Estimation of the lung uptake ratio of 201Tl in cardiopulmonary diseases

On intravenous administration of 201TlCl (2-3mCi), the initial transit of it through the heart and lungs as well as subsequent uptake by the lung were recorded in the supine position using a scintillation camera coupling to a small digital computer. Leaving the patient in the same position the anterior image of perfusion lung scintigram with sup(99m)Tc-macroaggregated albumin or transmission scintigram with a point source of sup(99m)TcO4- taken. The radioactivity of total injected dosage (T) was calculated from the counts of the entire region on the initial transit of the tracer bolus through the heart and lungs, and counts per each pixel (E), total counts (L) and number of pixels (A) in the unilateral lung were calculated from the anterior image of 201Tl on which the isocount map of the perfusion lung scintigram or transmission one was superimposed. By these procedures, the uptake ratio of 201Tl per unilateral lung, the mean and each uptake ratio per pixel in the unilateral lung were calculated by L/T, L/T.A and E/T. Following results were obtained; 1) The mean value of the uptake ratio of it per unilateral lung in the right and left lung, were 1.5+-0.9%, 1.2+-0.6% in healthy lung; 3.2+-1.7%, 1.8+-1.0% in diffuse pulmonary diseases and 4.0+-1.6%, 2.5+-1.3% in cardiac diseases with left heart failure, respectively. 2) In the two groups using the perfusion lung scintigram and transmission one, the mean uptake ratio per pixel and number of pixels in the unilateral lung showed significant difference, but the uptake ratio per the unilateral lung did no significant difference. 3) These techniques are seemed to be useful for quantifying the lung uptake ratio of 201Tl on the lung scintigram with 201TlCl. (author)