Billing code 78635: CSF imagingMedicare rate & RVUs in Rhode Island
Nuclear imaging tracks radiotracer movement through ventricular cerebrospinal fluid when clinicians need to assess flow within the brain’s ventricular system.
Medicare pays $303.66 for 78635 in the office in Rhode Island (Rhode Island). Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What 78635 covers
This nuclear medicine study follows radiotracer distribution through cerebrospinal fluid in the ventricular system. It is used when clinicians need information about ventricular CSF flow, such as in evaluating a suspected flow abnormality. A nuclear medicine physician interprets the images; the study may involve ventricular access for tracer administration, with imaging performed in a nuclear medicine department.
Report 78635 for the ventricular CSF imaging service, rather than a general brain scan or a study focused on shunt function or CSF leakage. The record should support the clinical question, tracer administration and access route, images obtained, and the physician’s interpretation. CMS recognizes a professional component, reported with modifier 26 for interpretation, and a technical component, reported with modifier TC for equipment and staff. Without either modifier, the claim represents the global service.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
78635 in Rhode Island
| Payment locality | Office | Facility |
|---|---|---|
| Rhode Island | $303.66 | Unavailable |
How the 78635 rate is calculated
Each of 78635’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 78635
RVUs × geographic indexes × conversion factor
Work0.59
0.59 RVUs× 1.000 GPCI
Practice expense8.15
8.15 RVUs× 1.000 GPCI
Malpractice0.08
0.08 RVUs× 1.000 GPCI
Adjusted RVUs
8.8200
Conversion factor
$33.4009
Medicare rate
$294.60
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 78635
The CMS indicators that decide how 78635 is paid alongside other services.
CMS payment indicators · 78635
CSF imaging
| Rule | CMS value | What it means |
|---|---|---|
| Global period | XXX | The global surgery concept doesn’t apply. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 1 | Diagnostic test with separate professional (26) and technical (TC) components. |
What modifiers do to the payment
Modifier 26 · payment effect
With and without the modifier
78635 without 26 · national office
$294.60
CSF imaging
78635-26 · Professional component
$28.06
Pays only the interpretation and report.
78635 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 78630CSF scan
- Choose 78635 for imaging focused on ventricular CSF flow. Code 78630 describes a CSF scan using a different approach to assess CSF circulation.
- 78645CSF shunt study
- Use 78645 when the study evaluates a CSF shunt. Use 78635 for ventricular CSF imaging when shunt function is not the specific study target.
- 78650CSF leak imaging
- Code 78650 is for imaging directed at a suspected CSF leak; 78635 focuses on CSF movement through the ventricles.
78635 billing questions
How does 78635 differ from a CSF scan?
78635 describes imaging focused on CSF movement through the ventricular system. A CSF scan such as 78630 is used for a different CSF imaging approach and clinical question.
When should 78645 be considered instead?
Use 78645 when the study evaluates CSF shunt function. Code 78635 describes ventricular CSF imaging, not a shunt-specific evaluation.
Can the professional and technical portions be billed separately?
Yes. Report modifier 26 for the physician’s interpretation or TC for the technical service, which includes equipment and staff. Billing without a modifier represents the global service.
What documentation supports reporting 78635?
Document the reason for evaluating ventricular CSF flow, the tracer administration and access route, the imaging performed, and the interpreting physician’s findings.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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