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:

In vivo binding of the dopamine-1 receptor PET tracers [(11)C]NNC112 and [ (11)C]SCH23390: a comparison study in individuals with schizophrenia. RATIONALE: A deficit in dopamine-1 (D1) receptor function in the prefrontal cortex is suggested to play a role in the cognitive dysfunction observed in patients with schizophrenia. However, the results from positron emission tomography imaging studies of D1 receptor levels in individuals with schizophrenia are mixed. OBJECTIVES: The aim of this investigation was to determine whether the in vivo characteristics of the different D1 receptor tracers used in previous reports, [(11)C]SCH23390 and [(11)C]NNC112, may have contributed to these discrepancies reported in the literature. METHODS: Eight patients with schizophrenia and 12 healthy control subjects were scanned with both [(11)C]SCH23390 and [(11)C]NNC112. RESULTS: [(11)C]SCH23390 and [(11)C]NNC112 binding potentials in both patients and control subjects were compared and no tracer by diagnosis interactions were observed. CONCLUSIONS: The results of this study suggest that differences in the binding of [(11)C]SCH23390 and [(11)C]NNC112 observed in previous studies are not due to differences in the in vivo behavior of these tracers.
{"Chemical": ["[(11)C]NNC112", "[ (11)C]SCH23390", "[(11)C]SCH23390", "dopamine"]}