Diagnosing carotid near-occlusion is a difficult task—but it might get easier

Johansson, Elias; Holmgren, Madelene; Henze, Alexander; Fox, Allan J.

doi:10.1007/s00234-022-03007-7

Cited by 4 publications

(6 citation statements)

References 34 publications

(35 reference statements)

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“…The analysis of cases with unclear causes of small distal ICA showed that flow rates shared similar recruitment patterns as between conventional stenoses to near-occlusions. These unclear cases would benefit the most from improved diagnostics, but a final diagnosis would require a post-operative CTA [ 31 ], which is not yet an established method and is therefore beyond the scope of this study.…”

Section: Discussionmentioning

confidence: 99%

Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion

Holmgren,

Henze,

Wåhlin

et al. 2024

Neuroradiology

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Purpose Compare extracranial internal carotid artery flow rates and intracranial collateral use between conventional ≥ 50% carotid stenosis and carotid near-occlusion, and between symptomatic and asymptomatic carotid near-occlusion. Methods We included patients with ≥ 50% carotid stenosis. Degree of stenosis was diagnosed on CTA. Mean blood flow rates were assessed with four-dimensional phase-contrast MRI. Results We included 110 patients of which 83% were symptomatic, and 38% had near-occlusion. Near-occlusions had lower mean internal carotid artery flow (70 ml/min) than conventional ≥ 50% stenoses (203 ml/min, P < .001). Definite use of ≥ 1 collateral was found in 83% (35/42) of near-occlusions and 10% (7/68) of conventional stenoses (P < .001). However, there were no differences in total cerebral blood flow (514 ml/min vs. 519 ml/min, P = .78) or ipsilateral hemispheric blood flow (234 vs. 227 ml/min, P = .52), between near-occlusions and conventional ≥ 50% stenoses, based on phase-contrast MRI flow rates. There were no differences in total cerebral or hemispheric blood flow, or collateral use, between symptomatic and asymptomatic near-occlusions. Conclusion Near-occlusions have lower internal carotid artery flow rates and more collateral use, but similar total cerebral blood flow and hemispheric blood flow, compared to conventional ≥ 50% carotid stenosis.

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Section: Discussionmentioning

confidence: 99%

Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion

Holmgren,

Henze,

Wåhlin

et al. 2024

Neuroradiology

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“…In addition to the standard reference, we also used postoperative CTA as recently suggested. 4 This is not an established method and was only available in selected participants. Rather than a new standard reference, this method should be viewed as providing supplementary information, why most of the information about this method is presented in the data supplement.…”

Section: Discussionmentioning

confidence: 99%

“…When introduced, quality control in terms of monitoring the long-term prognosis when patients with symptomatic near-occlusion are conservatively treated is warranted. 4 Diagnostic validation in additional cohort, especially against a larger sample of >70% stenoses, is warranted. Also, given the issues with PC-MRI, it should be performed in addition to (not instead of) other modalities such as contrast-enhanced MRA, ultrasound or CTA.…”

Section: Discussionmentioning

confidence: 99%

“… 2 However, near-occlusion diagnostics in large trials and prognostic studies have been based on systematic feature interpretation. 1 , 4 – 7 While collaborating experts can archive good reliability (kappa 0.80), 6 this approach is seldom used in routine practice 8 and has limited feasibility in routine practice, as there are no clear thresholds or rules. Suggested angiographic thresholds have been suggested by one recent guideline 2 but is approximately 80%–90% sensitivity and specificity when applied in a manner resembling routine practice.…”

Section: Introductionmentioning

confidence: 99%

“…Suggested angiographic thresholds have been suggested by one recent guideline 2 but is approximately 80%–90% sensitivity and specificity when applied in a manner resembling routine practice. 4 , 9 Low-flow findings on ultrasound has very poor sensitivity as most near-occlusions have high stenosis velocity. 10 , 11 Promisingly, a recent study suggested that thresholds of ICA flow ⩽110 ml/min and ICA flow rate ratio (ipsilateral/contralateral) <0.35 measured with phase-contrast MRI (PC-MRI) were both 100% accurate for diagnosing near-occlusion.…”

Section: Introductionmentioning

confidence: 99%

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Diagnostic separation of conventional ⩾50% carotid stenosis and near-occlusion with phase-contrast MRI

Holmgren,

Henze,

Wåhlin

et al. 2023

European Stroke Journal

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Introduction: The aim of this study was to assess sensitivity, specificity and interrater reliability of phase-contrast MRI (PC-MRI) for diagnosing carotid near-occlusion. Patients and methods: Prospective cross-sectional study conducted between 2018 and 2021. We included participants with suspected 50%–100% carotid stenosis on at least one side, all were examined with CT angiography (CTA) and PC-MRI and both ICAs were analyzed. Degree of stenosis on CTA was the reference test. PC-MRI-based blood flow rates in extracranial ICA and intracranial cerebral arteries were assessed. ICA-cerebral blood flow (CBF) ratio was defined as ICA divided by sum of both ICAs and Basilar artery. Results: We included 136 participants. The ICAs were 102 < 50% stenosis, 88 conventional ⩾50% stenosis (31 with ⩾70%), 49 near-occlusion, 12 occlusions, 20 unclear cause of small distal ICA on CTA and one excluded. For separation of near-occlusion and conventional stenoses, ICA flow rate and ICA-CBF ratio had the highest area under the curve (AUC; 0.98–0.99) for near-occlusion. ICA-CBF ratio ⩽0.225 was 90% (45/49) sensitive and 99% (188/190) specific for near-occlusion. Inter-rater reliability for this threshold was excellent (kappa 0.98). Specificity was 94% (29/31) for cases with ⩾70% stenosis. PC-MRI had modest performance for separating <50% and conventional ⩾50% stenosis (highest AUC 0.74), and eight (16%) of near-occlusions were not distinguishable from occlusion (no visible flow). Conclusion: ICA-CBF ratio ⩽0.225 on PC-MRI is an accurate and reliable method to separate conventional ⩾50% stenosis and near-occlusion that is feasible for routine use. PC-MRI should be considered further as a potential standard method for near-occlusion detection, to be used side-by-side with established modalities as PC-MRI cannot separate other degrees of stenosis.

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Assessments of arterial and venous phase radiodensity does not improve carotid near-occlusion diagnostics

Brunnander,

Henze,

Fox

et al. 2024

Sci Rep

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The hypothesis of this study was that evaluation of radiodensity assessment beyond a carotid stenosis in arterial and/or venous phase can be used to separate near-occlusion and conventional ≥ 50% stenosis. We prospectively included participants with ≥ 50% carotid stenosis with inclusion preference for cases with extracranial internal carotid artery (ICA) asymmetry. All participants were examined with a research biphasic computed tomography angiography (CTA) protocol (arterial and venous phase). Reference diagnosis was set by interpretation on CTA and radiodensity difference between ipsilateral and contralateral ICA (c-corrected) or vertebral (v-corrected) was compared. We included 93 participants, 62 with near-occlusion and 31 with conventional ≥ 50% stenosis. Just beyond the stenosis, median c-corrected radiodensity was − 20 Hounsfield units (HU) among near-occlusions and − 1 HU among conventional ≥ 50% stenoses (p < 0.001) in the arterial phase. For the venous phase, these findings were + 17 HU and + 3 HU (p = 0.007). Similar group differences were seen for v-correction. No parameter had good diagnostic performance, area under the curve ≤ 0.82. With specificity set at ≥ 95%, detected near-occlusions were foremost those with large side-to-side differences in distal ICA-diameter. Carotid near-occlusions can have reduced radiodensity beyond the stenosis in arterial phases and increased radiodensity in venous phases compared to a reference artery—which was not clearly seen for conventional stenoses. However, these radiodensity findings are best seen in near-occlusion cases that are not diagnostically challenging, while they work poorly as additional diagnostic aids.

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Diagnosing carotid near-occlusion is a difficult task—but it might get easier

Cited by 4 publications

References 34 publications

Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion

Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion

Diagnostic separation of conventional ⩾50% carotid stenosis and near-occlusion with phase-contrast MRI

Assessments of arterial and venous phase radiodensity does not improve carotid near-occlusion diagnostics

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