A Computerized System for Rapid Evaluation of Thyroid Function

To improve the accuracy and speed of determination of thyroid structure and function, we have developed a system that combines the use of 99mTc-pertechnetate, the scintillation camera and a small general-purpose computer. With the pinhole collimator of the gamma camera over the patient's thyroid, five mCi of 99mTc-pertechnetate is injected intravenously. Data are accumulated in the core memory of an Image Display and Analysis System (“IDA”). The activity of a standard amount of 99mTc in a thyroid phantom is also measured. Data are displayed as serial images on a video screen. The exact area and activity of the thyroid are then computed by simple programs used together with a light-pen. The activity in tissue adjacent to the thyroid is subtracted to correct for extrathyroidal activity. The entire gland and focal regions within the gland are characterized by rates of uptake of 99mTc-pertechnetate. The method was tested with respect to variations in the size, position and activity of the thyroid. There was good correlation between 99m-Tc-pertechnetate uptake and the clinical status in 22 normal volunteers and 54 patients. The method requires only 10 minutes of technician time; the results are available within 40 minutes and the patient need not return for subsequent study. Both structure and function are examined at the same time, and regional as well as total function can be measured.