Interdisciplinary Neurosurgery (Sep 2020)
Arterial spin-labeling perfusion MR images with dual postlabeling delay reveals hemodynamic changes in dural arteriovenous fistulas following endovascular surgery
Abstract
Background: Previous studies have demonstrated that, in patients with dural arteriovenous fistulas (DAVF), magnetic resonance perfusion images with arterial spin labeling (ASL) with a conventional single postlabeling delay (PLD) of 1.5 s, can be used to depict dural sinus and cortical venous reflux (CVR). However, because ASL is highly sensitive to arterial transit time (ATT), slow-flowing CVR cannot be fully evaluated. Furthermore, cerebral blood flow in the entire cortex can be underestimated because of prolonged ATT associated with venous congestion. To overcome these problems, we used a simple ASL technique with dual PLD settings with a longer PLD of 2.5 s in addition to 1.5 s. Methods: We retrospectively selected two patients with DAVF who underwent endovascular surgery, and visually analyzed the diagnostic performance of the dual PLD method for evaluating perioperative changes of dural sinus and slow-flowing CVR and the associated hemodynamic state. Patient 1 had left transverse sinus-DAVF with severe venous congestion and Patient 2 developed an intracerebral hemorrhage in the left temporal lobe associated with left tentorial DAVF. Results: Preoperatively, slow-flowing CVR in the left frontal lobe in Patient 1 and CVR in the vein of Trolard in Patient 2 were not detected using ASL with PLD at 1.5 s, but became apparent at 2.5 s. In both patients, the preoperative ATT of the entire brain was prolonged; ASL signals of the entire brain were decreased at 1.5 s and somewhat increased at 2.5 s. Postoperatively, the dural sinus and CVR disappeared. Furthermore, the prolonged ATT of the entire brain was improved. Conclusion: Although further research with a large number of the patients is required, ASL with dual PLD method may enhance the detection of slow-flowing CVR and allow the evaluation of perioperative hemodynamic changes, including the improvement of prolonged ATT caused by venous congestion.
