title: Size and Growth Assessment of Pulmonary Nodules: Consequences of the Rounding.
abstract: The aim of this study was to understand the effect of rounding nodule size measurements on the frequency of positive results in the setting of lung cancer screening.
  
  
  
  Four methods for determining nodule size were compared, including rounding each individual length and width measurement and also rounding the overall average. These were applied to the International Early Lung Cancer Action Program database, in which we determined the frequency of a positive result by using standard size thresholds of 6.0 mm on baseline screening and 3.0 mm on repeat scanning. We also explored how rounding influences the ability to measure growth according to a predefined cutoff value of 1.5 mm as required in the Lung Computed Tomography Screening Reporting and Data System (Lung-RADS) (version 1.0).
  
  
  
  Each method for rounding increased the frequency of positive results compared with that with no rounding. The largest increases-28.9% and 22.3% for the baseline and repeat round, respectively-occurred when rounding was used for both the individual length and width measurements and again for the final diameter. If the 1.5-mm increase in size were used for determining growth, a 4-mm nodule would need to have a volume doubling time of 130.6 days or less to demonstrate growth in 6 months (Lung-RADS category 3) whereas a 6-mm nodule would need volume doubling time of 93.2 days to demonstrate growth in 3 months (Lung-RADS category 4A). In addition, rounding can have the effect of having nodules that appear to not be growing meet the criteria for growth and vice versa.
  
  
  
  Rounding influences the frequency of positive results and growth assessment, substantially decreasing the efficiency of screening.
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Radiology, Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, People's Republic of China.
authors.forename: Kunwei
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Rowena
authors.initials: R
authors.lastname: Yip
authors.affiliation: Accumetra, LLC, Clifton Park, New York.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Avila
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York. Electronic address: Claudia.Henschke@mountsainai.org.
authors.forename: Claudia I
authors.initials: CI
authors.lastname: Henschke
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: David F
authors.initials: DF
authors.lastname: Yankelevitz
mesh_terms: D016208:Databases, Factual; D055088:Early Detection of Cancer / Q000379:methods*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D055613:Multiple Pulmonary Nodules / Q000000981:diagnostic imaging / Q000473:pathology*; D009367:Neoplasm Staging; D011379:Prognosis; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: False positive; Lung cancer screening; Measurement error; Nodule growth assessment; Rounding; Volume doubling time (VDT)