title: Analysis of the thoracic aorta using a semi-automated post processing tool.
abstract: OBJECTIVE
  To evaluates a semi-automated method for Thoracic Aortic Aneurysm (TAA) measurement using ECG-gated Dual Source CT Angiogram (DSCTA).
  
  
  METHODS
  This retrospective HIPAA compliant study was approved by our IRB. Transaxial maximum diameters of outer wall to outer wall were studied in fifty patients at seven anatomic locations of the thoracic aorta: annulus, sinus, sinotubular junction (STJ), mid ascending aorta (MAA) at the level of right pulmonary artery, proximal aortic arch (PROX) immediately proximal to innominate artery, distal aortic arch (DIST) immediately distal to left subclavian artery, and descending aorta (DESC) at the level of diaphragm. Measurements were performed using a manual method and semi-automated software. All readers repeated their measurements. Inter-method, intra-observer and inter-observer agreements were evaluated according to intraclass correlation coefficient (ICC) and Bland-Altman plot. The number of cases with manual contouring or center line adjustment for the semi-automated method and also the post-processing time for each method were recorded.
  
  
  RESULTS
  The mean difference between semi-automated and manual methods was less than 1.3mm at all seven points. Strong inter-method, inter-observer and intra-observer agreement was recorded at all levels (ICC ≥ 0.9). The maximum rate of manual adjustment of center line and contour was at the level of annulus. The average time for manual post-processing of the aorta was 19 ± 0.3 min, while it took 8.26 ± 2.1 min to do the measurements with the semi-automated tool (Vitrea version 6.0.0.1 software). The center line was edited manually at all levels, with most corrections at the level of annulus (60%), while the contour was adjusted at all levels with highest and lowest number of corrections at the levels of annulus and DESC (75% and 0.07% of the cases), respectively.
  
  
  CONCLUSIONS
  Compared to the commonly used manual method, semi-automated measurement of vessel dimensions is feasible in the thoracic aorta with the advantage of reduced post-processing time.
authors.affiliation: Department of Radiology, Cardiovascular Imaging, Northwestern University, Chicago, IL, United States. p-entezari@northwestern.edu
authors.forename: Pegah
authors.initials: P
authors.lastname: Entezari
authors.forename: Aya
authors.initials: A
authors.lastname: Kino
authors.forename: Amir R
authors.initials: AR
authors.lastname: Honarmand
authors.forename: Mauricio S
authors.initials: MS
authors.lastname: Galizia
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.forename: Jeremy
authors.initials: J
authors.lastname: Collins
authors.forename: Vahid
authors.initials: V
authors.lastname: Yaghmai
authors.forename: James C
authors.initials: JC
authors.lastname: Carr
mesh_terms: D000465:Algorithms; D001013:Aorta, Thoracic; D017545:Aortic Aneurysm, Thoracic / Q000000981:diagnostic imaging*; D001027:Aortography / Q000379:methods*; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010363:Pattern Recognition, Automated / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014584:User-Computer Interface
keywords: 3D segmentation; Aortic aneurysm; Aortic luminal diameter measurement; CT Angiography; Quantitative analysis; Thoracic Aorta