Do you want to ensure that your practice gets the maximum possible reimbursement for radiology claims? Then you have to learn to bill your services accurately. Today, we will cover CPT code 73721, which is a vital MRI code frequently used in radiology billing.
Magnetic resonance imaging (MRI) is a common, safe, and non-invasive diagnostic procedure. Almost 40 million MRI scans are performed each year in the United States. Despite its extensive use, healthcare providers still face difficulty in billing the procedure.
That’s what we are going to discuss in this blog: How to bill CPT 73721 (diagnostic MRI of lower extremities) correctly. So, let’s start.
CPT Code 73721 – Description
CPT code 73721 reports a diagnostic radiological procedure. During this procedure, the healthcare provider performs magnetic resonance imaging, or MRI, of a lower extremity joint (such as the knee, ankle, or hip) without contrast material.
While contrast used in MRI makes the image clearer, it can pose risks such as allergic reactions or kidney issues. In the case of CPT 73721, a non-contrast MRI of a lower extremity joint is just as effective in diagnosing bone fractures, ligament tears, or meniscus issues.
Appropriate Use Cases for CPT Code 73721
The following are a few examples of MRI without contrast, where healthcare providers may bill their services with CPT code 73721.
Ruptured Ligament
Ligament injuries are common among athletes and active individuals. So, let’s take an example of a 19-year-old athlete who twists his knee while practicing for his upcoming football match. His friends bring him to the physician, who suspects an anterior cruciate ligament ACL rupture and orders an MRI to confirm the diagnosis and plan surgery.
MRI will help in examining soft tissues, allowing the provider to customize a patient-specific treatment plan. So, if a physician orders an MRI and the radiology center performs it, the biller can use CPT code 73721 for the service.
Joint Abnormality
Suppose a 50-year-old mother persistently experiences severe knee pain. She visits her physician regarding the discomfort. Initially, the physician performs physical exams, orders X-rays, and prescribes pain medication. However, these first-line diagnostic and treatment methods fail to curb the pain. So, after 6 weeks of failed conservative treatment, the physician decides to perform an MRI.
MRIs help diagnose the cause of pain and discomfort in lower extremity joints. Hence, the provider orders a knee MRI to diagnose a possible joint irregularity and plan the course of her treatment. Using CPT code 73721 is justified in this scenario because the patient had joint pain and showed symptoms of abnormalities such as osteoarthritis.
Modifiers to Append with CPT Code 73721
These are some essential modifiers for CPT code 73721. These help in explaining the nature of the service and the anatomical site to the insurance payer.
Modifier 26
Modifier 26 indicates that a physician provided only the professional component (interpretation and report) of an MRI.
Modifier TC
Modifier TC represents the technical component of a service. It is used when a facility or entity owns the equipment and employs the staff to perform the scan, but does not interpret the results.
Modifier LT
The modifier LT is appended to CPT code 73721 to indicate that the scan was performed on a left lower extremity joint (e.g., left knee, ankle, hip, or foot).
Modifier RT
Modifier RT is appended to CPT code 73721 to specify that the scan was performed on the right side of the lower body.
Modifier 50
CPT code 73721 is not inherently bilateral. So, if the MRI is performed on both lower extremities during the same session, you will use modifier 50 to indicate this.
However, note that according to the National PFS RVU 2026, the bilateral surgery indicator for 73721 is ‘3’. Meaning, “the usual payment adjustment for bilateral procedures does not apply”. So, even if you append modifier 50, Medicare will reimburse MRI for both sides at 100% of the allowed amount for each side instead of the usual 150% per code.
Reimbursement Guidelines for CPT Code 73721
The following billing and reimbursement guidelines for CPT code 73721 will help you avoid any errors while submitting claims to the insurance payer.
Maintain Accurate and Complete Paperwork
Since you are here to find ways to avoid claim denials, proper documentation is key to avoiding billing errors and claim denials. A justification for the medical necessity of the procedure is something that every payer looks for in your documents.
Therefore, your medical records must mention specific clinical indications or symptoms for the MRI procedure, such as persistent joint pain or ligament tears supported by the patient’s relevant medical history and the diagnostic question that the imaging study is intended to answer. Plus, the records must also clearly specify the joint or region being scanned.
Comply with the Payer’s Guidelines
Adhering to the established guidelines of insurance payers is crucial to ensure coverage for MRI procedures. For example, most payers may ask you to provide proof of prior authorization to reimburse an MRI. If that is the case, you must obtain a pre-authorization letter from the insurance payer before performing an MRI scan on a lower extremity joint.
Final Thoughts on CPT Code 73721
Hopefully, we have covered all the intricacies of CPT code 73721, and now, you can file your claims confidently. In short, this code is for MRI of lower extremity joints, including hips, knees, ankles, and feet. The diagnostic imaging procedure aids precise diagnosis and evaluation of conditions like ligament tears or joint degeneration, as we have discussed in our examples.
You must append the relevant modifiers (26, TC, LT, RT, or 50) where necessary to avoid claim rejection.
In case we missed something or you are still struggling with claim creation and denials, we suggest opting for radiology billing services from NeuraBill. Medical billing professionals employed at the firm can help you file clean claims and secure accurate reimbursement for your services.
