Use of Radioisotopes in the Study of Shoulder to Thigh Circulation Time

SummaryA method is described for the measurement of shoulder to thigh circulation times using isotopic methodology. Following the positioning of scintillation probes over the subclavian vein at the shoulder and the femoral artery at the level of the inguinal ligament, one millicurie of 99mTcO4 – is injected as a bolus into the arm distal to the shoulder probe. The time between arrival of the radionuclide at the shoulder and femoral artery is the circulation time. The method is accurate and reproducible. Normal circulation times averaged 13.7 ± 2.8 seconds. Patients with congestive heart failure averaged 32 seconds with a range of 19.6—15.6. Hyperthyroid patients averaged 9.1 seconds with a range of 6.2— 13.8. Following treatment the hyperthyroid patients who became euthyroid generally developed normal circulation times while those that remained hyperthyroid continued to have shortened circulation times. The method for doing the circulation time described is useful since it is completely objective, non toxic, may be used in studying the comatose patient, and gives a written record for incorporation into the patient’s clinical chart.