Nuclear-Medizin最新文献

The distribution of intravenously administered 14C-ascorbic acid (AA) into various tissues of the dog, and the effect of dexamethasone and ACTH administration on the AA distribution was studied. As a function of time, the differences of 14C-AA distribution between adrenal and surrounding organs become greater, and 24 hours after the administration of the dose, the adrenal to liver ratio, as well as adrenal to kidney, is about 10:1. Also concentration of AA in the pituitary showed a gradual increase and reached its peak between 24 and 48 hours. Dexamethasone administration lowered significantly the uptake of 14C-AA by the adrenals, but did not affect the uptake by the pituitary. Three consecutive days administration of ACTH did not affect the uptake of the drug by either glands, but one single dose of ACTH administered one hour prior to the 14C-AA increased the uptake of AA by both glands. These results indicate that properly labeled AA may be an effective pituitary and adrenal scanning agent. Possible ways of labeling AA without changing its pharmacological properties are suggested.

In a retrospective and prospective study the scintigraphically measured kinetics of intrathecally injected tracers are classified and compared with the final clinical diagnoses confirmed by additional examinations and clinical course. The results of the studies show characteristic dynamics of the tracer in patients without neurological diseases, whereas typically abnormal images are demonstrated in different neurological diseases.

New chromatographic procedures are needed to accurately determine the radiochemical purity of technetium-99m labeled radiopharmaceuticals. A chromatography system has been developed for technetium-99m diethylenetriaminepentacetic acid, technetium-99m diphosphonate, and technetium-99m pyrophosphate. The technique involves spotting the radiopharmaceuticals on instant thin layer chromatography-silica gel and developing with acetone (solvent from migrates approximately 12 cm from the origin), air drying, and redeveloping the strip in normal saline (solvent front migrates approximately 6 cm from the origin). The procedure is simple to perform, rapid, accurate, and clearly separates technetium-99m pertechnetate, the technetium-99m radiopharmaceutical, and hydrolyzed reduced technetium-99m. It can be applied in most nuclear medicine laboratories and has the potential to predict the quality of radionuclide images obtained.

The efficiency and accuracy of four different methods of tissue preparation for the recovery of dotriacontane-16,17-14C (DOT-16,17-14C) from rat respiratory tissue were compared by means of liquid scintillation counting. A DOT-16,17-14C standard solution was placed on the respiratory epithelium of the nasal apex, larynx, trachea and main bronchi. Combustion of the lyophilized organs in a Packard sample oxidizer revealed the highest recovery and accuracy (93--100%), sample oxidizing by combustion without lyophilization the lowest recovery and accuracy (73--92%). Tissue solubilization by the commercially available tissue solubilizer TS-1 revealed a better recovery and accuracy (89--95%) than tissue maceration by boiling in methanolic KOH and toluene extraction (74--91%). Depending on the laboratory equipment, lyophilization or tissue solubilization is preferred; maceration and toluene extraction as well as combustion without freeze-drying are disregarded for further investigations because of the cumbersome procedure as well as the low recovery and accuracy, respectively.

Our investigations of the peripheral metabolism of T4 and T3 in man demonstrate clearly that T3 is secreted by the thyroid gland and is peripherally formed by conversion from T4. The calculation of the disposal rates indicate furthermore that 40% of the daily metabolised T4 is converted to T3. In this way more than 60% of the daily production of T3 results from peripheral conversion of T4. Our results support the hypothesis that the physiological action of the thyroid hormones is effected mainly by T3.

Practical aspects of the use of computer systems in Nuclear Medicine were discussed in a symposium sponsored by the "Rheinisch-Westfälische Gesellschaft für Nuklearmedizin" which was held at Bonn in December '74. In the opening session the president of the Society, Prof. Winkler (Bonn), gave a brief survey upon the development of data processing procedures for radionuclide diagnostics. He pointed out that at present computer application is not only of essential significance for camera scintigraphy but also for most of the other test methods as well as for the solution of organizing problems when running departments of Nuclear Medicine. For the performance of all these tasks and also for scientific purposes a special process control computer system has been developed in the Institute of Nuclear Medicine at the University of Bonn. A detailed description of this system was given by R. Knopp (Bonn). He emphasized in his paper that the rather bulky Bonn System, which consists of a dual computer (Siemens 305/306) and an extensive operating system, can not be regarded as a standard device for routine use in hospitals. However, on the basis of experiences which have been gathered on hand of the research system in Bonn efforts are in full activity for developing a compact Nuclear Medicine Computer system (CNMCS) suitable for the application within departments of any size. The CNMCS (which will be commercially available in the near future) is based on a 64 K, 16 bit central unit with a highly flexible operating system which permits a simultaneous multi user application of the computer. For CNMCS a comprehensive user software package will be at the clinician's disposal which can be easily handled.

Angioscintiphotography with 99mTc has been performed in 310 cases of space-occupying kidney lesions with the purpose of establishing the diagnostic value of the kidney perfusion. In the presence of a neoplasm, a more or less marked blood flow in the lesion generally appears as a hot area. This pattern is not observed in poor vascularized carcinomas or in Wilms' tumors. The percentage of poorly vascularized tumors is moderate and does not affect the value of the method. Cystic lesions appear usually to be cold. Large cysts exhibit no uptake; on the contrary, the degree of vascularization in the small cysts is more difficult to evaluate, as the normally supplied surrounding parenchyma overlaps the cold area caused by the cyst. In the evaluation of the angioscintiphotographic picture, we must take into account the concomitant hepatic or splenic vascularization, which may cause some doubts of interpretation because of projection interferences. The renal angioscintiphotography has an important rule in specifying the nature of a space-occupying kidney lesion and may be regarded as a useful screening test.

An electrolytic method for labelling fibrinogen with zirconium as a reductant for 99mTc is presented. The optimal labelling conditions and the in-vitro screening are subject of the study. First clinical experience indicates that the substance is clottable in vivo and applicable for localization.

The concentration of 99mTc-pyrophosphate was determined in the lower extremities of rabbits (normal, abacterial and bacterial affected soft tissues), in osteoarthritis of the hip joint (capsule and muscle) as well as in knee joint effusions. Compared with the 85Sr-concentration, reflecting the calcification capacity, concentrations of 99mTc-pyrophosphate in soft tissues were found to be lower 2 hours p.i., but were up to elevenfold higher 24 hours p.i. These findings should be due to a fixation of 99mTc-pyrophosphate in collagen containing tissues as in the soft tissue tumors (myosarcoma, synvialioma, breast cancer) presented. A mechanism of delayed equilibration could explain augmented uptake in lymph-edema, ascites and effusions in florid osteoarthritis of the knee joint. The possible dependence of 99mTc-pyrophosphate concentration in bone and soft tissue on collagenous contents is discussed.

160 sera of patients with normal or disturbed thyroid function was tested by ETR (Byk-Mallinckrodt) and Quantisorb (Abbott) for their metabolically effective thyroxine concentration. In 124 cases the in vitro findings were correlated with extensive clinical data, which had permitted to establish a definite judgement of thyroid function. 5,5--13,5 mug% were considered as normal values with Quantisorb, 0,8--1,18 (see article) with ETR. A critical evaluation of the test results showed a better distinction between normal and abnormal thyroid function with Quantisorb, which explains also the higher diagnostic accuracy of this kit (92,75% : 85,5%). "Grey-zones" between normal and abnormal thyroid function were found with both tests, they were smaller, however, with Quantisorb than with ETR. The Quantisorb kit can therefore be recommended for routine function tests in vitro, although the slightly greater laboratory work should be considered.