The young science of psychoneuroimmunology studies how our minds affect our ability to heal. It has found that imagery does aid healing. It can boost the immune system, help control pain, and alter internal conditions, such as pulse and blood pressure. Visualization has been used with reports of success in treating diabetes, heart disease, cancer and other diseases. It is not a replacement for medical treatment, but evidence suggests that it is beneficial.
Imagery is a personal matter.
The type of imagery you use depends on you. What is most likely to work for you is symbolism that resonates with your imagination. Some people have used warlike images of white blood cells fighting cancer, while others find such images objectionable. Create images that you are comfortable with. Create images of your body healing itself, and images of your body as you would like it to be.