gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

Diagnostic sensitivity and specificity of FET-PET in adult patients with an MRI based suspicion of a supratentorial WHO Grade II glioma

Meeting Abstract

  • M. Kunz - Klinik für Neurochirurgie, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
  • G. Pöpperl - Klinik für Nuklearmedizin, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
  • R. Egensperger - Institut für Neuropathologie, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
  • J.-C. Tonn - Klinik für Neurochirurgie, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
  • H. Kretzschmar - Institut für Neuropathologie, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
  • F.-W. Kreth - Klinik für Neurochirurgie, Klinikum Großhadern, Ludwig-Maximilians-Universität, München

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocMO.06-04

DOI: 10.3205/09dgnc030, URN: urn:nbn:de:0183-09dgnc0301

Published: May 20, 2009

© 2009 Kunz et al.
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Outline

Text

Objective: Histological grading of gliomas is mandatory to assess prognosis and determine treatment concepts. Conventional MRI using T1 (± gadolinium) and T2 sequences lacks diagnostic sensitivity and specificity. Significant diagnostic improvement has been shown for metabolic imaging such as [18F]-fluoroethyl-thyrosine (FET) PET using kinetic evaluation. A retro-spective analysis of 20 patients with suspected Grade II gliomas revealed sensitivity and specificity values of 93% and 94%, respectively. For prospective validation the current study was conducted.

Methods: Adult patients with an MRI-based suspicion of supratentorial WHO Grade II glioma were included after prior informed consent (02/06–10/08). For PET evaluation, tumour SUV(max) and ratio to background (SUVmax/BG) was calculated. For dynamic evaluation, mean SUV values within a 90% isocontour ROI (SUV90) and the SUV90/BG ratios were determined to evaluate the course of FET uptake. All patients underwent multimodal (MRI, FET-PET) imaging guided stereotactic serial biopsy. Histopathological findings (WHO based classification) were evaluated by two independent neuropathologists, not aware of FET-PET findings.

Results: Forty-one patients (mean age 43.6y±15) were included. Histopathological analysis revealed 32 astrocytomas and 9 oligo-astrocytomas. Twenty-nine tumours were classified as WHO II, and 12 as WHO III gliomas. Even though a significant increase of SUVmax/BG was seen in Grade III astrocytomas (mean SUVmax/BG 2.7±0.9 vs. 1.8±0.9 (Grade II), p<0.001), a marked overlap of the SUVmax/BG distribution between both tumour entities hampered valid tumour grading. Dynamic evaluation revealed malignant kinetics in 11 tumours and all of them were classified as WHO III gliomas. Benign kinetic was seen in 30 tumours, confirmed as WHO II gliomas in 29 tumours. The positive predictive value to detect a low grade glioma was 97% for FET-PET and 71% for conventional MRI (p<0.01). Sensitivity and specificity values of dynamic PET were 100% and 91.7%, respectively.

Conclusions: The current prospective validation set underscores the diagnostic power of dynamic FET-PET evaluation for differentiation of WHO II and III. Limitations of standard analysis using SUVmax/BG are confirmed.