Semi-automated mapping of occluded arterial segments in acute large vessel stroke from computed tomography angiography.

OBJECTIVES: Catheterisation of occluded artery is the most crucial step in the mechanical thrombectomy of large vessel occlusions. Being a blind procedure, potential major untoward events could be anticipated at this stage. In this study, we evaluated the feasibility of reconstruction of the occluded vascular segment from CT angiography, exploiting the attenuation difference between the clot and adjacent brain parenchyma. METHODS AND RESULTS: Twenty-five patients with large vessel occlusion who achieved TICI2B/3 recanalization were identified. The semi-automated reconstruction was done using an open-source 3D segmentation software by two observers. The generated arterial anatomy was categorized as congruent, if all the major arterial segments namely, internal carotid artery, M1 middle cerebral artery, bifurcation, and major divisions matched with post thrombectomy angiograms. The discrepancy of one or more than one arterial segment was classified as mild or total mismatch respectively. Congruent arterial mapping was possible in 88% and 92 % patients for observer 1 and observer 2 respectively, while mild mismatch was noted in two patients for both the observers. Mismatch mostly occurred in superior division for both observers(100% vs 66.6%). The interrater agreement was good (0.77) and the accuracy was not influenced by the length of the clot. The median time for reconstruction was 4 minutes for both the observers (p - 0.21). CONCLUSION: Delineation of the anatomy of the occluded major intracranial artery is possible and corresponds with the actual anatomy. It could be used as a guide during thrombectomy procedures.

Does thrombus imaging characteristics predict the degree of recanalisation after endovascular thrombectomy in acute ischaemic stroke?

BACKGROUND: Identification of computed tomography (CT) thrombus imaging characteristics can predict the degree of recanalization and outcome after endovascular thrombectomy (EVT) in patients with acute ischaemic stroke and large vessel occlusion. AIM: We analyzed the thrombus imaging characteristics and procedural factors and correlated with the degree of recanalization and functional outcome after EVT. METHODS: We evaluated the thrombus imaging characteristics (hyperdense MCA sign, thrombus location, length and thrombus permeability) from thin slice CT and CT angiogram. In addition, groin to recanalization time, number of passes, and EVT technique were documented. The primary outcome was degree of recanalization (mTICI score) and secondary outcome was modified Rankin scale (mRS) at 3 months. RESULTS: The mean age of 102 patients was 60.5±11.8 years. Patients with hyperdense MCA sign (90 % vs 75%, p=0.07) and permeable thrombus (86 % vs 70 %, p=0.09) had good recanalization (mTICI grade 2b,2c or 3). The requirement of <3 passes (90 % vs 62 %, p= 0.001) was associated with good recanalization. Multiple logistic regression analysis showed thrombus permeability (OR 5.9; 95% CI 1.3-26.6, p=0.02), use of stent retreiver alone (without aspiration) (OR 5.4; 95% CI 1.3-22.5, p=0.02) and a puncture to recanalization ≤60 minutes (OR 7.9; 95% CI 1.7-36.8; p=0.008) were associated with good recanalization. The requirement of ≥3 passes was associated with poor functional outcome (OR 3.4;95% CI 1.2-9.8; p=0.02). CONCLUSIONS: Thrombus permeability was a predictor of successful recanalization after EVT. The requirement of three or more passes during EVT was associated with poor recanalization and poor functional outcome.

Impact of non-contrast enhanced volumetric MRI-based feeder localization in the treatment of spinal dural arteriovenous fistula.

BACKGROUND: The preoperative localization of the feeder of spinal dural arteriovenous fistula (SDAVF) could simplify the diagnostic spinal angiographic procedure. Localization by non-contrast-enhanced MRI-based techniques is an attractive option. However, the usefulness of such an approach for evaluation of SDAVF has not yet been reported. OBJECTIVE: To study the impact of non-contrast MRI-based feeder localization, followed by targeted spinal angiography, in the evaluation of SDAVF before endovascular intervention. MATERIALS AND METHODS: Prospectively collected data were analyzed and the level of the feeder was localized preoperatively. The procedural time for targeted spinal angiography was calculated and compared with that of a historical cohort, who underwent routine spinal angiographic examination before the study period. Follow-up MRI was carried out to assess the reliability of this model for detection of occasional metachronous lesions that might be missed with this approach. RESULTS: Seven patients underwent targeted spinal angiography during the study. The feeder level was accurately identified in five patients and was localized to one vertebral level in six patients. The correlation between MRI and DSA was statistically significant. The number of spinal levels assessed was fewer and overall procedure time was significantly shorter compared to historical cohort (58 min vs 162 min, respectively; p<0.001). Intervention was coupled with targeted angiography in two patients. Follow-up MRI demonstrated flow voids in one patient, who had recurrent fistula at one vertebral level below the previously embolized feeder. CONCLUSIONS: The non-contrast MRI-based localization technique can reliably detect the level of feeder and help in therapeutic planning of SDAVF. The localization techniques potentially shorten the angiographic procedure and may facilitate simultaneous endovascular definitive treatment. Inclusion of follow-up MRI may be useful for detection of synchronous or metachronous lesions if a targeted approach is adopted. Additionally, this helps to identify failed endovascular therapy.

Utility of 3D SPACE T2-weighted volumetric sequence in the localization of spinal dural arteriovenous fistula.

OBJECTIVE The aim of this study was to investigate the utility of a heavily T2-weighted volumetric MRI sequence (3D sampling perfection with application-optimized contrasts using different flip-angle evolutions [SPACE]) in the feeder localization of spinal dural arteriovenous fistula (SDAVF). METHODS Patients who were diagnosed with SDAVF and who had 3D SPACE source images available for review were identified from a retrospective review of medical records. A total of 16 patients were identified, and MR images were analyzed separately by 2 blinded observers. The accuracy of the observation and interobserver agreement were measured by Kendall's tau and kappa statistics. RESULTS The site of fistula was accurately predicted by Observers 1 and 2 in 81% and 88% of cases, respectively, which improved to 94% when the level was considered within 1 vertebral level. The observer agreement with gold-standard angiography and interobserver agreement were found to be highly significant (p < 0.0001). CONCLUSIONS The 3D SPACE MRI sequence is valuable in the precise detection of the site of SDAVF. It may help to tailor digital subtraction angiography and thereby reduce the radiation exposure, contrast load, and study time.