Introduction: Endovascular stenting is an effective treatment available for patients with clinically significant cerebral venous sinus stenosis. Traditionally, stenting success has been determined by intravascular pressure measurements; new imaging modalities, however, show great potential in documenting improved flow and providing noninvasive monitoring of venous patency after treatment. Quantitative MRA (NOVA, VasSol Inc) is a novel imaging modality that quantifies blood flow using MR imaging. Well established in the arterial system, applications to the cerebral venous sinuses have been limited. In this study, we examined venous QMRA flow in patients before and after venous stenting and correlated these results with intravascular pressure and clinical outcomes.
Methods: Five patients underwent cerebral venous stenting between 2009 and 2013 at a single institution. Preoperatively patients were examined clinically, cerebral venous flow was determined using QMRA, and intravascular pressure measured during angiography. After stenting, intravascular pressure, QMRA flow, and clinical outcomes were repeated and compared.
Results: An average prestenotic intravascular pressure of 45.2mmHg (range 31-55) was recorded prior to stenting which decreased significantly to 27.4mmHg (range 16-37) afterwards (paired t-test p=0.036). The average pressure gradient decreased by 20.4 mmHg after the procedure. Flow on QMRA increased by 302.3ml/min at the area of stenosis and 304.4ml/min at the ipsilateral internal jugular vein after stenting. When both jugular veins were considered, the total cerebral venous outflow increased by 260.2ml/min. Statistical analysis of the change in intravascular pressure proximal to stenosis and change in QMRA flow identified a linear relationship (Pearson’s correlation r=0.926). Clinical improvement, including vision, was observed in all patients.
Conclusions: Ipsilateral and total venous quantitative flow measurements by QMRA increase after endovascular stenting and correlate with significantly improved intravascular pressures. These findings establish QMRA as a useful adjunct to measure venous flow after stenting, and as valuable tool for noninvasive monitoring of stent patency.
Patient Care: This research establishes a role for quantitative MRA (NOVA) as a useful tool to document improved venous sinus flow after endovascular stenting. Research results show that decreased intravascular venous pressures after stenting are strongly correlated with improved flow on QMRA and clinical outcomes. These findings establish an important role for QMRA in measuring venous flow after stenting, as well as noninvasive monitoring of stent patency.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Identify venous stenting as a treatment for clinically significant cerebral venous sinus stenosis.
2) Recognize the relationship between intravascular pressure, venous sinus flow rate, and clinical outcomes.
3) Become familiar with QMRA as a useful tool for quantifying blood flow in the cerebral venous sinus system before and after treatment.