Diagnostic imaging is a form of medical imaging which is performed with the intention of diagnosing disease, in contrast with medical imaging which is conducted to monitor the progress of a disease, or to guide a medical procedure. Many people experience diagnostic imaging at some point in their lives; an x-ray to confirm a broken limb, for example, is a type of diagnostic imaging. The goal of diagnostic imaging is to gather more information about the specifics of the patient's condition, hopefully reaching a conclusion about what condition the patient has, and how it might be treated.

There are a number of different types of diagnostic imaging, each of which can be used for a variety of conditions. Some are minimally invasive, requiring only that the patient hold still. Others are more invasive, involving the swallowing of various substances, or the use of imaging devices which are used internally. In all cases, when an imaging study is ordered to diagnose a problem, the procedure is usually explained to the patient so that he or she knows what to expect.

Some examples of minimally invasive studies include ultrasound, in which the body is bombarded with high frequency sound waves to create a picture of the inside of the body, and magnetic resonance imaging (MRI), in which the internal structures of the body are visualized with the use of large magnetic field. The body can also be bombarded with x-rays to generate an image which can be recorded on special film.

In some cases, patients may be asked to swallow a substance like barium, which makes the digestive tract more visible on an x-ray, or to submit to an injection of a radioactive isotope for a procedure like a positron emission tomography (PET) scan, in which the radiation emitted by the isotope can be used to track its progress through the body. Cameras and transducers may also be introduced to the body through the esophagus or intestinal tract.

A wide variety of medical fields rely on diagnostic imaging to get a picture of the inside of the body without actually opening the body up. Imaging studies can reveal things like tumors, circulatory problems, and broken bones, allowing doctors to use this information in the development of a treatment plan. Diagnostic imaging is often combined with bloodwork, analysis of urine samples, and other diagnostic techniques which provide more information about the patient's condition. This minimally invasive form of diagnosis is much better for patients than exploratory surgery, which is the only other way to see what's going on inside the body.