It is useful to understand a little bit about imaging. Standard “plain film” x-rays – where some x-ray radiation is shot through your body to expose a piece of film – is still the gold standard for the initial evaluation some areas such as chest x-rays and looking at bones – for fractures, arthritic changes, cysts, etc.
X-rays do not show “soft tissue” – the body parts other than bone – very well. This limitation can often be overcome by using a contrast agent. Barium, which blocks x-rays, can be mixed in a heavy shake which is fed to the patient – it coats the esophagus and stomach and allows an x-ray to show the wall of the stomach – often revealing ulcers or other problems. Of course, barium can be pumped up from below as well in the form of a “barium enema”, which still has usefulness, although colonoscopy, where the GI doctor can actually look up into the colon, has largely replaced it.
Contrast can be injected into almost any soft tissue to improve the return of information. Years ago – before there was an MRI machine in Maine – I had my sore knee evaluated. I had an “arthrogram” – my knee was injected with an iodine-based dye (which blocks x-rays) followed by three big syringes full of air! This highlighted the meniscus and cartilage surfaces of my knee. It felt like I had bubbles in my knee for the rest of the day. Other types of contrast are concentrated in the kidney or in the liver and allow x-rays to be used to evaluate those organs.
CT scans use information from narrow beams of x-rays coming from different directions to generate highly detailed “slices” of the body which shows bones as well as soft tissue. Sometimes contrast is used to highlight certain areas. CT scans are fast and easy, and are often used in the ER to look for appendicitis or bleeding in the skull after an injury. The downside is that they expose the patient to large amounts of radiation – something of growing concern, especially for children.
An MRI scan does not use radiation – it uses strong magnetic waves to paint a high-resolution picture representing a slice through the body. It takes longer – up to an hour – and for the “closed MRI” requires the patient to lie still in a coffin-like confined space for that time period. That can be difficult for someone in pain or who suffers from anxiety, and it is not unusual to administer pain medication, tranquilizers, or even anesthesia to patients undergoing an MRI. The magnetic field is so strong that serious injury could occur should a patient have an MRI who has any steel wires, implants, or pacemakers. Often times, especially with patients who work around grinding and welding equipment, an x-ray will be taken of the eyes to look for small pieces of steel which might be embedded in the cornea – pieces of steel which could move in response to the magnetic field of the MRI!
Below are samples of imaging studies and the amount that Medicare pays for these studies in this part of Florida. Remember that insurance companies often pay a little more than Medicare rates.