title: [Usefulness of subtraction computed tomography angiography employing orbital synchronized helical scanning for diagnosis of lower extremity arteries with vessel wall calcification].
abstract: OBJECTIVE
  Massive calcification complicates the diagnosis of the blood vessel lumen in computed tomography angiography (CTA) of the arteries of the lower extremities. The purpose of this study was to evaluate subtraction CTA with the use of orbital synchronized helical scanning (OS-SCTA).
  
  
  METHODS
  Phantom study: We performed OS-SCTA and non-OSCTA of a calcified vessel phantom (ψ2.5 mm), and compared them with a non-calcified vessel phantom as the reference by full width at half maximum (FWHM) and full width at tenth maximum (FWTM) of maximum intensity projection (MIP) images. Clinical study: 58 patients with peripheral artery disease who were referred for angiography also underwent OS-SCTA. OS-SCTA was produced using MIP images. Findings were graded according to three categories: (1) stenosis greater than 50% or occluded; (2) stenosis less than 50%; (3) not detected due to insufficient image quality. OS-SCTA findings were compared with the angiographic findings for each arterial segment.
  
  
  RESULTS
  In the phantom study, FWHM showed no significant difference between OS-SCTA and the reference (P=0.135), whereas FWTM showed a significant difference (P<0.001). FWHM and FWTM showed a significant difference between non-OS-SCTA and the reference (P<0.001), due to misregistration with helical artifacts. In a clinical study comparing OS-SCTA with angiography, the sensitivity and specificity were 93.3% and 95.1% in calcified segments, 91.8% and 93.9% in non-calcified segments, and 92.2% and 94.6% in all segments. There was no significant difference between calcified segments and non-calcified segments (sensitivity: P=0.568, specificity: P=0.549).
  
  
  CONCLUSIONS
  OS-SCTA is beneficial for the diagnosis of lower extremity arteries with vessel wall calcification, since it shows detection accuracy comparable to that of angiography.
authors.affiliation: Department of Medical Technology, Tsuchiya General Hospital.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Inada
authors.forename: Takanori
authors.initials: T
authors.lastname: Masuda
authors.forename: Naoya
authors.initials: N
authors.lastname: Maruyama
authors.forename: Yoriaki
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kusunoki
authors.forename: Toru
authors.initials: T
authors.lastname: Ishibashi
authors.forename: Hideo
authors.initials: H
authors.lastname: Onishi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takigawa
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Sato
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Imada
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction / Q000379:methods*; D001158:Arteries; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000379:methods*; D061205:Vascular Calcification / Q000000981:diagnostic imaging