Lower Back (Lumbar Spine) CT scan (with and without contrast)

What it is

CT is the bone test of the spine. It takes x-ray measurements from all around the body and reconstructs them into thin slices, so the shape of each vertebra, the width of the bony canal, a fracture line, or the seating of a screw shows with a clarity no other scan matches. MRI is generally better at discs, nerves, and the cord; CT is better at bone and at anything metal. The with-and-without version described by this code means the scan was run once plain and again after iodine-based dye went into a vein. That is unusual for a routine back complaint — a plain lumbar CT answers most bone questions on its own. Contrast is added when the radiologist needs to see blood supply: active infection, tumor, or vessels.

Why it is done

• To look at the bones of the low back in detail after an injury, or when a fracture is suspected and plain films are inconclusive
• To assess narrowing of the spinal canal caused by bony overgrowth rather than by soft tissue
• To check fusion hardware, screw position, and whether bone has healed across a surgical fusion
• To image the lumbar spine in someone who cannot have an MRI — a pacemaker, certain implants, or severe claustrophobia
• To evaluate suspected infection or a tumor in or around the vertebrae, which is the situation the contrast series is for

What to expect

Fasting for a few hours is usually asked for when contrast is planned, and kidney function may be checked first. An IV goes into the arm. The scan itself is quick — the patient lies still on a table that slides through a short ring while it rotates, and each pass takes well under a minute, though the whole appointment is longer. When the iodine dye is injected, a warm flush through the body and a metallic taste in the mouth are common and pass within seconds. Unlike MRI, CT uses ionizing radiation. A radiologist reads the images and reports afterward.

Questions worth asking

• Was MRI considered for this question? It is a different code at a different price, and for disc and nerve problems it is often the study that gets ordered.
• Is the contrast injection billed on its own line, separately from the scan?
• If only the plain pass ends up being performed, will the charge drop to the without-contrast code, and who makes that call?
• Is this a CT myelogram, where dye is placed into the spinal canal by a needle? That is a different and considerably more involved bill, with a procedure charge attached.
• Am I being scanned in a hospital department, and is a facility fee added to the scan and the radiologist's reading?