title: Comparison of artifacts on coronal reformation and axial CT pulmonary angiography images using single-detector and 4- and 8-detector multidetector-row helical CT scanners.
abstract: OBJECTIVE
  The aim of this study is to compare the degree of stair-step artifact on coronal reformation computed tomographic (CT) pulmonary angiography images obtained using single-detector helical CT (SDCT), four-detector (4-MDCT), and eight-detector multidetector-row CT (8-MDCT) and compare the degree of motion artifact on the corresponding axial CT images.
  
  
  METHODS
  Three groups of consecutive patients imaged by means of CT angiography for suspected pulmonary embolus were retrospectively identified by using CT records at our institution: (1) group A (n = 38), SDCT; (2) group B (n = 36), 4-MDCT; and (3) group C (n = 74), 8-MDCT. For each case, coronal multiplanar volume reformation maximal intensity projection images were created by using a standard technique. All images were reviewed in a randomized fashion by two thoracic radiologists who were blinded to the type of CT scanner. Stair-step artifact of pulmonary arteries on coronal reformation images was graded by consensus agreement using a four-point scale (0 = no artifact to 3 = severe artifact). Axial images were assessed for six parameters of motion artifact. The sum of these grades resulted in a total motion score, with a potential range of 0 (no motion) to 12 (severe motion). Statistical analysis was performed using the Mann-Whitney test.
  
  
  RESULTS
  Stair-step artifacts were significantly higher for SDCT (mean, 2.9; median, 3) compared with 4-MDCT (mean, 2.2; median, 2; P < .0001) and 8-MDCT (mean, 1.5; median, 1; P < .0001). Total motion scores were significantly higher for SDCT (mean, 9.3) compared with 4-MDCT (mean, 8.4; P = .03) and 8-MDCT (mean, 6.8; P < .0001).
  
  
  CONCLUSIONS
  Stair-step artifacts are significantly higher with SDCT compared with MDCT. For MDCT, eight-detector scanners produce images with significantly less artifact than four-detector scanners.
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston MA 02215, USA.
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Boiselle
authors.forename: I
authors.initials: I
authors.lastname: Hasegawa
authors.forename: Mizuki
authors.initials: M
authors.lastname: Nishino
authors.forename: Vassillios
authors.initials: V
authors.lastname: Raptopoulos
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hatabu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D016477:Artifacts; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D015898:Tomography Scanners, X-Ray Computed; D036542:Tomography, Spiral Computed / Q000379:methods*