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

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.

Two or More Ischaemic Events Within 7 Days Before Carotid Endarterectomy Increases the Risk of Peri-operative Stroke or Death.

OBJECTIVE: The aim of this study was to determine how many pre-operative ischaemic events occurring within a specific timeframe before carotid endarterectomy (CEA) are needed to increase the peri-operative 30 day risk of stroke or death. METHODS: This was a secondary exploratory analysis based on pooled data from three observational studies sourced from a single centre. Patients with recently symptomatic conventional ≥ 50% carotid stenosis were included. The principal analysis was limited to patients presenting with stroke or transient ischaemic attack (TIA). The primary outcome was 30 day risk of peri-operative stroke or death. Whether one, two, three, or four or more ipsilateral pre-operative ischaemic events within 3, 7, 14, or 30 days before CEA were associated with the primary outcome was assessed. RESULTS: The study included 382 patients who underwent CEA with symptomatic conventional ≥ 50% carotid stenosis with stroke or TIA as the presenting event. Mean patient age ± standard deviation was 72 ± 7 years, 117 (30.6%) were female, and 6% were treated with dual antiplatelet therapy. The primary outcome occurred in 21 patients (5.5%). Two or more events within 7 days before CEA was the most discriminative definition of repeated events, with a 14.3% (8/56) risk of the primary outcome. Those who fell outside this definition of two or more events within 7 days before CEA had a 4.0% (13 of 326; p = .006) risk of experiencing the primary outcome (adjusted odds ratio 4.1, 95% confidence interval 1.6 - 10.5). Several alternative definitions were assessed, but patients with two or more events within 7 days before CEA and negative for these alternatives still had a > 10% risk of the primary outcome. CONCLUSION: Two or more ipsilateral ischaemic events within 7 days before CEA are associated with an increased risk of peri-operative stroke or death in cases with symptomatic conventional ≥ 50% carotid stenosis and TIA or stroke as the presenting event. Studies assessing whether delayed or immediate CEA is preferable for this patient group are warranted.

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

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.

High risk of early recurrent stroke in patients with near-occlusion with full collapse of the internal carotid artery.

We aimed to validate the prognostic ability and assess interrater reliability of a recently suggested measurement-based definition of near-occlusion with full collapse (distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42). 118 consecutive patients with symptomatic near-occlusion were prospectively included and assessed on computed tomography angiography by 2 blinded observers, 26 (22%) had full collapse. At 2 days after presenting event, the risk of preoperative stroke was 3% for without full collapse and 16% for with full collapse (p = 0.01). At 28 days, this risk was 16% for without full collapse and 22% for with full collapse (p = 0.22). Interrater reliability was perfect (kappa 1.0). Thus, near-occlusion with full collapse should be defined as distal ICA ≤ 2.0 mm and/or ICA ratio ≤ 0.42 in order to detect cases with very high risk of early stroke recurrence.

Quantifying Carotid Stenosis: History, Current Applications, Limitations, and Potential: How Imaging Is Changing the Scenario.

Carotid artery stenosis is a major cause of morbidity and mortality. The journey to understanding carotid disease has developed over time and radiology has a pivotal role in diagnosis, risk stratification and therapeutic management. This paper reviews the history of diagnostic imaging in carotid disease, its evolution towards its current applications in the clinical and research fields, and the potential of new technologies to aid clinicians in identifying the disease and tailoring medical and surgical treatment.