CTV Head (Cerebral Venogram) — Dictation, Appropriateness, and Dose for Residents
1. That Stat CTV Head from the ED
It’s 4 PM. Stat CTV head from the ED. Young patient on oral contraceptives with a thunderclap headache. The non-contrast was negative for hemorrhage, but the clinical suspicion for cerebral venous sinus thrombosis is high. Your attending is going to want a definitive call on the superior sagittal sinus, and “equivocal for filling defect versus arachnoid granulation” isn’t going to cut it. You need to systematically check every major dural sinus, rule out a subtle cortical vein thrombosis, and not mistake a hypoplastic transverse sinus for an occluded one.
When I was a resident, this was the kind of study where I’d pull up a separate browser window with an anatomy diagram just to be sure I didn’t miss anything. The pressure isn’t just about getting the diagnosis right; it’s about dictating a report that’s clean, structured, and answers the clinical question without ambiguity. For more high-yield guides like this, check out our free trainee calculators and references.
2. What a CT Venogram of the Head Covers and What Attendings Look For
A CT Venogram (CTV) of the head is a dedicated, timed, contrast-enhanced study designed to opacify the cerebral dural venous sinuses and major cortical veins. The primary goal is to identify filling defects that signify thrombosis. While MR venography is an excellent alternative, especially for subacute thrombus, the speed and accessibility of CT make it a frontline tool in the acute setting.
Your attending expects a systematic evaluation that definitively answers these key questions:
- Cerebral Venous Sinus Thrombosis (CVST): Is there a filling defect in the superior sagittal, transverse, sigmoid, or straight sinuses? What about the internal jugular veins?
- Cortical Vein Thrombosis: Are there any subtle filling defects in the superficial cortical veins? Is there a “cord sign” on the non-contrast images?
- Extrinsic Compression: Is a mass, like a meningioma, compressing or invading a sinus?
- Dural Venous Sinus Stenosis: In the workup for idiopathic intracranial hypertension, are there bilateral transverse sinus stenoses?
- Variant Anatomy: Is a small transverse sinus truly thrombosed or just a common hypoplastic variant? (Hint: check the jugular foramen on bone windows).
3. Radiology Report Template for CTV Head (Cerebral Venogram)
This is a solid starting point for your personal macro. Remember to always compare with the paired non-contrast head CT, as acute thrombus can appear as a hyperdense sinus before contrast is even given.
Technique
Non-contrast and contrast-enhanced CT images of the head were acquired in the venous phase. Axial, coronal, and sagittal reconstructions, including maximum intensity projections (MIPs), were reviewed.
Comparison: [Date of prior study]
Findings
Dural Venous Sinuses:
Superior Sagittal Sinus: [Patent / Filling defect consistent with thrombosis / Attenuated]
Straight Sinus: [Patent / Filling defect consistent with thrombosis]
Transverse Sinuses: [Symmetric and patent / Right is dominant/codominant/hypoplastic / Left is dominant/codominant/hypoplastic / Filling defect in the right/left transverse sinus]
Sigmoid Sinuses: [Symmetric and patent / Filling defect in the right/left sigmoid sinus]
Confluence of Sinuses (Torcular Herophili): [Patent / Filling defect]
Deep and Superficial Venous System:
Internal Cerebral Veins: [Patent]
Vein of Galen: [Patent]
Cortical Veins: [No evidence of cortical vein thrombosis / Filling defect in a [location] cortical vein with associated [edema/hemorrhage]]
Internal Jugular Veins: [Symmetric and patent / Filling defect in the right/left internal jugular vein]
Parenchyma: No acute intracranial hemorrhage, mass effect, or territorial infarct. [or describe findings of venous congestion, edema, or hemorrhage].
Other Findings: The visualized paranasal sinuses and mastoid air cells are clear. No acute osseous abnormality.
Impression
1. [No evidence of dural venous sinus or cortical vein thrombosis.]
OR
1. [Acute/Subacute] thrombosis of the [e.g., superior sagittal and left transverse sinuses], as described above. Associated findings include [e.g., venous congestion and edema in the left parietal lobe].
2. [Anatomic variants, such as a hypoplastic left transverse sinus.]
4. Free Template Sources from Around the Web
Building a personal library of macros is a rite of passage. If you’re looking for more templates to adapt, two great free repositories exist. The Radiological Society of North America (RSNA) curates a comprehensive library at RadReport.org, covering nearly every modality and subspecialty. Another excellent resource is maintained by our Australian colleagues at RadiologyTemplates.com.au.
5. The Next-Level Move: From Free-Form Dictation to Structured Report
The template above is great for a normal study, but what happens when you have multiple positive findings? You start free-form dictating: “There’s a filling defect in the posterior superior sagittal sinus extending into the right transverse sinus… also looks like there’s some venous edema in the right parietal lobe…” This is where things can get messy, and key details get buried in the prose.
The goal is to capture those free-form thoughts but have them land in a perfectly structured report every time. This is what GigHz Precision AI is designed to do. You dictate your positive findings naturally, and the AI engine structures them into the appropriate sections of an ACR or SIR-based template. It helps ensure your final report is clean, consistent, and easy for clinicians to read, which makes you look polished and efficient, especially on a busy call shift.
6. When Should You Order a CTV Head? ACR Appropriateness Criteria
The American College of Radiology (ACR) provides evidence-based guidelines on imaging appropriateness. For a CTV head, the key indications often revolve around headaches with specific red flags.
Per the ACR’s “Headache” criteria, for a patient presenting with a headache with features of intracranial hypertension (like papilledema, pulsatile tinnitus, or visual changes), both CT Venography and MR Venography are rated “Usually Appropriate.” This is the classic workup for idiopathic intracranial hypertension (pseudotumor cerebri) to evaluate for bilateral transverse sinus stenosis.
For a patient with a sudden onset severe headache (a “thunderclap” headache), a non-contrast head CT is the first step to rule out subarachnoid hemorrhage. If that is negative, CTV is “Usually Appropriate” to evaluate for reversible cerebral vasoconstriction syndrome or cerebral venous sinus thrombosis, which can present identically.
In other scenarios, like a typical primary migraine or tension-type headache with a normal neurologic exam, advanced imaging like CTV is “Usually Not Appropriate.” These guidelines help ensure the right test is ordered for the right clinical question.
7. How Much Radiation Does a CTV Head Deliver?
Patients and ordering providers are increasingly aware of radiation dose. It’s good to have a confident, accurate answer when they ask. A CT Venogram of the head delivers an estimated effective dose of 1-3 mSv.
To put that in perspective, this is in the low-dose tier for CT studies. It’s comparable to the amount of natural background radiation a person receives over several months to a few years. While MR Venography is an alternative that avoids ionizing radiation, its longer scan time and lower accessibility can be limitations in an acute setting where CVST is suspected.
| Exposure | Effective Dose (mSv) |
|---|---|
| CTV Head | 1-3 mSv |
| Annual Natural Background Radiation (US) | ~3 mSv |
| CT Head (Non-contrast) | ~2 mSv |
| CT Abdomen/Pelvis | ~10 mSv |
Modern CT scanners use dose modulation techniques to minimize radiation while maintaining diagnostic quality. The protocol is tailored to answer the specific clinical question, avoiding unnecessary radiation exposure.
8. CTV Head Imaging Protocol — Phases, Contrast, and Reconstructions
A successful CTV hinges entirely on technique, specifically the timing of the contrast bolus to opacify the venous sinuses. Unlike a CTA where you want peak arterial enhancement, here you are intentionally delaying the scan. Always ensure a non-contrast head CT is performed first, as the hyperdense sinus of acute thrombus is a critical finding that can be obscured by contrast.
The scan is a single helical acquisition timed for the venous phase, typically 30-45 seconds after contrast injection, though bolus tracking can also be used. From this single dataset, thin-slice reconstructions and multiplanar MIPs are generated to trace the course of the dural sinuses.
| Phase / Sequence | Key Parameters | Purpose |
|---|---|---|
| Topogram | kVp: 120 | Scan planning |
| Venous Phase Helical | kVp: 100-120; Slice: 0.6-1 mm; Contrast: 100 mL @ 4-5 mL/s; Delay: 30-45 sec | Primary acquisition for opacifying dural sinuses and cortical veins |
| Reconstructions | Axial: 2 mm; MIPs: 5 mm slabs (Axial, Coronal, Sagittal) | Detailed evaluation of venous anatomy and detection of filling defects |
Common protocol pitfalls:
- Timing: Scanning too early results in poor venous opacification and a non-diagnostic study. Scanning too late can lead to venous washout and equivocal findings.
- Skipping the Non-Contrast: The pre-contrast scan is essential. A hyperdense “cord sign” in a cortical vein or a dense triangle sign in the superior sagittal sinus can be the most obvious signs of acute thrombosis.
- Cortical Veins: For subtle cortical vein thrombosis, a delayed phase at ~120 seconds can sometimes be helpful to visualize slow flow, but this is not part of a standard protocol.
9. The 3-Months-Free Offer for Residents and Fellows
3+ months free for radiology residents and fellows.
Look like a rockstar on your reports. The goal of GigHz Precision AI is to let you focus on the images. Dictate your positive findings in free form, and the AI generates a clean, structured report using ACR and SIR templates. It helps you hit all the key points your attending is looking for without having to manually structure every sentence.
All we ask in return is your feedback so we can keep improving the product for trainees. The signup is simple. No credit card, no long forms. To get started, just provide three items:
- Your PGY year (e.g., PGY-2, PGY-4)
- Your training type (radiology residency or fellowship specialty)
- Your training program / hospital name
You can apply for the residents free-access program here. We’ll get you set up quickly.
10. Frequently Asked Questions
Is it HIPAA-compliant?
Yes. The platform is designed for de-identified workflows. No patient health information (PHI) is required to use the tool for structuring your dictations.
Do I need IT to set it up?
No. GigHz Precision AI is browser-based. There’s no software to install on hospital computers. It works on the call-room desktop, your personal laptop, or even an iPad.
Does this replace PowerScribe or other dictation systems?
No, it works alongside them. You can use it to generate the structured text of your report, then copy and paste it into your facility’s official dictation system for sign-off.
Can I use this on my phone or iPad?
Yes, the tool is web-based and responsive, making it accessible on most devices with an internet connection.
Can I customize the templates?
Yes, you can create and save your own variations of standard templates to match your personal style or your institution’s preferred format.
What happens after my residency or fellowship ends?
The free access program is specifically for trainees. After you graduate, you can transition to a standard plan. We offer discounts for recent graduates to help you get started in your practice.
Free GigHz Tools That Pair With This Article
Three free tools that complement the material above:
- ACR Appropriateness Criteria Lookup — Type an indication or clinical scenario in plain language and get the imaging studies the ACR rates for it, with adult and pediatric radiation levels. Built directly from 297 ACR topics, 1,336 clinical variants, and 15,823 procedure ratings.
- GigHz Imaging Protocol Library — A searchable library of 131 imaging protocols with the physics specs surfaced and the matching ACR Appropriateness Criteria alongside. Plain-English narratives readable in 60 seconds, organized by modality.
- GigHz Radiation Dose Calculator — Pick the imaging studies a patient has had and see total dose in millisieverts (mSv) with comparisons to natural background radiation, transatlantic flights, and chest X-rays. Useful for shared decision-making.
Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 7, 2026
