title: Impact of image quality, radiologists, lung segments, and Gunnar eyewear on detectability of lung nodules in chest CT.
abstract: BACKGROUND
  Despite the increasingly higher spatial and contrast resolution of CT, nodular lesions are prone to be missed on chest CT. Tinted lenses increase visual acuity and contrast sensitivity by filtering short wavelength light of solar and artificial origin.
  
  
  OBJECTIVE
  To test the impact of Gunnar eyewear, image quality (standard versus low dose CT) and nodule location on detectability of lung nodules in CT and to compare their individual influence.
  
  
  METHODS
  A pre-existing database of CT images of patients with lung nodules >5 mm, scanned with standard does image quality (150 ref mAs/120 kVp) and lower dose/quality (40 ref mAs/120 kVp), was used. Five radiologists read 60 chest CTs twice: once with Gunnar glasses and once without glasses with a 1 month break between. At both read-outs the cases were shown at lower dose or standard dose level to quantify the influence of both variables (eyewear vs. image quality) on nodule sensitivity.
  
  
  RESULTS
  The sensitivity of CT for lung nodules increased significantly using Gunnar eyewear for two readers and insignificantly for two other readers. Over all, the mean sensitivity of all radiologist raised significantly from 50% to 53%, using the glasses (P value = 0.034). In contrast, sensitivity for lung nodules was not significantly affected by lowering the image quality from 150 to 40 ref mAs. The average sensitivity was 52% at low dose level, that was even 0.7% higher than at standard dose level (P value = 0.40). The strongest impact on sensitivity had the factors readers and nodule location (lung segments).
  
  
  CONCLUSIONS
  Sensitivity for lung nodules was significantly enhanced by Gunnar eyewear (+3%), while lower image quality (40 ref mAs) had no impact on nodule sensitivity. Not using the glasses had a bigger impact on sensitivity than lowering the image quality.
authors.affiliation: Department of Radiology, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Andreas
authors.initials: A
authors.lastname: Christe
authors.forename: Lukas
authors.initials: L
authors.lastname: Ebner
authors.forename: Philipp
authors.initials: P
authors.lastname: Steiger
authors.forename: Sachin R
authors.initials: SR
authors.lastname: Parikh
authors.forename: Akash D
authors.initials: AD
authors.lastname: Shah
authors.forename: Kingshuk
authors.initials: K
authors.lastname: Roychoudhury
authors.forename: Peter
authors.initials: P
authors.lastname: Vock
authors.forename: Justus E
authors.initials: JE
authors.lastname: Roos
mesh_terms: D000328:Adult; D000368:Aged; D005139:Eyeglasses; D005260:Female; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D013902:Radiography, Thoracic; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Lung nodule; eyewear; image quality; inter-observer agreement; low dose CT