title: Quantitative apparent diffusion coefficients in the characterization of brain tumors and associated peritumoral edema.
abstract: BACKGROUND
  Conventional magnetic resonance (MR) imaging has a number of limitations in the diagnosis of the most common intracranial brain tumors, including tumor specification and the detection of tumoral infiltration in regions of peritumoral edema.
  
  
  OBJECTIVE
  To prospectively assess if diffusion-weighted MR imaging (DWI) could be used to differentiate between different types of brain tumors and to distinguish between peritumoral infiltration in high-grade gliomas, lymphomas, and pure vasogenic edema in metastases and meningiomas.
  
  
  METHODS
  MR imaging and DWI was performed on 93 patients with newly diagnosed brain tumors: 59 patients had histologically verified high-grade gliomas (37 glioblastomas multiforme, 22 anaplastic astrocytomas), 23 patients had metastatic brain tumors, five patients had primary cerebral lymphomas, and six patients had meningiomas. Apparent diffusion coefficient (ADC) values of tumor (enhancing regions or the solid portion of tumor) and peritumoral edema, and ADC ratios (ADC of tumor or peritumoral edema to ADC of contralateral white matter, ADC of tumor to ADC of peritumoral edema) were compared with the histologic diagnosis. ADC values and ratios of high-grade gliomas, primary cerebral lymphomas, metastases, and meningiomas were compared by using ANOVA and multiple comparisons. Optimal thresholds of ADC values and ADC ratios for distinguishing high-grade gliomas from metastases were determined by receiver operating characteristic (ROC) curve analysis.
  
  
  RESULTS
  Statistically significant differences were found for minimum and mean of ADC tumor and ADC tumor ratio values between metastases and high-grade gliomas when including only one factor at a time. Including a combination of in total four parameters (mean ADC tumor, and minimum, maximum and mean ADC tumor ratio) resulted in sensitivity, specificity, positive (PPV), and negative predictive values (NPV) of 72.9, 82.6, 91.5, and 54.3% respectively. In the ROC curve analysis, the area under the curve of the combined four parameters was the largest (0.84), indicating a good test.
  
  
  CONCLUSIONS
  Our results suggest that ADC values and ADC ratios (minimum and mean of ADC tumor and ADC tumor ratio) may be helpful in the differentiation of metastases from high-grade gliomas. It cannot distinguish high-grade gliomas from lymphomas, and lymphomas from metastases. ADC values and ADC ratios in peritumoral edema cannot be used to differentiate edema with infiltration of tumor cells from vasogenic edema when measurements for high-grade gliomas, lymphomas, metastases, and meningiomas were compared.
authors.affiliation: Department of Neuroradiology, Division of Radiology, Ullevaal University Hospital, University of Oslo, Kirkeveien 166, Oslo, Norway. a.s.alonso@medisin.uio.no
authors.forename: A
authors.initials: A
authors.lastname: Server
authors.forename: B
authors.initials: B
authors.lastname: Kulle
authors.forename: J
authors.initials: J
authors.lastname: Maehlen
authors.forename: R
authors.initials: R
authors.lastname: Josefsen
authors.forename: T
authors.initials: T
authors.lastname: Schellhorn
authors.forename: T
authors.initials: T
authors.lastname: Kumar
authors.forename: C W
authors.initials: CW
authors.lastname: Langberg
authors.forename: P H
authors.initials: PH
authors.lastname: Nakstad
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001929:Brain Edema / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology* / Q000556:secondary; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005910:Glioma / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D008223:Lymphoma / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008579:Meningioma / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000473:pathology*; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity