title: Acute intracranial hemorrhage in CT: benefits of sinogram-affirmed iterative reconstruction techniques.
abstract: OBJECTIVE
  Acute intracranial hemorrhage represents a severe and time critical pathology that requires precise and quick diagnosis, mainly by performing a CT scan. The purpose of this study was to compare image quality and intracranial hemorrhage conspicuity in brain CT with sinogram-affirmed iterative reconstruction and filtered back-projection reconstruction techniques at standard (340 mAs) and low-dose tube current levels (260 mAs).
  
  
  METHODS
  A total of 94 consecutive patients with intracranial hemorrhage received CT scans either with standard or low-dose protocol by random assignment. Group 1 (n=54; mean age, 64 ± 20 years) received CT at 340 mAs, and group 2 (n=40; mean age, 57 ± 23 years) received CT at 260 mAs. Images of both groups were reconstructed with filtered back-projection reconstruction and 5 iterative strengths (S1-S5) and ranked blind by 2 radiologists for image quality and intracranial hemorrhage on a 5-point scale. Image noise, SNR, dose-length product (mGycm), and mean effective dose (mSv) were calculated.
  
  
  RESULTS
  In both groups, image quality and intracranial hemorrhage conspicuity were rated subjectively with an excellent/good image quality. A higher strength of sinogram-affirmed iterative reconstruction showed an increase in image quality with a difference to filtered back-projection reconstruction (P < .05). Subjective rating showed the best score of image quality and intracranial hemorrhage conspicuity achieved through S3/S4-5. Objective analysis of image quality showed in an increase of SNR with a higher strength of sinogram-affirmed iterative reconstruction. Patients in group 2 (mean: 744 mGycm/1.71 mSv) were exposed to a significantly lower dose than those in group 1 (mean: 1045 mGycm/2.40 mSv, P < .01).
  
  
  CONCLUSIONS
  S3 provides better image quality and visualization of intracranial hemorrhage in brain CT at 260 mAs. Dose reduction by almost one-third is possible without significant loss in diagnostic quality.
authors.affiliation: From the Departments of Diagnostic and Interventional Radiology (B.B., E.K., N.N.N.N., R.W.B., J.M.K., F.A.-B., J.L.W., T.L., T.J.V., B.S.).
authors.forename: B
authors.initials: B
authors.lastname: Bodelle
authors.forename: E
authors.initials: E
authors.lastname: Klein
authors.forename: N N N
authors.initials: NN
authors.lastname: Naguib
authors.forename: R W
authors.initials: RW
authors.lastname: Bauer
authors.forename: J M
authors.initials: JM
authors.lastname: Kerl
authors.forename: F
authors.initials: F
authors.lastname: Al-Butmeh
authors.forename: J L
authors.initials: JL
authors.lastname: Wichmann
authors.forename: H
authors.initials: H
authors.lastname: Ackermann
authors.forename: T
authors.initials: T
authors.lastname: Lehnert
authors.forename: T J
authors.initials: TJ
authors.lastname: Vogl
authors.forename: B
authors.initials: B
authors.lastname: Schulz
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D020300:Intracranial Hemorrhages / Q000000981:diagnostic imaging*; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D055815:Young Adult