title: Effect of CTA Tube Current on Spot Sign Detection and Accuracy for Prediction of Intracerebral Hemorrhage Expansion.
abstract: OBJECTIVE
  Reduction of CT tube current is an effective strategy to minimize radiation load. However, tube current is also a major determinant of image quality. We investigated the impact of CTA tube current on spot sign detection and diagnostic performance for intracerebral hemorrhage expansion.
  
  
  METHODS
  We retrospectively analyzed a prospectively collected cohort of consecutive patients with primary intracerebral hemorrhage from January 2001 to April 2015 who underwent CTA. The study population was divided into 2 groups according to the median CTA tube current level: low current (<350 mA) and high current (≥350 mA). CTA first-pass readings for spot sign presence were independently analyzed by 2 readers. Baseline and follow-up hematoma volumes were assessed by semiautomated computer-assisted volumetric analysis. Sensitivity, specificity, positive and negative predictive values, and accuracy of spot sign in predicting hematoma expansion were calculated.
  
  
  RESULTS
  This study included 709 patients (288 and 421 in the low- and high-current groups, respectively). A higher proportion of low-current scans identified at least 1 spot sign (20.8% versus 14.7%,P= .034), but hematoma expansion frequency was similar in the 2 groups (18.4% versus 16.2%,P= .434). Sensitivity and positive and negative predictive values were not significantly different between the 2 groups. Conversely, high-current scans showed superior specificity (91% versus 84%,P= .015) and overall accuracy (84% versus 77%,P= .038).
  
  
  CONCLUSIONS
  CTA obtained at high levels of tube current showed better diagnostic accuracy for prediction of hematoma expansion by using spot sign. These findings may have implications for future studies using the CTA spot sign to predict hematoma expansion for clinical trials.
authors.affiliation: From the Department of Clinical and Experimental Sciences (A.M.), Neurology Clinic, University of Brescia, Brescia, Italy amorotti@mgh.harvard.edu a.morotti@ymail.com.|J.P. Kistler Stroke Research Center (A.M., M.J.J., K.S., A. Vashkevich, A.A., C.D.A., M.E.G., A. Viswanathan, S.M.G., J.R., J.N.G.).
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