I’ve heard that for some the experience of undergoing an MRI scan is claustrophobic, but I find it oddly comfy and cocoon-like. OK, there are those gear-grinding screeches and thumps interrupting the music in the earphones. And the cumbersome set-up for imaging breasts, along with the usual admonition to keep perfectly still, does not leave me in a position I would choose for a nap. Still, I’m on the verge of dropping off when the whole table starts shaking under me. They had warned me about this before I climbed onto the apparatus, but for a second I’m not sure whether to laugh (without…