FIGURE 1. Multitracer PET imaging of ventilated cat allows functional analysis of various tissues of total body at same physiologic status over prolonged period of time using specific radiotracers. Coregistered MRI allows anatomic delineation of various organs. In healthy cat brain, physiologic glucose ([¹⁸F]FDG) and oxygen ([¹⁵O]O₂) consumption with normal cerebral blood flow ([¹⁵O]H₂O) is not accompanied by significant uptake of amino acid ([¹¹C]MET) or nucleoside analog ([¹²⁴I]FIAU).