BACKGROUND: To evaluate and compare the diagnostic power of [18F]FLT-PET with ceMRI in patients with brain tumours or other focal lesions. METHODS: 121 patients with suspected brain tumour or those after brain tumour surgery were enroled in this retrospective study (61 females, 60 males, mean age 37.3 years, range 1-80 years). All patients underwent [18F]FLT-PET/MRI with gadolinium contrast agent application. In 118 of these patients, a final diagnosis was made, verified by histopathology or by follow-up. Agreement between ceMRI and [18F]FLT-PET of the whole study group was established. Further, sensitivity and specificity of ceMRI and [18F]FLT-PET were calculated for differentiation of high-grade vs. low-grade tumours, high-grade vs. low-grade tumours together with non-tumour lesions and for differentiation of high-grade tumours from all other verified lesions. RESULTS: [18F]FLT-PET and ceMRI findings were concordant in 119 cases (98%). On closer analysis of a subset of 64 patients with verified gliomas, the sensitivity and specificity of both PET and ceMRI were identical (90% and 84%, respectively) for differentiating low-grade from high-grade tumours, if the contrast enhancement and [18F]FLT uptake were considered as hallmarks of high-grade tumour. For differentiation of high-grade tumours from low-grade tumours and lesions of nontumorous aetiology (e.g., inflammatory lesions or post-therapeutic changes) in a subgroup of 93 patients by visual evaluation, the sensitivity of both PET and ceMRI was 90%, whereas the specificity of PET was slightly higher (61%) compared to ceMRI (57%). By receiver operating characteristic analysis, the sensitivity and specificity were 82% and 74%, respectively, when the threshold of SUVmax in the tumour was set to 0.9 g/ml. CONCLUSION: We demonstrated a generally very high correlation of [18F]FLT accumulation with contrast enhancement visible on ceMRI and a comparable diagnostic yield in both modalities for differentiating high-grade tumours from low-grade tumours and lesions of other aetiology.

• Keywords
• Brain tumour, High grade, Low grade, PET/MRI, Tumour-like lesions, [18F]FLT,
• MeSH
• Dideoxynucleosides MeSH
• Child MeSH
• Adult MeSH
• Gadolinium * pharmacokinetics   MeSH
• Infant MeSH
• Contrast Media MeSH
• Middle Aged MeSH
• Humans MeSH
• Magnetic Resonance Imaging * methods   MeSH
• Adolescent MeSH
• Young Adult MeSH
• Multimodal Imaging methods   MeSH
• Brain Neoplasms * diagnostic imaging   pathology   metabolism   MeSH
• Positron-Emission Tomography * methods   MeSH
• Child, Preschool MeSH
• Radiopharmaceuticals MeSH
• Retrospective Studies MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Sensitivity and Specificity MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Infant MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Child, Preschool MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• alovudine MeSH Browser
• Dideoxynucleosides MeSH
• Gadolinium * MeSH
• Contrast Media MeSH
• Radiopharmaceuticals MeSH