For detailed characterization of a particular lesion, there is emerging evidence MK-2206 supplier of synergistic value of simultaneous PET and MRI for certain indications, including local staging, treatment planning and response assessment.

Recent studies have described such potential synergies for brain, head/neck and pancreatic malignancies. For brain tumor radiation treatment planning, one recent study showed advantages of adding 18F-fluoro-ethyl-tyrosine to anatomical MRI for determining the gross tumor volume (GTV) for high-grade glioma [77]. A similar result was found in a meningioma case study in which 68Ga-DOTATOC was employed during simultaneous PET–MRI [78]. The authors used both the PET and MRI data to delineate the GTV and concluded that the combination of the two techniques is clinically feasible, allowed a more detailed visualization of the tumor, may be more accurate for delineation of the target volume and may improve the workflow for radiation therapy planning. While both of these studies made use of simultaneous PET–MRI, there have also been studies that have employed retrospective PET–MRI registration to assess the ability of the two modalities to improve patient care. For head and neck cancer, Huang et al. investigated the diagnostic value of fluorodeoxyglucose

PET (FDG-PET) co-registered to anatomical MRI compared to PET–CT, CT and MRI in advanced buccal squamous cell carcinoma (BSCC; [79]). The authors found that fused PET–MRI images have the highest sensitivity and specificity of the four approaches. Furthermore,

tumor size (i.e., mean maximal diameter) as ABT-199 concentration measured by PET–MRI had a higher correlation coefficient (r2= 0.96) with pathologic Edoxaban tumor size than CT (r2= 0.55), MRI (r2= 0.58) or PET/CT (r2= 0.74). The authors concluded that fused PET–MRI is more reliable for assessment of invasion and tumor size delineation in advanced BSCC [79]. For pancreatic cancer, Tatsumi et al. recently contributed a study in which they retrospectively registered 47 FDG-PET data sets to anatomical MRI in order to demonstrate the feasibility of PET–MRI to evaluate pancreatic cancer [80]. They assessed the ability of PET–MRI to visualize the tumors using a five-point scale and also assessed the overall image quality using a three-point scale, with all evaluations compared to PET–CT. The fused PET–MRI data were able to offer additional diagnostic information over stand-alone PET, and the overall image quality was higher with PET–MRI. While not statistically significant, the diagnostic accuracy of PET–MRI was higher (93.0%) than PET–CT (88.4%). This study is of particular interest because it involves image registration of a disease site that is below the neck, where retrospective image registration is especially challenging due to a paucity of rigid fiducials as well as the presence of peristaltic motion.