To investigate the diagnostic value of 18F-fluoroethyl-L-tyrosine (FET) positron emission tomography (PET) in patients with suspected tumefactive demyelinating disease.
We retrospectively examined FET-PET and MR imaging of 21 patients (12 female, 9 male) with known demyelinating disease and newly diagnosed tumefactive lesions. The maximum standardized uptake value (SUVmax), time activity curves (TAC) and lesion-to-background ratio (TBR) of these lesions were calculated. The standard of reference consisted of biopsy and/or follow-up imaging. FET parameters of true neoplastic lesions and tumefactive demyelinating lesions were compared using Mann-Whitney U-test and receiver operating characteristic (ROC) analysis.
Nine patients (42.9%) had neoplastic lesions, 12 patients (57.1%) had tumefactive demyelinating lesions. TBRmax, SUVmax and TAC were significantly different between demyelinating lesions and neoplastic lesions: Tumors had a higher TBRmax (3.53 ± 1.09 vs. 1.48 ± 0.31, respectively; P < 0.001) and SUVmax (3.95 ± 1.59 vs. 1.86 ± 0.50, respectively; P < 0.001) than tumefactive demyelinating lesions. The TAC of tumors was significantly higher compared to tumefactive demyelinating lesions at all time points (P < 0.05). ROC analysis revealed that a TBRmax threshold of 2.2 and a SUVmax threshold of 2.5 could reliably differentiate tumor and tumefactive demyelination (area under the curve, 1.000 and 0.958, respectively).
In patients with demyelinating disease, FET-PET parameters TBRmax (cut-off 2.2) and SUVmax (cut-off 2.5) are able to distinguish tumefactive demyelinations from true neoplastic lesions.
From the *Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Rämistrasse, Zürich, Switzerland;
†Department of Diagnostic Radiology, Prince Sultan Medical Military City, Riyadh, Saudi Arabia;
‡Neurology Clinic, University Hospital Zurich/University of Zurich, Frauenklinikstrasse; and
§Department of Neuroradiology, University Hospital Zurich/University of Zurich, Rämistrasse, Zürich, Switzerland.
Received for publication May 14, 2018; revision accepted July 5, 2018.
Conflicts of interest and sources of funding: M.W.H. received speaker’s fees from GE Healthcare. The institution of M.B., M.W.H., A.A.A., and A.B. received grants from GE Healthcare. None declared to all other authors.
Correspondence to: Martin W. Huellner, MD, Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland. E-mail: firstname.lastname@example.org.