title: Can shape analysis differentiate free-floating internal carotid artery thrombus from atherosclerotic plaque in patients evaluated with CTA for stroke or transient ischemic attack?
abstract: OBJECTIVE
  Patients presenting with transient ischemic attack or stroke may have symptom-related lesions on acute computed tomography angiography (CTA) such as free-floating intraluminal thrombus (FFT). It is difficult to distinguish FFT from carotid plaque, but the distinction is critical as management differs. By contouring the shape of these vascular lesions ("virtual endarterectomy"), advanced morphometric analysis can be performed. The objective of our study is to determine whether quantitative shape analysis can accurately differentiate FFT from atherosclerotic plaque.
  
  
  METHODS
  We collected 23 consecutive cases of suspected carotid FFT seen on CTA (13 men, 65 ± 10 years; 10 women, 65.5 ± 8.8 years). True-positive FFT cases (FFT+) were defined as filling defects resolving with anticoagulant therapy versus false-positives (FFT-), which remained unchanged. Lesion volumes were extracted from CTA images and quantitative shape descriptors were computed. The five most discriminative features were used to construct receiver operator characteristic (ROC) curves and to generate three machine-learning classifiers. Average classification accuracy was determined by cross-validation.
  
  
  RESULTS
  Follow-up imaging confirmed sixteen FFT+ and seven FFT- cases. Five shape descriptors delineated FFT+ from FFT- cases. The logistic regression model produced from combining all five shape features demonstrated a sensitivity of 87.5% and a specificity of 71.4% with an area under the ROC curve = 0.85 ± 0.09. Average accuracy for each classifier ranged from 65.2%-76.4%.
  
  
  CONCLUSIONS
  We identified five quantitative shape descriptors of carotid FFT. This shape "signature" shows potential for supplementing conventional lesion characterization in cases of suspected FFT.
authors: Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada; Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada. Electronic address: rthornhi@gmail.com.
authors: Rebecca E
authors: RE
authors: Thornhill
authors: Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada; Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors: Cheemun
authors: C
authors: Lum
authors: Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada.
authors: Arash
authors: A
authors: Jaberi
authors: Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada.
authors: Pawel
authors: P
authors: Stefanski
authors: Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada; Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors: Carlos H
authors: CH
authors: Torres
authors: Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
authors: Franco
authors: F
authors: Momoli
authors: Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors: William
authors: W
authors: Petrcich
authors: Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Division of Neurology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
authors: Dar
authors: D
authors: Dowlatshahi
mesh_terms: D000368:Aged; D002341:Carotid Artery Thrombosis / Q000150:complications / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000150:complications / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography / Q000379:methods; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D010363:Pattern Recognition, Automated / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020521:Stroke / Q000000981:diagnostic imaging* / Q000209:etiology; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: CT angiography; computer aided diagnosis; free-floating thrombus; image postprocessing; stroke