Dual energy CTA of the carotid bifurcation: Advantage of plaque subtraction for assessment of grade of the stenosis and morphology

• Published in: European journal of radiology 2011-11, Vol.80 (2), p.e120-e125
• Main Authors: Korn, A, Bender, B, Thomas, C, Danz, S, Fenchel, M, Nägele, T, Heuschmid, M, Ernemann, U, Hauser, T.K
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Angiography, Digital Subtraction - methods; Calcinosis - diagnostic imaging; Carotid bifurcation stenosis; Carotid Stenosis - diagnostic imaging; Cerebral Angiography - methods; Dual energy CTA; Female; Humans; Male; Middle Aged; Plaque morphology; Plaque subtraction; Radiographic Image Interpretation, Computer-Assisted; Radiology; Reproducibility of Results
• ISSN: 0720-048X; 1872-7727
• DOI: 10.1016/j.ejrad.2010.08.028

Abstract Objectives Calcifications adjacent to the vessel lumen often limit the assessment of stenoses at the carotid bifurcation in 3D multi intensity projection images (3D-MIP) using conventional single energy CT. Aim of the study was to evaluate the diagnostic value of 3D-MIP images after subtraction of bone and calcified plaques (PBS) using dual energy CT for the assessment of carotid bifurcation stenoses. Materials and methods 36 patients with a total of 46 stenoses at the carotid bifurcation were examined with a dual energy CT system. Grade of the stenoses and plaque morphology were assessed in axial multi planar projections (axMPR) and freely rotatable 3D-MIP images before and after PBS and compared with results from DSA. Results Grade of the stenosis could be evaluated in all 46 cases in DSA, axMPR and 3D-MIP after PBS. However, in 25 cases grade of the stenosis was not assessable prior to PBS. The average grade of the stenosis increased from DSA (81.4%) to axMPR (83.5%) to 3D-MIP before and after PBS (86.5% and 85.6%). The amount of pseudo-occlusions increased in concordance with the grade of the stenosis (0 < 9 < 16). Using 3D-MIP reconstructions, plaque morphology could be evaluated in 32/46 stenoses before PBS and in 44/46 cases after PBS. Conclusions PBS facilitated the evaluation of grade of the stenosis in all cases. Nevertheless, after PBS stenoses were overrated in 3D-MIP in comparison to DSA and axMPR. Moreover, plaque morphology, as an independent risk factor for stroke, can be evaluated even in calcified plaques after PBS. Therefore dual energy CTA with plaque subtraction has the potential to identify patients with vulnerable plaques better than conventional CTA.