MRV vs MRA for Pulsatile Tinnitus with Previous Normal Imaging
Yes, an MRV is appropriate and potentially more important than an MRA in your case, given that you have pulsatile tinnitus with previous normal imaging—your provider is correctly investigating venous causes, which are frequently missed on initial CT and CTV scans. 1
Why MRV Is the Right Choice
For pulsatile tinnitus, both arterial (MRA) and venous (MRV) imaging are equally appropriate initial studies, with the ACR rating both at 8 out of 9 for appropriateness. 2 The key distinction is that venous causes of pulsatile tinnitus—particularly dural arteriovenous fistulas involving the transverse or sigmoid sinus—are among the most serious and treatable causes, yet they can be missed on standard CT and CTV imaging. 3
Venous Pathology Is Common and Dangerous
- Dural arteriovenous fistulas (DAVF) of the transverse or sigmoid sinus are a leading vascular cause of pulsatile tinnitus and can result in significant morbidity and mortality if left untreated. 3
- MRV combined with MRI detects anatomical abnormalities contributing to pulsatile tinnitus in 63% of patients with subjective pulsatile tinnitus and normal otoscopy. 3
- Venous sinus stenosis, jugular bulb variants, and other venous anomalies are frequently identified on MRV and may not be adequately visualized on CTV. 4
The Imaging Algorithm for Your Situation
Given your constellation of symptoms (pulsatile tinnitus, balance problems, facial/head pressure) and previous normal imaging:
MRV is appropriate as the next step to evaluate for venous sinus stenosis, DAVF, or other venous pathology that may have been missed on CTV. 2
MRA should ideally be obtained at the same time since both arterial and venous causes need evaluation in pulsatile tinnitus, and obtaining both studies together is standard practice. 1, 2
If MRV/MRA shows abnormalities suggestive of DAVF or other vascular malformations, conventional angiography remains the gold standard for definitive diagnosis and treatment planning. 3, 5
Why Your Previous CTV May Have Been Inadequate
- CT venography has limitations in detecting subtle venous sinus stenosis and dural arteriovenous fistulas compared to MRV, particularly when combined with MRI sequences. 3
- MRI/MRA combined is significantly more sensitive than CT in detecting vascular causes of pulsatile tinnitus. 3
- 46% of vascular lesions causing pulsatile tinnitus are seen best on MRA, and 36% are seen only on MRA, highlighting why repeat vascular imaging with MR techniques is justified even after normal CT/CTV. 4
Critical Next Steps
If you have an objective bruit (a sound your doctor can hear with a stethoscope), conventional angiography should be considered directly to ensure a transverse or sigmoid sinus DAVF is not missed. 3
If your MRV is normal but symptoms persist, particularly with balance problems and pressure symptoms, consider:
- Evaluation for benign intracranial hypertension (idiopathic intracranial hypertension), which often has normal imaging findings but can cause pulsatile tinnitus. 6
- Conventional angiography if clinical suspicion remains high, as some DAVFs are elusive on all cross-sectional imaging. 6, 5
Common Pitfall to Avoid
Do not be falsely reassured by normal CT/CTV—these studies miss a significant proportion of treatable vascular causes of pulsatile tinnitus, particularly venous pathology and dural arteriovenous fistulas. 3 Your provider is appropriately pursuing MR-based vascular imaging despite previous normal studies.