In-room assessment of intravascular velocity from time-resolved rotational angiography in patients with arteriovenous malformation: a pilot study

Background: Time-resolved rotational angiography (t-RA) enables interventionists to better comprehend complex arteriovenous malformations (AVMs), thereby facilitating endovascular treatment. However, its use in evaluating hemodynamic changes has rarely been explored.

Objective: This study uses t-RA to estimate intravascular flow in patients with AVM to compare this with flow in the normal population.

Methods: Patients with available t-RA scans were prospectively categorized into one of three groups: hemorrhagic AVM, non-hemorrhagic AVM and control. Pulsatile time-density curves (TDCs) for C1, C6 and VOI_MCA were used for amplitude and velocity estimation. C1 was at the cervical internal carotid artery (ICA), 2-3 cm below the carotid canal, C6 was at the paraclinoid segment of the ICA, and VOI_MCA was at the junction of the first and second segment of the middle cerebral artery (MCA). A waveform amplitude ratio was defined as (peak - trough)/trough contrast intensity. V_ICA was defined as the distance between C6 and C1 divided by the time required for the wave to pass, and correspondingly, the average velocity of MCA (V_MCA) was defined as the distance between C6 and VOI_MCA divided by the duration for the same peak to travel from C6 and VOI_MCA, AVM volume was estimated by MR angiography.

Results: Amplitude ratios A_C1 and A_C6, and average flow velocities V_ICA and V_MCA were significantly larger in the non-hemorrhagic group than in the control group, while the hemorrhagic AVM group was not significantly different from the controls. V_ICA and V_MCA showed moderate to good correlations with AVM volume (r=0.51 and 0.73, respectively). V_MCA (33.0±9.1) was significantly lower than V_ICA (41.3±13.2) in the control group, but not in the two AVM groups.

Conclusion: TDC waveform propagation derived from t-RA can quantify hemodynamic differences between AVM and the control group. t-RA provides both real-time anatomic and hemodynamic evaluation, and can thus potentially improve the interventional workflow.