Enrico Martin

130 Chapter 6 Conclusion Conventional MRI may rule out MPNSTs in the presence of a target sign and obviates the need for biopsies or additional FDG-PET scans. Presence of ill-defined margins or perilesional edema is highly suspect of malignant transformation and requires biopsies or FDG-PET scans in NF1 for further characterization even in the presence of a target sign. However, MRI characteristics are varyingly present in MPNSTs. Therefore, cystic changes, heterogeneity on T1 weighted images, intratumoral lobulation, and large tumor size should be taken into account as well. FDG-PET scans should be offered to NF1 patients with symptomatic and suspect lesions on MRI to further reduce the need for biopsies. SUVmax and T/L ratio have similar accuracies. Ideal threshold for SUVmax seems to be ≥3.5. Functional MRI sequences may be useful as well, but require more research for their exact implementation. Liquid biopsies have not yet proven higher diagnostic accuracy than available imaging techniques.