Multiphasic Computed Tomography Angiography Findings for Identifying Pseudo-Occlusion of the Internal Carotid Artery.

BACKGROUND AND PURPOSE: Differentiation between pseudo-occlusion and true occlusion of internal carotid artery (ICA) is important in treatment planning for acute ischemic stroke patients. We compared the findings of multiphasic computed tomography angiography between cervical ICA pseudo-occlusion and true occlusion at the cervical ICA in patients with anterior circulation acute ischemic stroke to determine their diagnostic value. METHODS: Thirty patients with nonvisualization of the proximal ICA were included. Diagnosis of pseudo- or true occlusion of the ICA was made based on digital subtraction angiography. Diagnostic performances of multiphasic computed tomography angiography findings-(1) a flame-shaped stump and (2) delayed contrast filling at the cervical ICA- were evaluated and compared. The Fisher exact test, χ2 test, or Wilcoxon rank-sum test and McNemar test were used in the data analysis. RESULTS: Twelve patients had true proximal ICA occlusion and 18 had pseudo-occlusion. Delayed contrast filling at the cervical ICA on multiphasic computed tomography angiography was found in all patients with pseudo-occlusion of the ICA, while 1 case of true occlusion showed delayed contrast filling (P<0.001). The presence of a flame-shaped stump was not significantly different between the pseudo- and true occlusion groups. The sensitivity of delayed contrast filling (0.94 [95% CI, 0.73-1]) was significantly higher than that of flame-shaped stump (0.75 [95% CI, 0.36-0.83]). CONCLUSIONS: We demonstrated that the delayed filling sign on multiphasic computed tomography angiography could be a useful and readily available finding for differentiating proximal ICA pseudo-occlusion from true occlusion.

Cervical Carotid Pseudo-Occlusions and False Dissections: Intracranial Occlusions Masquerading as Extracranial Occlusions.

BACKGROUND AND PURPOSE: Pseudo-occlusion (PO) of the cervical internal carotid artery (ICA) refers to an isolated occlusion of the intracranial ICA that appears as an extracranial ICA occlusion on computed tomography angiography (CTA) or digital subtraction angiography because of blockage of distal contrast penetration by a stagnant column of unopacified blood. We aim to better characterize this poorly recognized entity. METHODS: Retrospective review of an endovascular database (2010-2015; n=898). Only patients with isolated intracranial ICA occlusions as confirmed by angiographic exploration were included. CTA and digital subtraction angiography images were categorized according to their apparent site of occlusion as (1) extracranial ICA PO or (2) discernible intracranial ICA occlusion. RESULTS: Cervical ICA PO occurred in 21/46 (46%) patients on CTA (17 proximal cervical; 4 midcervical). Fifteen (71%) of these patients also had PO on digital subtraction angiography. A flame-shaped PO mimicking a carotid dissection was seen in 7 (33%) patients on CTA and in 6 (29%) patients on digital subtraction angiography. Patients with and without CTA PO had similar age (64.8±17.1 versus 60.2±15.7 years; P=0.35), sex (male, 47% versus 52%; P=1.00), and intravenous tissue-type plasminogen activator use (38% versus 40%; P=1.00). The rates of modified Treatment In Cerebral Ischemia 2b-3 reperfusion were 71.4% in the PO versus 100% in the non-PO cohorts (P<0.01). The rates of parenchymal hematoma, 90-day modified Rankin Scale score 0-2, and 90-day mortality were 4.8% versus 8% (P=0.66), 40% versus 66.7% (P=0.12), and 25% versus 21% (P=0.77) in PO versus non-PO patients, respectively. Multivariate analysis indicated that PO patients had lower chances of modified Treatment In Cerebral Ischemia 3 reperfusion (odds ratio 0.14; 95% confidence interval 0.02-0.70; P=0.01). CONCLUSIONS: Cervical ICA PO is a relatively common entity and may be associated with decreased reperfusion rates.

Mid-cervical flame-shaped pseudo-occlusion: diagnostic performance of mid-cervical flame-shaped extracranial internal carotid artery sign on computed tomographic angiography in hyperacute ischemic stroke.

PURPOSE: Flame-shaped pseudo-occlusion of the extracranial internal carotid artery (ICA) is a flow-related phenomenon that creates computed tomographic angiography (CTA) and digital subtraction angiography (DSA) findings that mimic tandem intracranial-extracranial ICA occlusion or dissection. We aim to determine the diagnostic performance of mid-cervical flame-shaped extracranial ICA sign on CTA in hyperacute ischemic stroke patients. METHODS: We retrospectively included consecutive anterior circulation ischemic stroke patients presenting within 6 h of symptom onset who underwent 4D brain CTA and arterial-phase neck CTA using a 320-detector CT scanner during August 2012 to July 2015. Two blinded readers independently reviewed arterial-phase neck CTA and characterized the extracranial ICA configurations into mid-cervical flame-shaped, proximal blunt/beak-shaped, and tubular-shaped groups. 4D whole brain CTA was used as a reference standard for intracranial ICA occlusion detection. Diagnostic performance of the mid-cervical flame-shaped extracranial ICA sign and interobserver reliability were calculated. RESULTS: Of the 81 cases, 11 had isolated intracranial ICA occlusion, and 6 had true extracranial ICA occlusion. Mid-cervical flame-shaped extracranial ICA sign was found in 45.5% (5/11) of isolated intracranial ICA occlusions but none in the true extracranial ICA occlusion group. The sensitivity, specificity, PPV, NPV, and accuracy of the mid-cervical flame-shaped extracranial ICA sign for the detection of isolated intracranial ICA occlusion were 45.5, 100, 100, 92.1, and 92.6%, respectively. Interobserver reliability was 0.90. CONCLUSION: The mid-cervical flame-shaped extracranial ICA sign may suggest the presence of isolated intracranial ICA occlusion and allow reliable exclusion of tandem extracranial-intracranial ICA occlusion in hyperacute ischemic stroke setting.

Time-Resolved 4-Dimensional Computed-Tomography Angiography Can Correctly Identify Carotid Pseudo-Occlusion.

Correct identification of symptomatic high-grade internal carotid artery stenosis from low-grade or total chronic occlusion is critical for patient selection for urgent carotid endarterectomy. Carotid pseudo-occlusion is a flow-related artifact on noninvasive imaging that can lead to an incorrect diagnosis of total internal carotid artery occlusion, thereby denying an eligible patient for appropriate surgical treatment. We present an 82-year-old man with a symptomatic critical internal carotid artery, which was detected on time-resolved 4-dimensional computed-tomography angiography, whereas single-phase computed-tomography angiography, magnetic resonance angiography, and Doppler ultrasonography suggested apparent occlusion. To our understanding, the use of 4-dimensional computed-tomography angiography to identify carotid pseudo-occlusion has not been previously reported.

CT angiographic patterns predict carotid pseudo-occlusion in acute ischemic stroke.

Background: Identifying carotid pseudo-occlusion (PO) from true occlusion (TO) has implications in determining the candidacy and feasibility of successful endovascular thrombectomy (EVT) in acute ischemic stroke (AIS). Purpose: We reviewed the computed tomography angiographic (CTA) patterns differentiating a PO from a TO and analyzed the rate of successful recanalization after EVT. Materials and Methods: Patients with AIS and proximal internal carotid artery (ICA) occlusion who underwent EVT from 2014 to 2021 were identified. The patterns of carotid occlusion in CTA were classified into beak, dome, and flat patterns and correlated with microcatheter digital subtraction angiography (DSA) as PO and TO. The rates of successful recanalization in PO and TO were analyzed. Results: Of the 24 patients, 16 (66%) had ICA PO and eight (33%) had TO in DSA. A beak pattern of the proximal ICA on CTA was significantly higher among the PO group patients (87.5% vs. 25%, P = 0.005), and a flat pattern was significantly higher among the TO group patients (50% vs. 12%, P = 0.005). A gradual contrast decline of the proximal ICA on CTA images was seen only in PO group patients (85.7% vs. 0%, P = 0.05). There was no significant difference in the rate of successful recanalization between PO and TO group patients (81.25% vs. 62.5%, P = 0.362). Conclusion: Beak pattern and gradual contrast decline at the proximal ICA occlusion site in CTA are suggestive of carotid PO. Identification of PO in CTA can help in planning intervention strategies and prognostication.

Acute intracranial internal carotid artery occlusion: Extension and location of the thrombus as an influencing factor in Computed Tomography angiography findings.

Purpose: Acute intracranial internal carotid artery (ICA) occlusion can mimic an extracranial affectation on Computed Tomography angiography (CTA). This fact could be explained by the extension of the thrombus in the ICA concerning its arterial branches. This study aims to determine how this factor may influence imaging findings. Methods: A retrospective study was conducted from a single-center database of patients undergoing mechanical thrombectomy due to ICA occlusion between October 2017 and March 2022 (n = 77). Patients with acute intracranial ICA occlusion were included (n = 29) and divided into two groups, according to ICA opacification on CTA: the discernible extracranial ICA or group D, and the pseudo-occlusion or group P. Patency of posterior communicating, anterior choroidal, and ophthalmic arteries on digital subtraction angiography were collected to determine thrombus extension. Sensitivity and specificity were calculated for CTA. Results: Significant differences were found in DSA between group P (n = 17) and group D (n = 12) in the frequency of patency of major artery branches: the presence of posterior communicating (PCOM) and anterior choroidal arteries (AChA) was observed in 2 patients in group P vs. 10 in group D (p < 0.001); whereas the patency of the ophthalmic artery (OA) was visualized in 10 patients in group P vs. 12 in group D, p = 0.023). For the diagnosis of isolated intracranial ICA occlusion, CTA had a sensitivity of 43.5% and a specificity of 97.2%. Conclusions: The location and extent of the thrombus in the intracranial ICA concerning major artery branches may influence CTA findings.

Outcomes in acute ischemic stroke patients undergoing endovascular thrombectomy: Cervical internal carotid artery pseudo-occlusion vs. true occlusion.

Background and purpose: Pseudo-occlusion of the cervical internal carotid artery (cICA) refers to an absence of intraluminal contrast on computed tomography angiography (CTA), while the artery is patent on digital subtraction angiography during endovascular thrombectomy. We aimed to compare the outcomes between the cICA pseudo-occlusion and true occlusion after thrombectomy. Methods: We retrospectively analyzed patients with apparent cICA occlusion on CTA who underwent thrombectomy between January 2016 and August 2021, and divided them into the pseudo-occlusion and true occlusion groups based on angiographic exploration. Recanalization failure was defined as a modified Thrombolysis in Cerebral Infarction score of 0-2a. Poor outcome was defined as a 90-day modified Rankin Scale score of 3-6. Propensity score matching was performed to compare the outcomes. Sensitivity analysis using multivariate-adjusted regression in the original cohort was conducted to test the robustness of the findings. Results: Of the 146 patients included, 79 patients (54.1%) had cICA pseudo-occlusion and 67 patients (45.9%) had true occlusion. Following 1:1 propensity score-matched analysis, patients with pseudo-occlusion had an increased likelihood of recanalization failure (OR, 3.18; 95% CI, 1.06-9.59; P = 0.040) and poor outcome (OR, 2.80; 95% CI, 1.07-7.30; P = 0.035) compared with patients with true occlusion. Sensitivity analysis showed that cICA pseudo-occlusion remained independently associated with recanalization failure (OR, 2.55; 95% CI, 1.07-6.09; P = 0.036) and poor outcome (OR, 2.48; 95% CI, 1.08-5.67; P = 0.032). Conclusions: Patients with cICA pseudo-occlusion on CTA treated with thrombectomy had an increased risk of reperfusion failure and poor outcome compared with true occlusion patients.

Beyond the collaterals: Additional value of multiphase CTA in acute ischemic stroke evaluation.

PURPOSE: Multiphase computed tomography angiography (MP-CTA) is an innovative imaging tool that can give those managing acute ischemic stroke temporal information on degree and extent of pial collateral arterial filling in the affected brain. We sought to estimate the incidence of false-positive or -negative evaluation of the carotid bifurcation or intracranial thrombus on single-phase CTA (SP-CTA) compared with MP-CTA. MATERIAL AND METHODS: A single-center, retrospective consecutive review was conducted of imaging and clinical records of 150 patients in two months who presented with neurological symptoms with a National Institutes of Health Stroke Scale score ≥ 2 and who received an MP-CTA as part of their investigative work-up. The cohort consisted of 52.3% male and 47.7% female patients. Median individual age was 68 years (interquartile range 60-79). Extracranial and intracranial vessel images of the initial early arterial phase were evaluated and compared with late arterial and early venous phase images. RESULTS: In the cohort of 150 patients, in three patients (2%) SP-CTA would have led to an incorrect diagnosis and management without MP-CTA-acquired source imaging. The three scenarios represented differentiating a carotid string sign from internal carotid artery occlusion, determining the appearance and extent of thrombus in carotid T-occlusion, and differentiating slow flow and contrast mixing-related artifacts from intraluminal thrombus. CONCLUSIONS: In addition to improving assessment of collateral circulation in acute stroke patients, MP-CTA is also useful in assessing specific flow-related scenarios for which SP-CTA may give spurious results.

Advantages of Staged Angioplasty in a Patient with Internal Carotid Artery Pseudo-Occlusion Besides Prevention of Cerebral Hyperperfusion Syndrome.

BACKGROUND: Staged angioplasty for carotid artery stenosis has been reported to be effective in preventing postoperative cerebral hyperperfusion syndrome (CHS) in patients with severe carotid stenosis; thus, it is also recommended for patients with internal carotid artery (ICA) pseudo-occlusion, the treatment strategy for which is controversial. CASE DESCRIPTION: This study reports the case of an Asian man in his 50s who had motor aphasia and right-side weakness caused by pseudo-occlusion of the left ICA. After medical treatment, he underwent a staged angioplasty. After the first stage of percutaneous transluminal angioplasty, anterograde blood flow to the left ICA increased but the distal ICA remained partially collapsed. Initially, the second stage of carotid artery stenting (CAS) was planned for 2 weeks after the first stage; however, hemorrhagic infarction was observed the day before the CAS, and it was postponed by 2 weeks, after adjustment of antiplatelet therapy. At the time of the CAS, the diameter of the initially collapsed left distal ICA was remodeled and it was fully dilated; thus, we used a balloon-type embolic protection device and conducted CAS successfully without apparent embolic complications. The postoperative course was uneventful. The patient did not develop CHS. CONCLUSIONS: Besides preventing CHS, staged angioplasty has advantages when used for treating patients with ICA pseudo-occlusions in that the extent of dilation of the distal ICA after percutaneous transluminal angioplasty can be confirmed and the development of a possible hemorrhagic infarction can be assessed before stent placement.

Endovascular Treatment for Near Occlusion of the Internal Carotid Artery : 30-Day Outcome and Long-Term Follow-Up.

BACKGROUND: The treatment strategy and the correct incidence of near occlusion (NO) of the internal carotid artery (ICA) is still controversial. In routine radiological imaging NO can easily be misdiagnosed as complete occlusion and there is no consensus on the standard treatment strategy. PURPOSE: To present our perioperative and long-term follow-up results of ICA NO patients treated with carotid artery stenting (CAS). MATERIAL AND METHODS: Between 2004-2014 a total of 182 patients with ICA NO were evaluated for CAS. The study included 132 male (72.5 %) and 50 female (27.5 %) patients with a mean age of 70.2 years. Patients underwent a clinical neurological evaluation and radiological imaging of the carotid arteries before the CAS procedure. Of the patients 80 (44 %) were asymptomatic. The median clinical and carotid Doppler ultrasound (DUS) follow-up period was 64 months (range 18-124 months). RESULTS: In 182 patients CAS were performed, 4 patients (2.2 %) developed minor stroke, 2 patients (1.1 %) developed myocardial infarction but no major stroke or death occurred in the following 30-day period. Asymptomatic restenosis was detected in seven patients (3.8 %) in the follow-up period. CONCLUSION: With sufficient neurological evaluation during pretreatment and posttreatment periods and when the procedure is performed with technologically developed products by an experienced interventional team, CAS is beneficial in patients with ICA NO.

Use of 4D Computer Tomographic Angiography to Accurately Identify Distal Internal Carotid Artery Occlusions and Pseudo-Occlusions: Technical Note.

BACKGROUND AND PURPOSE: Traditional methods of computed tomographic angiography (CTA) can be unreliable in detecting carotid artery pseudo-occlusions or in accurately locating the site of carotid artery occlusion. With these methods, lack of adequate distal runoff due to pseudo-occlusion or intracranial occlusion can result in the inaccurate diagnoses of complete occlusion or cervical carotid occlusion, respectively. The site of carotid occlusion has important therapeutic and interventional considerations. We present several cases in which 4D CTA was utilized to accurately and noninvasively diagnose carotid pseudo-occlusion and intracranial internal carotid artery (ICA) occlusion. METHODS: We identified five patients who presented to our institute with ischemic stroke symptoms and evaluated images from traditional CTA protocols and 4D CTA protocols in each of these patients, comparing diagnoses rendered by each imaging technique. RESULTS: In two patients, traditional CTA suggested the presence of complete ICA occlusion. However, 4D CTA demonstrated pseudo-occlusion. Similarly, in three patients, traditional CTA demonstrated cervical ICA occlusion, whereas the 4D CTA demonstrated intracranial ICA occlusion. CONCLUSION: 4D CTA may be a more effective noninvasive imaging technique than traditional CTA to detect intracranial carotid artery occlusions and carotid artery pseudo-occlusions. Accurate, rapid, and noninvasive diagnosis of carotid artery lesions may help tailor and expedite endovascular intervention.

A case in which contrast-enhanced transoral carotid ultrasonography was useful for pre- and post-procedural evaluation in carotid artery stenting.

Contrast-enhanced transoral carotid ultrasonography (CETOCU) is a novel examination modality that is superior to other modalities in the cases of pseudo-occlusion with severe arteriosclerotic stenosis of the distal internal carotid artery (ICA), and is also useful for noninvasively evaluating changes over time in the vessel distal to the stent following carotid artery stenting (CAS). We report a case of a patient who we evaluated with CETOCU for a pseudo-occlusive ICA before and after CAS.

Perfusion-Derived Dynamic 4D CT Angiography Identifies Carotid Pseudo-Occlusion in Hyperacute Stroke.

BACKGROUND: Differentiation between true acute tandem occlusion involving the extracranial internal carotid artery (ICA) from pseudotandem occlusion with a patent extracranial ICA has important prognostic and therapeutic implications. We explored the utility of perfusion-derived 4-dimensional CT angiogram (4D-CTA) in identifying carotid pseudo-occlusion in a single-center pilot study. METHODS: Acute stroke patients with delayed antegrade ICA flow on 4D-CTA despite an apparent tandem occlusion on conventional single-phase CTA were prospectively identified over a 2.5-year period (2013-2015). RESULTS: Eight patients were identified. Delayed antegrade intracranial flow from the apparently occluded ICA was detected up to 50 seconds after contrast administration on 4D-CTA. The distal intracranial ICA was the most common site of true occlusion. Reconstruction of the 4D-CTA images required an additional processing time of 2-3 minutes. CONCLUSIONS: 4D-CTA is a novel noninvasive technique that can identify carotid pseudo-occlusion in the acute stroke setting. Our preliminary findings suggest that 4D-CTA can be easily incorporated into an existing acute stroke neuroimaging protocol.

Surgical treatment for pseudo-occlusion of the internal carotid artery.

OBJECTIVES: Carotid artery pseudo-occlusion is a rare condition and its natural history and clinicopathological characteristics are not well defined. We reported our 7-year experience in the surgical treatment of carotid artery pseudo-occlusion to determine the real benefit of the surgical option. METHODS: From January 2006 to December 2013, 1414 patients were treated for high-grade stenosis of the internal carotid artery, 33 (2.3%) presented with a carotid pseudo-occlusion (26 males and 7 females, mean age: 70 ± 10). Nineteen patients were symptomatic, and 14 asymptomatic. Carotid artery pseudo-occlusion was identified by duplex scan (segmental occlusion at the origin of internal carotid artery with very thin distal flow) and the diagnostic confirmation was obtained by angio-computed-tomography (CT) scan. The operation was performed under general anaesthesia and constant Electroencephalography (EEG) monitoring. The follow-up was performed by duplex scan at discharge, 30 days, 6 months and yearly. RESULTS: Politetrafluoroetilene (PTFE) patch endarterectomy, eversion endarterectomy and carotid bypass were performed in 20 (61%), 10 (30%) and 3 patients (9%), respectively. No mortality or stroke was observed in postoperative period. Four patients presented with an asymptomatic postoperative thrombosis of the internal carotid artery. No restenosis was observed. CONCLUSIONS: Surgical treatment for carotid artery pseudo-occlusion is safe and effective.