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: ["Disease", "Chemical"].

Please return the output as a JSON object of the format: {"Chemical" : ["Naloxone", ...], "Disease" : ["Hypotensive", ...]}. 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:

Relation of perfusion defects observed with myocardial contrast echocardiography to the severity of coronary stenosis: correlation with thallium-201 single-photon emission tomography. It has been previously shown that myocardial contrast echocardiography is a valuable technique for delineating regions of myocardial underperfusion secondary to coronary occlusion and to critical coronary stenoses in the presence of hyperemic stimulation. The aim of this study was to determine whether myocardial contrast echocardiography performed with a stable solution of sonicated albumin could detect regions of myocardial underperfusion resulting from various degrees of coronary stenosis. The perfusion defect produced in 16 open chest dogs was compared with the anatomic area at risk measured by the postmortem dual-perfusion technique and with thallium-201 single-photon emission tomography (SPECT). During a transient (20-s) coronary occlusion, a perfusion defect was observed with contrast echocardiography in 14 of the 15 dogs in which the occlusion was produced. The perfusion defect correlated significantly with the anatomic area at risk (r = 0.74; p less than 0.002). During dipyridamole-induced hyperemia, 12 of the 16 dogs with a partial coronary stenosis had a visible area of hypoperfusion by contrast echocardiography. The four dogs without a perfusion defect had a stenosis that resulted in a mild (0% to 50%) reduction in dipyridamole-induced hyperemia. The size of the perfusion defect during stenosis correlated significantly with the anatomic area at risk (r = 0.61; p = 0.02). Thallium-201 SPECT demonstrated a perfusion defect in all 14 dogs analyzed during dipyridamole-induced hyperemia; the size of the perfusion defect correlated with the anatomic area at risk (r = 0.58; p less than 0.03) and with the perfusion defect by contrast echocardiography (r = 0.58; p less than 0.03). Thus, myocardial contrast echocardiography can be used to visualize and quantitate the amount of jeopardized myocardium during moderate to severe degrees of coronary stenosis. The results obtained show a correlation with the anatomic area at risk similar to that obtained with thallium-201 SPECT.
{"Chemical": ["thallium", "dipyridamole", "Thallium"], "Disease": ["coronary stenoses", "hyperemic", "coronary occlusion", "coronary stenosis", "hyperemia"]}