Hiromi Wakao

Ga-67 scan as a prognostic indicator in primary lung carcinoma.

Ga-67 scintigraphy was performed on 74 patients with a variety of histologic types of untreated primary lung carcinoma. Ga-67 uptake was determined, allowing for differences in tumor size. Ga-67 uptake was compared with the response to the incidence of metastases, and to host survival in the 74 patients. From these results, it is suggested that the greater the Ga-67 accumulation in the tumor, the higher the incidence of metastases and the shorter the host survival. Ga-67 scintigraphy appears to be a valuable tool in indicating the prognosis following radiation therapy in patients with primary lung carcinoma.

Technetium-99m pertechnetate and Gallium-67 imaging in salivary gland disease

Thirty–two patients with salivary gland tumors or sialadenitis were studied with Tc–99m pertechnetate and Ga–67 imaging and, in some instances, sialography. The diagnostic algorithm presented allows the correct categorization of the salivary gland pathology in the vast majority of patients. The patients were studied serially with Tc–99m pertechnetate, Ga–67, and in certain situations sialography (or CT–sialography). Use of the algorithm can distinguish benign salivary tumors from malignant tumors and malignant tumors from inflammatory disease. The limitations and pitfalls of interpretation are discussed.

The relationship between Ga-67 accumulation and cell cycle in malignant tumor cells in vitro

Previously we reported that the deposition of 67Ga into malignant tumor may be a sensitive index of proliferative activity in tumor cells. For the purpose of elucidation of this hypothesis, we investigated the relationship between the accumulation of 67Ga into malignant tumor cells and the cell cycle in vitro. We discovered that the uptake of both 67Ga and 59Fe into synchronized mouse tumor cells reaches a peak at the G2 stage which precedes cellular proliferation. Both iron and transferrin are specifically required by cells in culture for cell division, and the fact that 67Ga and 59Fe uptake into tumor cells peaks at the G2 stage of the cell cycle suggests that there is a correlation between 67Ga uptake and the rate of cellular proliferation in malignant tumor cells.

Bone scintigraphy in detection of bone invasion by oral carcinoma

Detecting osseous involvement is clinically important in the management of oral carcinoma. Thirtyone patients with osseous involvement due to oral carcinoma who underwent panoramic radiography and bone scintigraphy were evaluated retrospectively. Bone scintigraphy confirmed osseous involvement in all 31 (100%) of these patients. In 27 (87%) of 31 patients with osseous involvement, both the panoramic radiogram and bone scintigram were positive. In the remaining four patients (13%), bone scintigram was positive for mandibular or maxillary invasion, while panoramic radiogram was negative. There were no instances of an abnormal radiogram with a normal bone scintigram. These findings strongly suggest that bone scintigraphy is more sensitive than panoramic radiography in detecting osseous involvement of the mandible and maxilla due to oral carcinoma. Furthermore, bone scintigraphy was a critical pre-surgical tool in determining the extent of the osseous involvement.

The relationship between 67Ga accumulation and ATP metabolism in tumor cells in vitro

Previously, we reported that the deposition of 67Ga into malignant tumors may be a sensitive index of proliferative activity in tumor cells. For the purpose of elucidation of this hypothesis, we investigated the relationship between the accumulation of 67Ga into malignant tumor cells and the intra cellular ATP metabolism in vitro.The uptake of 67Ga into tumor cells was inhibited by adding NaF which is an inhibitor of ATP production. Furthermore, the uptake of 67Ga into tumor cells was strongly inhibited by adding ouabain which is a specific inhibitor of Na+−K+-ATPase. From these in vitro results, it was concluded that there is a correlation between 67Ga uptake and intra cellular ATP metabolism in tumor cells.

99mTc-MDP accumulation mechanisms in bone: Basic study on the adsorption onto hydroxyapatite

The accumulation mechanisms of technetium-99m methylene diphosphonate (99mTc-MDP) were investigated using hydroxyapatite powder and various phosphates. After reaction with99mTc-MDP, radioactivity was analyzed using a scintillation counter. The adsorption of99mTc-MDP onto hydroxyapatite occurred within 30 sec, and was not temperature dependent at 0–95°C. There was no change in the adsorption of99mTc-MDP onto hydroxyapatite in 5 or 50mM water-soluble organic compounds (glucose or urea). Anions had a greater effect on adsorption than cations. The only phosphate with adsorption equal to that of hydroxyapatite was calcium pyrophosphate. Adsorption onto calcium hydrogenphosphate was low at a pH of 6.0 in comparison with hydroxyapatite. These findings suggest that the adsorption of99mTc-MDP onto hydroxyapatite is influenced by the concentration of coexisting anions and by the chemical constitution of the phosphate components.