[18F]-Spa-RQ
[18F]-labeled Substance P Antagonist Receptor Quantifier is a radioconjugate consisting of the positron emitting radioisotope fluorine F 18 conjugated to the substance P antagonist receptor quantifier (SPA-RQ) used in radioimaging. [18F]-labeled substance P antagonist receptor quantifier is an antagonist of the neurokinin 1 (substance P) receptor (NK1R) and can function as a positron emission tomography (PET) imaging agent for detecting NK1R-expressing cells and tissues. NK1Rs are frequently expressed on the plasma membranes of tumor cells from glioblastoma and breast and pancreatic carcinomas.