Accelerated MR Evaluation of Patients with Suspected Large Arterial Vessel Occlusion: Diagnostic Performances of the FLAIR Vessel Hyperintensities

Background: Fluid attenuated inversion recovery (FLAIR) vascular hyperintensity (FVH) document slowed vascular flow at the level and after the occlusion site patients with acute ischemic stroke (AIS). We aimed to assess the accuracy of FVH for the confirmation and location of a large vessel occlusion (LVO). Methods: Three radiologists reviewed the FLAIR sequence of the admission MRI exam of patients with suspected AIS at a single academic center. Readers were provided with the main clinical deficit with National Institute of Health Stroke Severity score and were asked to identify and locate an LVO when appropriate. Kappa coefficients were calculated for agreement along with diagnosis performances of FVH to recognize and locate an LVO with digital subtracted angiography (DSA) as gold standard. Results: Among 125 patients screened with MRI for a suspected AIS, 96 (81%) were diagnosed with AIS and 47 (38%) patients had an anterior LVO of whom 25 (20%) had a DSA for mechanical thrombectomy. Kappa coefficients for intra- and inter-readers were good to excellent. Overall, the sensitivity and the specificity of the FVH to predict an anterior LVO was 0.98 (95% confidence interval [CI]: 0.94–1) and 0.86 (95% CI: 0.79–0.96), respectively, while PPV and NPV were 0.87 (95% CI: 0.85–0.95) and 0.98 (0.97–1), respectively. FVH also showed good to excellent accuracy for identifying M1 and M2 versus internal carotid artery occlusion site. Conclusion: We found that FVH demonstrated excellent diagnostic performances for the identification of LVO and its level with good to excellent reproducibility. This MRI radio marker of occlusion provides additional arguments and may speed-up the detection of potential candidates for MT.

Flat-detector computed tomography evaluation in an experimental animal aneurysm model after endovascular treatment: A pilot study

We compared flat-detector computed tomography angiography (FD-CTA) to multislice computed tomography (MS-CTA) and digital subtracted angiography (DSA) for the visualization of experimental aneurysms treated with stents, coils or a combination of both. In 20 rabbits, aneurysms were created using the rabbit elastase aneurysm model. Seven aneurysms were treated with coils, seven with coils and stents, and six with self-expandable stents alone. Imaging was performed by DSA, MS-CTA and FD-CTA immediately after treatment. Multiplanar reconstruction (MPR) was performed and two experienced reviewers compared aneurysm/coil package size, aneurysm occlusion, stent diameters and artifacts for each modality. In aneurysms treated with stents alone, the visualization of the aneurysms was identical in all three imaging modalities. Residual aneurysm perfusion was present in two cases and visible in DSA and FD-CTA but not in MS-CTA. The diameter of coil-packages was overestimated in MS-CT by 56% and only by 16% in FD-CTA compared to DSA ( p < 0.05). The diameter of stents was identical for DSA and FD-CTA and was significantly overestimated in MS-CTA ( p < 0.05). Beam/metal hardening artifacts impaired image quality more severely in MS-CTA compared to FD-CTA. MS-CTA is impaired by blooming and beam/metal hardening artifacts in the visualization of implanted devices. There was no significant difference between measurements made with noninvasive FD-CTA compared to gold standard of DSA after stenting and after coiling/stent-assisted coiling of aneurysms. FD-CTA may be considered as a non-invasive alternative to the gold standard 2D DSA in selected patients that require follow up imaging after stenting.

Intracranial Pseudoaneurysms, Fusiform Aneurysms and Carotid-Cavernous Fistulas

The study assessed the effectiveness and safety of endovascular covered stents in the management of intracranial pseudoaneurysms, fusiform aneurysms and direct carotid-cavernous fistulas. Fourteen endovascular covered stents were used to repair three pseudoaneurysms, six fusiform aneurysms and six direct carotid-cavernous fistulas. Aneurysms were in the carotid artery in seven cases, in the vertebral artery two cases. It was not possible to treat two additional cases transcutaneously for technical reasons 2/15. Percutaneous closure of the lesions with an endovascular covered stent was successful in 13 of 15 cases. Initial follow-up showed good stent patency. No complications were observed after stent implantation. During follow-up, stent thromboses were detected in two of nine patients with follow-up digital subtracted angiography. One carotid-cavernous fistula of Barrow Type A transformed into Barrow Type D at nine month follow-up study was cured with a procudure of Onyx-18 injection. Endovascular covered stents may be an option for percutaneous closure of intracranial pseudoaneurysms, fusiform aneurysms and direct carotid-cavernous fistulas. Endoluminal vascular repair with covered stents offers an alternative therapeutic approach to conventional modalities.