The diameter-cube hypothesis: a new biophysical model of aneurysm rupture.

Background: Recent discussions on the relationship between intracranial aneurysm diameter and rupture probability have focused on the presence of an apparent critical diameter of 10 mm for aneurysm rupture. Despite the fact that many investigators have argued against the existence of this critical diameter, no one has yet proposed a viable alternative concept. In this report we present a scientifically rigorous alternative concept, that the size-specific rupture probability (RP) of an aneurysm varies as the third power of the aneurysm diameter.

Quantitative assessment of polymerization-binding mechanics of cyanoacrylates: model development and validation.

Background And Purpose: Although commonly acknowledged as paramount in significance, the mechanics of cyanoacrylate polymerization remain poorly characterized and quantified for clinical applications. This prompted development of a simplistic model for the systematic study of polymerization and binding behaviors of cyanoacrylates.

Methods: A sliding bed apparatus was constructed that linked a strain gage with a vessel that could be filled with liquid medium, cyanoacrylate, and a microcatheter.

Technetium-99m-labeled myocardial perfusion agents: Are they better than thallium-201?

Currently, thallium-201 (201Tl)- and technetium-99m (99mTc)-labeled tracers are used interchangeably for the detection of coronary artery disease, the assessment of myocardial viability, and risk stratification. This article reviews some of the potential advantages and disadvantages of the 99mTc-labeled tracers relative to 201Tl. The basic myocardial kinetic properties and biodistribution of the commonly used 99mTc-labeled perfusion tracers are compared with those of 201Tl.

Intracarotid pressure measurements in the evaluation of a computer model of the cerebral circulation.

Background: It is difficult to predict which patients will tolerate occlusion of the internal carotid artery. This difficulty arises primarily because of uncertainties in the prediction of the adequacy of collateral circulation. Because of these uncertainties, balloon test occlusion and other methods have been developed to determine a priori the safety of carotid occlusion.

A multiplicative statistical model predicts the size distribution of unruptured intracranial aneurysms.

A statistical model for characterizing the erratic nature of aneurysm evolution is developed and tested. This model is based upon a multiplicative hypothesis, whereby it is theorized that the progressive changes in the size of a given aneurysm are determined by random multipliers. Such a model would predict that within a large population of aneurysms, a lognormal histogram for aneurysm sizes would occur (i.

Technical feasibility and performance studies of a 0.009-inch nitinol microguidewire for potential neuroendovascular applications.

Rationale And Objectives: The authors conduct technical feasibility and performance studies on a new 0.009-inch nitinol microguidewire for potential neuroendovascular applications.

Methods: In vivo microcatheterizations of brachiocephalic arteries were performed in four pigs using the 0.

Mathematical modeling of AVM physiology using compartmental network analysis: theoretical considerations and preliminary in vivo validation using a previously developed animal model.

The development of computer modeling technique of cerebral arteriovenous malformations using circuit network analysis, validated with a previously developed animal model is presented. Such a malformation and its vascular connections are rendered into a complex system of interconnecting tubes, which is then simulated by an analogous electrical circuit using commercially available computer software. This methodology was tested using a swine model, of which a detailed computer model was constructed from anatomic and angiographic measurements of the cranial vessels.

Computer modeling of cerebral blood flow following internal carotid artery occlusion.

It is difficult to predict the adequacy of the collateral blood flow in patients who undergo internal carotid artery occlusion. In order to address this difficulty, the authors have created a computer model of the cerebral circulation. This model features individualized simulations of the Circle of Willis and its afferent and efferent branches which can predict changes in flow that will occur during internal carotid artery occlusion.