CPT 78645Radiology

Csf shunt evaluation

CPT code 78645 covers a nuclear medicine test that checks whether a cerebrospinal fluid (CSF) shunt is working properly. This imaging procedure uses radioactive tracers to track fluid movement through the shunt system in patients with hydrocephalus or other conditions requiring CSF drainage.

Showing rates for

National Average

Base Medicare rate

$281.41

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

0.57

PE RVU (NF)

8.05

MP RVU

0.08

Total RVU

8.7

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

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Billing tips

Document all imaging time points and elapsed time from radiopharmaceutical injection through final imaging series
Impact: Supports full reimbursement of $281.41 and prevents downcoding to simpler imaging studies worth 30-40% less
Separately report radiopharmaceutical supply using HCPCS code A9548 (Indium In-111 DTPA) or A9539 (Tc-99m) with appropriate units
Impact: Recovers additional $150-400 in radiopharmaceutical costs not included in the procedure reimbursement
Bill injection procedure separately using CPT 61026 (ventricular puncture) or 62270 (spinal puncture) when performed by your practice
Impact: Captures additional $75-200 for injection procedure depending on approach and payer policies
Ensure medical necessity documentation includes specific symptoms of shunt malfunction and impact on treatment decisions
Impact: Reduces denial rate by approximately 15-25% based on improved medical necessity support
Report both facility and non-facility rates are identical at $281.41, so verify place of service code accuracy (22 for hospital outpatient, 24 for ASC)
Impact: Prevents payment delays from place of service mismatches even though rates are equal
Coordinate billing between nuclear medicine and neurosurgery when injection is performed by different provider to avoid duplicate or missed charges
Impact: Ensures complete revenue capture and prevents $75-200 in lost injection fees

Common denials

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Frequently asked questions

What is the Medicare reimbursement rate for CPT code 78645 in 2025?

The 2025 Medicare national average reimbursement for CPT 78645 is $281.41 for both facility and non-facility settings. This rate is based on 8.7 total RVUs multiplied by the 2025 conversion factor of 32.3465.

Can CPT 78645 be billed with modifier 26 for professional component only?

Yes, CPT 78645 can be split into professional and technical components using modifier 26 for the physician interpretation and modifier TC for the technical component. This is common when a hospital performs the imaging but an outside physician provides the interpretation.

What radiopharmaceutical codes should be billed with CPT 78645?

The most commonly billed radiopharmaceuticals with 78645 are HCPCS A9548 for Indium-111 DTPA or A9539 for Technetium-99m DTPA. These are billed separately from the procedure code to capture the radiopharmaceutical supply costs.

How often can CPT 78645 be billed for the same patient?

Medicare does not have a specific frequency limitation for 78645, but medical necessity must be documented for each study. Repeat studies within 90 days typically require documentation of interval symptom change, shunt revision, or new clinical findings to support medical necessity.

Can the shunt injection procedure be billed separately from CPT 78645?

Yes, when documented separately, you can bill CPT 61026 for ventricular puncture through shunt or CPT 62270 for lumbar puncture for radiopharmaceutical injection. These codes are not bundled with 78645 and represent distinct procedural work, typically performed by a neurosurgeon.

What is the difference between CPT 78645 and 78630 for CSF imaging?

CPT 78645 specifically evaluates CSF shunt patency and function, while 78630 is a broader cerebrospinal fluid flow imaging study used to evaluate CSF leaks or flow dynamics without a shunt. Code selection depends on whether a shunt system is being evaluated.

What documentation is required to support medical necessity for CPT 78645?

Required documentation includes clinical symptoms suggesting shunt malfunction (headaches, altered mental status, nausea), physical examination findings, description of shunt type and location, explanation of why other imaging is insufficient, and how results will impact treatment decisions such as shunt revision or adjustment.