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Contrast settling in cerebral aneurysm angiography.
Wang, Zhi-Jie; Hoffmann, Kenneth R; Wang, Zhou; Rudin, Stephen; Guterman, Lee R; Meng, Hui.
Affiliation
  • Wang ZJ; Toshiba Stroke Research Center, University at Buffalo, State University of New York, 3435 Main Street, 445 BRB, Buffalo, NY 14214, USA.
Phys Med Biol ; 50(13): 3171-81, 2005 Jul 07.
Article in En | MEDLINE | ID: mdl-15972988
ABSTRACT
During angiography, blood flow is visualized with a radiopaque contrast agent, which is denser than blood. In complex vasculature, such as cerebral saccular aneurysms, the density difference may produce an appreciable gravity effect, where the contrast material separates from blood and settles along the gravity direction. Although contrast settling has been occasionally reported before, the fluid mechanics behind it have not been explored. Furthermore, the severity of contrast settling in cerebral aneurysms varies significantly from case to case. Therefore, a better understanding of the physical principles behind this phenomenon is needed to evaluate contrast settling in clinical angiography. In this study, flow in two identical groups of sidewall aneurysm models with varying parent-vessel curvature was examined by angiography. Intravascular stents were deployed into one group of the models. To detect contrast settling, we used lateral view angiography. Time-intensity curves were analysed from the angiographic data, and a computational fluid dynamic analysis was conducted. Results showed that contrast settling was strongly related to the local flow dynamics. We used the Froude number, a ratio of flow inertia to gravity force, to characterize the significance of gravity force. An aneurysm with a larger vessel curvature experienced higher flow, which resulted in a larger Froude number and, thus, less gravitational settling. Addition of a stent reduced the aneurysmal flow, thereby increasing the contrast settling. We found that contrast settling resulted in an elevated washout tail in the time-intensity curve. However, this signature is not unique to contrast settling. To determine whether contrast settling is present, a lateral view should be obtained in addition to the anteroposterior (AP) view routinely used clinically so as to rule out contrast settling and hence to enable a valid time-intensity curve analysis of blood flow in the aneurysm.
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Database: MEDLINE Main subject: Algorithms / Cerebral Angiography / Radiographic Image Interpretation, Computer-Assisted / Intracranial Aneurysm / Artifacts / Contrast Media / Models, Cardiovascular Type of study: Evaluation_studies / Prognostic_studies Limits: Female / Humans / Middle aged Language: En Year: 2005 Type: Article
Search on Google
Database: MEDLINE Main subject: Algorithms / Cerebral Angiography / Radiographic Image Interpretation, Computer-Assisted / Intracranial Aneurysm / Artifacts / Contrast Media / Models, Cardiovascular Type of study: Evaluation_studies / Prognostic_studies Limits: Female / Humans / Middle aged Language: En Year: 2005 Type: Article