Current Procedural Terminology (CPT) codes are a standardized system of five-digit numbers used by healthcare providers to document and bill for medical services and procedures. This system ensures consistent communication between doctors, hospitals, and insurance companies regarding the services rendered to a patient and is necessary for determining coverage and reimbursement. This article examines CPT code 73718, which is used for a specific type of imaging procedure.
Decoding CPT Code 73718
CPT Code 73718 specifically identifies a Magnetic Resonance Imaging (MRI) examination of the lower extremity joint, performed without the use of intravenous contrast material. An MRI is a non-invasive imaging technique that uses strong magnetic fields and radio waves to create highly detailed, cross-sectional images of the body’s soft tissues and bones, avoiding ionizing radiation.
The phrase “lower extremity joint” refers to a major joint in the leg, such as the hip, knee, ankle, or the joints within the foot. The primary reason for performing this non-contrast MRI is to visualize the internal structures of these joints, including the cartilage, ligaments, tendons, and surrounding soft tissues. The “without contrast” designation signifies that no enhancing agent was injected during the scan, which is a crucial detail for billing and clinical interpretation.
This code applies specifically to the joint itself, rather than the non-joint soft tissue of the lower extremity. The detailed images allow physicians to assess structural integrity and look for internal derangements within the joint capsule. The non-contrast approach is often sufficient for initial evaluations of mechanical problems or injuries where a clear view of the anatomy is the main objective.
Clinical Applications of Lower Extremity Joint MRI
A physician orders CPT 73718 when they suspect a structural problem within a lower extremity joint that cannot be fully diagnosed with standard X-rays. It is often considered the standard for analyzing soft tissues due to its high resolution and multiplanar capabilities. It is useful in evaluating acute or chronic injuries affecting the knee, ankle, and hip.
One frequent application is the diagnosis of ligament and tendon tears, such as a torn anterior cruciate ligament (ACL) or meniscus damage in the knee. MRI can show the extent of the tear and any associated bone bruising, which is often invisible on plain radiographs. The scan also provides detail for assessing cartilage defects associated with osteoarthritis.
A non-contrast MRI helps evaluate complex fractures that extend into the joint space, as well as early stages of avascular necrosis. It is also used to investigate chronic, unexplained joint pain that has not responded to initial conservative treatments. These anatomical pictures guide both non-surgical treatment plans and surgical preparations.
Understanding Contrast and Related CPT Codes
The absence of contrast material differentiates CPT 73718 from procedures where an intravenous agent is used to enhance specific tissues. Contrast agents, typically gadolinium-based, are injected to alter the magnetic properties of water molecules in the body. This process makes certain structures, like blood vessels, tumors, or areas of inflammation, appear brighter on the images, significantly improves diagnostic accuracy in specific cases.
When contrast is necessary, such as when looking for infection, tumors, or inflammation, the CPT code changes to reflect the different procedure. CPT Code 73722 represents an MRI of a lower extremity joint performed with contrast material only. This code is used when the primary diagnostic question involves blood supply or the presence of abnormal tissue enhancement.
A third scenario is covered by CPT Code 73723, which is an MRI of the lower extremity joint performed without contrast, followed by with contrast. In this comprehensive study, initial images establish a baseline before the contrast agent is administered and a second set of images is acquired.
This two-part approach is often requested when a physician needs to compare the native appearance of tissue to its enhanced appearance. This is common in cases involving suspected soft tissue masses or osteomyelitis. The selection of which code to use is based entirely on the physician’s medical necessity and the specific diagnostic information required.