Another limitation is that a heterogeneous group of NETs has been included, which could have hampered the detection of more specific tumor-related alterations in tracer distribution, such as those associated with monoamine oxidase (MAO)-A expression (mainly upregulated in pancreas and GE NETs [15]) or the vesicular monoamine transporter (VMAT, inversely correlated with prognosis [16]). The gene discussed is MAOA; the disease is neoplasm.