title: Computed tomography angiography intraluminal filling defect is predictive of internal carotid artery free-floating thrombus.
abstract: BACKGROUND
  Filling defects at the internal carotid artery (ICA) origin in the work-up of stroke or transient ischemic attack may be an ulcerated plaque or free-floating thrombus (FFT). This may be challenging to distinguish, as they can appear morphologically similar. This is an important distinction as FFT can potentially embolize distally, and its management differs. We describe a series of patients with suspected FFT and evaluate its imaging appearance, clinical features, and evolution with therapy.
  
  
  METHODS
  Between 2008 and 2013, we prospectively collected consecutive patients with proximal ICA filling defects in the axial plane surrounded by contrast on CT/MR angiography. We defined FFT as a filling defect that resolved on follow-up imaging. We assessed the cranial-caudal dimension of the filling defect and receiver operating characteristics to identify clinical and radiological variables that distinguished FFT from complex ulcerated plaque.
  
  
  RESULTS
  Intraluminal filling defects were identified in 32 patients. Filling defects and resolved or decreased in 25 patients (78 %) and felt to be FFT; there was no change in 7 (22 %). Resolved defects and those that decreased in size extended more cranially than those that remained unchanged: 7.3 mm (4.2-15.9) versus 3.1 mm (2.7-3.7; p = 0.0038). Receiver operating characteristic analysis established a threshold of 3.8 mm (filling defect length), sensitivity of 88 %, specificity of 86 %, and area under the curve of 0.86 (p < 0.0001) for distinguishing FFT from plaque.
  
  
  CONCLUSIONS
  Filling defects in the proximal ICA extending cranially >3.8 mm were more likely to be FFT than complex ulcerated plaque. Further studies evaluating filling defect length as a predictor for FFT are warranted.
authors.affiliation: Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada, ajaberi@toh.on.ca.
authors.forename: A
authors.initials: A
authors.lastname: Jaberi
authors.forename: C
authors.initials: C
authors.lastname: Lum
authors.forename: P
authors.initials: P
authors.lastname: Stefanski
authors.forename: R
authors.initials: R
authors.lastname: Thornhill
authors.forename: D
authors.initials: D
authors.lastname: Iancu
authors.forename: W
authors.initials: W
authors.lastname: Petrcich
authors.forename: F
authors.initials: F
authors.lastname: Momoli
authors.forename: C
authors.initials: C
authors.lastname: Torres
authors.forename: D
authors.initials: D
authors.lastname: Dowlatshahi
mesh_terms: D000368:Aged; D002341:Carotid Artery Thrombosis / Q000150:complications / Q000175:diagnosis*; D016893:Carotid Stenosis / Q000150:complications / Q000175:diagnosis*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis* / Q000209:etiology; D014057:Tomography, X-Ray Computed / Q000379:methods