title: Tumour enhancing fraction (EnF) in glioma: relationship to tumour grade.
abstract: The aim of this research was to determine whether the proportion of a tumour that enhances (enhancing fraction, EnF) and changes in EnF with enhancement threshold differ between low and high grade glioma. Forty-four patients (45 gliomas comprising 16 grade II, 5 grade III and 24 grade IV) were studied. Imaging included pre- and post-contrast-enhanced T(1)-weighted sequences and T(1)-weighted DCE-MRI. Thresholded enhancement maps were generated for each tumour by using a range of values of the initial area under the contrast concentration curve (IAUC). A plot of EnF versus threshold value was generated. We examined the relationship between tumour grade and enhancement metrics including: EnF (threshold IAUC > 0 mMol s), EnF (threshold IAUC > 2.5 mMol s), initial slope of the EnF/threshold curve (partial differentialEnF), IAUC, and two previously described signal-intensity-based metrics. EnF, defined as the proportion of tumour showing any enhancement (threshold IAUC > 0 mMol s), showed no difference between low and high grade glioma. All other measures demonstrated significant differences between grade II and IV, and low (grade II) and high grade (grades III/ IV) gliomas (p < 0.01). Two measures, partial differentialEnF and Pronin's measure of enhancement, showed differences between grade III and IV (p < 0.05). No measure separated grade II from III. Metrics which describe the enhancing fraction and its variation with enhancement threshold partial differentialEnF show considerably different behaviour in low and high grade tumours. These observations suggest that these metrics may provide important biological information concerning tumour biology and therapeutic responses and encourage further research to characterise and validate these novel biomarkers.
authors.affiliation: Wolfson Molecular Imaging Centre, Imaging Science and Biomedical Engineering, University of Manchester, 27 Palatine Road, Withington, Manchester, M20 3LJ, UK. samantha.mills@manchester.ac.uk
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Mills
authors.forename: Calvin
authors.initials: C
authors.lastname: Soh
authors.forename: James P B
authors.initials: JP
authors.lastname: O'Connor
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Rose
authors.forename: Giovanni A
authors.initials: GA
authors.lastname: Buonaccorsi
authors.forename: Susan
authors.initials: S
authors.lastname: Cheung
authors.forename: Sha
authors.initials: S
authors.lastname: Zhao
authors.forename: Geoff J M
authors.initials: GJ
authors.lastname: Parker
authors.forename: Alan
authors.initials: A
authors.lastname: Jackson
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005909:Glioblastoma / Q000175:diagnosis*; D005910:Glioma / Q000175:diagnosis*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult