Entry requirements for Canada by country can be found here. You can also check whether you need an entry visa using the Government of Canada’s web tool.
Visitors from visa-exempt countries will need an electronic Travel Authorization (eTA) to enter Canada. These can be purchased online for $7 CAD.
If you are coming from a country requiring a visa for entry and you need a letter of invitation from the IMRF 2018 organizing committee, please indicate this in your abstract submission. You can also send an email directly to imrf2018@gmail.com.