You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Metabolism and quantification of [(18)F]DPA-714, a new TSPO positron emission tomography radioligand. [(18)F]DPA-714 [N,N-diethyl-2-(2-(4-(2[(18)F]-fluoroethoxy)phenyl)5,7dimethylpyrazolo[1,5a]pyrimidin-3-yl)acetamide] is a new radioligand currently used for imaging the 18-kDa translocator protein in animal models of neuroinflammation and recently in humans. The biodistribution by positron emission tomography (PET) in baboons and the in vitro and in vivo metabolism of [(18)F]DPA-714 were investigated in rats, baboons, and humans. Whole-body PET experiments showed a high uptake of radioactivity in the kidneys, heart, liver, and gallbladder. The liver was a major route of elimination of [(18)F]DPA-714, and urine was a route of excretion for radiometabolites. In rat and baboon plasma, high-performance liquid chromatography (HPLC) metabolic profiles showed three major radiometabolites accounting for 85% and 89% of total radioactivity at 120 minutes after injection, respectively. Rat microsomal incubations and analyses by liquid chromatography-mass spectrometry (LC-MS) identified seven metabolites, characterized as O-deethyl, hydroxyl, and N-deethyl derivatives of nonradioactive DPA-714, two of them having the same retention times than those detected in rat and baboon plasma. The third plasma radiometabolite was suggested to be a carboxylic acid compound that accounted for 15% of the rat brain radioactivity. O-deethylation led to a nonradioactive compound and [(18)F]fluoroacetic acid. Human CYP3A4 and CYP2D6 were shown to be involved in the oxidation of the radioligand. Finally an easy, rapid, and accurate method--indispensable for PET quantitative clinical studies--for quantifying [(18)F]DPA-714 by solid-phase extraction was developed. In vivo, an extensive metabolism of [(18)F]DPA-714 was observed in rats and baboons, identified as [(18)F]deethyl, [(18)F]hydroxyl, and [(18)F]carboxylic acid derivatives of [(18)F]DPA-714. The main route of excretion of the unchanged radioligand in baboons was hepatobiliary while that of radiometabolites was the urinary system.
{"Chemical": ["N-deethyl", "O", "O-deethyl", "[(18)F]fluoroacetic acid", "carboxylic acid", "N,N-diethyl-2-(2-(4-(2[(18)F]-fluoroethoxy)phenyl)5,7dimethylpyrazolo[1,5a]pyrimidin-3-yl)acetamide", "[(18)F]hydroxyl", "DPA-714", "hydroxyl", "[(18)F]DPA-714", "[(18)F]deethyl", "[(18)F]carboxylic acid"]}