Kevin Lian

University of Toronto, Toronto, Ontario, Canada

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Publications (5)10.25 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare North American Symptomatic Carotid Endarterectomy Trial (NASCET) stenosis values and NASCET grade categorization (mild, moderate, severe) of semi-automated vessel analysis software versus manual measurements on computed tomography angiography (CTA). There were four observers. Two independently analyzed 81 carotid artery CTAs using semi-automated vessel analysis software according to a blinded protocol. The software measured the narrowest stenosis in millimeters (mm), distal internal carotid artery (ICA) in mm, and calculated percent stenosis based on NASCET criteria. One of these two observers performed this task twice on each carotid, the second analysis was delayed two months in order to mitigate recall bias. Two other observers manually measured the narrowest stenosis in mm, distal ICA in mm, and calculated NASCET percent stenosis in a blinded fashion. The calculated NASCET stenoses were categorized into mild, moderate, or severe. Chi square and analysis of variance (ANOVA) were used to test for statistical differences. ANOVA did not find a statistically significant difference in the mean percent stenosis when comparing the two manual measurements, the two semi-automated measurements, and the repeat semi-automated. Chi square demonstrated that the distribution of grades of stenosis were statistically different (p<0.05) between the manual and semiautomated grades. Semi-automated vessel analysis tended to underestimate the degree of stenosis compared to manual measurement. The mean percentage stenosis determined by semi-automated vessel analysis is not significantly different from manual measurement. However, when the data is categorized into mild, moderate and severe stenosis, there is a significant difference between semi-automated and manual measurements. The semi-automated software tends to underestimate the stenosis grade compared to manual measurement.
    The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques 05/2012; 39(3):343-6. · 1.33 Impact Factor
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    ABSTRACT: Epidermoid cysts are slow-growing benign tumors derived from ectodermal tissue that are hypothesized to have been inwardly displaced from the ectodermal surfaces during embryologic development. These cysts represent 1% to 2% of all intracranial tumors, and occur most commonly in the cerebellopontine angle, parasellar region, and subarachnoid spaces of the basal cisterns. Epidermoid cysts that are exclusively intraparenchymal are very rare, and can be difficult to diagnose as they often do not have classic radiologic findings, and share many similar radiologic features to other tumors such as astrocytomas, arachnoid cysts, dermoid cysts, and cavernomas. The authors present a patient with a rare intraparenchymal epidermoid cyst of the frontal lobe with atypical imaging features.
    Journal of Clinical Neuroscience 04/2012; 19(8):1185-7. · 1.25 Impact Factor
  • K Lian, E Bartlett, E Yu
    American Journal of Neuroradiology 09/2011; 32(9):E178. · 3.17 Impact Factor
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    ABSTRACT: CTA provides high-resolution imaging of the head and neck vasculature but also of the soft tissues and bones. This results in a large volume of information to be interpreted. This study examines interpretation errors with head and neck CTAs and assesses whether double reading reduces miss rates. Consecutive CTAs of the neck and intracranial circulation were retrospectively identified and reviewed for vascular and nonvascular findings by a consensus of 2 neuroradiologists. The results were compared with the official report. Significant discrepancies were considered those that would have influenced follow-up or management. We reviewed 503 studies; 144 were originally reported by a staff neuroradiologist alone, 209 by staff and diagnostic radiology resident, and 150 by staff and neuroradiology fellow. Twenty-six significant discrepancies were discovered in 20 studies, corresponding to 4.0% of studies with at least 1 miss, and an overall miss rate per study of 5.2%. There was at least 1 miss in 6.3% of studies interpreted by a staff neuroradiologist alone, 3.3% by staff and resident, and 2.7% by staff and fellow. The miss rate differences were not statistically significant. The most common misses were small aneurysms (50% of misses). CTA neck and head datasets are now large, and there is a potential for missed findings. Significant discrepancies can occur with a low but not insignificant rate. Arterial pathology accounted for most discrepancies. This study emphasizes the need for careful systematic scrutiny for both vascular and nonvascular pathology regardless of indication. Double reading reduces error rates.
    American Journal of Neuroradiology 09/2011; 32(11):2132-5. · 3.17 Impact Factor
  • The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques 03/2011; 38(2):335-7. · 1.33 Impact Factor