[Lala]

Now to add my 2 cents. Here's how the scans are used in a stage 4 case.
Every 2 to 3 months I have various scans to see the response to treatment. The Catscan of the Abdomen and Chest are used to monitor my Liver mets. I have the Bone Scan for a full skeletal picture to monitor my bone mets. In addition, I have a MRI of the Thoracic and Lumbar region of the Spine, this offers a far better view than the bone scan. I have a Brain MRI every 6 months as per the request of my oncologist whom thinks all Stage 4 Her2+ need to do this schedule. I have recently changed that schedule. I now have a Brain MRI every few months to make sure I am NED in the Brain.
I have a Pet Scan after every treatment course is completed in order to see the total response of the treatment, this is usually every 6 months or even yearly.

Every person is different, I believe every newly diagnosed cancer patient needs baseline scans to insure proper staging.