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: ["HealthCareActivity", "InjuryOrPoisoning", "BodySubstance", "IntellectualProduct", "AnatomicalStructure", "SpatialConcept", "Chemical", "Bacterium", "MedicalDevice", "Organization", "BiomedicalOccupationOrDiscipline", "Finding", "BiologicFunction", "Virus", "ResearchActivity", "ClinicalAttribute", "PopulationGroup", "Eukaryote", "BodySystem", "Food", "ProfessionalOrOccupationalGroup"].

Please return the output as a JSON object of the format: {"Virus": ["HIV", ...], "Bacterium": ["MRSA", ...], "AnatomicalStructure": ["Lung", ...], "BodySystem": ["CNS", ...], "BodySubstance": ["Serum", ...], "Finding": ["Headache", ...], "InjuryOrPoisoning": ["Fracture", ...], "BiologicFunction": ["Death", ...], "HealthCareActivity": ["Biopsy", ...], "ResearchActivity": ["Clinical trial", ...], "MedicalDevice": ["Lenses", ...], "SpatialConcept": ["Camps", ...], "BiomedicalOccupationOrDiscipline": ["Forensic medicine", ...], "Organization": ["WHO", ...], "ProfessionalOrOccupationalGroup": ["Provider", ...], "PopulationGroup": ["Swimmers", ...], "Chemical": ["Gold", ...], "Food": ["Rice", ...], "IntellectualProduct": ["RPAM", ...], "ClinicalAttribute": ["Biomarker", ...], "Eukaryote": ["Dogs", ...]}. 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:

Three-dimensional constructive interference in steady-state (3D-CISS) sequences and Phase-contrast MRI of arrested hydrocephalus to evaluate role of three-dimensional constructive interference in steady-state (3D-CISS) sequences and phase-contrast magnetic resonance imaging (PC-MRI) in patients with arrested hydrocephalus. Prospective study was conducted on 20 patients with arrested hydrocephalus. All patients underwent PC-MRI and 3D-CISS for assessment of the aqueduct. Axial (through-plane), sagittal (in-plane) PC-MRI and sagittal 3D-CISS were applied to assess the cerebral aqueduct and the spontaneous third ventriculostomy if present. Aqueductal patency was graded using 3D-CISS and PC-MRI. Quantitative analysis of flow through the aqueduct was done using PC-MRI. The causes of obstruction were aqueductal obstruction in 75% (n=15), 3rd ventricular obstruction in 5% (n=1) and 4th ventricular obstruction in 20 % (n=4). The cause of arrest of hydrocephalus was spontaneous third ventriculostomy in 65% (n=13), endoscopic third ventriculostomy in 10% (n=2), ventriculo-peritoneal shunt in 5% (n=1) and no cause could be detected in 20% of patients (n=4). There is a positive correlation (r= 0.80) and moderate agreement (κ= 0.509) of grading with PC-MRI and 3D-CISS sequences. The mean peak systolic velocity of CSF was 1.86 ± 2.48 cm/sec, the stroke volume was 6.43 ± 13.81μl/cycle, and the mean flow was 0.21 ± 0.32 ml/min. We concluded that 3D-CISS and PC-MRI are non-invasive sequences for diagnosis of the level and cause of arrested hydrocephalus.
{"AnatomicalStructure": [], "Bacterium": [], "BiologicFunction": ["arrested hydrocephalus", "ventricular obstruction", "obstruction", "hydrocephalus"], "BiomedicalOccupationOrDiscipline": [], "BodySubstance": ["CSF"], "BodySystem": [], "Chemical": [], "ClinicalAttribute": ["stroke volume"], "Eukaryote": [], "Finding": ["diagnosis", "detected", "positive"], "Food": [], "HealthCareActivity": ["PC-MRI", "Quantitative analysis", "endoscopic third ventriculostomy", "phase-contrast magnetic resonance imaging", "assessment", "Phase-contrast MRI"], "InjuryOrPoisoning": [], "IntellectualProduct": ["grading", "graded"], "MedicalDevice": ["ventriculo-peritoneal shunt"], "Organization": [], "PopulationGroup": [], "ProfessionalOrOccupationalGroup": [], "ResearchActivity": ["Prospective study"], "SpatialConcept": ["Aqueductal", "patency", "aqueduct", "Axial", "aqueductal", "sagittal", "cerebral aqueduct"], "Virus": []}