hidden

PET or MRI, that is the question – Part 1

In our previous blogs, we discussed that doctors can diagnose Moyamoya disease using medical imaging systems, such as positron emission tomography (PET) and magnetic resonance imaging (MRI). But which one is better?

According to some recent studies performed by Dr. Moss Zhao (AHA Postdoctoral Fellow, 2021) at Stanford University, MRI is better thanks to its accessibility, safety, and affordability.

For decades, PET has been the gold standard technique for diagnosing Moyamoya disease based on imaging the blood flow in the abnormal blood vessels in the brain. However, PET uses radioactive tracers to create the images, making it complex and expensive. Although the amount of radiation is less than a 5-hour flight, doctors have sought for alternative and less invasive techniques to replace PET, especially for children. In recent years, arterial spin labeling (ASL), an advanced MRI technique, has emerged to replace PET imaging to measure blood flow in the brain. Because ASL MRI is more accessible at most hospitals and the procedure is less complex than PET, ASL has gained popularity in many research and clinical institutions for Moyamoya patients.

At Stanford University, Dr. Moss Zhao demonstrated that ASL could replace the conventional PET imaging technique without exposing patients to radiation and causing side effects. The image quality and measurement accuracy of ASL are compatible with PET, implying that ASL can be used to characterize the abnormal blood flow and circulation in Moyamoya patients. Among the different implementations of ASL, Dr. Zhao developed an advanced technique dubbed ‘multi-delay ASL’ that gives the best image quality with the least amount of scanning time. For less than 5 minutes, multi-delay ASL can produce images that require more than 20 minutes for PET imaging. The image in this blog shows the images collected by ASL and PET at the same time from normal and healthy people. Using the latest ASL techniques, doctors can identify patients with a high risk for stroke based on their MRI scans for just under 5 minutes without using any radioactive substances. Dr. Zhao’s team is currently testing this technique on the pediatric population to enable this non-invasive imaging technology to be accessible to patients across the lifespan.

Image source: NeuroImage

References:

https://doi.org/10.1016/j.neuroimage.2021.117955

 

“The views, opinions, and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness, and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions, or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your health matters. If you think you are having a heart attack, stroke, or another emergency, please call 911 immediately.”

hidden

Bypass Surgery – Reducing Risk for Stroke in Moyamoya Patients

In our previous blog, we discussed the diagnosis of Moyamoya disease using medical imaging such as CT and MRI. Patients with Moyamoya disease often have a higher risk for stroke due to their abnormal blood vessels in the brain. Once the diagnosis is confirmed, several treatment strategies are available to prevent strokes from happening. One of the most effective ways is bypass surgery.

In essence, a bypass surgery connects a blood vessel from outside the brain to a vessel inside the brain to redirect blood flow around a blocked artery. The figure in this blog illustrates the bypass procedure for Moyamoya patients. In this case, the superficial temporal artery (STA) outside the brain is connect to the middle cerebral artery (MCA) inside the brain to restore cerebral blood flow (CBF). It is a very complicated procedure that often requires more than 6 hours to perform by well-trained neurosurgeons. If the patient has blocked vessels on both sides of the brain, the neurosurgeon often has to perform two procedures to treat each side separately. After the surgery, the patient will recover in the ICU before being discharged. The patient will also need to have regular imaging exams such as MRI or CT after the surgery. The images can help doctors monitor the recovery from the surgery and identify any new vessel occlusions and risk for strokes.

At Stanford Moyamoya center, Dr. Gary Steinberg is an eminent neurosurgeon who has performed hundreds of such bypass surgeries for Moyamoya patients all over the world. The center offers a highly experienced group of professionals who see several new patients every week, making Stanford the largest Moyamoya referral center in the world. The bypass procedures require approximately three days of hospitalization at Stanford Hospital or Lucile Packard Children’s Hospital Stanford. Post-operatively, patients experience some minor scalp pain from the incision while some patients may get mild headaches. Patients with Moyamoya have minimal restrictions after surgery. The Moyamoya center also has a team to support international patients who want to receive care and treatment in the US.

Source: Stroke https://www.ahajournals.org/doi/10.1161/strokeaha.117.018563

References:

https://www.ahajournals.org/doi/10.1161/strokeaha.117.018563

“The views, opinions, and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness, and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions, or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your health matters. If you think you are having a heart attack, stroke, or another emergency, please call 911 immediately.”

hidden

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

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

Image source: Stroke

References:

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

“The views, opinions, and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness, and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions, or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your health matters. If you think you are having a heart attack, stroke, or another emergency, please call 911 immediately.”

hidden

Moyamoya Disease

Moyamoya disease is a progressive cerebrovascular disorder that often begins during childhood. Patients with Moyamoya disease have injuries in their blood vessels at the base of the brain. The term ‘moyamoya’ comes from Japanese and means ‘puff of smoke’, which describes the appearance of abnormal blood vessels. Symptoms of Moyamoya disease include acute strokes, transient ischemic attacks (TIA), blurred vision, and weakness of one side of the body. Some researchers believe that Moyamoya disease is the result of inherited genetic disorders because individuals with Moyamoya often have close relatives who are also affected.

If the disease is not treated properly, patients will suffer from mental decline and recurrent strokes due to insufficient blood supply caused by moyamoya vessels in the brain. In severe cases, Moyamoya disease can cause death and life-long disabilities. The primary goal of treatment is to reduce the risk of strokes using medical and/or surgical interventions. In mild cases, medications are effective to prevent acute or recurrent strokes. In more severe cases, revascularization surgeries can restore normal blood flow bypassing affected blood vessels.

Imaging exams (such as CT or MRI) are often performed to diagnose Moyamoya disease and identify the location of the affected blood vessels. The most widely used techniques include CT perfusion, digital subtraction angiography, and MR angiography. In recent years, more advanced techniques such as arterial spin labeling have been employed to evaluate the blood flow and circulation without radiation or contrast agents.

AHA has been a pioneer in providing support for Moyamoya patients and funding research on this disease. I am honored to be supported by AHA to develop advanced imaging technologies to identify Moyamoya patients with a higher risk of stroke.

A recent story of a patient recovering from Moyamoya disease was covered by the AHA news:

https://www.heart.org/en/news/2019/03/27/after-4-strokes-rare-disease-and-brain-surgery-woman-helps-others

Image source: Moyamoya Foundation

 

References:

https://www.ninds.nih.gov/Disorders/All-Disorders/Moyamoya-Disease-Information-Page

https://stanfordhealthcare.org/medical-clinics/moyamoya-center.html

https://moyamoya-foundation.org/inspiration

 

“The views, opinions and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your personal health matters. If you think you are having a heart attack, stroke or another emergency, please call 911 immediately.”

hidden

Reaction of AHA Scientific Sessions 2021

This was my second time participating in AHA Scientific Sessions. Unlike previous years, I served as an AHA Early Career Blogger to livestream the conference on social media. Together with nearly 20 other bloggers, we created hundreds of tweets to keep the world engaged with AHA events and talks. For me, it was also a great opportunity to network and seek new collaborations. During the conference, I met over 50 clinicians and scientists who shared similar research interests and scientific passions with me. We have already set up plans to further discuss our thoughts to put our ideas into practice.

Supported by my AHA Postdoctoral Fellowship, I presented my abstract on novel stroke imaging to identify high-risk patients before a stroke happens. It is amazing to see the increasing number of early career investigators tackling the challenge of cardiovascular and cerebrovascular diseases. A larger number of them have been also funded by AHA grants and fellowships. A lot of shared the positive influence of receiving research support from AHA and how the award propelled their career development. We encouraged all trainees to apply for the numerous grants and fellowships that AHA offers.

Another highlight of this year’s conference was the international components where speakers from Europe and Asia demonstrated their amazing work virtually. For example, a joint event was held in collaboration with the Japanese Circulation Society (JCS) on the first day of the conference. Colleagues from Japan demonstrated their wonderful research and clinical practice to improve patient care for cardiovascular and cerebrovascular diseases. Like all the other sessions, there was so little time for all the conversations. Everybody is looking forward to an in-person event in 2022.

“The views, opinions and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your personal health matters. If you think you are having a heart attack, stroke or another emergency, please call 911 immediately.”

hidden

Being an Early Career Investigator at AHA21

Over 50 emerging scientists and clinicians were among the finalists of the Early Career Investigator Award in AHA Scientific Sessions 2021. These prestigious awards were designed to recognize the marvelous endeavors by early career investigators who submitted their abstracts to AHA Scientific Sessions 2021. The selection process included not only the quality of the abstracts but also their scientific acumen and contributions to their disciplines.

It is amazing to see the increasing number of early career investigators tackling the challenge of cardiovascular and cerebrovascular diseases. A larger number of them have been funded by AHA grants and fellowships. There are also more than international ten finalists from institutions in Europe and Asia. During the AHA Scientific Sessions, the finalists will present their oral abstracts. These presentations cover a wide range of topics ranging from basic sciences research to clinical applications. There are also several dedicated networking sessions for junior scientists and clinicians to expand their professional network for career development.

Another highlight of this year’s AHA Scientific Sessions is the joint event of AHA and Japanese Circulation Society (JCS) held on Nov 12, 2021. JCS has been one of the leading organizations of cardiovascular research for nearly 90 years. JCS is not only responsible for research and medical care for cardiovascular disease in Japan and Asia but also for aims to improve the health care system and train future researchers and physicians for cardiovascular diseases. During the annual meeting of JCS, the society always provide emerging scientists, clinicians, nurses, and other healthcare professionals with endless opportunities for networking and career development.

Last but not least, a team of AHA Career Bloggers will be live Tweeting during the scientific sessions. Make sure to follow the hashtag #AHA21 for the latest.

“The views, opinions and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your personal health matters. If you think you are having a heart attack, stroke or another emergency, please call 911 immediately.”