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64th Annual Meeting of the German Society of Neurosurgery (DGNC)

German Society of Neurosurgery (DGNC)

26 - 29 May 2013, Düsseldorf

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Detecting pseudoprogression in malignant glioma using CT-perfusion and FET-PET imaging – a non-randomized prospective single-center study

Meeting Abstract

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  • Sebastian A. Ahmadi - Neurochirurgische Klinik, Universitätsklinikum Düsseldorf
  • Catharina Schröter - Neurochirurgische Klinik, Universitätsklinikum Düsseldorf
  • Karl-Josef Langen - Institut für Neurowissenschaften und Medizin Forschungszentrum Jülich
  • Bernd Turowski - Institut für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Düsseldorf
  • Hans-Jakob Steiger - Neurochirurgische Klinik, Universitätsklinikum Düsseldorf
  • Michael Sabel - Neurochirurgische Klinik, Universitätsklinikum Düsseldorf

Deutsche Gesellschaft für Neurochirurgie. 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Düsseldorf, 26.-29.05.2013. Düsseldorf: German Medical Science GMS Publishing House; 2013. DocDI.05.01

doi: 10.3205/13dgnc194, urn:nbn:de:0183-13dgnc1949

Published: May 21, 2013

© 2013 Ahmadi et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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Objective: Gadolinium-enhanced MR imaging remains the mainstay modality in current glioma treatment and follow-up. However, when using the Macdonald criteria,it has previously been shown to be of limited value in differentiating brain tumor recurrence from pseudoprogression due to the therapeutic effects of irradiation and chemotherapy. Metabolic imaging (FET-PET) or computed tomography (CT) perfusion studies could help in delineating pseudoprogression from tumor recurrence. Here we analyze the incidence of confirmed pseudoprogression and evaluate sensitivity, specificity as well as predictive values of CT perfusion and FET-PET imaging in identifying cases of pseudoprogression.

Method: 52 patients presenting with new or increased contrast enhancement on MR imaging after surgical resection and combined radio-chemo-therapy were enrolled in this ongoing prospective single-center study. For 27 patients (17 male, 10 female) complete data sets (MR, CT perfusion and FET-PET studies) were available for analysis. Cases of pseudoprogression were identified using either serial imaging as outlined by the Response Assessment in Neuro-Oncology (RANO) Working Group or histopathology results in those undergoing surgical removal of suspicious lesions.

Results: In these 27 patients pseudoprogression was confirmed in 9 cases (33%). Of these, 7 were identified using RANO criteria, 2 were identified by histopathology results. FET-PET predicted pseudoprogression in 6 cases (22%) and proved correct in 4 cases. FET-PET had a positive predictive value (PPV) of 0.66. CT perfusion predicted pseudoprogression in 5 cases (19%) and was correct in 4, resulting in a PPV of 0.80. Thus both tests showed good specificity (FET-PET: 0.89, CT perfusion: 0.94) but equally low sensitivity (0.44).

Conclusions: In this limited case series, CT perfusion imaging and FET-PET both lacked good sensitivity in detecting true pseudoprogression but showed good specificity. Both modalities can support the neurosurgeon in preventing potentially unnecessary surgical exploration. Larger prospective studies are needed to permit statistically sound analyses of differences in specificity and PPV.