title: qPET - a quantitative extension of the Deauville scale to assess response in interim FDG-PET scans in lymphoma.
abstract: BACKGROUND
  Interim FDG-PET is used for treatment tailoring in lymphoma. Deauville response criteria consist of five ordinal categories based on visual comparison of residual tumor uptake to physiological reference uptakes. However, PET-response is a continuum and visual assessments can be distorted by optical illusions.
  
  
  OBJECTIVE
  With a novel semi-automatic quantification tool we eliminate optical illusions and extend the Deauville score to a continuous scale.
  
  
  METHODS
  SUVpeak of residual tumors and average uptake of the liver is measured with standardized volumes of interest. The qPET value is the quotient of these measurements. Deauville scores and qPET-values were determined in 898 pediatric Hodgkin's lymphoma patients after two OEPA chemotherapy cycles.
  
  
  RESULTS
  Deauville categories translate to thresholds on the qPET scale: Categories 3, 4, 5 correspond to qPET values of 0.95, 1.3 and 2.0, respectively. The distribution of qPET values is unimodal with a peak representing metabolically normal responses and a tail of clearly abnormal outliers. In our patients, the peak is at qPET = 0.95 coinciding with the border between Deauville 2 and 3. qPET cut values of 1.3 or 2 (determined by fitting mixture models) select abnormal metabolic responses with high sensitivity, respectively, specificity.
  
  
  CONCLUSIONS
  qPET methodology provides semi-automatic quantification for interim FDG-PET response in lymphoma extending ordinal Deauville scoring to a continuous scale. Deauville categories correspond to certain qPET cut values. Thresholds between normal and abnormal response can be derived from the qPET-distribution without need for follow-up data. In our patients, qPET < 1.3 excludes abnormal response with high sensitivity.
authors.affiliation: Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Hasenclever
authors.forename: Lars
authors.initials: L
authors.lastname: Kurch
authors.forename: Christine
authors.initials: C
authors.lastname: Mauz-Körholz
authors.forename: Andreas
authors.initials: A
authors.lastname: Elsner
authors.forename: Thomas
authors.initials: T
authors.lastname: Georgi
authors.forename: Hamish
authors.initials: H
authors.lastname: Wallace
authors.forename: Judith
authors.initials: J
authors.lastname: Landman-Parker
authors.forename: Angelina
authors.initials: A
authors.lastname: Moryl-Bujakowska
authors.forename: Michaela
authors.initials: M
authors.lastname: Cepelová
authors.forename: Jonas
authors.initials: J
authors.lastname: Karlén
authors.forename: Ana
authors.initials: A
authors.lastname: Álvarez Fernández-Teijeiro
authors.forename: Andishe
authors.initials: A
authors.lastname: Attarbaschi
authors.forename: Alexander
authors.initials: A
authors.lastname: Fosså
authors.forename: Jane
authors.initials: J
authors.lastname: Pears
authors.forename: Andrea
authors.initials: A
authors.lastname: Hraskova
authors.forename: Eva
authors.initials: E
authors.lastname: Bergsträsser
authors.forename: Auke
authors.initials: A
authors.lastname: Beishuizen
authors.forename: Anne
authors.initials: A
authors.lastname: Uyttebroeck
authors.forename: Eckhard
authors.initials: E
authors.lastname: Schomerus
authors.forename: Osama
authors.initials: O
authors.lastname: Sabri
authors.forename: Dieter
authors.initials: D
authors.lastname: Körholz
authors.forename: Regine
authors.initials: R
authors.lastname: Kluge
mesh_terms: D000293:Adolescent; D001692:Biological Transport; D002648:Child; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006689:Hodgkin Disease / Q000000981:diagnostic imaging* / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*
chemical_list: D019788:Fluorodeoxyglucose F18