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Three cases of suspected pericardial effusion were evaluated with rapid, noninvasive procedure, combined use of macroaggregated albumin technetium 99m and human serum albumin technetium 99m to produce a single radiography showing the heart, liver, and lung perfusion simultaneously. This technic confirmed the diagnosis of pericardial effusion in two cases and ruled out this possibility in the third case.
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Technetium 99m pyrophosphate or polyphosphate administered intravenously soon after acute myocardial infarction produces positive images of the area and extent of myocardial necrosis. Forty-four patients have been studied of whom 39 had myocardial infarction. There was good correlation of the site and extent of infarction as indicated by the scintigram with electrocardiogram and cardiac enzyme criteria.
Sixteen patients with abdominal neuroblastoma had 99m Technetium Phosphate Compounds (99m TC-PC) bone scans as a preoperative evaluation for metastatic disease. Ten patients (62%) had extraosseous tumor uptake while six patients (38%) did not. There was no difference in the incidence of tumor calcification, tumor necrosis or hydronephrosis in the two groups. However, VMA levels were significantly higher in the group with extraosseous tumor uptake. Various bone seeking radionuclides are compared to 99m TC-PC and possible mechanism for extraosseous uptake of such radionuclides are postulated. Awareness of the frequency of such uptake should reduce the possibility of errors in the interpretation of bone scans in patients with neuroblastoma.
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This study describes the preparation and synthesis of a new class of cationic technetium compounds, the hexakis(alkylisonitrile)technetium(+ 1) complexes, at both carrier added and no carrier added concentrations in aqueous media from pertechnetate. Biological distribution and imaging data in animals indicate that certain members of this class may be effective for cardiac imaging in man. The usefulness of these lipophilic water-soluble species for labeling mammalian cells is also reported.
An 18-year-old male was evaluated for recurrent attacks of right abdominal pain and intermittent jaundice caused by hydatid cysts of the liver. The case illustrates the value of dynamic functional information provided by Tc-99m-HIDA imaging over noninvasive modalities that demonstrate structural changes, such as ultrasound, computed tomography, and tin colloid liver imaging.
Complexing of reduced 99mTc, 99Tc and of 113Sn(II) by pyrophosphate was studied, using the in vivo distribution in the rat as an indicator for complex formation. 99mTc-pyrophosphate was only formed at very low technetium concentrations, otherwise colloid formation occurred. Reduced 99mTc in trace amounts and 113Sn(II) complexed equimolarly with pyrophosphate were concentrated in bone and excreted in urine in comparable amounts. The in vivo distribution of 32P-orthophosphate and -pyrophosphate was characterized by a considerable uptake in the liver and a poor urinary excretion. The distribution patterns of 32P-pyrophosphate, complexed equimolarly with tin(II), remained unchanged. Despite these findings it is concluded that real chelates are formed, since non-complexed reduced 99mTc was not concentrated in bone. Two variants of reduced technetium could be discerned: a 99mTc-kidney agent and a 99mTc protein-bound agent. Some evidence was found that reduced technetium may change its oxidation state, but it seems much more likely that both agents are technetium(IV) compounds. It is suggested that the kidney agent is hydrated technetium dioxide whereas the protein-bound agent is a charged technetium(IV) compound. Only hydrated technetium dioxide is obviously complexed by chelating phosphate compounds.
Technetium is a man-made element produced in increasing amounts during the last decades. The chemical and physical properties of some technetium compounds are considered, and a discussion of possible source terms is included. Literature on the environmental behavior of technetium is reviewed to evaluate its transfer and equilibrium distribution in aquatic and terrestrial ecosystems. Considerable effort has been expended in the last years in order to understand the biogeochemical processes responsible for the long-term behavior of technetium in the environment and its transfer through food chains as well as to identify critical pathways of the long-lived radioisotope Tc-99 from the environment to man.
Various reaction mixtures for the preparation of 99Tc(Sn)-pyrophosphate were investigated by means of gel chromatography. All components were radioactively labeled. The most likely composition of the complexes, which also appear in "no carrier added" preparations, was determined. At pH 7 one complex is found with the composition TcPyp2. Two complexes are found at pH 4: TcPyp and TcPyp2. Further, at pH 7 a polymeric technetium compound is found not containing tin or pyrophosphate.
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Uptake of Tc-99m di-isopropyliminodiacetic acid (DISIDA) by hepatocellular carcinoma was assessed in 30 patients showing obvious liver defects on a Tc-99m tin colloid image. In none of these patients was there complete "filling in" of the defects, and even partial "filling in" occurred in only 11 (36.7%). There was no uptake of Tc-99m DISIDA by the primary tumor in the remaining 19 patients (63.3%). In 19 of the 30 patients an attempt was made to correlate the degree of histologic differentiation of the tumor with the uptake of DISIDA by the tumor. No difference in uptake could be demonstrated between well, moderately, and poorly differentiated tumors. Tc-99m DISIDA was not taken up by pulmonary metastases in the only two patients tested. We conclude that imaging with Tc-99m DISIDA in conjunction with Tc-99m colloid is of no value in the specific diagnosis of hepatocellular carcinoma.
For the recognition and characterisation of oesophageal motor disorders, manometry represents the most reliable tool but yields no information on bolus transport. The transport can be quantitated by radionuclide techniques. The patient is positioned supine beneath a gamma-camera and instructed to swallow a radiolabelled bolus in a single gulp. Using a marker over the cricoid and the activity in the stomach as landmarks, regions of interest are drawn representing the upper, middle and lower third of the oesophagus and the gastric fundus. Activity-time curves enable one to recognise the clearance patterns in these regions. In combination, manometric and radionuclide transit studies recognise a higher number of motor disorders than either procedure alone. Radionuclide methods also are the most reliable and sensitive to quantitate gastric emptying. Procedure, meal size and composition as well as patient position must be standardised and correction techniques applied. The emptying of solid and liquid meal constituents can be evaluated concomitantly. Solids start to empty only after a lag phase of varying extent. With semi-solid meals, which are emptied at the same rate as solid meals of identical composition in the postlag phase, the recording time can be considerably shorter. Besides gastric emptying, the amplitude, frequency and propagation velocity of antral contractions can be recorded using serial images of short frame time and specially devised analytic techniques.
The quality of a number of commercial human albumin kits used at Danish hospitals for preparation of 99mTc-labelled human serum albumin has been investigated by column chromatography and HPLC. In general, the radiochemical purity was found to be low (75% or less). In some cases with a poor radiochemical purity, the main radiochemical impurity, 99mTc-labelled tin colloid, amounted to 29% or more. A large molar tin to albumin ratio seems to lead to a low radiochemical purity and it is suggested that products with a high content of stannous chloride may be more correctly termed 99mTc-albumin/tin-colloid kits.