CD8A and neoplasm: The PET sensitivity levels that have been achieved utilizing radionucleotide-labelled anti CD8+ antibody fragments range from 2 × 104 CD8+ T cells per milligram in lymphoid organs [13] to 1.6–4 × 106 CD8+ lymphocytes in a tumor volume of ~480 mm3 [49], equaling 3.3–8.3 × 106 cells/mL.