To view a good painting with undisturbed concentration, taking time to potentiate the salience of its principal genius and bask in its effect (that is, to really let the essence of the art of it sink in), would, I believe, exceed imagery as alternative therapy (having the patient imagine and mentally dwell on a consoling situation).
Imagery has proved its efficacy tomographically at reducing stress and heart rate, stimulating the production of immune cells, and, in elderly patients, at stimulating the production of killer T-cells. It has also helped patients endure chemotherapy and arthritis and to prepare for surgery.
Still, I believe deep study of a good painting treating a consolatory theme, though identical to imagery in technique, would have the advantage over imagery by virtue of greater vividness of affect and greater stability of attention.
Dean Sparks, Lucerne