title: Differentiation of pseudoprogression and real progression in glioblastoma using ADC parametric response maps.
abstract: OBJECTIVE
  The purpose of this study was to investigate whether a voxel-wise analysis of apparent diffusion coefficient (ADC) values may differentiate between progressive disease (PD) and pseudoprogression (PsP) in patients with high-grade glioma using the parametric response map, a newly introduced postprocessing tool.
  
  
  METHODS
  Twenty-eight patients with proven PD and seven patients with PsP were identified in this retrospective feasibility study. For all patients ADC baseline and follow-up maps on four subsequent MRIs were available. ADC maps were coregistered on contrast enhanced T1-weighted follow-up images. Subsequently, enhancement in the follow-up contrast enhanced T1-weighted image was manually delineated and a reference region of interest (ROI) was drawn in the contralateral white matter. Both ROIs were transferred to the ADC images. Relative ADC (rADC) (baseline)/reference ROI values and rADC (follow up)/reference ROI values were calculated for each voxel within the ROI. The corresponding voxels of rADC (follow up) and rADC (baseline) were subtracted and the percentage of all voxels within the ROI that exceeded the threshold of 0.25 was quantified.
  
  
  RESULTS
  rADC voxels showed a decrease of 59.2% (1st quartile (Q1) 36.7; 3rd quartile (Q3) 78.6) above 0.25 in patients with PD and 18.6% (Q1 3.04; Q3 26.5) in patients with PsP (p = 0.005). Receiver operating characteristic curve analysis showed the optimal decreasing rADC cut-off value for identifying PD of > 27.05% (area under the curve 0.844±0.065, sensitivity 0.86, specificity 0.86, p = 0.014).
  
  
  CONCLUSIONS
  This feasibility study shows that the assessment of rADC using parametric response maps might be a promising approach to contribute to the differentiation between PD and PsP. Further research in larger patient cohorts is necessary to finally determine its clinical utility.
authors.affiliation: Department of Neuroradiology, University of Heidelberg Medical Center, Heidelberg, Germany.
authors.forename: Caroline
authors.initials: C
authors.lastname: Reimer
authors.affiliation: Department of Radiology, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.
authors.forename: Katerina
authors.initials: K
authors.lastname: Deike
authors.affiliation: Department of Radiology, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Graf
authors.affiliation: Institute of Diagnostic and Interventional Radiology, Klinikum Karlsruhe, Academic Teaching Hospital of the University of Freiburg, Karlsruhe, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Reimer
authors.affiliation: Department of Neuroradiology, University of Heidelberg Medical Center, Heidelberg, Germany.|Department of Neuroradiology, Technical University Munich, Munich, Germany.|Department of Neurology, University of Heidelberg Medical Center, Heidelberg, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Wiestler
authors.affiliation: Department of Radiology, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.
authors.forename: Ralf Omar
authors.initials: RO
authors.lastname: Floca
authors.affiliation: Department of Neuroradiology, University of Heidelberg Medical Center, Heidelberg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kickingereder
authors.affiliation: Department of Radiology, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schlemmer
authors.affiliation: Department of Neurology, University of Heidelberg Medical Center, Heidelberg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wick
authors.affiliation: Department of Neuroradiology, University of Heidelberg Medical Center, Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bendszus
authors.affiliation: Department of Neuroradiology, University of Heidelberg Medical Center, Heidelberg, Germany.|Department of Radiology, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.|Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.|German Cancer Consortium (DKTK), Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Radbruch
mesh_terms: D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D005260:Female; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies