title: Dose reduction in dynamic perfusion CT of the brain: effects of the scan frequency on measurements of cerebral blood flow, cerebral blood volume, and mean transit time.
abstract: The influence of the frequency of computed tomography (CT) image acquisition on the diagnostic quality of dynamic perfusion CT (PCT) studies of the brain was investigated. Eight patients with clinically suspected acute ischemia of one hemisphere underwent PCT, performed on average 3.4 h after the onset of symptoms. Sixty consecutive images per slice were obtained with individual CT images obtained at a temporal resolution of two images per second. Eight additional data sets were reconstructed with temporal resolutions ranging from one image per second to one image per 5 s. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) measurements were performed in identical regions of interest. Two neuroradiologists evaluated the PCT images visually to identify areas of abnormal perfusion. Perfusion images created up to a temporal resolution of one image per 3 s were rated to be diagnostically equal to the original data. Even at one image per 4 s, all areas of infarction were identified. Quantitative differences of CBF, CBV and MTT measurements were < or = 10% up to one image per 3 s. For PCT of the brain, temporal resolution can be reduced to one image per 3 s without significant compromise in image quality. This significantly reduces the radiation dose of the patient.
authors.affiliation: Department of Neuroradiology, University of Munich, Marchioninistr. 15, 81377, München, Germany. martin.wiesmann@med.uni-muenchen.de
authors.forename: Martin
authors.initials: M
authors.lastname: Wiesmann
authors.forename: Scott
authors.initials: S
authors.lastname: Berg
authors.forename: G
authors.initials: G
authors.lastname: Bohner
authors.forename: R
authors.initials: R
authors.lastname: Klingebiel
authors.forename: V
authors.initials: V
authors.lastname: Schöpf
authors.forename: B M
authors.initials: BM
authors.lastname: Stoeckelhuber
authors.forename: I
authors.initials: I
authors.lastname: Yousry
authors.forename: J
authors.initials: J
authors.lastname: Linn
authors.forename: U
authors.initials: U
authors.lastname: Missler
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D001810:Blood Volume; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging*; D002545:Brain Ischemia / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography / Q000379:methods; D002560:Cerebrovascular Circulation; D003287:Contrast Media / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide