The volumetric methods in the lesions for radioisotope therapy

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The estimation of functioning volume in the lesion is an important factor to know the severity of illness. We had been tried to develop the easy method of functioning volume in the organ or lesion tht accumulated radiopharmaceuticals. Clinical evaluation of volumetric analysis following the basic study was performed to estimate the thyroid volume for I-131 therapy in the patients with Graves' hyperthyroidism and to decide the cardiac ejection fraction in the patients with cardiac disease. Of the 57 patients with hyperthyroidism due to Graves' disease who were treated with I-131 was included in this study and compared with the therapeutic effects. The calculated thyroid volume became under 50gram in 87% of patients by scintigraphy with Tc-99m pertechnetate. The patients were classified in three groups according to the absorbed dose, low dose (50-60Gy), middle does (60-80Gy), and high dose (80-90Gy) randomly. And, the relationship between the absorbed dose and therapeutic effect was evaluated. 85% of patiesnts treated with low dose showed euthyroid at 1 year after I-131 therapy. The rate of hypothyroidism was increased in the patients treated with high dose. Low dose therapy was thought to be adequate for leading the patients of Graves' thyrotoxicosis to euthyroidism. The volumetric method by using RI technique was potential use for therapy with I-131. The methodology of heart pool volume for the measurement of cardiac ejection fraction was evaluated in 27 patients with heart disease. The ECG gated SPECT compined with QGS program was used for the measurement of the end diastolic volume and end systolic volume of ventricle and compared with the results of coronary angiongraphy. The ejection fractions of left ventricle was well correlated with the levels measured by cardiac catheterization (y = 1.27X+9.25, r = 0.962). It was recognized that the volumetric method by ECG gated SPECT combined with QGS program become a promising method of cadiac function.