title: Early Detection of Malignant Transformation in Resected WHO II Low-Grade Glioma Using Diffusion Tensor-Derived Quantitative Measures.
abstract: OBJECTIVE
  Here, we retrospectively investigate the value of voxel-wisely plotted diffusion tensor-derived (DTI) axial, radial and mean diffusivity for the early detection of malignant transformation (MT) in WHO II glioma compared to contrast-enhanced images.
  
  
  METHODS
  Forty-seven patients underwent brain magnetic resonance imaging follow-up between 2006-2014 after gross-tumor resection of intra-axial WHO II glioma. Axial/Mean/Radial diffusivity maps (AD/MD/RD) were generated from DTI data. ADmin/MDmin/RDmin values were quantified within tumor regions-of-interest generated by two independent readers including tumor contrast-to-noise (CNR). Sensitivity/specificity and area-under-the-curve (AUC) were calculated using receiver-operating-characteristic analysis. Inter-reader agreement was assessed (Cohen's kappa).
  
  
  RESULTS
  Eighteen patients demonstrated malignant transformation (MT) confirmed in 8/18 by histopathology and in 10/18 through imaging follow-up. Twelve of 18 patients (66.6%) with MT showed diffusion restriction timely coincidental with contrast-enhancement (CE). In the remaining six patients (33.3%), the diffusion restriction preceded the CE. The mean gain in detection time using DTI was (0.8±0.5 years, p = 0.028). Compared to MDmin and RDmin, ROC-analysis showed best diagnostic value for ADmin (sensitivity/specificity 94.94%/89.7%, AUC 0.96; p<0.0001) to detect MT. CNR was highest for AD (1.83±0.14), compared to MD (1.31±0.19; p<0.003) and RD (0.90±0.23; p<0.0001). Cohen's Kappa was 0.77 for ADmin, 0.71 for MDmin and 0.65 for RDmin (p<0.0001, respectively).
  
  
  CONCLUSIONS
  MT is detectable at the same time point or earlier compared to T1w-CE by diffusion restriction in diffusion-tensor-derived maps. AD demonstrated highest sensitivity/specificity/tumor-contrast compared to radial or mean diffusivity (= apparent diffusion coefficient) to detect MT.
authors.affiliation: Quantitative Imaging-based Disease Characterization, German Cancer Research Center, Heidelberg, Germany.|Department of Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Martin T
authors.initials: MT
authors.lastname: Freitag
authors.affiliation: Junior Group Medical Image Computing, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Klaus H
authors.initials: KH
authors.lastname: Maier-Hein
authors.affiliation: Silesian University of Technology, Data Mining Group, Gliwice, Poland.
authors.forename: Francisczek
authors.initials: F
authors.lastname: Binczyk
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Frederik B
authors.initials: FB
authors.lastname: Laun
authors.affiliation: Junior Group Medical Image Computing, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Weber
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Bonekamp
authors.affiliation: Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Department of Radiology, Gliwice, Poland.
authors.forename: Rafal
authors.initials: R
authors.lastname: Tarnawski
authors.affiliation: Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Department of Radiology, Gliwice, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bobek-Billewicz
authors.affiliation: Silesian University of Technology, Data Mining Group, Gliwice, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Polanska
authors.affiliation: Department of Neurosurgery, Medical University of Silesia, Sosnowiec, Katowice, Poland.
authors.forename: Henryk
authors.initials: H
authors.lastname: Majchrzak
authors.affiliation: Quantitative Imaging-based Disease Characterization, German Cancer Research Center, Heidelberg, Germany.|Department of Radiology, University Hospital Basel, Basel, Switzerland.
authors.forename: Bram
authors.initials: B
authors.lastname: Stieltjes
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001932:Brain Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D042241:Early Diagnosis; D005260:Female; D005910:Glioma / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D012372:ROC Curve; D012680:Sensitivity and Specificity