title: Spiral CT: decreased spatial resolution in vivo due to broadening of section-sensitivity profile.
abstract: Comparable conventional and spiral computed tomographic (CT) scanning protocols for transaxial (n = 30) and multiplanar reformation (MPR) (n = 15) imaging were performed to image the adrenal gland and the upper pole of the right kidney in the same patient, without use of intravenously administered contrast media. The sharpness of soft-tissue-fat interfaces oriented in the transverse (xy) and longitudinal (z) directions was measured as the maximum and full width at half maximum (FWHM) of the edge attenuation profile first derivative. Edge sharpness was qualitatively assessed by three blinded reviewers, who used a four-point scale. In vivo transaxial CT studies showed that the conventional scans produced slightly sharper edges than the spiral scans (mean difference of spiral and conventional FWHM = 0.30 mm [P < .05] [in z direction] and 0.21 mm [P < .05] [in xy direction]). In vivo MPR studies showed that interfaces in the xy plane were significantly less sharp with spiral scanning, whereas interfaces in the z direction were equivalent for conventional and spiral scanning (mean difference of spiral and conventional FWHM = 0.03 mm [P > .05] [in z direction] and 1.19 mm [P < .05] [in xy direction]). Significant respiratory misregistration was present on seven of 15 (47%) conventional MPR scans and on no spiral MPR scans.
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO 63110.
authors.forename: J A
authors.initials: JA
authors.lastname: Brink
authors.forename: J P
authors.initials: JP
authors.lastname: Heiken
authors.forename: D M
authors.initials: DM
authors.lastname: Balfe
authors.forename: S S
authors.initials: SS
authors.lastname: Sagel
authors.forename: J
authors.initials: J
authors.lastname: DiCroce
authors.forename: M W
authors.initials: MW
authors.lastname: Vannier
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000311:Adrenal Glands / Q000000981:diagnostic imaging; D000535:Aluminum; D016477:Artifacts; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007668:Kidney / Q000000981:diagnostic imaging; D008961:Models, Structural; D011856:Radiographic Image Enhancement / Q000379:methods*; D013997:Time Factors; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
chemical_list: D000535:Aluminum