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Bedside myocardial scintigraphy was performed on 149 patients admitted to the Coronary Care Unit (CCU), after IV injection of 74 MBq 201Tl, using a mobile gamma camera (Dynamo). The study was displayed on Polaroïd pictures, without any image treatment, and read by two independent readers. Clinical history, findings, and final diagnosis were assessed by an independent clinician. The following conclusions were reached: 1) The sensitivity of the study for the detection of a recent myocardial infarction (MI) was 0.84 with a specificity of 0.87. 2) There was a good correlation between scintigraphic and ECG localization. 3) No firm correlation was found between scintigraphic and enzymatic estimates of infarct size. 4) Abnormal visualization of the right ventricle was probably associated with more extensive infarction.

The action of antithrombotic drugs can be evaluated by measuring the deposition of 111In-labelled platelets on peripheral bypass grafts several days after injection. This evaluation can be performed qualitatively (visual interpretation on the daily images) or quantitatively. Four different methods which calculate the ratio of platelet uptake with a reference region are compared: two methods use a gamma camera and two a detector. A blood sample or the region under the sternal angle are used as reference. The daily ratio of the counts, recorded by a gamma camera in a region of interest covering the graft, and the blood radioactivity interpolated from a platelet survival curve appears to be the most reliable method. The information of all the ratios can be combined in a single thrombogenicity index which reflects the daily rise of a linear or exponential regression versus time.