[en] With increasingly frequent request for a large number of radioimmunoassay, it requires to preparate in a limited short time. For this request, the Hitachi 4 Channel Radioimmunoassay Counting System (RMA-4A) has been designed specifically for the expanding needs in this field. This system accomodates 12 samples racks. A NAI crystal with a side through-hole serves as radiation detector. It is located above the sample changer, and individual samples are elevated into it. Counting 4 samples at once and changing sample faster by moving the elevator results in a considerable time saving for large sample numbers. This arrangement provides better shielding as well as reduced volume dependence. An important additional feature of this counting system is that permits counting of individual samples without interruption of the sample number sequence. The calculated values in each 4 detectors are in good statistical agreement with those theoretical values, when their correcting coefficient for 4 channels are estimated. (author)

[en] In order to clarify the mechanism of N-isopropyl-p-iodoamphetamine (IMP) liver accumulation, liver dynamic study by the portal injection of ¹²³I-IMP and liver microautoradiography by ¹²⁵I-IMP were performed using 5, 2 male rats, respectively. The initial uptake of ¹²³I-IMP in the liver was very high and thereafter ¹²³I-IMP showed relatively rapid wash-out (count ratio of lung to liver at 10 min after the injection was 0.12, 0.15). On the other hand, the addition of 5 mg, 8 mg ketamine hydrochloride decreased the initial ¹²³I-IMP liver uptake and its lung accumulation was noted immediately after the injection (count ratio of lung to liver at 10 min was 0.20). Microautoradiography of the liver using ¹²⁵I-IMP showed grain density in the central vein and sinusoids, but not in the liver parenchymal cell. These results suggest that non-specific amine receptor (binding site) may exist in the endothelial cell in the central vein, although the number of experimental rats in this series was small for conclusion. (author)

[en] In 14 patients with radiologically proven pulmonary lesions, factor analysis was performed for pulmonary scintigrams with N-isopropyl-p[I-123]iodoamphetamine (I-123 IMP). Pulmonary areas extracted by factor analysis were coincident with areas of decreased activities on first pass images in ll patients. In the other three patients with space-occupying lesions which showed discordance between first pass and factor analysis studies, photon deficiency was observed on 5-hr images. Factor analysis clearly depicted a decreased or deficient blood flow of the pulmonary area as an abnormal factor in all patients. Factor analysis would replace delayed images because of its advantage of extracting abnormal blood flow of the pulmonary artery, and aid in the evaluation of residual pulmonary tissue because of its ability to differentiate space-occupying lesions from inflammatory tissues. (Namekawa, K)

[en] N-isopropyl-p-[¹²³I]iodoamphetamine (¹²³I-IMP) is lipophilic substance and permeates through the alveolar epithelium via intracellular transport, whereas ^99mTc-DTPA is water-soluble substance and permeates through the alveolar epithelium via paracellular transport. We performed inhalation lung imaging using ¹²³I-IMP and ^99mTc-DTPA in order to assess alveolar epithelial permeability in 4 patients with restrictive ventilatory impairment, and 5 volunteers including one smoker. The time-activity (T/A) curves of ¹²³I-IMP were well fitted into two compartments, first and slow, by least-squares fit technique, in contrast to ^99mTc-DTPA fitted well with one compartment. In 4 normal volunteers, the T/A curves of the lower pulmonary fields declined faster than those of other pulmonary fields. In ^99mTc-DTPA studies, the Kep values of patients with restrictive ventilatory impairment (n=4) were higher than those of normal volunteers (n=4) (2.14±0.30 x 10^-4 vs 1.48±0.41 x 10^-4, p<0.005). On the other hand, in ¹²³I-IMP studies, the Kep values of the patients were much lower than those of normal volunteers (6.79±0.55 x 10^-5 vs 1.52±0.45 x 10^-3, p<0.005). (author)

[en] In order to evaluate the diagnostic efficacy of pinhole collimator (PHC) imaging combined with an X-ray for vertebral metastasis, our prospective study has employed receiver operating characteristics (ROC) analysis in 21 patients, 11 with osseous metastasis and 15 with degenerative joint disease in the lumbar vertebrae. PHC imaging provided better anatomic information on the extent of ^99mTc-MDP accumulation. PHC vertebral scintigraphy had a considerable impact on the decision-making process, although with variations and not very satisfactory results among the physicians with little experience. Our study suggests that PHC imaging and X-ray film are useful in differentiating between osseous metastasis and degenerative joint disease in the vertebra. (author)

[en] Extraction index (EI₅) was introduced to evaluate liver function quantitatively with ^99mTc-GSA (GSA) scintigraphy, and it was compared with conventional indices; receptor index (LHL₁₅) and clearance index (HH₁₅). EI₅ is expressed as the following equation: EI₅=(L₅-L₃)/(H₃+H₅)*P_H/P_L where L₃, L₅: counts at 3 or 5 minutes after the injection in the liver ROI, respectively, H₃, H₅: counts at 3 or 5 minutes in the heart ROI, respectively; P_L, P_H: numbers of pixels in the liver- and heart-ROI, respectively. We performed GSA scintigraphy in 40 patients with liver dysfunction and calculated values of the indices. Good correlations were observed between EI₅ and liver function tests. Correlation coefficients were almost equal to or higher than those between conventional parameters and liver functional tests. EI₅ was thought to be a practical index, and it could be calculated in a short time without aid of computer. Evaluation of local liver function may be possible, because EI₅ was corrected with numbers of pixels in the liver- and heart-ROI; which was not considered in the conventional parameters. (author)