Nearly every week, billing teams search for the 73721 CPT code. It includes contrast-dye-free MRI scans of lower body joints. It is ordered by radiologists for the foot, ankle, hip, and knee. What the code does and does not cover is explained in this guide. The current Medicare rates and modifier rules will be explained to you. Coders use it correctly, as demonstrated by real-world examples.
What Is CPT Code 73721?
It is very important to know that what is CPT code 73721. An MRI of any lower extremity joint performed without contrast material is reported using CPT code 73721. It is defined by the American Medical Association as magnetic resonance imaging of any lower extremity joint without contrast. That is the official 73721 CPT code description.
The code includes the hip, knee, ankle, and foot joints. excludes the calf, thigh, and other soft tissues that are far from a joint. Coders typically get confused when an order simply states “lower extremity MRI” without mentioning a joint. The joint should always be named in a clear order. Write knee, hip, ankle, and foot upon request. The assertion is cleaned up by that one detail, which also prevents a later denial.
CPT 73721 Description Compared with Related Codes
Examining the complete family of lower extremity joint imaging codes is necessary to comprehend the 73721 CPT code description. Claims are rejected right away if the incorrect code is selected based on contrast usage.
| CPT Code | Contrast Usage | Clinical Focus |
| 73721 | Without contrast | Joint evaluation (Knee, Hip, Ankle) |
| 73722 | With contrast | Joint evaluation with IV contrast dye |
| 73723 | Without contrast, followed by contrast | Complex joint imaging (with & without) |
| 73718 | Without contrast | Non-joint lower extremity (Thigh, Calf) |
The order number 73721, MRI knee no contrast exam, is the correct CPT code. The code needs to be changed to 73723 to reflect the complete service if the radiologist administers the contrast in the middle of the procedure.
MRI Knee, Ankle, Hip, and Foot: Which Studies Map to Code 73721?
This code isn’t used by every lower leg scan. Only joints are covered by Code 73721.
- Knee Joint: For meniscus rupture, ACL damage, or arthritic evaluation, map to 73721.
- Hip Joint: 73721 for avascular necrosis or labral tears.
- Ankle Joint: The same as 73721 in cases of joint instability, ligament tears, or chronic sprains.
- Anatomical Modifiers (LT / RT):: Foot (Non-Joint areas) & Long Bones: Map to foot-specific codes or CPT 73718 (lower extremity, non-joint).
- 73718 Bill if the calf or thigh muscle tissue is scanned rather than the joint region.
Does CPT 73721 Need a Modifier?
CPT code 73721 frequently requires modifiers to indicate the location and mode of service delivery.
- Modifier 26 (Professional Component): The physician does not own the MRI machine; instead, they read and interpret the scan.
- The facility that owns the machine performing the technical scan uses the Modifier TC (Technical Component).
- Anatomical Modifiers (LT/RT): Medicare and commercial payers must specify if the right knee (RT) or left knee (left knee MRI CPT code) was scanned.
- Modifier 50 (Bilateral): In accordance with specific payer requirements, this modifier is applied if both the left and right joints are scanned during the same encounter.
When modifiers are used correctly, claims processing can be kept tidy and unwelcome audits can be avoided.
When CPT 73721 Should Not Be Used
The following clinical situations should not be used with 73721:
- Non-Joint Soft Tissue: Code 73718 is needed for scans of the calf or thigh muscles.
- Contrast Administration: Use 73722 or 73723 if contrast is administered intravenously.
- Follow-Up Scans in Global Windows: Denials will occur if routine follow-ups are unbundled without a clear clinical indication.
- Stress Fractures of Long Bones: When a scan is focused on the femur or tibia shaft rather than the joint area, non-joint imaging codes are utilized.
Read More: 78452 CPT Code Description, Documentation, and Modifier Use.
Common Reasons Claims Get Denied
The majority of denials linked to this code are caused by vague documentation. A coder is forced to speculate when a note simply states “lower extremity MRI” without identifying the joint. The second frequent issue is a diagnosis code (MRI left knee without contrast cpt code) that is either missing or incorrect. Before authorizing payment, payers compare the diagnosis to their own coverage regulations. Before approving an MRI at all, some plans also require documentation of a few weeks of conservative treatment, like rest or physical therapy.
CPT Code 73721 Medicare Reimbursement
The 73721 CPT code description is reimbursed by Medicare using a relative value unit system (RVUs). Physician effort, practice costs, and malpractice risk are all combined to create the RVU, which is then multiplied by an annual conversion factor. The standard conversion factor for CMS in 2026 is more than $33.40 per RVU, with a marginally higher rate for providers using approved alternative payment models. In total, it has slightly more than six RVUs. Medicare adjusts payments for local cost variances, so the exact amount still differs by region.
Medical necessity determines coverage. If the diagnosis includes conditions like avascular necrosis, joint derangement, infection, or unexplained discomfort that did not go away after conservative treatment, Medicare will typically pay.
CPT Code 73721 Cost and 2026 Payment Rates
Changes in conversion factors and facility oversight are reflected in the 2026 national average Medicare rates.
- Global Fee: Between $210 and $260 (Facility + Doctor)
- Technical Component (TC): Between $160 and $200
- Professional Component (26): Between $50 and $60
Rates for commercial insurance differ according to provider agreements. Depending on the type of facility, self-pay cash rates for patients paying out-of-pocket without insurance typically range from $400 to $1,200.
Conclusion
A single lower extremity joint MRI performed without contrast is covered by the 73721 CPT code. Accurate diagnoses, joints, and modifiers ensure timely payments and clean claims. The majority of denials associated with this code are still caused by minor gaps in the documentation.
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FAQs
What does CPT 73721 cover?
It covers an MRI of one lower extremity joint, the knee, hip, ankle, or foot, done without contrast dye.
Is a knee MRI without contrast always billed as 73721?
Yes, when the study targets the knee joint alone and no contrast agent is used during the scan.
Does Medicare need a modifier for a bilateral study?
Yes, use modifier 50 or bill each side separately with RT and LT, depending on payer preference.
What code applies if contrast is added later in the same visit?
That combination study moves to CPT 73723, since it mixes a non-contrast and a contrast phase.
