Summary & Overview
HCPCS A9591: Fluoroestradiol F 18 Diagnostic PET Agent, 1 mCi
HCPCS Level II code A9591 identifies Fluoroestradiol F 18, a diagnostic radiopharmaceutical supplied in a 1 millicurie unit for PET molecular imaging. This agent is used in nuclear medicine to image estrogen receptor expression and can inform diagnosis and treatment planning in oncology. Nationally, accurate coding for radiopharmaceuticals supports appropriate billing, clinical tracking, and reimbursement consistency for high-cost imaging agents.
Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for the agent, benchmarks and common payer coverage patterns, and relevant billing considerations for institutional and outpatient imaging sites. The publication highlights typical service settings, common modifiers in use (for reference), and implications for claims processing workflows.
The report provides a concise reference for revenue cycle, coding, and clinical teams on how A9591 is represented in claim lines, what to expect in payer handling, and what operational elements are relevant when administering and billing this PET radiopharmaceutical. Data not available in the input will be noted where applicable.
Billing Code Overview
HCPCS Level II code A9591 describes Fluoroestradiol F 18, diagnostic, 1 millicurie. This entry represents a radiopharmaceutical diagnostic agent used in nuclear medicine imaging that contains fluorine-18 labeled fluoroestradiol. The service type is a diagnostic nuclear medicine radiopharmaceutical administration for molecular imaging. The typical site of service is an outpatient imaging center or hospital nuclear medicine department for PET imaging procedures.
Clinical & Coding Specifications
Clinical Context
A typical patient is a woman with a history of estrogen receptor–positive breast cancer being evaluated for recurrent or metastatic disease. The referring oncologist orders a PET imaging study using A9591 (fluoroestradiol F 18, diagnostic, 1 millicurie) to assess in vivo estrogen receptor expression in suspected metastatic lesions or to clarify equivocal findings on conventional imaging. The clinical workflow: the patient arrives at an outpatient nuclear medicine or PET/CT center, screening for pregnancy and recent hormonal therapies is performed, IV access is obtained, and the radiopharmaceutical A9591 is administered. After an uptake period per protocol, PET/CT imaging is performed. Images are reviewed by a nuclear medicine physician or radiologist; findings are reported to the referring oncologist to guide systemic therapy selection (for example, endocrine therapy eligibility) or further biopsy planning. Typical site of service is an outpatient imaging center or hospital-based nuclear medicine/PET suite. Usual patient preparation includes fasting per site protocol, withholding select endocrine agents as clinically indicated, and assessing renal function when relevant.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | No modifier — default | Use when no applicable modifier applies to the service. |