Dear all,
As many of you are aware, the primary magnet and other components of the Siemens Terra 7T scanner have been delivered in recent weeks.
We are of course hoping that this new scanner will be enthusiastically adopted by researchers, and I would like to provide some additional information to help planning studies.
Timeline
The system is scheduled to be ramped up in March, with Siemens commissioning to end in April. At present, the area is an active construction site with restricted access.
We will reserve two additional weeks for internal commissioning by the MRI Unit, and plan to open the schedule to research users the week of May 20 (after the May 17 Inaugural Symposium that I hope will be well attended).
IRB Approvals
With regards to ethics approval, researchers wishing to use the Terra (7T) in humans or animals will require either an amendment to an existing IRB protocol or a new protocol describing the procedures to be performed at 7T.
In general, it will not be necessary to file an Investigational Testing Authorization with Health Canada in human subjects older than one month, so long as standard limits for SAR, dB/dt, and sound levels are met (exceeding the latter limits requires a deliberate override of scanner safety features; neonates aged one month and less will require an ITA).
Ethics procedures are thus identical to those for 3T MRI and other imaging modalities at the BIC.
User Fees
The 7T MRI will be more expensive to operate than the 3T, due largely to the increased cost of the service contract. The expanded MRI program will also require additional staff to reap the full benefit of the new 7T instrument, with associated salary costs.
Initially, we will have some relief from these new operating costs thanks to various CFI sources. We will thus be able to offer a progressive pricing structure on the 7T, according to the following schedule:
Years 1-2: $500/hour
Years 3-4: $600/hour
Years 5+: $700/hour
(this applies only to the Siemens Terra 7T system, not the 3T Prisma)
Note that the above rates apply to academic research initiated by a non-profit entity. Researchers interested in conducting industry-sponsored research on the 7T should contact helene.day@mcgill.ca.
Patient Comfort and Safety
Some of you may have experienced the sense of vertigo that can arise when the head moves rapidly through the fringe fields of the 3T scanner. This effect, which is caused by magnetic forces on the inner ear, is more pronounced at 7T. MRI Unit technologists will work with participants to minimize this phenomenon, aided by the fact that the movable patient table is programmed to avoid rapid movements through fringe fields. Overall, this is not expected to be a significant issue.
With regards to surgical implants, we will adhere to previous policy for the 1.5T and 3T systems. Implants will be evaluated on a case-by-case basis by the MRI technologists, and other healthcare professionals associated with the study, to ensure safety at the relevant magnetic field. A similar policy will be observed regarding tattoos and other potential MR safety concerns.
It should be noted that the head coils included with the system are very tight fitting, to an extent that may be an issue for claustrophobic participants or individuals with a large head. These head coils do include a mirror and permit viewing of visual stimuli, albeit with a somewhat restricted angular field. We plan to procure additional coils in the coming months, which should help to overcome these limitations.
System Capabilities
As noted above, the system comes with two phased-array head coils (both 32-channel receive; one is 8-channel transmit, while the other transmits on a single quadrature channel). These coils are somewhat tight fitting, but will permit visual stimulation. Additional coils, such as occipital visual coils, will be obtained to facilitate visual stimulation and improve performance in occipital cortex.
With regards to the pulse sequence capabilities, the strength of the system will be in high-resolution structural and functional imaging, as well as spectroscopy. More details, and examples of MR protocols that should work ‘out of the box’ are available by request in pdf format (please send requests to ilana.leppert@mcgill.ca).
Realizing the full potential of the system, which goes far beyond the ‘out of the box’ sequences, will require ongoing collaboration between MRI Unit staff and the research community.
Access to 7T Facility
The new 7T MRI suite is located on North Wing level 2B, near the MEG Unit.
For reasons of safety and the privacy of research participants, access to the 7T facility will be controlled through card access in the same way as the current 3T. The change rooms on Webster 3B, currently used for 3T studies, will also be used by participants in 7T studies.
In order to shield adjacent facilities from magnetic fringe fields, it was necessary to raise the floor of the entire 7T suite by almost a metre. Access from North Wing Level B2 is thus gained via a short flight of stairs, or by a small lift. The lift is capable of transporting a hospital stretcher, wheelchair, or cart with equipment.
The 7T suite includes a toilet and an adjacent room that can be used for preparation of human participants or animal subjects. Medical and veterinary gases will be available, as well as stimulus presentation equipment similar to that in the 3T suite (please contact michael.ferreira@mcgill.ca for further details).
Scheduling of scanning sessions will be carried out using the same online system as the 3T MRI and other BIC systems (also used for billing). The schedule should open to research users the week of May 20.
I trust the above information will be helpful in your planning, and invite you to contact any member of the MRI Unit with further questions.
Best regards,
Rick
Rick Hoge, Ph.D.
Director, MRI Unit
McConnell Brain Imaging Centre, Montreal Neurological Institute
Associate Professor and Killam Scholar, Dept. of Neurology & Neurosurgery
Associate Member, Dept. of Biomedical Engineering
McGill University
rick.hoge@mcgill.ca
514-398-1929
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