title: Optimizing z-axis coverage of abdominal CT scans of the urinary tract: a proposed alternative proximal landmark for acquisition planning.
abstract: OBJECTIVE
  To evaluate an alternative method to reduce the acquisition coverage of urinary tract CT.
  
  
  METHODS
  This retrospective study included 365 abdominopelvic CT studies. Three radiographers simulated shortened acquisition coverages using three methods to determine the upper limit of the acquisition: Method 1 used the renal contours; Method 2 used the inferior margin of the 10th thoracic vertebra; and Method 3 used the point of intersection of the left diaphragmatic dome and the anterior margin of the vertebral bodies. Reductions in acquisition coverage and number of CT scans with a portion of the kidney excluded from the simulated reduced acquisition were compared between the three methods.
  
  
  RESULTS
  The mean ± standard deviation reduction of acquisition coverage for the three readers with Methods 1, 2 and 3 were 20.5 ± 4.8, 15.1 ± 6.5 and 18.2 ± 5.3%, respectively. Compared with Method 2, Method 3 allowed a mean scan length reduction of 3.6%. The proportions of CT scans with a portion of the kidney excluded from the simulated reduced acquisition with Methods 1, 2 and 3 and averaged over the three readers were 6.7, 0.7 and 1.4%, respectively, with no significant difference between Methods 2 and 3. Interreader and intrareader agreements were excellent with all methods, but interclass correlation coefficients were higher with Method 3.
  
  
  CONCLUSIONS
  The method using the renal contours should not be used owing to its high proportion of kidneys with a portion excluded from the acquisition. Using the intersection of the left diaphragmatic dome and the anterior margin of the vertebral bodies for proximal landmark for urinary tract CT represents a new alternative method with a better reduction of scan length compared with the method using the inferior margin of T10 and with no significant increase in the number of kidneys with a portion excluded from the reduced acquisition. Advances in knowledge: A new method using the point of intersection of the left diaphragmatic dome and the anterior border of the vertebral bodies on the lateral scout radiograph is introduced to reduce the z-axis coverage of urinary tract CT scans.
authors.affiliation: 1 Service d'Imagerie Médicale, HIA Legouest, Metz, France.|2 Service d'Imagerie Guilloz, Hôpital Central, CHRU Nancy, Nancy, France.|3 U947, INSERM, Nancy, France.|4 IADI, Université de Lorraine, Nancy, France.
authors.forename: Alban
authors.initials: A
authors.lastname: Gervaise
authors.affiliation: 2 Service d'Imagerie Guilloz, Hôpital Central, CHRU Nancy, Nancy, France.|3 U947, INSERM, Nancy, France.|4 IADI, Université de Lorraine, Nancy, France.
authors.forename: Pedro
authors.initials: P
authors.lastname: Teixeira
authors.affiliation: 5 CIC-IT 1433, INSERM, Nancy, France.|6 Pôle S2R, CHRU Nancy, Nancy, France.|7 CIC-IT, Université de Lorraine, Nancy, France.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Hossu
authors.affiliation: 2 Service d'Imagerie Guilloz, Hôpital Central, CHRU Nancy, Nancy, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Blum
authors.affiliation: 1 Service d'Imagerie Médicale, HIA Legouest, Metz, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Lapierre-Combes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D011860:Radiography, Abdominal / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014551:Urinary Tract / Q000000981:diagnostic imaging*
chemical_list: D003287:Contrast Media