title: Bone-subtraction CT angiography: evaluation of two different fully automated image-registration procedures for interscan motion compensation.
abstract: OBJECTIVE
  Bone-subtraction techniques have been shown to enhance CT angiography (CTA) interpretation, but motion can lead to incomplete bone removal. The aim of this study was to evaluate 2 novel registration techniques to compensate for patient motion.
  
  
  METHODS
  Fifty-four patients underwent bone-subtraction CTA (BSCTA) for the evaluation of the neck vessels with 64-section CT. We tested 3 different registration procedures: pure rigid registration (BSCTA), slab-based registration (SB-BSCTA), and a partially rigid registration (PR-BSCTA) approach. Subtraction quality for the assessment of different vascular segments was evaluated by 2 examiners in a blinded fashion. The Cohen kappa test was applied for interobserver variability, and the Wilcoxon signed rank test, for differences between the procedures. Motion between the corresponding datasets was measured and plotted against image-quality scores.
  
  
  RESULTS
  Algorithms with motion compensation revealed higher image-quality scores (SB-BSCTA, mean 4.31; PR-BSCTA, mean 4.43) than pure rigid registration (BSCTA, mean 3.88). PR-BSCTA was rated superior to SB-BSCTA for the evaluation of the cervical internal and external carotid arteries (P<.001), whereas there was no significant difference for the other vessels (P=.157-.655). Both algorithms were clearly superior to pure rigid registration for all vessels except the basilar and ophthalmic artery. Interobserver agreement was high (kappa=0.46-0.98).
  
  
  CONCLUSIONS
  Bone-subtraction algorithms with motion compensation provided higher image-quality scores than pure rigid registration methods, especially in cases with complex motion. PR-BSCTA was rated superior to SB-BSCTA in the visualization of the internal and external carotid arteries.
authors: Department of Radiological Sciences, David Geffen School of Medicine at the University of California, Los Angeles, CA 90095, USA. Michael.Lell@idr.med.uni-erlangen.de
authors: M M
authors: MM
authors: Lell
authors: H
authors: H
authors: Ditt
authors: C
authors: C
authors: Panknin
authors: J W
authors: JW
authors: Sayre
authors: S G
authors: SG
authors: Ruehm
authors: E
authors: E
authors: Klotz
authors: B F
authors: BF
authors: Tomandl
authors: J P
authors: JP
authors: Villablanca
mesh_terms: D016477:Artifacts; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography / Q000379:methods*; D006257:Head / Q000098:blood supply / Q000000981:diagnostic imaging; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D009038:Motion; D009333:Neck / Q000098:blood supply / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*
references: Eur Radiol. 2005 Nov;15(11):2219-29
references: 15983776
references: Circulation. 2004 Mar 30;109(12 Suppl 1):I15-21
references: 15051664
references: Eur Heart J. 2005 Oct;26(19):1978-86
references: 15923203
references: Eur Radiol. 2006 Apr;16(4):889-97
references: 16267665
references: AJNR Am J Neuroradiol. 2002 Aug;23(7):1187-98
references: 12169479
references: Neuroradiology. 2004 Oct;46(10):842-50
references: 15448952
references: J Thorac Imaging. 2005 Feb;20(1):24-31
references: 15729119
references: AJNR Am J Neuroradiol. 2004 May;25(5):787-91
references: 15140721
references: AJR Am J Roentgenol. 2006 Jan;186(1):177-84
references: 16357399
references: J Comput Assist Tomogr. 1994 Sep-Oct;18(5):839-41
references: 8089342
references: Eur Radiol. 1997;7(1):82-9
references: 9000404
references: Radiology. 2001 Mar;218(3):893-8
references: 11230672
references: AJNR Am J Neuroradiol. 2003 Mar;24(3):451-5
references: 12637296
references: AJNR Am J Neuroradiol. 2006 Jan;27(1):13-9
references: 16418349
references: Eur Radiol. 1999;9(3):555-62
references: 10087133
references: Neurosurgery. 2002 Jul;51(1):264-8; discussion 268-9
references: 12182430
references: IEEE Trans Med Imaging. 2003 Aug;22(8):986-1004
references: 12906253
references: AJNR Am J Neuroradiol. 2006 Jan;27(1):55-9
references: 16418356
references: Med Phys. 2004 Oct;31(10):2924-33
references: 15543801
references: Stroke. 2006 Feb;37(2):414-8
references: 16385095
references: AJNR Am J Neuroradiol. 2006 Jun-Jul;27(6):1332-7
references: 16775292
references: Biometrics. 1977 Mar;33(1):159-74
references: 843571