Yes, even people who aren't very claustrophobic can be pretty unhappy about having to climb into a tube and lay perfectly still while listening to weird, loud, grinding machine noises.
We made the Relaxed and Awake guided imagery precisely for such yucky medical procedures (- I actually wanted to call this one Yucky Medical Procedures, but I was out-voted by the staff -), and it's designed to provide relaxation, de-stressing and distraction, in the form of warm and fuzzy emotional support and other calming, supportive images during the procedure. This guided meditation narrative even has suggestions for keeping the listener warm, because most of these procedures require chilly rooms to keep the machinery running properly.
We recommend this guided imagery for heart caths, biopsies, aspirations, PET scans, MRI's, certain proctological and gynecological exams, and any surgery that requires that the patient be awake. In other words, it’s good for anything that can make a compis mentus person on the receiving end anxious or fearful.
It might benefit your patient to listen to it a few times in a relaxed setting at home before going for the procedure, so there can be a pleasant association with it beforehand – we suggest this with our chemotherapy guided imagery, too.
Hope this helps.