title: Iterative Reconstruction Leads to Increased Subjective and Objective Image Quality in Cranial CT in Patients With Stroke.
abstract: OBJECTIVE
  The purpose of this study was to determine whether iterative reconstruction improves the quality of cranial CT (CCT) images of stroke patients.
  
  
  METHODS
  Fifty-one CCT studies of patients with infarction performed with either a low (260 mAs; n = 21) or standard (340 mAs; n = 30) dose were reconstructed with both filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) with five strength levels (S1-S5). The resulting six image sets (one FBP and one each for SAFIRE levels S1-S5) were rated separately by two blinded radiologists in terms of conspicuity of infarcted areas on a 5-point scale. Noise and infarct-to-normal brain as well as medullary-to-cortical contrast-to-noise ratios (CNRs) were measured. Ratings, noise, and CNRs were intraindividually compared within the same dose group (Fisher exact test) and interindividually between the different dose groups (Wilcoxon-Mann-Whitney U test).
  
  
  RESULTS
  The strength level S4 showed the best conspicuity of infarcted areas. Compared with FBP, SAFIRE S4 statistically significantly (p < 0.01) reduced noise and improved CNRs without statistically significant differences in all subjective and objective criteria (p > 0.01) when the dose was reduced. Patients examined with a 260-mAs low-dose were exposed to a statistically significantly lower dose (1.77 vs 2.33 mSv; p < 0.01).
  
  
  CONCLUSIONS
  Iterative reconstruction (SAFIRE at strength level S4) leads to increased subjective and objective image quality in CCT and allows dose reduction (-24%) without losses in the demarcation of ischemic lesions.
authors: 1 All authors: Department of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors: Boris
authors: B
authors: Bodelle
authors: 1 All authors: Department of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors: Julian L
authors: JL
authors: Wichmann
authors: 1 All authors: Department of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors: Jan-Eric
authors: JE
authors: Scholtz
authors: 1 All authors: Department of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors: Thomas
authors: T
authors: Lehnert
authors: 1 All authors: Department of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors: Thomas J
authors: TJ
authors: Vogl
authors: 1 All authors: Department of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors: Wolfgang
authors: W
authors: Luboldt
authors: 1 All authors: Department of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors: Boris
authors: B
authors: Schulz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061214:Patient Safety; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D059629:Signal-To-Noise Ratio; D020521:Stroke / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: MDCT; brain infarction; low dose; radiation safety; sinogram-affirmed iterative reconstruction