title: Effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies.
abstract: The purpose of this study was to investigate the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using multi-detector row CT (MDCT). Following the standard CT perfusion study protocol, continuous (cine) scans (1 s/rotation x 60 s) consisting of four 5 mm thick contiguous slices were performed using an MDCT scanner with a tube voltage of 80 kVp and a tube current of 200 mA. We generated the simulated images with tube currents of 50 mA, 100 mA and 150 mA by adding the corresponding noise to the raw scan data of the original image acquired above using a noise simulation tool. From the original and simulated images, we generated the functional images of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in seven patients with cerebrovascular disease, and compared the correlation coefficients (CCs) between the perfusion parameter values obtained from the original and simulated images. The coefficients of variation (CVs) in the white matter were also compared. The CC values deteriorated with decreasing tube current. There was a significant difference between 50 mA and 100 mA for all perfusion parameters. The CV values increased with decreasing tube current. There were significant differences between 50 mA and 100 mA and between 100 mA and 150 mA for CBF. For CBV and MTT, there was also a significant difference between 150 mA and 200 mA. This study will be useful for understanding the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using MDCT, and for selecting the tube current.
authors.affiliation: Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan. murase@sahs.med.osaka-u.ac.jp
authors.forename: Kenya
authors.initials: K
authors.lastname: Murase
authors.forename: Takafumi
authors.initials: T
authors.lastname: Nanjo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ii
authors.forename: Shohei
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Masaaki
authors.initials: M
authors.lastname: Hirata
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Sugawara
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kudo
authors.forename: Kousuke
authors.initials: K
authors.lastname: Sasaki
authors.forename: Teruhito
authors.initials: T
authors.lastname: Mochizuki
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply* / Q000473:pathology; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging* / Q000473:pathology; D003198:Computer Simulation; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D013997:Time Factors; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*; D014867:Water / Q000737:chemistry; D014965:X-Rays
chemical_list: D003287:Contrast Media; D014867:Water