No, CTV and CTA Are Not the Same—They Image Different Vascular Systems
CT venography (CTV) images the venous system while CT angiography (CTA) images the arterial system, and for pulsatile tinnitus with potential IIH, you need to evaluate BOTH vascular systems, which can be accomplished with a single mixed-phase CTA protocol. 1
Key Technical Differences
CTA captures arterial anatomy by timing contrast injection to peak arterial enhancement (typically 15-20 seconds post-injection), evaluating arterial causes like carotid atherosclerosis, arterial dissection, and dural arteriovenous fistulas 1
CTV captures venous anatomy with delayed imaging (typically 60-90 seconds post-injection), evaluating venous causes like sigmoid sinus stenosis, jugular bulb abnormalities, and venous sinus thrombosis 1
Mixed arterial-venous phase CTA can be performed at approximately 20-25 seconds post-contrast injection, capturing both arterial and venous anatomy in a single acquisition with lower total radiation dose compared to separate CTA and CTV examinations 1
Why This Matters for Your Clinical Scenario
For unilateral pulsatile tinnitus with suspected IIH, you must evaluate both vascular systems because:
IIH is the second most common cause of pulsatile tinnitus (after atherosclerotic carotid disease), and is strongly associated with venous abnormalities including sigmoid sinus stenosis, sigmoid sinus wall dehiscence, and sigmoid sinus diverticulum 2, 3, 4
Venous-sided pathology (sigmoid sinus dehiscence, diverticulum, transverse sinus stenosis) shows significant correlation with the symptomatic side in unilateral pulsatile tinnitus, with 78% prevalence on the symptomatic side versus 50% on the asymptomatic side 3, 4
Life-threatening arterial causes like dural arteriovenous fistulas (8% of pulsatile tinnitus cases) and arterial dissection must be excluded, requiring arterial phase imaging 2
Recommended Imaging Protocol
Order a mixed-phase CTA of the head and neck with IV contrast (20-25 seconds post-injection) that includes thin-section temporal bone reconstructions. 1 This single study provides:
- Arterial anatomy to exclude dural AVF, arterial dissection, and atherosclerotic disease 1
- Venous anatomy to evaluate for transverse/sigmoid sinus stenosis, sigmoid sinus dehiscence, and diverticulum 1, 2
- Bone algorithm reconstructions to assess for sigmoid plate dehiscence and other bony abnormalities 1
Common Pitfall to Avoid
Do not order CTV alone for pulsatile tinnitus—this misses critical arterial pathology including dural AVF, which can present with isolated pulsatile tinnitus before catastrophic hemorrhage. 2 The mixed-phase protocol captures both systems efficiently without requiring two separate studies. 1