Recanalization of the Chronically Occluded Internal Carotid Artery: Review of the Literature

MR-VWI concentric ring sign: a potential imaging feature of internal carotid artery pseudo occlusion and predictive value for successful recanalization

BACKGROUND

Predicting the success of endovascular recanalization in non-acute internal carotid artery occlusion (NICAO) remains a challenge.

OBJECTIVE

To examine the hypothesis that the concentric ring sign observed on high-resolution magnetic resonance vessel wall imaging (MR-VWI) could serve as a potential imaging biomarker to improve the accuracy of predicting recanalization success and guide treatment decisions.

METHODS

A retrospective analysis was conducted on patients with NICAO who underwent endovascular treatment at our institution between January 2020 and December 2023. Baseline data and details of preoperative digital subtraction angiography (DSA) and MR-VWI, perioperative complications, technical success rates, and follow-up outcomes were collected. A nomogram model was constructed via stepwise regression based on statistically significant variables to predict recanalization success.

RESULTS

In total, 63 cases were included in this study. The overall recanalization success rate was 82.5% (52/63), and the periprocedural complication rate was 12.7% (8/63). Stepwise regression identified key predictors, including tapered stumps, occlusion segments ≤4, short occlusion duration, and the C2 concentric ring sign (P<0.05). The resulting nomogram demonstrated excellent predictive capabilities for successful recanalization (area under the curve 0.971).

CONCLUSION

The predictive model, integrating MR-VWI and digital subtraction angiography features-including the newly identified 'concentric ring sign'-exhibited excellent predictive performance and clinical usefulness, providing a reliable tool for preoperative evaluation and treatment planning in patients with NICAO.

Endovascular recanalization of subacute or chronic symptomatic occlusion of the internal carotid artery ophthalmic segment

OBJECTIVE

To investigate the safety and effect of endovascular recanalization for subacute or chronic occlusion of the internal carotid artery (ICA) ophthalmic segment and risk factors for the prognosis.

MATERIALS AND METHODS

135 patients with subacute or chronic occlusion of the ICA ophthalmic segment were retrospectively enrolled to undergo endovascular recanalization, with the clinical, imaging and follow-up data being analyzed.

RESULTS

Among 135 patients with ICA ophthalmic segment occlusion, hypertension was presented in 72 (53.3 %) patients, diabetes mellitus in 44 (32.6 %), coronary heart disease in 12 (8.9 %), smoking in 51 (37.8 %), and alcohol abuse in 38 (28.1 %). Endovascular recanalization was performed in all patients, and recanalization was successful in 130 (96.3 %). Five patients (3.7 %) were not recanalized because of intraprocedural complications. Periprocedural complications occurred in 16 patients, resulting in a total complication rate of 11.9 %. The mRS (modified Rankin Scale score) was 1.45 ± 0.03 after recanalization, significantly (P < 0.001) better than that (2.25 ± 0.12) before recanalization. The NIHSS (National Institute of Health Stroke Scale) was 11.91 ± 0.67, significantly (P < 0.0001) better than that (18.45 ± 1.33) before recanalization. Eighty-nine (65.9 %) patients underwent angiography at follow-up 6-86 (mean 48) months after recanalization, which demonstrated good prognosis in 72 (80.9 %) patients and poor prognosis in the other 17 (19.1 %) with instent restenosis > 50 %. Telephone follow-up was conducted in 46 (34.1 %) patients 6-38 (mean 27) months after recanalization, which revealed good prognosis in 38 (82.6 %) patients and poor prognosis in 8 (17.4 %). In total, good prognosis was present in 110 (81.5 %) patients while poor prognosis in 25 (18.5 %). In angiographic follow-up, instent restenosis > 50 % was present in nine (10.1 %) patients. Univariate analysis showed age (OR = 1.82), hypertension (OR = 2.38), diabetes mellitus (OR = 1.84), and alcohol abuse (OR = 1.49) were significant (P < 0.05) risk factors, whereas multivariate analysis demonstrated that only hypertension (OR = 1.54) and diabetes mellitus (OR = 2.67) were significant (P < 0.05) independent risk factors to affect the prognosis of recanalization.

CONCLUSION

Subacute or chronic occlusion of the internal carotid artery ophthalmic segment can be safely and efficiently recanalized using endovascular skills, and hypertension and diabetes mellitus are the independent risk factors for the prognosis of endovascular recanalization.

Feasibility and efficiency of a new classification based on high-resolution MRI for carotid artery pseudo-occlusion and occlusion: Hybrid revascularization pilot study

BACKGROUND AND PURPOSE

Studies on changes in the distal internal carotid artery based on high resolution magnetic resonance imaging (HRMRI) are scarce. Herein, we propose a histological classification system for patients with carotid artery pseudo-occlusion or occlusion based on preoperative HRMRI, for which we evaluated the feasibility and clinical implications.

MATERIALS AND METHODS

From January 2017 to June 2021, 40 patients with Doppler ultrasound, CTA or MRA suggesting carotid artery occlusion were enrolled in this study. A new classification system based on HRMRI was established and subsequently verified by postoperative specimens. We recorded and analyzed patient characteristics, HRMRI data, recanalization rate, requirements of additional endovascular procedures, complications, and outcomes.

RESULTS

Four histological classifications (type Ⅰ-Ⅳ) were identified. According to our classification system, 20 patients (50.00%) were type I, nine (22.50%) were type II, 7 (17.50%) were type III, and four (10.00%) were type Ⅳ. The success rate of recanalization was 88.89% (32/36) in type I-III patients. Four (44.44%) type Ⅱ patients and five (71.43%) type Ⅲ patients suffered from intraoperative dissection.

CONCLUSION

Patients identified as types I (pseudo-occlusion) and II (thrombotic-occlusion) were able to be treated via hybrid revascularization with relatively low risk, while patients identified as type III (fibrous-occlusion) required more careful treatment. Recanalization is not suitable for patients identified as type Ⅳ. Our proposed classification system based on HRMRI data can be used as an adjunctive guide to predict the technical feasibility and success of revascularization via a hybrid technique.

Endovascular recanalization in patients with severely disabling non-acute ischemic stroke

BACKGROUND

It is unclear whether patients with severely disabling ischemic stroke (SDIS-that is, modified Rankin scale (mRS) scores of 3-5) benefit from non-acute endovascular recanalization (ER).

OBJECTIVE

To determine the effect of non-acute ER or medical treatment in severely disabled patients with non-acute ischemic stroke (mRS scores of 3-5).

METHODS

Between January 2018 and August 2021, non-acute patients with SDIS and large vessel occlusion were collected from two regional stroke centers. Patients who met the inclusion and exclusion criteria were assigned to two groups based on whether they underwent ER (ER group) or not (medical group). The primary functional outcome was the mRS score at 90 days. The primary safety outcomes were the recurrence of stroke and mortality.

RESULTS

Of the 325 patients with hypoperfusion cerebral infarction caused by large vessel occlusion, 63 met the inclusion criteria (32 patients in the ER group, 31 patients in the medical group). A favorable outcome (mRS score ≤2) occurred more often in the ER group than in the medical group (59.4% vs 22.6%, respectively; OR=0.12, 95% CI 0.02 to 0.58; P<0.01). There were no significant differences in new-onset ischemic stroke (6.3% vs 3.2%, respectively; P=1.000), symptomatic intracerebral hemorrhage (12.5% vs 0%, respectively; P=0.113), or mortality within 90 days (6.3% vs 6.5%, respectively; P=1.000) between the two groups. Preoperative mRS scores (OR=7.34, 95% CI 1.56 to 34.5; P=0.02) and ER (OR=0.12, 95% CI 0.02 to 0.58; P<0.01) were significantly associated with outcome.

CONCLUSION

Our data suggest that patients with SDIS (mRS score 3-5) with smaller infarct cores and better collateral circulation can benefit from non-acute ER, with no additional perioperative complications or mortality.

Hybrid surgery recanalization for high-level chronic internal carotid artery occlusion

Objective

Although endovascular recanalization is considered a more effective treatment for chronic internal carotid artery occlusion (CICAO), the success rate of complex CICAO remains inadequate. We present hybrid surgery (carotid endarterectomy combined with carotid stenting) for complex CICAO and explore the influential factors and effects of hybrid surgery recanalization.

Methods

We retrospectively analyzed the clinical, imaging, and follow-up data of 22 patients with complex CICAO treated by hybrid surgery at the Zhongnan Hospital of Wuhan University from December 2016 to December 2020. We also summarize the technical points related to hybrid surgery recanalization.

Results

A total of 22 patients with complex CICAO underwent hybrid surgery recanalization. There were no postoperative deaths in all patients after hybrid surgery recanalization. Nineteen patients successfully underwent recanalization with a success rate of 86.4% and three cases with a failure rate of 13.6%. Patients were divided into success and failure groups. Significantly different radiographic classification of lesions was observed between the success group and the failure group (P = 0.019). The rates of CICAO with reverse ophthalmic artery blood flow in the internal carotid artery (ICA) preoperatively were 94.7% in the success group and 33.3% in the failure group (P = 0.038). Three cases of hybrid surgery recanalization failure were transferred for EC-IC bypass and had good neurological recovery. Postoperative average KPS scores of the 19 patients were improved compared to the preoperative ones (P < 0.001).

Conclusion

Hybrid surgery for complex CICAO is safe and effective with a high recanalization rate. The recanalization rate is related to whether the occluded segment surpasses the ophthalmic artery.

Three Days Delayed Recanalization Improved Neurological Function in pMCAO Rats by Increasing M2 Microglia-Possible Involvement of the IL-4R/STAT6/PPARγ Pathway

Current approved therapies for acute ischemic stroke have a restricted therapeutic time window. Delayed recanalization, which has been utilized clinically in patients who have missed the time window for administration, may be a promising alternative for stroke patients. However, the underlying molecular mechanisms remain undiscovered. Herein, we hypothesized that delayed recanalization would increase M2 microglial polarization through the IL-4R (interleukin-4 receptor)/STAT6 (signal transducer and activators of transcription 6)/PPARγ (peroxisome proliferator-activated receptor γ) pathway, subsequently promoting stroke recovery in rats. The permanent middle cerebral artery occlusion (pMCAO) model was induced via intravascular filament insertion. Recanalization was induced by withdrawing the filament at 3 days after MCAO (rMCAO). Interleukin (IL)-4 was administered intranasally at 3 days after pMCAO. AS1517499, a specific STAT6 inhibitor, was administered intranasally at 3 days after MCAO induction. Immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA), western blot analysis, volumetric measurements of brain infarct, and neurological behavior tests were conducted. Delayed recanalization at 3 days after MCAO increased the polarization of M2 microglia, decreased inflammation, and improved neurological behavior. IL-4 treatment administered on the 3rd day after pMCAO increased M2 microglial polarization, improved neurological behavior, and reduced infarction volume of pMCAO rats. The inhibition of STAT6 decreased the level of p-STAT6 and PPARγ in rats treated with delayed recanalization. Delayed recanalization improved neurological function by increasing microglial M2 polarization, possibly involved with the IL-4R/STAT6/PPARγ pathway after MCAO in rats.

Delayed revascularization in acute ischemic stroke patients

Stroke shares a significant burden of global mortality and disability. A significant decline in the quality of life is attributed to the so-called post-stroke cognitive impairment including mild to severe cognitive alterations, dementia, and functional disability. Currently, only two clinical interventions including pharmacological and mechanical thrombolysis are advised for successful revascularization of the occluded vessel. However, their therapeutic effect is limited to the acute phase of stroke onset only. This often results in the exclusion of a significant number of patients who are unable to reach within the therapeutic window. Advances in neuroimaging technologies have allowed better assessment of salvageable penumbra and occluded vessel status. Improvement in diagnostic tools and the advent of intravascular interventional devices such as stent retrievers have expanded the potential revascularization window. Clinical studies have demonstrated positive outcomes of delayed revascularization beyond the recommended therapeutic window. This review will discuss the current understanding of ischemic stroke, the latest revascularization doctrine, and evidence from clinical studies regarding effective delayed revascularization in ischemic stroke.

Morphological and Compositional Features of Chronic Internal Carotid Artery Occlusion in MR Vessel Wall Imaging Predict Successful Endovascular Recanalization

Background: We sought to determine if the morphological and compositional features of chronic internal carotid artery occlusion (CICAO), as assessed by MR vessel wall imaging (MR-VWI), initially predict successful endovascular recanalization. Methods: Consecutive patients with CICAO scheduled for endovascular recanalization were recruited. MR-VWI was performed within 1 week prior to surgery for evaluating the following features: proximal stump morphology, extent of occlusion, occlusion with collapse, arterial tortuosity, the presence of hyperintense signals (HIS) and calcification in the occluded C1 segment. Multivariate logistic regression was used to identify features associated with technical success and construct a prediction model. Results: Eighty-three patients were recruited, of which fifty-seven (68.7%) were recanalized successfully. The morphological and compositional characteristics of CICAO were associated with successful recanalization, including occlusions limited to C1 and extensive HIS, as well as the absence of extensive calcification, absence of high tortuosity, and absence of artery collapse. The MR CICAO score that comprised the five predictors showed a high predictive ability (area under the curve: 0.888, p < 0.001). Conclusion: the MR-VWI characteristics of CICAO predicted the technical success of endovascular recanalization and may be leveraged for identifying patients with a high probability of successful recanalization.

Spotlight on clinical strategies of Chronic Internal Carotid Artery Occlusion: Endovascular interventions and external-intracarotid bypasses compared to conservative treatment

Chronic internal carotid artery occlusion (CICAO) has high prevalence and incidence rates, and patients with CICAO can be completely asymptomatic, experience a devastating stroke or die. It is important to note that CICAO causes cerebrovascular accidents. Currently, the external carotid-internal carotid (EC-IC) bypass technique is used to treat CICAO. However, many clinical studies showed that EC-IC bypass was not beneficial for many patients with CICAO. Meanwhile, endovascular intervention treatment options for CICAO are evolving, and an increasing number of patients are undergoing endovascular intervention therapy. Accordingly, a review comparing both techniques is warranted. For this review, we searched PubMed and collected relevant case study reports comparing endovascular interventional therapy and internal and external cervical bypass surgeries to provide strategies for clinical treatment.

Hybrid surgery versus endovascular intervention for patients with chronic internal carotid artery occlusion: A single-center retrospective study

Objective

Chronic internal carotid artery occlusion (CICAO) can cause transient ischemic attack (TIA) and ischemic stroke. Carotid artery stenting (CAS) with embolic protection devices and hybrid surgery combining carotid endarterectomy and endovascular treatment are effective methods for carotid revascularization. The objective of this study was to evaluate and compare the effect and safety of the two surgical procedures.

Methods

This was a single-center retrospective study. In this study, 44 patients who underwent hybrid surgery and 35 who underwent endovascular intervention (EI) at our center were enrolled consecutively between May 2016 and March 2022. All patients were classified into four groups (A-D), as described by Hasan et al. We recorded and analyzed clinical data, angiographic characteristics, technical success rate, perioperative complications, and follow-up data.

Results

There was no significant difference in baseline characteristics between hybrid surgery group and EI group, except for plasma high density lipoproteins (HDL) levels (median [interquartile range]: hybrid surgery, 0.99 [0.88–1.18] vs. EI, 0.85 [0.78–0.98] mmol/L, P = 0.001). The technical success rate of hybrid surgery was higher than that of EI (37/44 [84.1%] vs. 18/35 [51.4%], P = 0.002; type A: 15/16 [93.8%] vs. 10/11 [90.9%], P = 1.000; type B: 9/10 [90.0%] vs. 5/7 [71.4%], P = 0.537; type C: 12/15 [80.0%] vs. 3/12 [25.0%], P = 0.004; type D: 1/3 [33.3%] vs. 0/5 [0%], P = 0.375). No significant difference was observed in the incidence of perioperative complications between the two procedures (hybrid surgery: 7/44 [15.9%] vs. EI: 6/35 [17.1%], P = 0.883). In addition, there were no significant differences in the rates of stroke and restenosis during follow-up.

Conclusions

For patients with symptomatic CICAO, hybrid surgery may have an advantage over EI in successfully recanalizing occluded segments. There was no significant difference in safety and restenosis between hybrid surgery and EI.

Long-Term Outcomes of Stenting on Non-Acute Phase Extracranial Supra-Aortic Dissections

Objective

Methods

Results

Conclusion

Multimodal recanalization for subacute symptomatic internal carotid artery occlusion due to atherosclerosis: Outcomes and notes on hybrid techniques

OBJECTIVES

Subacute internal carotid artery occlusion (ICAO) is associated with ipsilateral recurrent stroke, and successful recanalization of ICAO can improve cerebral blood perfusion (CBP) and prevent stroke. However, the optimal treatment remains controversial.

METHODS

We conducted a retrospective analysis of patients with subacute symptomatic ICAO due to atherosclerosis treated at our center. The hybrid surgical procedures included carotid endarterectomy, Fogarty balloon catheter embolectomy, aspiration thrombectomy and percutaneous transluminal angioplasty/stenting. Recanalization rates, CBP improvement, stroke recurrence and restenosis/reocclusion were investigated.

RESULTS

Fourteen symptomatic atherosclerotic ICAO patients (type A, 4; type C, 10; men, 11; women, 3; average age, 68.1 ± 7.9 years) in the subacute phase were treated with a multimodal recanalization technique. Symptoms included mild cerebral infarction, transient ischemic attack (TIA) and amaurosis fugax. The average onset-to-treatment time was 18.1 ± 4.8 days. The successful recanalization (thrombolysis in cerebral ischemia grade 2 or 3) rate was 100%. The ipsilateral-to-contralateral mean transit time ratio was significantly lower at the 1-year follow-up than preoperatively (1.01 ± 0.05 vs. 1.26 ± 0.09, P < 0.0001). There was one case of restenosis detected 1 year after surgery and no cases of reocclusion. During the 28.3 ± 10.0 months of follow-up, only 2 cases of TIA occurred. The average modified Rankin Scale score and National Institute of Health Stroke Scale score were significantly lower at themost recent follow-up than before recanalization (1.21 ± 0.89 vs. 1.86 ± 0.66, P = 0.0003; 1.36 ± 1.55 vs. 2.00 ± 1.88, P = 0.0066).

CONCLUSION

Multimodal recanalization techniques performed in a hybrid operation theater can safely achieve high recanalization rates in atherosclerotic ICAO patients in the subacute phase, which can be beneficial for recovering CBP and preventing stroke.

Evolution of the stroke paradigm: A review of delayed recanalization

While the time window for reperfusion after ischemic stroke continues to increase, many patients are not candidates for reperfusion under current guidelines that allow for reperfusion within 24 h after last known well time; however, many case studies report favorable outcomes beyond 24 h after symptom onset for both spontaneous and medically induced recanalization. Furthermore, modern imaging allows for identification of penumbra at extended time points, and reperfusion risk factors and complications are becoming better understood. Taken together, continued urgency exists to better understand the pathophysiologic mechanisms and ideal setting of delayed recanalization beyond 24 h after onset of ischemia.

Hybrid Recanalization for the Treatment of Carotid/Vertebral In-stent Restenosis or Occlusion: Pilot Surgery Experiences From One Single Center

Background : The hybrid recanalization of internal carotid artery (ICA) and vertebral artery (VA) in-stent restenosis or occlusion using a combination of endarterectomy and endovascular intervention has achieved technical success. We present our surgical experiences to further evaluate the safety and efficacy of the hybrid technique for the treatment of in-stent restenosis and occlusion. Methods : A cohort of 12 refractory patients with in-stent restenosis or occlusion who underwent hybrid recanalization, a combination of endarterectomy and endovascular intervention, were retrospectively analyzed. Medical records, including presenting symptoms, comorbidities, contralateral ICA/VA findings, use of antiplatelet drugs, postoperative complications, and angiographic outcomes, were collected. Results : Among 415 consecutive patients with ICA, common carotid artery, and V1 segment lesions, 12 refractory patients (2.89%) with 13 cases were enrolled in our study (1 female and 11 male). All patients underwent successful hybrid recanalization. There were no cases of postoperative stroke or death. Only two patients sustained hoarseness, but it resolved within 2 weeks after surgery. Three patients were treated with dual antiplatelet (aspirin and clopidogrel), seven with single antiplatelet (aspirin), one with single antiplatelet (clopidogrel), and one with single antiplatelet (ticagrelor). All patients were followed up in the outpatient department according to the protocol, with a mean follow-up period of 13 months (range, 6-24 months). No death or recurrent symptoms occurred during the regular follow-up period. Conclusion : The hybrid technique maybe a safe and feasible treatment option to recanalize in-stent restenosis or occlusion with acceptable complications.

Delayed Recanalization-How Late Is Not Too Late?

Stroke has become the second most prevalent cause of mortality in the world. Currently, the treatment of ischemic stroke is based on thrombolytic and thrombectomy therapy shortly after the ischemic event (≤ 4.5 h for thrombolytic strategies; ≤ 6 h for thrombectomy strategies). However, the majority of patients are unable to receive prompt treatment, particularly in undeveloped countries. Alternative solutions are lacking for those patients that miss the optimal window of opportunity for treatment. Recently, new developments in imaging techniques and intravascular interventional devices enable the expansion of the window of opportunity for treating stroke patients. Clinical studies have reported that delayed recanalization at 24 h, or even more than 1 month, was beneficial for some patients. However, the mechanisms of neuroprotection that underly the delayed recanalization in these ischemic stroke patients remain unclear. In this review, we will summarize the clinical studies of delayed recanalization, and organize them according to the duration of occlusion. Additionally, we will discuss the changing guidelines and possible mechanisms based on animal research, and attempt to draw conclusions and future perspectives.

Remodeling of occluded internal carotid artery in vessel wall magnetic resonance imaging

OBJECTIVE

The purpose of the present study was to investigate the remodeling pattern of the extracranial occluded internal carotid artery (OICA) by vessel wall magnetic resonance imaging (VWI).

METHODS

Thirty-nine atherosclerotic OICAs from 32 consecutive cases underwent 3-Tesla VWI to acquire pre- and post-contrast T1-weighted two-dimensional fluid-attenuated inversion recovery fast spin echo sequences. 25 symptomatic CAs exhibited ipsilateral downstream cerebral ischemia or ophthalmic artery embolism within last three months. The 14 remaining CAs were asymptomatic. Twenty-four CAs from 22 patients with atherosclerosis but no stenosis were recruited as control group. The outer wall area (OWA) was calculated based on the outer contour of the carotid artery drawn on the pre-contrast VWI. Negative remodeling was defined as a lower OWA compared to that of control group.

RESULTS

Clinical characteristics including age, sex and vascular risk factors showed no significant difference between the occluded and control group. However, the OWA was lower in the occluded group than in the control group (0.63 versus 0.90 cm², p = 0.004). For all OICAs, the OWA was larger in symptomatic cases than asymptomatic cases (0.71 versus 0.49cm², p = 0.025). Using a cutoff value of 0.44, the sensitivity and specificity of OWA for detecting symptomatic OICA were 0.88 and 0.57, respectively. Heterogeneous signal intensity and enhancement were more often observed at the proximal than the distal segment of occlusion (p < 0.001). The inter-observer agreement regarding the evaluation of VWI characteristics was desirable (κ = 0.805 ∼ 0.847).

CONCLUSIONS

Negative remodeling is prevalent in OICA, especially in asymptomatic cases.

Image-guided delayed recanalization of middle cerebral artery occlusion

Recent advance in devices, techniques, and peri-procedural patient management in the conduct of mechanical thrombectomy enables neuro-interventionists to recanalize occluded cerebral arteries with greater efficiency and safety than ever. It is conceivable that there exist a group of stroke patients who would benefit from recanalization beyond 24-h time window following the onset of symptom, if viable brain tissue remains at that time. We report a case of a 56-year-old patient who received mechanical thrombectomy 96 h after the onset of symptoms by diffusion/perfusion imaging. The application of advanced neuroimaging and analytical software can accurately estimate viable brain tissue, which enables clinicians to implement individualized therapeutic strategies for patients with acute stroke.

Evaluation of chronic carotid artery occlusion by non-contrast 3D-MERGE MR vessel wall imaging: comparison with 3D-TOF-MRA, contrast-enhanced MRA, and DSA

OBJECTIVES

To analyze the accuracy of a non-contrast MR vessel wall imaging technique, three-dimensional motion-sensitized driven equilibrium prepared rapid gradient echo (3D-MERGE) for diagnosing chronic carotid artery occlusion (CCAO) characteristics compared with 3D time-of-flight (TOF) MRA, and contrast-enhanced MRA (CE-MRA), using digital subtraction angiography (DSA) as a reference standard.

METHODS

Subjects diagnosed with possible CCAO by ultrasound were retrospectively analyzed. Patients underwent 3.0-T MR imaging with 3D-MERGE, 3D-TOF-MRA, and CE-MRA followed by DSA within 1 week. Diagnostic accuracy of occlusion, occlusion site, and proximal stump condition were assessed independently on 3 MRI sequences and DSA. Agreement of the above indicators was evaluated in reference to DSA.

RESULTS

One hundred twenty-four patients with 129 suspected CCAO (5 with bilateral occlusions) met the inclusion criteria for our study. 3D-MERGE demonstrated a sensitivity, specificity, and accuracy of 97.0%, 86.7%, and 94.6%, respectively, with excellent agreement (Cohen's κ = 0.85; 95% CI, 0.71, 0.94) for diagnosing CCAO in reference to DSA. 3D-MERGE was superior in diagnosing CCAO compared with 3D-TOF-MRA (Cohen's κ = 0.61; 95% CI, 0.42, 0.77) and similar to CE-MRA (Cohen's κ = 0.93; 95% CI, 0.86, 1.00). 3D-MERGE also had excellent agreement compared with DSA for assessing occlusion sites (Cohen's κ = 0.85; 95% CI, 0.71, 0.97) and stump condition (Cohen's κ = 0.83; 95% CI, 0.71, 0.94). Moreover, 3D-MERGE provided additional information regarding the occluded segment, such as distal lumen collapse and vessel wall lesion components.

CONCLUSION

3D-MERGE can reliably assess chronic carotid occlusive characteristics and has the ability to identify other vessel wall features of the occluded segment. This non-contrast MR vessel wall imaging technique is promising for assessment of CCAO.

KEY POINTS

• Excellent agreement was found between 3D-MERGE and DSA for assessing chronic carotid artery occlusion, occlusion site, and proximal stump condition. • 3D-MERGE was shown to be a more accurate and efficient tool than 3D-TOF-MRA to detect the characteristics of the occluded segment. • 3D-MERGE provides not only luminal images for characterizing the proximal characteristics of occlusion but also vessel wall images for assessing the distal lumen and morphology of occlusion segment, which might help clinicians to optimize the treatment strategy for patients with chronic carotid artery occlusion.

Transcirculation Approach for Mechanical Thrombectomy in Acute Ischemic Stroke: A Multicenter Study and Review of the Literature

Background: Transcirculation approaches, which consist of primary catheterization of a target artery from the contralateral side or opposite cerebral circulation, provide alternate endovascular routes when anterograde interventions are not feasible. We aimed to assess the safety and efficacy of mechanical thrombectomy (MT) through a transcirculation route.

Methods: Six centers provided retrospective data on acute ischemic stroke (AIS) patients who underwent MT via transcirculation approaches. Demographics and technical details of the endovascular intervention were collected. Recanalization rates, peri-procedural complications and clinical/angiographic outcomes immediately after the procedure and at last available follow-up were assessed. A review of the literature reporting on AIS patients whom underwent transcirculation MT was also performed.

Results: Our multicenter study included 14 AIS patients treated through transcirculation routes. Mean age was 57.8 ± 11.9 years, and 10 (71.4%) were men. Mean NIHSS at admission was 18.4 (range 8–27). TICI 2b-3 recanalization was achieved in 10/14 (71.4%) patients. Three patients died after intervention: one due to late recanalization, one due to acute in-stent thrombosis, and one due to a procedure-related thromboembolic brainstem infarct. Of 11 surviving patients with follow-up available (mean 9.7 months), mRS 0–2 was achieved in 6 (54.5%) cases. Our review of the literature pooled a total of 37 transcirculation MT cases. Most common occlusions were tandem lesions (ICA + MCA = 64.9%) and BA + bilateral VA (18.9%). ACOM and PCOM were crossed in 18 (48.6%) cases each; one patient required a combined ACOM-PCOM approach. Primary recanalization technique included intra-arterial (IA) thrombolytics alone in 10 (27%), angioplasty ± stenting in 6 (16.2%), stent-retriever in 8 (21.6%), contact aspiration in 6, and combined (MT ± IA-thrombolytics) in 6 cases. Twenty-eight (75.7%) AIS patients achieved successful TIMI 2-3/TICI 2b-3 recanalization. After a mean follow-up of 6.7 months, 23/31 (74.2%) patients achieved a favorable functional outcome.

Conclusions: Transcirculation approaches may be used to access the target lesion when the parent artery cannot be crossed through conventional antegrade routes. These techniques are feasible but should be reserved as a bailout maneuver when anterograde MT is not possible. Newer endovascular devices have improved neurological and angiographic outcomes in transcirculation cases.