title: Effect on perfusion values of sampling interval of computed tomographic perfusion acquisitions in neuroendocrine liver metastases and normal liver.
abstract: OBJECTIVE
  This study aimed to assess the effects of sampling interval (SI) of computed tomographic (CT) perfusion acquisitions on CT perfusion values in normal liver and liver metastases from neuroendocrine tumors.
  
  
  METHODS
  Computed tomographic perfusion in 16 patients with neuroendocrine liver metastases was analyzed using distributed-parameter modeling to yield tissue blood flow, blood volume, mean transit time, permeability, and hepatic arterial fraction for tumor and normal liver. Computed tomographic perfusion values for the reference SI of 0.5 s (SI0.5) were compared with those of SI data sets of 1 second, 2 seconds, 3 seconds, and 4 seconds using mixed-effects model analyses.
  
  
  RESULTS
  Increases in SI beyond 1 second were associated with significant and increasing departures of CT perfusion parameters from the reference values at SI0.5 (P ≤ 0.0009). Computed tomographic perfusion values deviated from the reference with increasing uncertainty with increasing SIs. Findings for normal liver were concordant.
  
  
  CONCLUSIONS
  Increasing SIs beyond 1 second yield significantly different CT perfusion parameter values compared with the reference values at SI0.5.
authors.affiliation: From the Departments of *Diagnostic Radiology, †Biostatistics, ‡Gastrointestinal Medical Oncology, and §Imaging Physics, The University of Texas, MD Anderson Cancer Center, Houston, TX; and ∥CT Research, GE Healthcare, Waukesha, WI.
authors.forename: Chaan S
authors.initials: CS
authors.lastname: Ng
authors.forename: Brian P
authors.initials: BP
authors.lastname: Hobbs
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Ella F
authors.initials: EF
authors.lastname: Anderson
authors.forename: Delise H
authors.initials: DH
authors.lastname: Herron
authors.forename: James C
authors.initials: JC
authors.lastname: Yao
authors.forename: Adam G
authors.initials: AG
authors.lastname: Chandler
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography / Q000379:methods; D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008102:Liver Circulation; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000556:secondary*; D008297:Male; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000556:secondary*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*