Diagnostic yield of simultaneous dynamic contrast-enhanced magnetic resonance perfusion measurements and [(18)F]FET PET in patients with suspected recurrent anaplastic astrocytoma and glioblastoma

PURPOSE: Both amino acid positron emission tomography (PET) and magnetic resonance imaging (MRI) blood volume (BV) measurements are used in suspected recurrent high-grade gliomas. We compared the separate and combined diagnostic yield of simultaneously acquired dynamic contrast-enhanced (DCE) perfusion MRI and O-(2-[(18)F]-fluoroethyl)-L-tyrosine ([(18)F]FET) PET in patients with anaplastic astrocytoma and glioblastoma following standard therapy. METHODS: A total of 76 lesions in 60 hybrid [(18)F]FET PET/MRI scans with DCE MRI from patients with suspected recurrence of anaplastic astrocytoma and glioblastoma were included retrospectively. BV was measured from DCE MRI employing a 2-compartment exchange model (2CXM). Diagnostic performances of maximal tumour-to-background [(18)F]FET uptake (TBR(max)), maximal BV (BV(max)) and normalised BV(max) (nBV(max)) were determined by ROC analysis using 6-month histopathological (n = 28) or clinical/radiographical follow-up (n = 48) as reference. Sensitivity and specificity at optimal cut-offs were determined separately for enhancing and non-enhancing lesions. RESULTS: In progressive lesions, all BV and [(18)F]FET metrics were higher than in non-progressive lesions. ROC analyses showed higher overall ROC AUCs for TBR(max) than both BV(max) and nBV(max) in both lesion-wise (all lesions, p = 0.04) and in patient-wise analysis (p < 0.01). Combining TBR(max) with BV metrics did not increase ROC AUC. Lesion-wise positive fraction/sensitivity/specificity at optimal cut-offs were 55%/91%/84% for TBR(max), 45%/77%/84% for BV(max) and 59%/84%/72% for nBV(max). Combining TBR(max) and best-performing BV cut-offs yielded lesion-wise sensitivity/specificity of 75/97%. The fraction of progressive lesions was 11% in concordant negative lesions, 33% in lesions only BV positive, 64% in lesions only [(18)F]FET positive and 97% in concordant positive lesions. CONCLUSION: The overall diagnostic accuracy of DCE BV imaging is good, but lower than that of [(18)F]FET PET. Adding DCE BV imaging did not improve the overall diagnostic accuracy of [(18)F]FET PET, but may improve specificity and allow better lesion-wise risk stratification than [(18)F]FET PET alone. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00259-022-05917-3.