A billing reference for cardiology group administrators and billing managers running PET and SPECT programs. Covers every imaging CPT code, the stress and radiopharmaceutical charges billed alongside them, modifier 26/TC scenarios, payer-specific prior auth requirements, and the Medicare LCD documentation that auditors check first.
Nuclear cardiology generates some of the highest per-study revenue in a cardiology practice and some of the most complex claims. A single cardiac PET perfusion study can involve five or more separately billable line items: the imaging code, the stress test, the pharmacologic stress agent, the radiopharmaceutical, and the quantitative flow add-on. Miss one line item and the revenue is gone. Bill the wrong modifier and the entire claim is denied.
This guide is written for the billing manager or administrator of a cardiology group, not for coders. It covers every PET and SPECT imaging code your program bills, the add-on charges that travel with them, the payer-specific prior auth rules that block claims before they start, and the Medicare LCD documentation that auditors review when they pull your charts. For a searchable database of all denial codes, see the Denial Code Reference or the Denial Code Lookup Tool.
Imaging CodesCardiac PET codes split into two groups: those performed with a concurrent CT transmission scan for attenuation correction (78429 to 78434) and those without CT (78491 and 78492). Nearly all modern PET/CT scanners acquire the CT automatically, so most programs bill from the 78429 to 78434 range. The non-CT codes (78491, 78492) apply when a standalone PET scanner is used without CT attenuation correction.
SPECT (single-photon emission computed tomography) remains the most commonly performed nuclear cardiology modality nationally. These codes use Tc-99m tracers (sestamibi or tetrofosmin) and include attenuation correction, wall motion, and ejection fraction analysis when performed.
The imaging code covers the scan itself. The stress test, the stress agent, and the radiopharmaceutical are each billed as separate line items. Missing any one of these is revenue left on the table. For an active PET program performing 10 studies per week, a missed radiopharmaceutical charge alone can cost $50,000 to $75,000 per year.
The stress test is billed separately from the imaging study. How it splits depends on who supervises, who runs the tracing, and who interprets.
When pharmacologic stress replaces exercise, the stress drug is billed separately using its HCPCS J-code. Documentation must state why the patient could not exercise (LBBB, severe COPD, orthopedic limitation, inability to achieve target heart rate).
A standard pharmacologic PET myocardial perfusion study with quantitative flow produces five separately billable line items on a single claim.
How a cardiology group bills nuclear imaging depends on whether it owns the PET or SPECT camera and employs the technical staff. The modifier determines who gets paid for which portion of the study.
Three of the four largest Medicare Advantage payers route cardiac PET authorization through eviCore (now part of Evernorth/Cigna). Authorization is valid for 90 days once approved. Submitting a claim without a valid auth number produces a CO-197 denial that is difficult to reverse after the fact.
UHC removed prior auth for certain nuclear imaging procedures effective January 2026, but cardiac PET may still require auth depending on the specific Medicare Advantage plan delegate.
Medical policy MMP242.21 covers cardiac PET for acute MI, unstable angina, chronic ischemic heart disease, cardiac sarcoidosis, and post-transplant evaluation.
Portal: uhcprovider.com
Cardiac PET explicitly requires prior auth under their cardiology advanced imaging program. Applies to Medicare (Aetna Next Generation), HMO, and PPO plans.
Auth valid for 90 days. ER, observation, and inpatient are excluded from auth requirements.
Submit: evicore.com/provider | 888-622-7329
Cardiac PET is explicitly listed as requiring preauthorization alongside nuclear cardiology, stress echo, cardiac CT, cardiac MRI, and cardiac catheterization.
eviCore manages the full cardiology prior auth program for Cigna plans.
Submit: evicore.com | 888-693-3297
PET scans, SPECT, and nuclear medicine studies require preauthorization. eviCore manages the delegation for applicable Humana plans including Humana Healthy Horizons.
Requirements vary by state and market. Verify the specific plan's auth requirement before scheduling.
Submit: evicore.com | 866-672-8115
eviCore reviews the same core elements across all four payers. An incomplete packet delays auth and pushes the study date past the patient's window.
Medicare covers cardiac PET nationally under NCD 220.6 for two primary indications: myocardial perfusion imaging (using Rb-82 or N-13 ammonia) and myocardial viability assessment (using FDG). The LCD that governs documentation requirements is L34625 (Myocardial Perfusion Imaging and Cardiac Blood Pool Studies), which applies across MAC jurisdictions including First Coast (Jurisdiction N) and Novitas (Jurisdictions JL and JH).
These two MACs are where audits on cardiac imaging most commonly originate. CMS has approved RAC audit topic 0010 specifically for cardiac PET scans, targeting medical necessity and documentation requirements. A chart that does not meet the LCD criteria at the time of the study will not survive the audit, regardless of whether the clinical decision was appropriate.
The LCD requires at least one qualifying diagnosis documented on the order and in the clinical record. The most common qualifying codes for cardiac PET fall into these categories.
RAC auditors reviewing cardiac PET claims under topic 0010 pull the full chart, not just the order. The documentation must establish four things.
The ASNC (American Society of Nuclear Cardiology) appropriate-use criteria provide a defensible framework. An "Appropriate" rating under ACC/ASNC guidelines should be universally covered. "Uncertain" ratings are covered but require stronger documentation, while "Inappropriate" ratings will be denied on audit.
These three CARC codes account for the majority of revenue lost in cardiac PET programs. Each one has a different root cause, a different fix, and a different prevention strategy.
A PET program's financial performance varies by site. The camera at one location may run at capacity with a 3% denial rate while another site runs at half volume with denials above 8%. Without per-site reporting, the underperforming location hides inside the group average.
The two numbers that matter most are PET volume by site (studies performed per week, trended monthly) and denial rate by site (denied charges as a percentage of billed charges, broken out by denial code). A site with rising volume and a stable denial rate is healthy. A site with flat volume and a rising denial rate has a documentation or authorization breakdown that needs attention before it becomes a revenue problem.
For cardiology groups operating across multiple locations, we build per-site dashboards that surface these metrics alongside payer mix, average reimbursement per study, and days in A/R. The goal is to make each site's PET program independently visible so that problems are caught at the site level, not discovered in the quarterly P&L. Learn how we work with multi-location groups.
Both codes bill a complete rest-plus-stress PET myocardial perfusion study. The difference is whether a concurrent CT transmission scan was acquired for attenuation correction. Code 78431 includes CT; 78492 does not. Nearly all modern PET/CT scanners acquire the CT automatically, so 78431 is the appropriate code for most programs. Use 78492 only when imaging on a standalone PET scanner without CT capability.
Code 78434 can only be billed alongside 78431 or 78492 on the same claim. It requires software capable of computing absolute myocardial blood flow (mL/min/g) and coronary flow reserve ratios from the dynamic PET acquisition. If a site's scanner or software does not produce quantitative flow data, 78434 cannot be billed there. In hospital outpatient settings, the technical component of 78434 is packaged into the APC payment and receives no separate reimbursement; the professional component (78434-26) is still separately payable.
Traditional Medicare (fee-for-service) does not require prior authorization for cardiac PET imaging. However, Medicare Advantage plans frequently do, and most route the auth through eviCore. The requirement varies by plan, not by payer brand, so verify the specific member's plan before scheduling. Traditional Medicare claims are subject to post-payment audit under LCD L34625 and RAC topic 0010, which makes medical-necessity documentation just as important as prior auth.
Rb-82 is billed per study dose using HCPCS code A9555. A rest-plus-stress study using Rb-82 requires two doses (one for the rest acquisition, one for the stress acquisition), so A9555 is typically billed with 2 units. The billed amount must reflect the actual acquisition cost of the rubidium per the generator invoice. Billing above acquisition cost exposes the practice to OIG enforcement; 16 cardiology practices paid a combined $17.76 million in settlements for this exact issue.
The auth must match the service performed. An authorization for 78452 (SPECT) does not cover 78431 (PET). If the clinical decision changes from SPECT to PET after the auth is obtained, contact the payer or eviCore before the study date to update the authorization. Submitting a PET claim under a SPECT auth produces a CO-197 denial. Some payers allow a retrospective auth update within a narrow window (typically 2 to 5 business days), but this is not guaranteed.
We audit PET and nuclear cardiology billing for multi-site groups and build the per-location reporting that surfaces denials before they compound. The analysis is free.
A-Z Medical Billing & Consulting | rh@a-zmedbilling.com | (888) 519-9970
Dr. Zain Vally founded A-Z Medical Billing & Consulting after identifying persistent revenue cycle inefficiencies while operating Vally Medical Group, a multi-location occupational medicine practice across Hawaii. The hands-on experience of managing billing operations across four clinic locations revealed systematic gaps in how billing services handle complex specialty coding, modifier requirements, and payer-specific documentation rules.
