title: Prognostic value of metabolic metrics extracted from baseline positron emission tomography images in non-small cell lung cancer.
abstract: BACKGROUND
  Maximum, mean and peak SUV of primary tumor at baseline FDG-PET scans, have often been found predictive for overall survival in non-small cell lung cancer (NSCLC) patients. In this study we further investigated the prognostic power of advanced metabolic metrics derived from intensity volume histograms (IVH) extracted from PET imaging.
  
  
  METHODS
  A cohort of 220 NSCLC patients (mean age, 66.6 years; 149 men, 71 women), stages I-IIIB, treated with radiotherapy with curative intent were included (NCT00522639). Each patient underwent standardized pre-treatment CT-PET imaging. Primary GTV was delineated by an experienced radiation oncologist on CT-PET images. Common PET descriptors such as maximum, mean and peak SUV, and metabolic tumor volume (MTV) were quantified. Advanced descriptors of metabolic activity were quantified by IVH. These comprised five groups of features: absolute and relative volume above relative intensity threshold (AVRI and RVRI), absolute and relative volume above absolute intensity threshold (AVAI and RVAI), and absolute intensity above relative volume threshold (AIRV). MTV was derived from the IVH curves for volumes with SUV above 2.5, 3 and 4, and of 40% and 50% maximum SUV. Univariable analysis using Cox Proportional Hazard Regression was performed for overall survival assessment.
  
  
  RESULTS
  Relative volume above higher SUV (80%) was an independent predictor of OS (p = 0.05). None of the possible surrogates for MTV based on volumes above SUV of 3, 40% and 50% of maximum SUV showed significant associations with OS [p (AVAI3) = 0.10, p (AVAI4) = 0.22, p (AVRI40%) = 0.15, p (AVRI50%) = 0.17]. Maximum and peak SUV (r = 0.99) revealed no prognostic value for OS [p (maximum SUV) = 0.20, p (peak SUV) = 0.22].
  
  
  CONCLUSIONS
  New methods using more advanced imaging features extracted from PET were analyzed. Best prognostic value for OS of NSCLC patients was found for relative portions of the tumor above higher uptakes (80% SUV).
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC +) , Maastricht , the Netherlands.
authors.forename: Sara
authors.initials: S
authors.lastname: Carvalho
authors.forename: Ralph T H
authors.initials: RT
authors.lastname: Leijenaar
authors.forename: Emmanuel Rios
authors.initials: ER
authors.lastname: Velazquez
authors.forename: Cary
authors.initials: C
authors.lastname: Oberije
authors.forename: Chintan
authors.initials: C
authors.lastname: Parmar
authors.forename: Wouter
authors.initials: W
authors.lastname: van Elmpt
authors.forename: Bart
authors.initials: B
authors.lastname: Reymen
authors.forename: Esther G C
authors.initials: EG
authors.lastname: Troost
authors.forename: Michel
authors.initials: M
authors.lastname: Oellers
authors.forename: Andre
authors.initials: A
authors.lastname: Dekker
authors.forename: Robert
authors.initials: R
authors.lastname: Gillies
authors.forename: Hugo J W L
authors.initials: HJ
authors.lastname: Aerts
authors.forename: Philippe
authors.initials: P
authors.lastname: Lambin
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000532:radiotherapy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000532:radiotherapy; D008297:Male; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D019275:Radiopharmaceuticals; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided; D047368:Tumor Burden
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
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