P14.17 Differentiation of treatment-related changes from tumor progression: A direct comparison between dynamic FET PET and ADC values obtained from DWI MRI

• Published in: Neuro-oncology (Charlottesville, Va.) Va.), 2019-09, Vol.21 (Supplement_3), p.iii70-iii70
• Main Authors: Werner, J, Stoffels, G, Lichtenstein, T, Borggrefe, J, Lohmann, P, Ceccon, G, Fink, G R, Langen, K, Kabbasch, C, Galldiks, N
• Format: Article
• Language: English
• Subjects: Poster Presentations
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/noz126.252

Abstract BACKGROUND Following brain cancer treatment, the capacity of anatomical MRI to differentiate neoplastic tissue from treatment-related changes (e.g., pseudoprogression) is limited. This study compared apparent diffusion coefficients (ADC) obtained by diffusion-weighted MRI (DWI) with static and dynamic parameters of O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET for the differentiation of treatment-related changes from tumor progression. MATERIAL AND METHODS Forty-eight pretreated high-grade glioma patients with anatomical MRI findings suspicious for progression (median time elapsed since last treatment, 16 weeks) were investigated using DWI and dynamic FET PET. Maximum and mean tumor-to-brain ratios (TBRmax, TBRmean) as well as dynamic parameters (time-to-peak and slope values) of FET uptake were calculated. For mean ADC calculation, regions-of-interest analyses were performed on ADC maps calculated from DWI co-registered with the contrast-enhanced MR image. Diagnoses were confirmed neuropathologically (21%) or clinicoradiologically. Diagnostic performance was evaluated using receiver-operating-characteristic analyses or Fisher’s exact test for a combinational approach. RESULTS Ten of 48 patients had treatment-related changes (21%). The diagnostic performance of FET PET was significantly higher (threshold for both TBRmax and TBRmean, 1.95; accuracy, 83%; AUC, 0.89±0.05; P