title: Impact of slice thickness on semi-automated measurements for volume and whole-tumor attenuation of colorectal hepatic metastases in multislice computed tomography.
abstract: BACKGROUND
  Volumetric and whole-tumor attenuation assessment of tumor are of value in assessment of treatment.
  
  
  OBJECTIVE
  To assess the impact of slice thickness on semi-automatic analyses (volume, whole-tumor attenuation) for small colorectal hepatic metastases.
  
  
  METHODS
  Computed tomography (CT) data of patients with colorectal hepatic metastases at 1.5-, 3-, and 5-mm slice thickness were semi-automatically evaluated for volume and whole-tumor attenuation by two radiologists independently. Statistical analysis included paired samples t-test and concordance correlation coefficient (CCC) analysis according to the longest axial tumor diameter (10-20 mm, 20-30 mm, 30-40 mm).
  
  
  RESULTS
  A total of 62 patients (32 men and 30 women) with 62 target tumors were included. The mean volume was significantly higher at 3- and 5-mm slice thicknesses in comparison with the reference (1.5 mm) for the target tumors between 10 mm and 20 mm (P = 0.0295, CCC = 0.9394 for 3 mm; P = 0.0029, CCC = 0.5129 for 5 mm, respectively) and at 5 mm slice thickness for the target tumors between 20 mm and 30 mm (P = 0.0071, CCC = 0.9102). For whole-tumor attenuation measurements, the significant difference was only seen at 5-mm slice thicknesses in comparison with the reference (1.5 mm) for the target tumors between 10 and 20 mm (P = 0.0015, CCC = 0.9389).
  
  
  CONCLUSIONS
  Slice thickness of 1.5 mm might be suggested for semi-automated volumetric measurements, and slice thickness of no more than 3 mm for whole-tumor CT attenuation in hepatic metastasis between 10 mm and 20 mm.
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; and Shanghai Medical Imaging Institute, Shanghai, People's Republic of China.
authors.forename: Sheng-Xiang
authors.initials: SX
authors.lastname: Rao
authors.forename: Tao
authors.initials: T
authors.lastname: Meng
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Meng-Su
authors.initials: MS
authors.lastname: Zeng
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D015588:Observer Variation; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D047368:Tumor Burden
keywords: Semi-automatic measurement; hepatic metastasis; slice thickness