title: The effects of computed tomography with iterative reconstruction on solid pulmonary nodule volume quantification.
abstract: BACKGROUND
  The objectives of this study were to evaluate the influence of iterative reconstruction (IR) on pulmonary nodule volumetry with chest computed tomography (CT).
  
  
  METHODS
  Twenty patients (12 women and 8 men, mean age 61.9, range 32-87) underwent evaluation of pulmonary nodules with a 64-slice CT-scanner. Data were reconstructed using filtered back projection (FBP) and IR (Philips Healthcare, iDose(4)-levels 2, 4 and 6) at similar radiation dose. Volumetric nodule measurements were performed with semi-automatic software on thin slice reconstructions. Only solid pulmonary nodules were measured, no additional selection criteria were used for the nature of nodules. For intra-observer and inter-observer variability, measurements were performed once by one observer and twice by another observer. Algorithms were compared using the concordance correlation-coefficient (pc) and Friedman-test, and post-hoc analysis with the Wilcoxon-signed ranks-test with Bonferroni-correction (significance-level p<0.017).
  
  
  RESULTS
  Seventy-eight nodules were present including 56 small nodules (volume<200 mm(3), diameter<8 mm) and 22 large nodules (volume≥200 mm(3), diameter≥8 mm). No significant differences in measured pulmonary nodule volumes between FBP, iDose(4)-levels 2, 4 and 6 were found in both small nodules and large nodules. FBP and iDose(4)-levels 2, 4 and 6 were correlated with pc-values of 0.98 or higher for both small and large nodules. Pc-values of intra-observer and inter-observer variability were 0.98 or higher.
  
  
  CONCLUSIONS
  Measurements of solid pulmonary nodule volume measured with standard-FBP were comparable with IR, regardless of the IR-level and no significant differences between measured volumes of both small and large solid nodules were found.
authors: Utrecht University Medical Center, Department of Radiology, Utrecht, The Netherlands. m.willemink@umcutrecht.nl
authors: Martin J
authors: MJ
authors: Willemink
authors: Jaap
authors: J
authors: Borstlap
authors: Richard A P
authors: RA
authors: Takx
authors: Arnold M R
authors: AM
authors: Schilham
authors: Tim
authors: T
authors: Leiner
authors: Ricardo P J
authors: RP
authors: Budde
authors: Pim A
authors: PA
authors: de Jong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011856:Radiographic Image Enhancement; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed