the scan performed, this report often includes information about the structure and functions of the patient’s brain, whether there are lesions, the blood flow in the brain, and the blood vessels in the brain and neck.

Doctors can also order an advanced MRI procedure whereby the patient is given a drug during the MRI exam. Typically, the drug is injected intravenously by the attending MR technologist during the scan. This drug is known as acetazolamide or Diamox, and it is often used to treat altitude sickness. Scientists found that acetazolamide can also increase the blood flow in the brain for a short period of time without harming the patient. As we mentioned in the previous blog, Moyamoya patients often have a high risk for stroke during stressful conditions. By giving the patient acetazolamide during an MRI scan, doctors can create a temporary and artificial stressful condition to determine if the patient has a high risk for stroke. The effect of acetazolamide should subside after a few hours of the MRI exam. Recently, researchers at Stanford University demonstrated this technique to identify high-risk Moyamoya patients.

Image source: Stroke

References:

https://www.ahajournals.org/doi/full/10.1161/STROKEAHA.117.017773

PET or MRI, that is the question – Part 2

Medical Imaging – the Window to the Brain of Moyamoya Disease Patients