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CPT 73721: MRI of Lower Extremity Joint, No Contrast
CPT code 73721 denotes magnetic resonance imaging of a lower extremity joint performed without contrast and is a widely used diagnostic tool for evaluating knee and other lower-limb joint pathology. Nationally, this non-contrast joint MRI is central to imaging pathways for acute injuries, degenerative disease, and preoperative planning, influencing downstream care decisions and utilization patterns. Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, United Healthcare, and Medicare. This publication provides a concise reference on clinical context, common diagnostic indications, and payer coverage considerations. Readers will find an overview of typical sites of service, associated ICD-10 diagnoses commonly billed with this code (including knee pain, primary osteoarthritis, and acute ligament sprains), and a comparison to related codes such as 73722 for MRI with contrast. The brief also highlights common billing modifiers used alongside 73721 and identifies where additional clinical documentation is typically required. The content is intended for billing professionals, clinical coders, and policy analysts seeking a clear summary of the code’s clinical use and payer landscape at a national level.
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Billing Code Overview
CPT code 73721 describes magnetic resonance imaging (MRI) of a lower extremity joint performed without contrast material. The procedure is a diagnostic imaging study focused on joints of the lower limb, commonly used to evaluate soft-tissue structures and osseous anatomy.
Service Type: Diagnostic imaging (MRI), non-contrast
Typical Site of Service: Outpatient imaging centers, hospital outpatient departments, and ambulatory surgical centers
National Reimbursement Benchmarks
Medicare’s national mean rate of $141.90 sits well below BUCA’s average commercial mean of $544.60, highlighting a large gulf between federal reimbursement and commercial rates for CPT 73721. The median Medicare locality payment of $145 underscores that most Medicare localities cluster near its mean, whereas BUCA’s distribution (P50 $486.40) reflects substantially higher commercial reimbursement levels compared with federal pricing.
Assessing dispersion via the interquartile range (P75 minus P25) shows that Blue Cross Blue Shield has the widest IQR at $285.80 (P75 $879.20 minus P25 $609.40), indicating the largest middle-range variability among payers. UnitedHealth Group and Aetna have narrower IQRs of $224.90 and $180.80 respectively, while Cigna’s IQR is $250.40. BUCA’s IQR is $258.20 and Medicare’s IQR is $131.50, making Medicare the tightest in middle-range variability.