Usually they will do a PET scan to look for lymph node involvement (this measures the sugars that are given off by cancer cells replicating). The MRI looks at the structures that are in the area being scanned. The CT is often combined with the PET, so that may be how they are doing it.

Each doctor is different on the plan, but my PET came back positive, so they did the neck dissection, removed and tested a bunch of nodes, but all were negative for cancer. Because there is nerve and muscle damage (it takes a good long while to get that back), it's not usually something they will do to investigate, unless there's an indication of need.

Glad you worked out a system with your wife. It's always easier for a loved one to see how we are doing - it's much easier to lie by email or text, and she would likely have felt that you were downplaying how you were doing to protect her.