MAPT and tauopathy: 18F-AV-1451-PET besides of its binding to tau, is associated with affinity to other factors, e.g., iron deposits, iron melanin, and hemorrhagic lesions (21, 22) It should be underlined, that another study stressed affinity of 18F-AV-1451-PET to MAO-A (23) A different work questioned the usefulness of 18F-AV-1451-PET in the examination of 4 repeats (4R) tauopathies, as the authors interpreted the binding properties of 18F-AV-1451-PET as minimal (24).