title: First pass dual input volume CT-perfusion of lung lesions: The influence of the CT- value range settings on the perfusion values of benign and malignant entities.
abstract: OBJECTIVE
  To assess the influence of the lower threshold for segmentation of the volume of interest on the perfusion values in first-pass dual input volume CT-perfusion of lung lesions.
  
  
  METHODS
  Dual input maximum slope volume CT-perfusion was performed in 48 patients (mean age±standard deviation [SD], 68±10years; range, 46-87 years) who underwent subsequent CT-guided biopsy to evaluate a lung lesion. Using commercial perfusion software, a lower and upper threshold was set for determination of the CT-value range, which again determined the volume of interest for perfusion calculation. The pulmonary arterial flow (PAF), bronchial arterial flow (BAF), and perfusion index (PI; PAF/(PAF+BAF)) were calculated at following pre contrast CT value range settings: -80 to 150HU (setting 1), -200 to 150HU (setting 2), -300 to 150HU (setting 3), and -500 to 150HU (setting 4). Perfusion parameters were compared between benign (n, 15) and malignant (n, 33) lesions for each setting. Intraobserver- and interobserver reliability were calculated for setting 4.
  
  
  RESULTS
  Median PAF was significantly higher in malignant lesions than in benign lesions for all settings (53-96 versus 29-62mL/min/100mL, P<0.05). There was no significant difference in BAF between malignant and benign lesions. Median PAF of all lesions was significantly influenced by the CT value range setting (P<0.05), whereas the values increased from setting 1 to 4. Intraobserver analysis as well as interobserver analysis of PAF at setting 4 showed excellent reliability (Cronbach's alpha 0.98 and 0.95, respectively, P<0.01).
  
  
  CONCLUSIONS
  PAF derived from first-pass dual-input maximum slope volume CT perfusion is statistically significantly higher in malignant than in benign lesion, whereas the measurements are influenced by the lower threshold of the CT value range setting. This has to be considered when using cutoff values provided in the literature for differentiation between benign and malignant lung lesions.
authors.affiliation: Division of General Radiology, Department of Radiology, Medical University of Graz, Auenbruggerplatz 9, Graz A-8036, Austria.
authors.forename: Dennis
authors.initials: D
authors.lastname: Bohlsen
authors.affiliation: Division of General Radiology, Department of Radiology, Medical University of Graz, Auenbruggerplatz 9, Graz A-8036, Austria.
authors.forename: Emina
authors.initials: E
authors.lastname: Talakic
authors.affiliation: Division of General Radiology, Department of Radiology, University Hospital Graz, Auenbruggerplatz 9, Graz A-8036, Austria.
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Fritz
authors.affiliation: Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Auenbruggerplatz 2, Graz A-8036, Austria.
authors.forename: Franz
authors.initials: F
authors.lastname: Quehenberger
authors.affiliation: Diagnostikum Graz Süd West GmbH, Institute for Computed Tomography and Magnetic Resonance Imaging, Weblinger Gürtel 25, Graz A-8054, Austria.
authors.forename: Manfred
authors.initials: M
authors.lastname: Tillich
authors.affiliation: Division of General Radiology, Department of Radiology, Medical University of Graz, Auenbruggerplatz 9, Graz A-8036, Austria. Electronic address: helmut.schoellnast@medunigraz.at.
authors.forename: Helmut
authors.initials: H
authors.lastname: Schoellnast
mesh_terms: D000230:Adenocarcinoma / Q000098:blood supply / Q000000981:diagnostic imaging; D000368:Aged; D000369:Aged, 80 and over; D001981:Bronchial Arteries / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D061705:Image-Guided Biopsy / Q000379:methods; D007479:Iopamidol / Q000008:administration & dosage / Q000031:analogs & derivatives; D008168:Lung / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011652:Pulmonary Circulation / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D012984:Software; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol
keywords: Lung neoplasms; Perfusion; Volume computed tomography