UBC researchers advance their multiple sclerosis imaging

At the UBC MRI Research Centre, which is currently staffed by 70 principal investigators, the majority of studies and clinical trials are brain research, with MSrelated research as a principle area of interest. The center installed a 3.0T Ingenia Elition scanner in December 2018 as a successor of their Achieva 3.0T, with the intention to use it for all future research studies.

Multiple sclerosis or MS is a neurodegenerative disease that is characterized by myelin degradation, resulting in cognitive and motor deficits. According to Dr. Shannon Kolind, MR imaging for diagnosis and monitoring of MS is moving to higher field strength and using more 3D sequences, as reflected in the CMSC guidelines [1-3].

Dr. Kolind says that Ingenia Elition has opened up a world of different options and features and it has been tremendously exciting to discover how these can benefit their protocols. “Switching from our old scanner to Elition is like jumping from a flip phone to the latest smart phone,” she adds.

“The biggest jump is being able to turn on Compressed SENSE; it has definitely made sequences faster, allowing us to fit in more types of images. However, in most studies one or two scans are the main focus, so we can also stick to the time and apply Compressed SENSE to improve the resolution or even the coverage. For example, instead

of limiting MWI to the brain, even without the cerebellum, we can now spend about the same amount of time and scan the whole brain and the cervical spinal cord, which is a huge boost for us.”

Dr. Rauscher says, “For MWI we perform 3D T2 with 32 or more echoes. This used to take a long time, but with Compressed SENSE we can decrease this to ten minutes for the whole head. Because of the large field of view (FOV) on the readout direction, we even get information from the brainstem, which we previously missed when we were using the GRASE approach. Having the whole head scan is nice because it has spatial resolution, orientation and FOV that are comparable to the standard 3D clinical MS scans, including the FLAIR and 3D T2, and a 3D T1 for brain volume.” 

For Dr. Kolind, the Elition excels in advanced neuroimaging for two main reasons. “It's image quality and access to so many different imaging parameters. We’re involved in several multi-center studies, and we can always easily identify the images that came from our Elition scanner, because they are just so beautiful – even though it seems like we’ve set our parameters similarly to other study participants. And as a physicist, being able to do many things, for instance to push resolution and save time, is really helpful.”

According to Dr. MacKay, MWI images benefit from Elition’s high quality gradients. “We need good gradients because we want to be able to do multi-echo sequences that have short TE times.”

Dr. Rauscher says, “With better gradients we can use a shorter echo spacing on the spin echo, so we get better sampling of the rapidly decaying myelin signal, which typically has T2 of around 10-20 milliseconds at 3 Tesla. If we can reduce echo spacing from about 8 to 5-6 milliseconds, we get a much better sampling of the short decay component and increase our SNR, which is a big advantage. The same is true for multi-echo gradient echo which we use for susceptibility mapping and for mapping venous vessels in MS.” 

In practice, Ingenia Elition allows the team to do things now that were not possible before: “There are some scans that we didn’t do before, because the scans were taking too long. With Elition we can combine scans that would have been prohibitively long on the old scanner.