%0 Journal Article
%T Advanced Imaging Modalities in the Detection of Cerebral Vasospasm
%A Jena N. Mills
%A Vivek Mehta
%A Jonathan Russin
%A Arun P. Amar
%A Anandh Rajamohan
%A William J. Mack
%J Neurology Research International
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/415960
%X The pathophysiology of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) is complex and is not entirely understood. Mechanistic insights have been gained through advances in the capabilities of diagnostic imaging. Core techniques have focused on the assessment of vessel caliber, tissue metabolism, and/or regional perfusion parameters. Advances in imaging have provided clinicians with a multifaceted approach to assist in the detection of cerebral vasospasm and the diagnosis of delayed ischemic neurologic deficits (DIND). However, a single test or algorithm with broad efficacy remains elusive. This paper examines both anatomical and physiological imaging modalities applicable to post-SAH vasospasm and offers a historical background. We consider cerebral blood flow velocities measured by Transcranial Doppler Ultrasonography (TCD). Structural imaging techniques, including catheter-based Digital Subtraction Angiography (DSA), CT Angiography (CTA), and MR Angiography (MRA), are reviewed. We examine physiologic assessment by PET, HMPAO SPECT, 133Xe Clearance, Xenon-Enhanced CT (Xe/CT), Perfusion CT (PCT), and Diffusion-Weighted/MR Perfusion Imaging. Comparative advantages and limitations are discussed. 1. Introduction and Historical Perspective Cerebral vasospasm is a delayed complication of subarachnoid hemorrhage. It generally occurs 4¨C14 days after aneurysmal rupture and is associated with morbidity and mortality rates between 10 and 30% [1]. While changes are commonly observed in the large caliber conveyance arteries, effects on the smaller vessels of the microcirculation, including alterations in blood brain barrier permeability, may be equally important in determining clinical impact. Such factors may account for the higher incidence of vasospasm as defined by imaging criteria (ˇ°radiographic vasospasmˇ±) than rates of neurological dysfunction (ˇ°clinical vasospasmˇ±). Early diagnosis and treatment could potentially prevent and/or minimize delayed ischemic neurological deficits (DIND). Advances in clinical management of cerebral vasospasm have lagged far behind innovations in brain imaging. Given that radiographic vasospasm does not strongly associate with DIND, efforts have refocused on understanding pathophysiology through advanced correlative imaging. Technological developments have enabled accurate assessment of tissue oxygenation, metabolic uptake, and cerebral perfusion. This paper will review imaging modalities applied to the detection of cerebral vasospasm and the diagnosis of DIND. A historical background is presented, and
%U http://www.hindawi.com/journals/nri/2013/415960/