Abstract
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Objectives The enforcement of combined acquisition technologies such as PET/CT and the recently introduced PET/MRI promote the diagnostic accuracy and biological understanding of cancer. However, still only static post contrast enhanced imaging technique in MRI and CT where co-registered with FDG-PET images. Our new approach was to combine microvascular tumor information using dynamic MRI (DCE-MRI and DSC-MRI) with FDG/FLT-PET image data to enable cross modality voxel based functional tumor analysis.
Methods 7 patient with brain lesions (4 with high grade gliomas; 3 with low grade gliomas) where acquired using MRI and PET. MRI protocol: T1w, T2, FLAIR and T1-dynamic (FLASH) /T2*(EPI)-dynamic for further kinetic analysis. The T1-/T2*-Dynamic MRI sequences were further analysed, undergoing a one- and two compartment kinetic modeling. The FDG-PET data were co-registered to the MRI kinetic modeling results using rigid body transformation and resampling technique.
Results In all 7 patients the data where successfully acquired and MRI kinetic modeling of the one- and two-compartment model enabled a discrimination of normal microcirculation of the gray/white matter and higher perfused tumor tissue. The rigid body co-registration allowed a direct intra-individual voxel based comparison of MRI contrast enhanced kinetic tumor tissue parameters (Amp, Kep, Kel, CBF, CBV, MMT) and metabolic rate of the FDG and FLT-PET data (SUV [k1,k2,k3]).
Conclusions This investigation presents a new approach of functional tumor analysis using information of functional MR and PET imaging modalities on a voxel level comparison. Further investigations are ongoing and have to verify the clinical impact of these initial results