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Abstract

A method of diagnosing a patient is carried out by delivering an aerosolized dose of a radioactive formulation to a patient and making a ventilation image of radioactive material deposited in the lung. This image is compared with a separately generated image (perfusion image) taken after injecting radiolabled particles into the pulmonary arterial circulation. A diagnosis of a pulmonary embolism can be made when areas of the lung which are shown in the ventilation image are not shown within the perfusion image, indicating that air flow to that area exists, whereas a blood flow to that area has been blocked. Devices, packaging and methodology for creating aerosols are provided which allow for efficient and repeatable delivery of radioaerosols to the lungs of a patient. Devices may be plug-in units or hand-held, self-contained units which are automatically actuated at the same release point in a patient's inspiratory flow cycle. The release point is automatically determined either mechanically or, more preferably calculated by a microprocessor which receives data from a sensor making it possible to determine inspiratory flow rate and inspiratory volume. The device is loaded with a container of a radioactive formulation such as .sup.99m Tc-labelled diethylene-triamine pentaacetic acid (DTPA). Actuation of the device forces the radioactive formulation through a porous membrane of the container which membrane has pores having a diameter in the range of about 0.25 to 6.0 microns. The container includes radioactive shielding in the form of a lead coating and/or a lead surrounding packet.

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First Claim