A proposed method for outlining occluded intracranial artery using 3D T2-weighted sampling perfection with application optimized contrasts using different flip angle evolution (SPACE)

Usefulness of the Preoperative Images Supporting Mechanical Thrombectomy Based on Susceptibility-Weighted Image for Stroke

Objective

This is a report on the usefulness of 3D fusion imaging with susceptibility-weighted imaging (SWI) as preoperative imaging for mechanical thrombectomy (MT) for acute ischemic stroke (AIS).

Case Presentations

Among 17 cases of patients who underwent MT in AIS between March 2021 and April 2022, 14 patients who underwent MRI with SWI (shortened SWI for stroke) and 3D T2-weighted sampling perfection with application-optimized contrasts using different flip angle evolution were targeted in the study. Three cases with motion artifacts due to body movement were excluded from the images.After imaging, 3D fusion images were constructed to visualize thrombi and occluded vessels. SWI for stroke obtained thrombus information in 11 of the 14 cases (78.5%) and 3D images of the thrombi could be created in all 11 cases. 3D fusion images could be created in nine of the 14 cases (64.2%).

Conclusion

3D fusion images, using SWI for stroke, can visualize thrombi and occluded vessels and may be effectively used as preoperative images for MT.

Magnetic Resonance Angiography and Cisternography fused images in acute ischemic stroke may save time during endovascular procedure revealing vessel anatomy

Background and purpose

Endovascular treatment (EVT) is a time-dependent procedure that aims to remove the arterial blood flow obstruction in brain vessels in acute ischemic stroke. In our center, the MRI patient selection protocol in acute ischemic stroke is performed with DWI, FLAIR, MR angiography (MRA) and MR cisternography (MRC) sequences. MRA and MRC are promptly and automatically fused in order to have a clear detection of vessel anatomy, before and during EVT.

Our study aim is to evaluate if the fusion process between MRA and MRC could be considered time-safe and could influence EVT duration or outcome.

Materials and methods

45 patients were retrospectively selected for the study and divided into 2 groups according to the presence of MRC sequence fused with MRA (Group 1) or not (Group 2 - controls).

Results

MRA and MRC fusion was able to depict vessel anatomy in all subjects of Group 1 (22 patients, 12 females; age 75.59 years ± 10.87). Group 1 presented EVT time reduction (p < 0.05;p = 0.040) (51.59 min ± 30.94) when compared to Group 2 (23 patients, 13 females; age 75.04 years ± 12.12) (71.96 min ± 34.55) of 20.37 min average. No differences between groups were detected evaluating: NIHSS at admission (p = 0.49) and discharge (p = 0.67), pre-stroke mRS (p = 0.89), mRS at 90 days (p = 0.62), ASPECT (p = 0.98) and ASPECT-DWI scores (p = 0.93), time from symptom onset to groin puncture (p = 0.80), thromboaspiration vs combined technique (p = 0.67), EVT success (p = 0.63).

Conclusion

Fusion of MRA and MRC is a safe and promising technique in promptly revealing vascular anatomy beyond vessel obstruction, and can play a role in EVT duration reduction.

3D T2-Weighted Sampling Perfection with Application-Optimized Contrasts Using Different Flip Angle Evolutions (SPACE) and 3D Time-of-Flight (TOF) MR Angiography Fusion Imaging for Occluded Intracranial Arteries

Objective

Determining the course of occluded vessels in advance will increase the success rate and safety of mechanical thrombectomy (MT). Herein, we evaluate the usefulness of MR fusion images created via 3D T2-weighted sampling perfection with application-optimized contrasts using different flip angle evolutions (T2-SPACE) and 3D time-of-flight (TOF)-MRA for visualization of occluded vessels in patients with acute ischemic stroke (AIS) before MT.

Methods

We enrolled 26 patients with AIS caused by intracranial large vessel occlusion who presented at our hospital and underwent MRI with fusion images unaffected by motion artifacts in our study. All patients underwent T2-SPACE and TOF-MRA followed by MT. We created fusion images of the T2-SPACE and TOF-MRA by combining a translucent image of the occluded artery produced by the flow void effect in T2-SPACE with the same vessel in a TOF-MRA image. Fusion images were compared with post-recanalization angiography and post-recanalization MRA, respectively, and the degree of agreement in depiction of M1 runs and M2 branching beyond the occlusion on three levels was assessed. Imaging evaluations were performed independently by two endovascular specialists.

Results

The interobserver agreement of the MRI findings about the concordance of the occluded vessel's run was excellent (kappa was 0.87 [confidence interval: 0.61-1.12]). In all, 21 patients (80.8%) had excellent imaging, four (15.4%) had fair imaging, and one (3.8%) had a divided opinion of the rating between excellent and fair imaging. No cases were judged to be poorly drawn. Even if there was a localized signal loss, its distal portion could be delineated, so it did not affect the estimation of the entire vessel run, and we found that the anatomical structures of the occluded vessels were distinctly visible in the fusion images.

Conclusion

We demonstrated that MR fusion images derived using T2-SPACE and MRA methodologies could determine the courses of occluded vessels prior to MT performed for AIS. Fusion MR imaging may have potential as a preoperative test for ensuring effective and safe MT procedures.

Fusion of magnetic resonance angiography and cisternography in acute ischemic stroke reveals the vessel anatomy ahead of the clot: a technical note to see beyond obstacles

We describe how the fusion process between magnetic resonance angiography (MRA) and cisternography (MRC) promptly reveals vessel anatomy ahead of the clot, in patients affected by acute anterior circulation large vessel occlusion. This technique showed in 100% of subjects (n = 22) a clear tracing of vessel anatomy before and beyond the clot. The duration of the whole process is short and could be considered safe since no outcome differences have been found when compared with a control group (n = 23). This technique could play a relevant role in guiding endovascular therapy, especially in unexpected unfavorable anatomical arteries configurations.