[A technique for quantifying lung uptake of 201Tl on the scintigram with 201TlCl]

On intravenous administration of 201TlCl (74 MBq (2 mCi), initial transit of it through the heart as well as subsequent uptake by the chest were recorded in the supine position using a scintillation camera coupling to a small digital computer, and remaining the patient in the same position perfusion scintigram with 99mTc-macroaggregated albumin (MAA) or transmission scintigram with a point source of 99mTcO4- too. The radioactivity of total injected dose of 201Tl (T) was calculated from the entire region on the initial transit of the tracer bolus through the heart, and that of unilateral lung (L) was done from the anterior image of 201Tl on which isocount map of the perfusion image or transmission one was superimposed. By these procedures, the lung uptake ratio of 201Tl was calculated by ratio of L/T, and expressed as percentage per entire unilateral lung and mean value (%) per pixel. The average values of the lung uptake ratio in circulatory diseases were 4.0 +/- 1.2% in the right lung, 2.7 +/- 1.2% in the left lung, and in respiratory diseases 4.5 +/- 2.1% and 2.3 +/- 1.0%, respectively. This technique is useful to quantify the lung uptake of 201Tl on the lung scintigram with 201TlCl.