Border Zone Infarcts: Pathophysiologic and Imaging Characteristics
Neurologic/Head and Neck Imaging:
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The causal mechanisms and anatomic locations of external (cortical) and internal (subcortical) border zone infarcts are reviewed, and their appearances at MR imaging, CT, and transcranial Doppler US are described in detail.
Border Zone Infarcts: Pathophysiologic and Imaging Characteristics [Neurologic/Head and Neck Imaging]:
Border zone or watershed infarcts are ischemic lesions that occur in characteristic locations at the junction between two main arterial territories. These lesions constitute approximately 10% of all brain infarcts and are well described in the literature. Their pathophysiology has not yet been fully elucidated, but a commonly accepted hypothesis holds that decreased perfusion in the distal regions of the vascular territories leaves them vulnerable to infarction. Two types of border zone infarcts are recognized: external (cortical) and internal (subcortical). To select the most appropriate methods for managing these infarcts, it is important to understand the underlying causal mechanisms. Internal border zone infarcts are caused mainly by hemodynamic compromise, whereas external border zone infarcts are believed to result from embolism but not always with associated hypoperfusion. Various imaging modalities have been used to determine the presence and extent of hemodynamic compromise or misery perfusion in association with border zone infarcts, and some findings (eg, multiple small internal infarcts) have proved to be independent predictors of subsequent ischemic stroke. A combination of several advanced techniques (eg, diffusion and perfusion magnetic resonance imaging and computed tomography, positron emission tomography, transcranial Doppler ultrasonography) can be useful for identifying the pathophysiologic process, making an early clinical diagnosis, guiding management, and predicting the outcome.
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Flow Diversion in Aneurysms Trial: the Design of the FIAT study
Click this link to open the journal webpageWith the increasing interest among interventional neuroradiologists of flow diversion therapy of intracranial aneurysms, it was only matter of time before an RCT came along. So here it is... The FIAT trial, consisting of both RCT and registry arms, to be conducted with a wel respected group led by Jean Raymond, and which will compare the imaging and clinical results of flow diversion with stents vs other techniques (observation, coiling, parent vessel sacrifice, surgery etc.)...
Flow Diversion in Aneurysms Trial: the Design of the FIAT study
Centre Hospitalier de l'Université de Montréal (CHUM), Notre-Dame Hospital, Department of Radiology and Interventional Neuroradiology Research Unit; Montreal, Quebec, Canada
Key words: aneurysms, intracranial stents, clinical trial
Summary
Intracranial aneurysms, particularly large and giant, fusiform or recurrent aneurysms are increasingly treated with flow diverters (FDs), a recently introduced and approved neurovascular device. While some rare cases may not be treated any other way, in most patients a more conventional, conservative, or validated approach such as coiling, parent vessel occlusion, or surgical clipping exists. Only a randomized clinical trial can answer the question of which treatment option leads to better patient outcomes.We report the design of the FIAT study, a clinical care trial aiming to compare angiographic and clinical outcomes following treatment with a Flow-Diverter or with the best conventional treatment option.
The FIAT study will include both a randomized and a registry portion. Patients will be proposed randomization to either FD stenting or best conventional treatment option (observation, coiling, stenting, or clipping) as determined by the treating physician. FIAT will recruit a total of 338 patients, to show that i) FD stenting can be performed with an ‘acceptable' immediate complication rate of less than 15% morbidity and mortality (defined as mRS > 2); ii) FD stenting can increase from 75 to 90% the proportion of patients with a “good outcome”, defined as complete or near-complete occlusion of the aneurysm AND a good clinical outcome (mRS ≤ 2) at one year, as compared to the best conventional option.
The FIAT study provides a scientific and ethical context to care for patients eligible for flow-diversion therapy.
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