Distribution and Dosimetry of 111In DTPA-D-Phe-octreotide in Man Assessed by Whole Body Scintigraphy

The distribution and dosimetry of the somatostatin analog 111In-DTPA-octreotide was evaluated in 6 patients. Whole body scintigraphy in anterior and posterior projections was performed 0.5, 5, 24 and 48 hours after injection. Region-of-interest analysis for different organs and the whole body was used to determine 111In octreotide half-life-corrected uptake in absolute and relative terms. A rapid initial uptake was seen in the kidneys (2-7%), the spleen (2-6%) and in the liver (4-8%). A lower uptake was seen in the pituitary gland (maximum 0.3%), the thyroid (maximum 0.07%), in the female breast (maximum 1.2%), in the urinary bladder and in the intestinal tract. The elimination pattern varied between different organs. The effective dose equivalent was evaluated to be in the range 0.08 to 0.13 mSv/MBq (average 0.10 mSv/MBq). The behavior of 111In-DTPA-octreotide suggests follow-up scintigraphy in a period extending up to at least 24 hours after injection.