| Abstract: |
Background and purpose Multimodal tissue characterization by combined MRI and PET has high clinical potential in the context of sub-target definition for dose painting and response assessment but its clinical exploration is yet limited. The aim of this study was to prove the potential and feasibility of hybrid PET/MRI to non-invasively measure tumor hypoxia, perfusion and microstructure at one stop in tumors of the uterine cervix during chemoradiotherapy. Material and methods Ten cervix cancer patients were subjected to simultaneous multiparametric PET/MRI with [18F]fluoromisonidazole ([18F]FMISO). Imaging was scheduled before, twice during and after chemoradiotherapy. Intra- and inter-time point analyses of the extracted parameters (i.e. ADC, Ktrans, ABrix, [18F]FMISO-tumor to background ratio (TBR)) were performed. The [18F]FMISO uptake- and ADC-spatio-temporal changes were assessed. Results Patient averaged ADC values increased from baseline to follow up (1.03 ± 0.11/1.30 ± 0.13 × 10−3 mm2/s), while the TBR decreased (1.73 ± 0.24/1.36 ± 0.19), Ktrans dropped over time (0.17 ± 0.05/0.05 ± 0.05 min−1); for all above p < 0.05. None of these parameters correlated significantly on a voxel-by-voxel basis. Low-ADC regions spatially varied over time. There was pronounced reduction of the [18F]FMISO-avid volumes during treatment. Conclusions The suggested hybrid PET/MRI protocol to non-invasively investigate tumor hypoxia, perfusion and microstructure at one stop was feasible, revealing spatio-temporal response patterns that could be utilized for comprehensive sub-target definition for dose painting and response assessment. © 2017 Elsevier B.V. |
