Subcutaneous (SC) injection of99mTc pertechnetate (99mTc) at acupuncture points K-3 is a new method of lower-limb radionuclide venography. To investigate the mechanism of absorption of 99mTc from SC injected sites into vascular system, various radioisotopes such as 201Tl chloride (201T1) and 67Ga citrate (67Ga) were SC injected at K-3 points in animal and humanbeings experiments. It was found that99mTc and 201Tl were absorbed rapidly from K-3 points through venous system and into whole body soft tissue. However, 67Ga with a larger effective ionic radius than201Tl did not be absorbed throughout the observation of 5 minutes. Furthermore, intravenous administration of digitalis, a Na+-K+pump blocker, did not inhibit the absorption of 99mTc and201Tl after SC injection at K-3 points. These results suggest that absorption of radionuclides on SC injection at K-3 points is mainly through the passive pathway of diffusion rather than the active transport, and the effective ionic radius may be a major factor influencing the absorption rate of the radionuclides.
The purpose of this study was to evaluate 99mTc-DTPA-HSA lymphoscintigraphy in 5 normal volunteers and 8 patients with metastases of malignant tumors (cancer, 3: and malignant lymphoma, 5) . The subjects underwent intradermal injection of 370 MBq of 99mTc-DTPA-HSA into digital web spaces of the feet and fingers and massage at the injection sites for 30s. Whole-body and local scintigrams were obtained 5-15 min (early image) and 50-60 min (delayed image) after injection. The tracer transport was prompt. Within 15 min after injection the tracer reached the termination of the thoracic duct in all normal volunteers. Normal lymphoscintigrams were obtained images of excellent quality delineated the lymph nodes and channels almost without background radioactivity. The images of 8 patients with malignant tumors showed clearly the following abnormal patterns: (1) obstruction of lymphatic system and absence of visualization of thoracic duct, (2) decreased or high uptakes in enlarged lymph nodes, (3) visualization of collateral circulation and tracer extravasation into more proximal soft tissue. We concluded that lymphoscintigraphy with 99mTc-DTPA-HSA was useful for detection of metastases to lymphatic system in the patients with malignant tumor.
Tritium concentrations of environmental waters in Aichi Prefecture were determined from 1973 to 1989. They are rain water, river waters and sea waters. In 1970's, tritium concentrations of environmental waters were more than the natural levels under the influence of the atmospheric nuclear tests. However, atmospheric nuclear tests have not been carried out after Oct. 1980 and the tritium concentrations are going to return to the natural levels. Annual means of tritium concentration in 1989 were as follows: 0.67 Bq/l for rain water, 1.1 Bq/l for Kiso river and Shonai river, 0.85 Bq/l for Yahagi river, 0.70 Bq/l for Toyo river, and 0.41 Bq/l for surface sea water. Also, tritium concentration of sea bottom water was 0.50±0.28 Bq/l and rather constant yearly. Among environmental waters, only rain water was previously having seasonal variation of tritium concentration and it was showing“spring peak”when the troposphere and the stratosphere were mixed actively. At present, tritium concentration of rain water has a little seasonal variation, and is slightly lower in summer under the influence of the atmosphere coming over from the ocean. With regard to the direct influence of rain water to river waters, it was found by means of time series analysis that Kiso river was the least affected of river waters and Yahagi river was the most. The apparent residence time, in which rain water stayed in the underground before it flowed out as river water, was presumed to be 4.9 years for Kiso river, 3.6 years for Yahagi river, 2.0 years for Toyo river, respectively.
A new type hygrometer utilizing α-ray absorption was devised employing two ZnS (Ag) scintillation detectors coupled with optical fiber cables for measuring dry air density and humid air density. It was shown that the counting rate difference of the two detectors is directly proportional to the absolute humidity and the absolute humidity could be measured with an accuracy of ±2g/m3 without the effects of variations in air density due to temperature and atmospheric pressure.
The parameters of renogram (Tmax, T1/2, T2/3) and 2-3 min renal uptake rate with 99mTc-MDP in 10 patients with no renal dysfunction were compared with those with 99mTC-DTPA in 5 patients with normal renal function. The parameters and renal uptake rate in the 8 patients except 2 with cardiac and pulmonary disease were analogous to those of 99mTc-DTPA group, Especially renal uptake rate contains the information of kidney and circulation, and can be obtained in a short time. Therefore it may be clinically useful to measure the renal uptake rate of the patient in whom 99mTc-MDP bone scintigraphy are performed.