Supplemental material for: Validation of intraluminal filling defect length to identify carotid free-floating thrombus in patients with stroke/TIA

<p><strong>Objective: </strong>To validate a previously proposed filling defect length threshold of &gt;3.8 mm on CT-angiography (CTA) to discriminate between free-floating thrombus (FFT) and plaque of atheroma.</p> <p><b>Materials and Methods: </b>Prospective multicenter observational study of 100 participants presenting with TIA/stroke symptoms and a carotid intraluminal filling defect on initial CTA.  Follow-up CTA was obtained within one week, and at weeks 2 and 4 if the intraluminal filling defect was unchanged in length.  Resolution or decreased length was diagnostic of FFT, whereas its static appearance after 4 weeks was indicative of plaque. Diagnostic accuracy of FFT length was assessed by receiver operating characteristic analysis.</p> <p><b>Results: </b>Ninety-five participants (mean age [standard deviation], 68 [13] years; 61 men; 83 participants with FFT; 12 participants with a plaque) were evaluated. The &gt;3.8 mm threshold had a sensitivity of 88% (73/83) (95% confidence interval {CI}: 78%, 94%) and specificity of 83% (10/12) (95% CI, 51%, 97%) (area under the curve [AUC], 0.91, p&lt;.001) for the diagnosis of FFT. The optimal length threshold was &gt;3.64 mm with a sensitivity of 89%( 74/83) (95% CI, 80%, 95%) and specificity of 83% (10/12) (95% CI, 51%, 97%). Adjusted logistic regression showed that every 1 mm increase in intraluminal filling defect length is associated with an increase in odds of FFT of 4.6 ([95% CI] 1.9-11.1; <i>p</i>=.01).</p> <p><b>Conclusion: </b>CTA enables accurate differentiation of FFT versus plaque using craniocaudal length thresholds.</p> <p><strong>Clinical Trial Identifier:</strong> <a href="http://www.clinicaltrials.gov">www.clinicaltrials.gov</a> NCT02405845.</p> <p><b>Classification of Evidence: </b>This study provides Class I evidence that in patients with TIA/stroke symptoms, the presence of a carotid intraluminal filling defect with length &gt; 3.8 mm on CTA accurately discriminates free-floating thrombus from atheromatous plaque.</p>