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    OpenPayerBilling CodesAdministrative, Miscellaneous and InvestigationalHCPCS hcpcs-a9521-technetium-tc-99m-exametazime-diagnostic-dose
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    HCPCS Level II A9521: Technetium Tc-99m Exametazime, Diagnostic

    HCPCS Level II code A9521 describes a diagnostic radiopharmaceutical — technetium tc-99m exametazime — billed per study dose, up to 25 millicuries; this service is used for nuclear medicine diagnostic imaging studies (brain perfusion or cerebral blood flow imaging) and is typically administered by a nuclear medicine or radiopharmacy team in an outpatient imaging center, hospital nuclear medicine department, or specialized diagnostic facility.

    For related coverage guidance, see recent payer policy updates: Interferential Stimulation Devices (for home use), Durable Medical Equipment (DME): Tumor Treating Fields (Alternating Electric Field Therapy) Medical Guideline, Durable Medical Equipment (DME): Bone Growth Stimulators Medical Guideline.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is an adult referred to nuclear medicine for a cerebral perfusion study using Technetium Tc-99m exametazime (A9521) to evaluate cerebral blood flow. Common indications include acute stroke evaluation to distinguish ischemic penumbra from infarcted tissue, assessment of suspected brain death when perfusion imaging is required, evaluation of seizure foci in pre-surgical epilepsy workup, or characterization of perfusion abnormalities in dementia and traumatic brain injury. The clinical workflow includes: ordering provider documents indication and relevant history; nuclear medicine schedules the study and screens for pregnancy or breastfeeding; the radiopharmacy dispenses a single study dose (up to 25 millicuries) of Technetium tc-99m exametazime labeled kit; a technologist administers the radiopharmaceutical intravenously and acquires planar and/or SPECT images per protocol; the interpreting nuclear medicine physician or neuroradiologist reviews images, generates a report with perfusion findings, and sends results to the referring clinician for further management. Typical site of service is an outpatient imaging center or hospital nuclear medicine department. Patient preparation may include explanation of procedure, IV access, and continued monitoring for adverse reaction during and after tracer administration.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    78801Radiopharmaceutical localization of tumor or distribution of radiopharmaceutical agent (eg, brain) for planar imaging; single studyPlanar cerebral perfusion imaging sometimes used with the A9521 radiopharmaceutical for initial localization or qualitative assessment
    78802Radiopharmaceutical localization for SPECT; single first studySPECT acquisition of cerebral perfusion after administration of A9521 when cross-sectional functional imaging is performed
    78306Brain imaging, limited (planar)Alternative planar brain imaging code that may be used for limited perfusion studies depending on payer and protocol
    78607Transcatheter therapy and diagnostic angiography codes (placeholder)Not typically used with A9521; no direct relationship but listed here for workflow awareness when vascular imaging is added — Data not available in the input.
    77012CT guidance for localizationMay be used when hybrid SPECT/CT or CT localization is performed adjunctively with the perfusion study

    Related Modifiers

    8 rows

    ModifierDescriptionWhen to Use
    23Modifier -23 (Unusual Anesthesia) is used on anesthesia service CPT codes when a procedure that normally requires no anesthesia or only local anesthesia must be performed under general anesthesia…- Use modifier -23 only on anesthesia CPT codes (00100–01999) when a procedure that normally requires no anesthesia or only local anesthesia must be performed under general anesthesia because of…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    62Modifier 62 indicates that two surgeons function as co‑surgeons, each performing distinct parts of the same primary surgical procedure. It is appended to the primary procedure code (and any…- Use modifier -62 when two surgeons act as co‑surgeons (both primary surgeons) on a single definitive primary procedure, each performing distinct parts of the same surgical procedure (append -62 to…
    78CPT modifier -78 indicates an unplanned, related return to the operating or procedure room by the same provider during the global postoperative period. It is appended when treatment for a…- Use modifier -78 when an unplanned, related complication during the original procedure’s global postoperative period requires the patient to return to a formal operating or procedure room and the…
    80CPT® Modifier 80 (Assistant Surgeon) is appended to a surgical CPT code when a physician (MD or DO) provides full, continuous assistance throughout the operative procedure. It is intended only for…- Use CPT Modifier -80 when a physician (MD or DO) serves as an assistant surgeon and provides full, continuous assistance throughout the entire operative procedure; append -80 to the surgical CPT…
    82Modifier 82 is appended to a surgical CPT code to indicate that an attending physician acted as an assistant because a qualified resident surgeon was unavailable. In teaching hospitals it documents…- When to use: Append modifier 82 in teaching-hospital settings to indicate a physician served as an assistant surgeon because a qualified resident surgeon was unavailable (includes situations where…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    261QR0400XRehabilitation Clinic/CenterAmbulatory Health Care Facilities · Clinic/Center
    2084N0402XNeurology with Special Qualifications in Child Neurology PhysicianA Child Neurologist specializes in neurology with special skills in diagnosis and treatment of neurologic disorders of the neonatal period, infancy, e…
    207R00000XInternal Medicine PhysicianA physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults…
    163W00000XRegistered Nurse(1) A registered nurse is a person qualified by graduation from an accredited nursing school (depending upon schooling, a registered nurse may receive…
    208M00000XHospitalist PhysicianHospitalists are physicians whose primary professional focus is the general medical care of hospitalized patients. Their activities include patient ca…
    2085R0202XDiagnostic Radiology PhysicianA radiologist who utilizes x-ray, radionuclides, ultrasound and electromagnetic radiation to diagnose and treat disease.
    2086S0120XPediatric Surgery PhysicianA surgeon with expertise in the management of surgical conditions in premature and newborn infants, children and adolescents.
    163WX0601XOtorhinolaryngology & Head-Neck Registered NurseNursing Service Providers · Registered Nurse

    Related ICD-10-CM Codes

    26 rows

    ICD-10-CM CodeDescription
    F02.80Dementia in other diseases classified elsewhere, unspecified severity, without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety
    F03.90Unspecified dementia, unspecified severity, without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety
    G30.9Alzheimer's disease, unspecified
    G45.9Transient cerebral ischemic attack, unspecified
    G46.3Brain stem stroke syndrome
    G81.90Hemiplegia, unspecified affecting unspecified side
    G93.1Anoxic brain damage, not elsewhere classified
    I20.9Angina pectoris, unspecified
    I21.9Acute myocardial infarction, unspecified
    I25.10Atherosclerotic heart disease of native coronary artery without angina pectoris

    Showing 1–10 of 26

    Related Payer Policy Updates

    Specialty: Durable Medical Equipment (DME)1 / 3

    5 rows

    PolicyPayerEffective Date
    Interferential Stimulation Devices (for home use)Moda Health2026-10-01
    Durable Medical Equipment (DME): Tumor Treating Fields (Alternating Electric Field Therapy) Medical GuidelineWPS Health Insurance2026-10-01
    Durable Medical Equipment (DME): Bone Growth Stimulators Medical GuidelineWPS Health Insurance2026-10-01
    General Durable Medical Equipment (DME) Medical GuidelineWPS Health Insurance2026-10-01
    Prior Authorization for Durable Medical Equipment (DME)Blue Cross Blue Shield - Rhode Island2026-10-01

    Related Codes

    HCPCS-A9150-NON-PRESCRIPTION-DRUGS

    HCPCS Level II A9150: Non-prescription Drugs

    HCPCS-A9152-SINGLE-ORAL-VITAMIN-MINERAL-DOSE

    HCPCS A9152: Single Oral Vitamin/Mineral/Trace Element

    HCPCS-A9153-MULTIVITAMIN-ORAL-PER-DOSE

    HCPCS A9153: Multiple Vitamins, Oral, Per Dose

    HCPCS-A9154-ARTIFICIAL-SALIVA-1ML

    HCPCS Level II A9154: Artificial saliva, 1 ml

    HCPCS-A9155-ARTIFICIAL-SALIVA-30ML

    HCPCS Level II A9155: Artificial Saliva, 30 mL

    HCPCS-A9156-ORAL-MUCOADHESIVE-PER-1ML

    HCPCS Level II A9156: Oral Mucoadhesive, Per 1 ml

    HCPCS-A9180-PEDICULOSIS-TOPICAL-TREATMENT-PATIENT-ADMINISTRATION

    HCPCS Level II A9180: Pediculosis Topical Treatment for Patient/Caretaker

    HCPCS-A9268-PROGRAMMER-TRANSIENT-INGESTED-CAPSULE

    HCPCS Level II A9268: Programmer for Transient Orally Ingested Capsule

    HCPCS-A9269-PROGRAMMABLE-TRANSIENT-ORAL-CAPSULE

    HCPCS Level II A9269: Programmable Orally Ingested Capsule, Per Month

    HCPCS-A9270-NON-COVERED-ITEM-OR-SERVICE

    HCPCS A9270: Non-covered Item or Service

    Showing 1–10 of 138

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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