Search NASA⌕ Search

SEARCH · Search NASA

Results for “CAROTID ARTERIES”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Incidence of New Ischaemic Brain Lesions After Carotid Artery Stenting with the Micromesh Roadsaver Carotid Artery Stent: A Prospective Single-Centre Study

AimsSeveral randomized trials of patients with carotid stenosis show increased adverse neurological events with stenting versus endarterectomy in the 30-day post-procedure. This study examines the incidence of new ischaemic lesions in patients treated in our centre using the new Roadsaver stent.Methods and resultsBetween September 2015 and January 2016, 23 consecutive patients (age 74.3 ± 7.3 years, 17.4 % female) underwent carotid artery stenting with the Roadsaver stent, a nitinol double-layer micromesh device. A distal protection device was used in all cases. Diffusion-weighted magnetic resonance imaging was performed 24 h before, and 24 h and 30 days after the procedure. The 24-h post-procedure imaging showed 15 new ipsilateral ischaemic lesions in 7 (30.4 %) patients: median volume 0.076 cm{sup 3} (interquartile range 0.065–0.146 cm{sup 3}). All lesions were asymptomatic. The 30-day imaging showed complete resolution of all lesions and no new ischaemic lesions. Follow-up clinical and ultrasound examinations at 30 days and 6 months recorded no adverse cardiac or cerebrovascular events.ConclusionsProtected stenting with micromesh Roadsaver stent showed good safety and efficacy in the treatment of carotid stenosis, with a low incidence of delayed embolic events and new ipsilateral ischaemic brain lesions. These preliminary results are encouraging, but need to be confirmed with larger populations.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

The 10-year Trend of Periprocedural Complication Following Carotid Artery Stenting; Single Center Experience

PurposeCarotid endarterectomy and stenting are used to treat carotid stenosis, with the volume of carotid artery procedures increasing over the past decade. We investigated the 10-year trend of periprocedural complications with an increasing procedure volume of carotid stenting at a single tertiary hospital.MethodsWe collected 416 consecutive cases (384 patients) of carotid artery stenting performed for either symptomatic (231 cases, 55.5 %) or asymptomatic (185 cases, 44.5 %) internal carotid artery stenosis at a single center. Periprocedural complication was defined as any stroke, myocardial infarction, or death. Procedure-related outcome included any dissection, hemodynamic event, or periprocedural complication.ResultsThe mean age was 68.8 years (82.8 % males; range of 20–89 years); 23.9 % were older than 75 years. Before the procedure, 99.3 and 56.0 % of patients received antiplatelet and lipid-lowering medication, respectively. The overall periprocedural complication rate was 3.6 % (1.6 and 5.2 % in the asymptomatic and symptomatic group, respectively). The composite outcome of any stroke or death was 3.4 %. Periprocedural complication and procedure-related outcome showed a decremental trend with increasing procedure volume, and this trend remained after adjusting for confounders.ConclusionsOur study suggests that carotid stenting at an experienced center might reduce the periprocedural complications. Our periprocedural complication rate of carotid artery stenting may be comparable to, or somewhat lower than, that reported in other clinical trials.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Comparison of Endovascular and Open Carotid Artery Treatment in Germany: A Retrospective Analysis from 2010 to 2015

Introduction: We analyzed trends in carotid artery stenting (CAS) and carotid endarterectomy (CEA) in hospitalized cases in Germany in the years 2010–2015. Methods: Data from national statistics (DRG statistics) published by the Federal Statistical Office in Germany describing the number of hospitalized patients treated with CEA and CAS were used. In addition, numbers of patients hospitalized with the principal diagnosis stroke associated with precerebral lesions (ICD code I63), transitory cerebral ischemic attacks (G45) and precerebral carotid artery stenosis (I65) treated by CEA and CAS were analyzed for the year 2015. Results: Total number of CEA decreased by 4.0% from 24.067 (2010) to 23.104 (2015) and CAS increased by 5.1% from 5.703 to 5.992. In 2015, 79.4% of all procedures coded concerning the internal carotid artery were CEA and 21.6% CAS. From 27.798 cases hospitalized with the principal diagnosis stroke associated with precerebral lesions, CEA was performed in 3.921 (14.1%) and in 2.132 (7.7%) CAS was documented, with CAS making up one-third of all treatments within the stroke group. In 28.273 cases hospitalized with a TIA, CEA was specified in 853 (3.0%) and CAS in 255 (0.9%) cases. In 27.553 cases with an occlusion and stenosis of precerebral arteries, not resulting in cerebral infarction, 17.036 (61.8%) had a CEA and 3.156 (11.5%) a CAS procedure. Conclusion: CEA is still the primary treatment of extracranial artery stenosis. The impact of CAS becomes mainly apparent in cases presenting with acute strokes.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Acute Carotid Artery Stent Thrombosis Due to Dual Antiplatelet Resistance

Carotid artery stenting (CAS) is a revascularization modality that is an alternative to carotid endarterectomy. The efficacy of CAS in primary and secondary prevention from ischemic stroke has been demonstrated in various trials. Acute thrombosis of CAS is a rare complication that can lead to dramatic and catastrophic consequences. We discuss a case of acute CAS thrombosis in a patient who had previously undergone successful CAS. CAS was performed in a 73-year-old man who had had dysarthria lasting 2 weeks with 95 % stenosis in his left internal carotid artery. An acute cerebrovascular event resulting in right-sided hemiplegia developed 24 h after the procedure. Computed tomographic carotid angiography revealed complete occlusion of the stent with thrombus. The cause of stent thrombosis was thought to be antiaggregant resistance to both acetylsalicylic acid and clopidogrel. The most important cause of acute CAS thrombosis is inadequate or ineffective antiaggregant therapy. Evaluating patients who are candidates for CAS for acetylsalicylic acid and clopidogrel resistance may preclude this complication.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Impact of intravenous contrast used in computed tomography on radiation dose to carotid arteries and thyroid in intensity-modulated radiation therapy planning for nasopharyngeal carcinoma

The aim of this study was to investigate if intravenous contrast injection affected the radiation doses to carotid arteries and thyroid during intensity-modulated radiation therapy (IMRT) planning for nasopharyngeal carcinoma (NPC). Thirty consecutive patients with NPC underwent plain computed tomography (CT) followed by repeated scanning after contrast injection. Carotid arteries (common, external, internal), thyroid, target volumes, and other organs-at-risk (OARs), as well as IMRT planning, were based on contrast-enhanced CT (CE-CT) images. All these structures and the IMRT plans were then copied and transferred to the non–contrast-enhanced CT (NCE-CT) images, and dose calculation without optimization was performed again. The radiation doses to the carotid arteries and the thyroid based on CE-CT and NCE-CT were then compared. Based on CE-CT, no statistical differences, despite minute numeric decreases, were noted in all dosimetric parameters (minimum, maximum, mean, median, D05, and D01) of the target volumes, the OARs, the carotid arteries, and the thyroid compared with NCE-CT. Our results suggested that compared with NCE-CT planning, CE-CT scanning should be performed during IMRT for better target and OAR delineation, without discernible change in radiation doses.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

Acute Stroke and Obstruction of the Extracranial Carotid Artery Combined with Intracranial Tandem Occlusion: Results of Interventional Revascularization

PurposeDue to high thrombus load, acute stroke patients with tandem obstructions of the extra- and intracranial carotid arteries or the middle cerebral artery show a very limited response to systemic thrombolysis. Interventional treatment with mechanical thrombectomy—often in combination with acute stenting of underlying atherosclerotic stenosis or dissection—is increasingly used. It has been shown that such complex interventions are technically feasible. The lack of optimal management strategies and clinical data encouraged us to review our acute stroke interventions in patient with anterior circulation tandem lesions to determine lesion patterns, interventional approaches, and angiographic or clinical outcomes.Patients and MethodsWe retrospectively analyzed a series of 39 consecutive patients with intracranial vessel occlusion of the anterior circulation simultaneously presenting with high-grade cervical internal carotid artery (ICA) stenosis or occlusion.ResultsEmergency ICA stent implantation was technically feasible in all patients, and intracranial recanalization with TICI ≥ 2b was reached in a large number of patients (64 %). Good clinical outcomes (mRS ≤ 2 at 3 months) were achieved in one third of the patients (36 %). Symptomatic hemorrhages occurred in four patients (10 %). Mortality was 10 %.ConclusionEndovascular recanalization of acute cervical carotid artery occlusion was technically feasible in all patients, and resulted in high extra- and intracranial revascularization rates. A trend for favorable clinical outcome was seen in a higher TICI score, younger age, good collateral status, and combined IV rTPA and endovascular therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1989

Computer-generated 3D ultrasound images of the carotid artery

A method is under development to measure carotid artery lesions from a computer-generated three-dimensional ultrasound image. For each image, the position of the transducer in six coordinates (x, y, z, azimuth, elevation, and roll) is recorded and used to position each B-mode picture element in its proper spatial position in a three-dimensional memory array. After all B-mode images have been assembled in the memory, the three-dimensional image is filtered and resampled to produce a new series of parallel-plane two-dimensional images from which arterial boundaries are determined using edge tracking methods.

Selzer, Robert H.↗
DOE OSTI2019

{sup 18}F-FDG PET/CT for the quantification of inflammation in large carotid artery plaques

Background: There is currently no consensus on the methodology for quantification of {sup 18}F-FDG uptake in inflammation in atherosclerosis. In this study, we explore different methods for quantification of {sup 18}F-FDG uptake in carotid atherosclerotic plaques and correlate the uptake values to histological assessments of inflammation. Methods and Results: Forty-four patients with atherosclerotic stenosis ≥70% of the internal carotid artery underwent {sup 18}F-FDG PET/CT. Maximum standardized uptake values (SUV{sub max}) from all plaque-containing slices were collected. SUV{sub max} for the single highest and the mean of multiple slices with and without blood background correction (by subtraction (cSUV) or by division (target-to-background ratio (TBR)) were calculated. Following endarterectomy 30 plaques were assessed histologically. The length of the plaques at CT was 6-32 mm. The {sup 18}F-FDG uptake in the plaques was 1.15-2.66 for uncorrected SUVs, 1.16-3.19 for TBRs, and 0.20-1.79 for cSUVs. There were significant correlations between the different uptake values (r = 0.57-0.99, P < 0.001). Methods with and without blood background correction showed similar, moderate correlations to the amount of inflammation assessed at histology (r = 0.44-0.59, P < 0.02). Conclusions: In large stenotic carotid plaques, {sup 18}F-FDG uptake reflects the inflammatory status as assessed at histology. Increasing number of PET slices or background correction did not change the correlation.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Early Embolization After Carotid Artery Stenting with Mesh-Covered Stent: Role of Diffusion-Weighted Magnetic Resonance Imaging as Pre-procedural Predictor and Discriminant Between Intra- and Post-procedural Events

Objectives: To evaluate the incidence and the time of onset of early micro-embolism after CAS (carotid artery stenting) with two different mesh-covered stents and to assess the role of DW-MRI (Diffusion-weighted magnetic resonance imaging) in their prediction. Methods: Single-institution prospective study including 50 patients (33 male, median age 74 years) who underwent CAS with Roadsaver{sup ®} or CGuard™. All patients with primary stenosis (37/50, 74%) had carotid plaque DW-MRI pre-procedure, with both qualitative evaluation of the hyperintensity and ADC (apparent diffusion coefficient) measurement of the plaque. All patients had brain DW-MRI pre-procedure, at 1 h, 24 h and 30 days post-procedure to evaluate the appearance of hyperintense lesions over time. Imaging analysis was performed in a double-blinded fashion by two radiologists. Results: There were no statistically significant differences between the two stents both in the incidence at 1 h (P = 0.23) and 24 h (P = 0.36) and in the volume of new DWI hyperintense brain lesions at 24 h (P = 0.27). Thirty-four new asymptomatic lesions in 19 patients (38%) were reported: 4 (11.8%) at 1 h, 30 (88.2%) at 24 h. The 30-day DWI-MR showed complete resolution of all lesions and no evidence of new lesion. The incidence of new lesions at 24 h resulted significantly higher in patients with DWI hyperintense carotid plaques (12/16, 75% vs. 0/21, 0%, P < 0.0001). This result was paralleled by the difference in ADC value (0.83 ± 0.21 vs. 1.42 ± 0.52). Conclusion: The majority of early asymptomatic brain lesion occurred during the first 24 h after CAS. Pre-procedure high DWI signal of the plaque was associated with an increased incidence of post-procedure microembolizations.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Real-time ultrasound-tagging to track the 2D motion of the common carotid artery wall in vivo

Purpose: Tracking the motion of biological tissues represents an important issue in the field of medical ultrasound imaging. However, the longitudinal component of the motion (i.e., perpendicular to the beam axis) remains more challenging to extract due to the rather coarse resolution cell of ultrasound scanners along this direction. The aim of this study is to introduce a real-time beamforming strategy dedicated to acquire tagged images featuring a distinct pattern in the objective to ease the tracking. Methods: Under the conditions of the Fraunhofer approximation, a specific apodization function was applied to the received raw channel data, in real-time during image acquisition, in order to introduce a periodic oscillations pattern along the longitudinal direction of the radio frequency signal. Analytic signals were then extracted from the tagged images, and subpixel motion tracking of the intima–media complex was subsequently performed offline, by means of a previously introduced bidimensional analytic phase-based estimator. Results: The authors’ framework was applied in vivo on the common carotid artery from 20 young healthy volunteers and 6 elderly patients with high atherosclerosis risk. Cine-loops of tagged images were acquired during three cardiac cycles. Evaluated against reference trajectories manually generated by three experienced analysts, the mean absolute tracking error was 98 ± 84 μm and 55 ± 44 μm in the longitudinal and axial directions, respectively. These errors corresponded to 28% ± 23% and 13% ± 9% of the longitudinal and axial amplitude of the assessed motion, respectively. Conclusions: The proposed framework enables tagged ultrasound images of in vivo tissues to be acquired in real-time. Such unconventional beamforming strategy contributes to improve tracking accuracy and could potentially benefit to the interpretation and diagnosis of biomedical images.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1974

Wave transmission characteristics and anisotropy of canine carotid arteries

A method was developed to generate and record three types of small amplitude waves (pressure, torsion and axial) in the exposed carotid artery of anesthetized dogs. The pressure waves were studied with the aid of miniature pressure transducers; electro-optical tracking units monitored the axial and circumferential surface displacements. Results from 6 dogs are presented in the form of the phase velocities and attenuation of three types of waves. The data demonstrate incompatibility with an isotropic elastic model for the mechanical behavior of the artery. The measured damping appears to be primarily due to the viscoelastic properties of the vessel wall material.

Moritz, W. E.↗
NASA NTRS2016

Influence of Exercise Modality on Cerebral-Ocular Hemodynamics and Pressures

Background: Moderate and high intensity aerobic or resistance exercise has clearly identified benefits for cardiac, muscle, and bone health. However, the impact of such exercise - either as a mitigating or an exacerbating factor - on the development of the visual impairment and intracranial pressure syndrome (VIIP) is unknown. Accordingly, our aim was to characterize the effect of an acute bout of resistance (RE), moderate-intensity continuous (CE), and high-intensity interval exercise (IE) during a cephalad fluid shift on cerebral-ocular hemodynamics and pressures. Methods: 10 male subjects (36 plus or minus 9 years) completed 4 testing days in a 15 degree head-down tilt (HDT): (1) assessment of maximum volume of O (sub 2), (2) RE session (4 sets of 12 repetition maximum leg press exercise), (3) CE session (30 minutes of cycling at 60 percent maximum volume of O (sub 2)), and (4) IE session (4 by 4-minute intervals of exercise at 85 percent maximum volume of O (sub 2) with 3-minute active rest periods). During each session, blood flow (Vivid-e, GE Healthcare) in extracranial arteries (common carotid artery, CCA; internal carotid artery, ICA; external carotid artery, ECA and vertebral artery, VA), and mean blood flow velocity in middle cerebral artery (MCA), internal jugular pressure (IJP; VeinPress), and intraocular pressure (IOP; Icare PRO) were measured at rest, at the end of each resistance or interval set, and every 5 minutes during continuous exercise. Translaminar pressure gradient (TLPG) was estimated by subtracting IJP from IOP. Results: There were no differences across days in pre-exercise resting blood flows or pressures. IOP decreased slightly from HDT rest (20.2 plus or minus 2.3 millimeters of mercury) to exercise (RE: 19.2 plus or minus 2.8 millimeters of mercury; CE: 18.9 plus or minus 3.2 millimeters of mercury; IE: 20.1 plus or minus 2.8 millimeters of mercury), while IJP decreased during CE (31.6 plus or minus 9.5 millimeters of mercury) and RE (32.0 plus or minus 8.1 millimeters of mercury), and increased during IE (35.1 plus or minus 9.5 millimeters of mercury) from HDT rest (33.3 plus or minus 6.5 millimeters of mercury). Estimated TLPG was increased during IE only. Compared to RE and CE, IE resulted in the greatest increase in MCA blood flow velocity and extracranial artery blood flow. Conclusions: These preliminary results suggest that high-intensity IE acutely increases cerebral blood flow, IJP, and TLPG. Alterations in TLPG is one mechanism that may contribute to optic nerve sheath edema in astronauts. Accordingly, acutely raising IOP and/or orbital pressure during exercise could optimize cerebral-ocular pressures during spaceflight.

Scott, J.↗