Faculty Bibliography

Atherosclerosis involving the carotid arteries has a high prevalence in the population worldwide. This condition is significant because accidents of the carotid artery plaque are associated with the development of cerebrovascular events. For this reason, carotid atherosclerotic disease needs to be diagnosed and those determinants that are associated to an increased risk of stroke need to be identified. The degree of stenosis typically has been considered the parameter of choice to determine the therapeutical approach, but several recently published investigations have demonstrated that the degree of luminal stenosis is only an indirect indicator of the atherosclerotic process and that direct assessment of the plaque structure and composition may be key to predict the development of future cerebrovascular ischemic events. The concept of "vulnerable plaque" was born, referring to those plaque's parameters that concur to the instability of the plaque making it more prone to the rupture and distal embolization. The purpose of this review is to describe the imaging characteristics of "vulnerable carotid plaques."

Ischemic stroke currently represents one of the leading causes of severe disability and mortality in the Western World. Until now, angiography was the most used imaging technique for the detection of the extra-cranial and intracranial vessel pathology. Currently, however, non-invasive imaging tool like ultrasound (US), magnetic resonance (MR) and computed tomography (CT) have proven capable of offering a detailed analysis of the vascular system. CT in particular represents an advanced system to explore the pathology of carotid arteries and intracranial vessels and also offers tools like CT perfusion (CTP) that provides valuable information of the brain's vascular physiology by increasing the stroke diagnostic. In this review, our purpose is to discuss stroke risk prediction and detection using CT.

We report a case of temporary Solitaire FR stent (Covidien, Mansfield, MA, USA) scaffolding to reduce coil herniation during embolization of a large neck anterior communicating artery aneurysm. In contrast to classic stent-assisted coiling, the fully retrievable stent is recaptured prior to detachment of the last coil. The presented technical nuance hence does not require institution of prolonged antiplatelet coverage. But the door is left open for coil-repositioning in case of coil basket instability. Permanent stent redeployment remains a fall-back option if critical hardware conflict occurs. In comparison to classic balloon remodeling, the presented method may offer easier distal access, particularly in tortuous arterial anatomy. Temporary occlusion of the parent artery, side branches, and perforators is also avoided. Given its specific potential advantages, temporary stent scaffolding using the fully retrievable Solitaire FR device may find its niche as a bailout option, primarily in a very specific subset of distally located wide neck aneurysms.

BACKGROUND AND PURPOSE: Previous studies demonstrated that carotid plaques analyzed by CTA can show contrast plaque enhancement. The purpose of this preliminary work was to evaluate the possible association between the fissured fibrous cap and contrast plaque enhancement. MATERIALS AND METHODS: Forty-seven consecutive (men = 25; average age = 66.8 +/- 9 years) symptomatic patients studied by use of a multidetector row CT scanner were prospectively analyzed. CTA was performed before and after contrast and radiation doses were recorded; analysis of contrast plaque enhancement was performed. Patients underwent carotid endarterectomy en bloc; histologic sections were prepared and evaluated for fissured fibrous cap and microvessel attenuation. The Mann-Whitney test was performed to evaluate the differences between the 2 groups. A multiple logistic regression analysis was performed to assess the effect of fissured fibrous cap and microvessel attenuation on contrast plaque enhancement. Receiver operating characteristic curve and area under the curve were also calculated. RESULTS: Twelve patients had fissured fibrous cap. In 92% (11/12) of fissured fibrous cap-positive plaques, we found contrast plaque enhancement, whereas in 69% (24/35) of the plaques without fissured fibrous cap contrast plaque enhancement was found. The Mann-Whitney test showed a statistically significant difference between the contrast enhancement in plaques with fissured fibrous cap (Hounsfield units = 22.6) and without fissured fibrous cap (Hounsfield units = 12.9) (P = .011). On the regression analysis, both fissured fibrous cap and neovascularization were associated with contrast plaque enhancement (P = .0366 and P = .0001). The receiver operating characteristic curve confirmed an association between fissured fibrous cap and contrast plaque enhancement with an area under the curve of 0.749 (P = .005). CONCLUSIONS: The presence of fissured fibrous cap is associated with contrast plaque enhancement. Histologic analysis showed that the presence of fissured fibrous cap is associated with a larger contrast plaque enhancement compared with the contrast plaque enhancement of plaques without fissured fibrous cap.

BACKGROUND AND PURPOSE: Low-porosity endoluminal devices for the treatment of intracranial aneurysms, also known as flow diverters, have been in experimental and clinical use for close to 10 years. Despite rigorous evidence of their safety and efficacy in well-controlled trials, a number of key factors concerning their use remain poorly defined. Among these, none has received more attention to date than the debate on how many devices are optimally required to achieve a safe, effective, and economical outcome. Additional, related questions concern device sizing relative to the parent artery and optimal method of deployment of the devices. While some or all of these issues may be ultimately answered on an empiric basis via subgroup analysis of growing treatment cohorts, we believe that careful in vitro examination of relevant device properties can also help guide its in vivo use. MATERIALS AND METHODS: We conducted a number of benchtop experiments to investigate the varied porosity of Pipeline Embolization Devices deployed in a simulated range of parent vessel diameters and applied these results toward conceptualizing optimal treatment strategies of fusiform and wide-neck aneurysms. RESULTS: The results of our studies confirm a predictable parabolic variability in device porosity based on the respective comparative sizes of the device and recipient artery, as well as device curvature. Even modest oversizing leads to a significant increase in porosity. CONCLUSIONS: The experiments demonstrate various deleterious effects of device oversizing relative to the parent artery and provide strategies for addressing size mismatches when they are unavoidable.

SUMMARY:Does the world need another ICA classification scheme? We believe so. The purpose of proposed angiography-driven classification is to optimize description of the carotid artery from the endovascular perspective. A review of existing, predominantly surgically-driven classifications is performed, and a new scheme, based on the study of NYU aneurysm angiographic and cross-sectional databases is proposed. Seven segments - cervical, petrous, cavernous, paraophthlamic, posterior communicating, choroidal, and terminus - are named. This nomenclature recognizes intrinsic uncertainty in precise angiographic and cross-sectional localization of aneurysms adjacent to the dural rings, regarding all lesions distal to the cavernous segment as potentially intradural. Rather than subdividing various transitional, ophthalmic, and hypophyseal aneurysm subtypes, as necessitated by their varied surgical approaches and risks, the proposed classification emphasizes their common endovascular treatment features, while recognizing that many complex, trans-segmental, and fusiform aneurysms not readily classifiable into presently available, saccular aneurysm-driven schemes, are being increasingly addressed by endovascular means. We believe this classification may find utility in standardizing nomenclature for outcome tracking, treatment trials and physician communication.

OBJECTIVE: To evaluate whether balance deficit in patients with multiple sclerosis (MS), as assessed with eyes opened (EO) and closed (EC), is associated with damage of different structures of the central nervous system (CNS). METHODS: Fifty patients with MS and 20 healthy controls (HCs) underwent static posturography to calculate the body's center of pressure displacement (COP path) with EO and EC. They were scanned using a 3.0T magnet to obtain PD/T2 and 3D-T1-weighted images of the brain and spinal cord. We determined the mid-sagittal cerebellum area (MSCA) and upper cervical cord cross-sectional area (UCCA). We also measured the patients' lesion volumes (T2-LVs) on the whole brain and at different infratentorial levels. RESULTS: MS patients had wider COP paths with both EO and EC (p < 0.001), and lower values in both MSCA (p = 0.01) and UCCA (p = 0.008) than HCs. The COP path with EO was associated with MSCA (Beta = - 0.58; p = 0.004) and T2-LV on middle cerebellar peduncles (Beta = 0.59; p = 0.002). The COP path with EC was associated with UCCA (Beta= - 22.74; p = 0.003) and brainstem T2-LV (Beta = 0.52; p = 0.01). CONCLUSIONS: Balance deficit in MS was related to atrophy of both the cerebellum and spinal cord, but the extent of COP path under the two different conditions (EO or EC) implied different patterns of damage in the CNS.

Objective. To compare periventricular lesions in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOsd). Materials and Methods. Sagittal and axial fluid attenuated inversion recovery (FLAIR) sequences of 20 NMOsd and 40 group frequency-matched MS patients were evaluated by two neuroradiologists. On axial FLAIR, periventricular area was characterized as free of lesions/smooth-bordered ("type A") or jagged-bordered ("type B") pattern. On sagittal FLAIR, the images were evaluated for presence of "Dawson's fingers." Results. Type A pattern was observed in 80% of NMOsd patients by Reader 1 and 85% by Reader 2 but only in 5% MS patients by either Reader. Type B was seen in 15% NMOsd patients by Reader 1 and 20% by Reader 2 and in 95% MS patients by either Reader. Dawson's fingers were observed in no NMOsd patients by Reader 1 and 5% by Reader 2. In MS, Dawson's fingers were seen in 92.5% patients by Reader 1 and 77.5% by Reader 2. The differences in periventricular patterns and Dawson's finger detection between NMOsd and MS were highly significant (P < 0.001). Conclusions. Dawson's fingers and "jagged-bordered" periventricular hyperintensities are typical of MS and almost never seen in NMOsd, which suggests a practical method for differentiating the two diseases.

OBJECTIVE. The purpose of this study was to compare the type of plaque and the degree of stenosis in the carotid artery bifurcation and the carotid siphon to explore potential correlations between these parameters. MATERIALS AND METHODS. A total of 119 patients (87 men, 32 women; mean age, 69 years) were retrospectively studied using MDCT angiography. Component types of the carotid artery bifurcation and the carotid siphon plaque were defined according to attenuation values, and the volumes of each plaque component were calculated. The degree of stenosis was calculated according to the North American Symptomatic Endarterectomy Trial method. Data were compared using the Wilcoxon signed-rank test, Spearman correlation analysis, and receiver operating characteristic (ROC) analysis. RESULTS. The results of the Wilcoxon test showed a statistically significant difference (p = 0.0001) between the degree of stenosis at the carotid artery bifurcation and that at the carotid siphon. We observed a statistically significant difference (p = 0.0001) between the total volumes of the carotid artery bifurcation (mean value, 748 mm(3)) and the carotid siphon (mean value, 54 mm(3)) plaque. Moreover, the respective mean percentages of calcified, mixed, and lipid components of plaque were 17%, 56%, and 27% in the carotid artery bifurcation and 73%, 19%, and 8% in the carotid siphon, showing a statistically significant difference (p = 0.001). ROC analysis did not show association between carotid siphon plaque volume and previous cerebrovascular events (Az = 0.562; p = 0.149), whereas the total volume of the carotid artery bifurcation plaque-and, in particular, the volume of the lipid components-showed a statistically significant association (Az = 0.691, and Az = 0.758; p < 0.001). CONCLUSION. No significant association was found between presence of mixed and fatty components of plaque in the carotid artery bifurcation and presence of similar components in the carotid siphon. The carotid artery bifurcation total plaque volume (and, in particular, carotid artery bifurcation lipid volume) was associated with previous cerebrovascular events, whereas no association with the volume of carotid siphon plaque (and its subcomponents) was found.