CPT code 77078 – Axial QCT bone density study

Key takeaways

CPT code 77078 is axial quantitative CT (QCT) of the hips, pelvis, or spine. The same sites scanned by DXA are billed under 77080.

Medicare covers 77078 once every 23 months for qualifying patients under NCD 150.3, and CMS Article A57132 lists the diagnoses that support it.

Add modifier TC or 26 when separate entities perform the scan and the interpretation. Billing globally without doing both is a compliance risk.

Pabau’s claims software runs automated validation checks and real-time eligibility checks through Claim.MD before a 77078 claim is sent.

CPT code 77078: Definition and official descriptor

CPT code 77078 is the American Medical Association’s code for a computed tomography bone mineral density study of the axial skeleton. It covers one or more sites, such as the hips, pelvis, or spine. The study uses quantitative computed tomography (QCT), which measures volumetric bone density from CT images.

CPT 77080 covers the same axial sites with dual-energy X-ray absorptiometry (DXA) instead. The two codes differ by modality, not by body region, so the equipment named in the radiology report decides which one you bill.

The American Medical Association’s CPT code set maintains 77078 within the Radiology section. Because the AMA revises descriptors periodically, always verify the current year’s codebook before submitting a claim.

77078 vs. 77080: The difference coders must know

CPT 77078 and CPT 77080 measure bone mineral density at the same axial sites: The hips, pelvis, and spine. The modality is what separates them. CPT 77078 is billed for quantitative CT, while 77080 is billed for DXA. Coders who choose between them by body region will get it wrong, because the region is identical under both codes.

The deciding factor is the equipment documented in the radiology report. If the report names DXA at the hip, pelvis, or spine, bill 77080. If it names QCT at those axial sites, bill CPT code 77078. Re-submitting with the corrected code after a denial requires a corrected claim, not just a reopening request.

Peripheral studies follow a different path. A DXA study of the wrist or heel is billed under 77081. A hand and wrist film read for skeletal maturity rather than density is a bone age study, billed under CPT 77072.

Peripheral QCT has had no dedicated CPT code since 77079 was deleted on January 1, 2012, so confirm payer guidance before scheduling one. The matrix below maps each modality and site to its code.

Full bone density CPT code family

Several CPT codes cover bone density studies. The table below helps coders select the correct code based on equipment and anatomical site.

Medicare coverage criteria for CPT code 77078

Medicare covers CPT code 77078 under National Coverage Determination (NCD) 150.3. CMS Billing and Coding Article A57132 sets out the coding rules that go with it. Coverage applies to qualifying patients in specific clinical categories, with a frequency limit of once every 23 months. Billing beyond this frequency without a documented exception generates an automatic denial.

The qualifying patient categories in the Medicare coverage rules are:

• Women aged 65 and older
• Men aged 70 and older
• Postmenopausal women under 65 with one or more clinical risk factors for osteoporosis (low body weight, smoking, family history, fragility fracture history)
• Men aged 50-69 with one or more clinical risk factors
• Patients with vertebral abnormalities identified on imaging suggesting osteoporosis or spinal fracture
• Patients receiving or planning to receive pharmacologic glucocorticoid therapy for 3 months or more
• Patients with primary hyperparathyroidism
• Patients being monitored to assess the response to, or efficacy of, an FDA-approved osteoporosis drug therapy

The ordering provider must document the qualifying condition in the medical record before the scan date. A physician order without a documented clinical indication does not meet the coverage rules for this code.

ICD-10 diagnosis codes that support medical necessity

Medicare denies CPT code 77078 as not medically necessary when the ICD-10-CM code on the claim is not one that CMS Article A57132 lists. The table below shows the accepted pairings and which codes carry higher denial risk.

Review the CMS ICD-10-CM code files and the current version of CMS Article A57132 to confirm the complete accepted list before submitting. The article is updated periodically, and codes that were acceptable in prior years may have been removed.

Modifiers for CPT code 77078

Modifier selection on CPT code 77078 depends on which entity owns the scanner and which entity provides the physician interpretation. Billing global (no modifier) when only one component was performed by your organization is a compliance violation.

Documentation requirements for a 77078 claim

Every 77078 claim must be supported by a specific set of clinical documentation. Missing any element is grounds for denial or post-payment audit. Confirm that every item below is present before the claim leaves your system.

• Physician order: Dated order with the ordering provider’s NPI, specialty, and the clinical indication for the scan
• Qualifying condition documented: The chart must show which coverage criterion the patient meets (patient age, risk factor, diagnosis, or drug therapy) before the scan date
• Date of last bone density test: Document that 23 months have passed since the patient’s last bone density measurement of any type. If this is the first study, record that instead
• Radiology report: Must name the modality (QCT), sites scanned, T-score and Z-score results, and the interpreting physician’s signature
• Interpreting physician credentials: Name, NPI, and supervising physician documentation if applicable
• Diagnosis code justification: The ICD-10-CM code on the claim must link directly to a clinical finding documented in the chart. Avoid coding from the order alone

In a superbill workflow, the superbill should carry the ICD-10 code, the CPT code, the modifier, and the physician order date. Missing the order date is a frequent audit finding on radiology procedure codes.

CPT 77078 reimbursement rates and the 2026 fee schedule

Medicare Physician Fee Schedule (MPFS) rates for CPT code 77078 vary by locality, site of service (facility vs. non-facility), and the components billed. The table below shows how the rate is built. Always verify current rates for your MAC jurisdiction and year using the CMS Physician Fee Schedule lookup tool. Rates are updated each January 1.

For precise 2025 and 2026 figures by locality, use the FastRVU RVU lookup tool, which pulls directly from published CMS data. Commercial payer rates are negotiated separately and typically exceed Medicare rates, though they vary significantly by contract and region. Review your electronic remittance advice (ERA) after each claim batch to track the allowed amount each payer pays.

Prior authorization requirements

Medicare

Medicare generally does not require prior authorization for CPT code 77078 when the qualifying criteria under NCD 150.3 are documented. The claim should process on medical necessity alone, supported by the correct ICD-10-CM pairing. Confirm with your MAC (for example, Palmetto GBA for JM jurisdiction) whether any additional payer-specific rules apply in your region.

Commercial payers

UnitedHealth, Cigna, Aetna, and many BCBS plans require prior authorization for bone density studies. Requirements vary by plan and year. Before scheduling the procedure, verify the patient’s insurance eligibility and check the specific plan’s prior authorization list. Document the authorization number in the patient chart and on the claim before submission.

Common denial reasons for CPT 77078 claims

CPT code 77078 has a predictable denial profile. The table below maps each denial category to its resolution path, including relevant denial codes in medical billing and correction steps. Reference your remittance advice remark codes (RARC) alongside this table to identify the exact denial category.

Effective denial management on 77078 requires a denial log that tracks CARC and RARC codes per claim. A recurring pattern, such as the same root cause on 10 or more claims in a quarter, signals a workflow issue. It needs a process correction, not just individual appeals.

How practice management software supports 77078 billing accuracy

Each denial in the table above can be caught before the claim is sent. Without a check at that stage, the billing team finds the error weeks later, working back from a remittance code to the radiology report.

Pabau’s pre-submission claims management runs validation checks in the background each time a claim is sent. Those checks confirm that the details insurers need, such as membership numbers and authorization codes, are in place.

In the US, Pabau connects to the Claim.MD clearinghouse, which sends CMS-1500 claims to thousands of US payers. Real-time eligibility checks confirm the patient’s coverage and benefits before the scan is performed.

Once the claim is out, its status updates in the Claims dashboard as the payer processes it. ERA remittances post back against the claims they settle. Denied claims are flagged for rework, so the billing team sees a 77078 denial as soon as the payer returns it.

Reduce bone density claim denials before they happen

Pabau runs automated validation checks on every claim and real-time eligibility checks through its Claim.MD integration. Your 77078 claims reach the payer with the details insurers ask for already in place.

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Conclusion

Billing CPT code 77078 starts with one check. The radiology report has to name QCT and an axial site, meaning the hip, pelvis, or spine, or the claim belongs under a different code.

Get that right at the point of order, then confirm the diagnosis against CMS Article A57132 and check the 23-month window. Each check takes a minute before submission, while an appeal takes weeks after it.

Pabau’s claim validation and real-time eligibility checks handle the payer-side details, so your coders can focus on modality and diagnosis. Book a demo to see how Pabau keeps bone density claims moving from submission to remittance.

Continue your research

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Frequently asked questions