Comparison of Carotid Endarterectomy and Stenting for Symptomatic Internal Carotid Artery Near-Occlusion.

BACKGROUND AND PURPOSE: Carotid near-occlusion is defined as severe stenosis of the internal carotid artery with partial or full collapse of the distal vessel wall. The major studies evaluating carotid revascularization excluded patients with carotid near-occlusion. Given the paucity of data in the literature, we attempted to evaluate the safety of carotid endarterectomy and carotid artery stenting in carotid near-occlusion. MATERIALS AND METHODS: A retrospective data base review was performed from January 2010 to December 2018 to identify patients who underwent carotid endarterectomy or carotid artery stenting for symptomatic ICA near-occlusion and had 1-month clinical and imaging follow-up with carotid sonography. The medical records and imaging studies of patients with ICA near-occlusion were selected for analysis. RESULTS: Forty-five patients met the criteria for ICA near-occlusion, of whom 39 were included in the study, given insufficient 1-month follow-up on 6 patients. Of the 39 patients, 25 underwent carotid endarterectomy and 14 underwent carotid artery stenting. All patients had technically successful immediate revascularization of the ICA. Most (33 of 39) had 1-year follow-up postoperatively. Patients with carotid artery stenting had 20% restenosis and 79% vessel maturation rates, while patients with carotid endarterectomy had 17.4% restenosis and 84% vessel maturation. There was no significant difference in periprocedural complication rates between the 2 procedures. CONCLUSIONS: Carotid artery stenting shows similar outcomes in restenosis and vessel maturation rates compared with carotid endarterectomy for ICA near-occlusion. There were no major differences between the 2 treatments in clinical outcomes or periprocedural complications. Carotid artery stenting is a revascularization option for carotid near-occlusion if the patient is considered at high risk for carotid endarterectomy.

Association between the severity of newly diagnosed obstructive sleep apnea and subclinical carotid atherosclerosis in patients without overt cardiovascular disease.

OBJECTIVE: Obstructive Sleep Apnea (OSA) has been associated with both subclinical and accelerated atherosclerosis; however, it still remains unknown whether this association is unique or is mediated by the higher burden of co-existing cardio-metabolic disorders frequently seen in patients with OSA. PATIENTS AND METHODS: A total of 40 subjects without clinically diagnosed cardiovascular disease (CVD) referred for polysomnography test were included in the study. Subjects with apnea/hypopnea index (AHI > 15/h) were classified as moderate/severe OSA. Subclinical changes in carotid atherosclerosis were assessed using mean carotid intima-media thickness (cIMT) and presence of atheromatic plaques on both carotid arteries. The measurement was performed using B-mode ultrasonogram. Framingham risk score was used in the approximation of cardiovascular risk. RESULTS: The mean age of our cohort was 56.8 years, 70% (n = 28) of whom were males. Moderate/severe OSA was diagnosed in 21 subjects. Both groups were well matched in terms of clinical and demographic characteristics, and cardiovascular risk profile, as shown in their respective Framingham risk scores (10.4 ± 6.6 vs. 11.8 ± 8.8, p = NS). Patients with moderate/severe OSA had a higher mean AHI, 3% oxygen desaturation index, and lower minimum nocturnal oxygen saturation than controls. No significant differences were detected in terms of C-reactive protein levels. The two groups had similar cIMT (0.66 ± 0.17 vs. 0.75 ± 0.20 p = 0.33) and presence of atheromatic plaque (50% vs. 45%, p = 1.00). CONCLUSIONS: Our study suggests that among patients with similar cardiovascular risk profile and free of overt CVD, the severity of newly diagnosed OSA was not correlated with increased inflammation or subclinical carotid atherosclerosis.

Factors associated with recurrent stroke and recanalization in patients presenting with isolated symptomatic carotid occlusion.

BACKGROUND AND PURPOSE: Patients with symptomatic internal carotid artery (ICA) occlusion constitute a small proportion of stroke/transient ischaemic attack patients who are at increased risk of early stroke recurrence and poor outcome. The optimal medical treatment for patients with symptomatic ICA occlusion who are ineligible for thrombolysis or thrombectomy is unknown. METHODS: Consecutive patients presenting at a single center with newly diagnosed symptomatic ICA occlusion (not involving the circle of Willis) were retrospectively reviewed. Those treated with intravenous thrombolysis or intra-arterial thrombolysis/thrombectomy were excluded. Patients were divided into two groups based on whether they experienced recurrent in-hospital stroke. RESULTS: The selected study population (n = 33) represented a small (20.4%) proportion of all newly symptomatic carotid occlusions, who nevertheless had an elevated risk of recurrent stroke during admission (24.2%). Of the variables examined (age, gender, admission National Institutes of Health Stroke Scale score, vascular risk factors, atrial fibrillation, prior stroke/transient ischaemic attack and anticoagulation within 48 h of presentation), only anticoagulation was significantly associated with a lower risk of in-hospital recurrent stroke. Anticoagulated patients showed a decreased incidence of stroke recurrence within the first week (6.7% vs. 38.9%, P = 0.032) and fewer strokes or deaths at 1 month (13.3% vs. 47.1%, P = 0.040). Hemorrhagic transformation was not observed in any patient. On follow-up imaging, ICA recanalization was significantly more frequent in anticoagulated patients (46.2% vs. 9.1%, P = 0.047). CONCLUSION: Patients with newly diagnosed symptomatic ICA occlusion (not involving the circle of Willis) represent a small but high risk subgroup of patients with carotid occlusion. Early anticoagulation was associated with fewer recurrent strokes and increased ICA recanalization. Larger scale prospective studies may be justified.

Interferometric spectroscopy of scattered light can quantify the statistics of subdiffractional refractive-index fluctuations.

Despite major importance in physics, biology, and other sciences, the optical sensing of nanoscale structures in the far zone remains an open problem due to the fundamental diffraction limit of resolution. We establish that the expected value of spectral variance (Σ[over ˜](2)) of a far-field, diffraction-limited microscope image can quantify the refractive-index fluctuations of a label-free, weakly scattering sample at subdiffraction length scales. We report the general expression of Σ[over ˜] for an arbitrary refractive-index distribution. For an exponential refractive-index spatial correlation, we obtain a closed-form solution of Σ[over ˜] that is in excellent agreement with three-dimensional finite-difference time-domain solutions of Maxwell's equations. Sensing complex inhomogeneous media at the nanoscale can benefit fields from material science to medical diagnostics.

Association of CT perfusion parameters with hemorrhagic transformation in acute ischemic stroke.

BACKGROUND AND PURPOSE: Prediction of hemorrhagic transformation in acute ischemic stroke could help determine treatment and prognostication. With increasing numbers of patients with acute ischemic stroke undergoing multimodal CT imaging, we examined whether CT perfusion could predict hemorrhagic transformation in acute ischemic stroke. MATERIALS AND METHODS: Patients with acute ischemic stroke who underwent CTP scanning within 12 hours of symptom onset were examined. Patients with and without hemorrhagic transformation were defined as cases and controls, respectively, and were matched as to IV rtPA administration and presentation NIHSS score (± 2). Relative mean transit time, relative CBF, and relative CBV values were calculated from CTP maps and normalized to the contralateral side. Receiver operating characteristic analysis curves were created, and threshold values for significant CTP parameters were obtained to predict hemorrhagic transformation. RESULTS: Of 83 patients with acute ischemic stroke, 16 developed hemorrhagic transformation (19.28%). By matching, 38 controls were found for only 14 patients with hemorrhagic transformation. Among the matched patients with hemorrhagic transformation, 13 developed hemorrhagic infarction (6 hemorrhagic infarction 1 and 7 hemorrhagic infarction 2) and 1 developed parenchymal hematoma 2. There was no significant difference between cases and controls with respect to age, sex, time to presentation from symptom onset, and comorbidities. Cases had significantly lower median rCBV (8% lower) compared with controls (11% higher) (P = .009; odds ratio, 1.14 for a 0.1-U decrease in rCBV). There was no difference in median total volume of ischemia, rMTT, and rCBF among cases and controls. The area under the receiver operating characteristic was computed to be 0.83 (standard error, 0.08), with a cutoff point for rCBV of 1.09. CONCLUSIONS: Of the examined CTP parameters, only lower rCBV was found to be significantly associated with a relatively higher chance of hemorrhagic transformation.

Targeted alteration of real and imaginary refractive index of biological cells by histological staining.

Various staining techniques are commonly used in biomedical research to investigate cellular morphology. By inducing absorption of light, staining dyes change the intracellular refractive index due to the Kramers-Kronig relationship. We present a method for creating 2D maps of real and imaginary refractive indices of stained biological cells using their thickness and absorptance. We validate our technique on dyed polystyrene microspheres and quantify the alteration in refractive index of stained biological cells. We reveal that specific staining of individual organelles can increase their scattering cross-section by orders of magnitudes, implying a major impact in the field of biophotonics.