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Help avoid repeat scans due to motion artifacts with an accelerated brain MR exam

Having a magnetic resonance (MR) scan of the head or brain can be intimidating for many patients. Some patients often have trouble with MR scans because of claustrophobia or anxiety. Other patients, such as children, on the other hand, have trouble staying still for the duration of the scan. This could be because they are bored, have too much energy, or are afraid. One way to reduce motion during a scan is to raise awareness of what is happening. Another way is to use shorter acquisition times, which may still feel like an eternity to a child but will often feel more comfortable for adult patients.

What is a brain MRI scan?

MR imaging (MRI) is a safe, non-invasive way to image a patient's body and head.1 The magnet inside the scanner is a super-conducting magnet, but patients often do not feel anything while going into the scanner or during the scan itself. To image the patient's brain, the radiologist will place a coil, an often-bulky, cage-like, white device, around the head.

This coil does two different things for brain and head MR.1 It picks up the signals emitted by a patient's body and transmits them to the computer, like an antenna. However, it can sometimes help to reduce head motion throughout the scan. The radiologist may place padding of some sort inside the coil and around a patient's head, which may make it harder to move. Unfortunately, this coil can be intimidating. This is because it is often a sturdy cage-like device and is sometimes called a bird-cage coil. The coil, like the scan itself, is non-invasive and very safe.

Brain and head MRI can be used to detect brain abnormalities, both structural and developmental, infections, blood vessel issues and lesions.1,2 A doctor may order an MRI of the brain to evaluate headaches, dizziness, weakness, blurry vision and seizures. It can also detect some diseases of the nervous system. The images that provide the information for the physician are detailed images of the tissue structures, and sometimes of the fluid, in the brain.

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Why are shorter acquisition and motion correction important?

Many researchers are working to enhance MR scans through faster pulse sequences and motion correction software.3 At Karolinska University Hospital, the team has been working to create a simplified echo planar imaging (EPI) method that may simplify the MR pulse sequence. Fast EPI can lead to a reduction in scan time by speeding up the sequences used to produce the images that the doctor needs to see.

The PROPELLER technique may help to correct for motion during a scan.3 PROPELLER stands for periodically rotated overlapping parallel lines with enhanced reconstruction. It is less susceptible to motion artifacts than the Cartesian method. This method is often combines with methods that acquire multiple slices at the same time, resulting in a reduction in scan time. When these two methods are combined with the fast EPI technique, the acquisition time may be significantly decreased.

Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital in South Korea also understand the need for quicker scanning protocols.4 They even use the phrase "time is brain" to refer to the effect ischemic stroke can have on the brain. Brain tissue may be rapidly lost as time progresses after a stroke. MR may be more sensitive for lesion detection and more specific for delineation of healthy and unhealthy tissue than CT in patients with acute ischemic stroke, meaning that the scan should be done as quickly as possible for the physician to best understand the patient's symptoms.4 Through the use of compressed sensing, doctors were able to understand the delineation of the lesions and imaged intracranial arteries in a short time. Through these images, they were able to decide on the more practical treatment plan. Their fast neuro-scan has helped a number of patients since then.

Through the use of knowledge and different techniques, radiology departments may see a reduction in motion artifacts. Education on the process of the MRI scan may reduce the anxiety experienced by patients, which may reduce the amount of motion artifacts seen on the images. Shorter acquisition time may also help reduce motion artifacts in pediatric patients and adult patients alike. This is due to the reduction in scan time that the patients experience. Hopefully, once patients become more aware of what is happening, brain and head MRI may seem less intimidating.

For more information, see "Two-minute MR ultra-fast neuro protocol."

References

1. Steven Dowshen. "Magnetic Resonance Imaging (MRI): Brain." KidsHealth.org. March 2014. Web. 26 March 2019. <https://kidshealth.org/en/parents/mri-brain.html>.

2. Jamie Crawford. "What to know about head and brain MRI scans." MedicalNewsToday. 10 October 2018. Web. 26 March 2019. <https://www.medicalnewstoday.com/articles/323303.php>.

3. Stefan Skare. "Multi-contrast EPI and the one-minute brain MR exam." SIGNA Pulse: Neuro Supplement. Autumn 2018; 24-27. Print. 26 March 2019.

4. Hye Jin Baek. "Two-minute MR ultra-fast neuro protocol." SIGNA Pulse. Autumn 2017. Web. 27 March 2019. <http://www.gesignapulse.com/signapulse/autumn-2017/MobilePagedArticle.action?articleId=1243894#articleId1243894>.