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Biomedical subjects

B Bubeck

Publications and source records attributed to B Bubeck.

At least 37 records · Page 2Linked to original sources
PubMed1992

Reduction of myocardial ischemia by gallopamil: a dual-isotope study with thallium-201 and iodine-123 phenylpentadecanoic acid.

The present study was performed for characterizing the effect of chronic oral treatment with the calcium antagonist gallopamil on regional myocardial perfusion and free fatty acid utilization in poststenotic human myocardium. Twenty-two patients with angiographically documented coronary artery disease and stable angina pectoris underwent consecutive dual-isotope studies following simultaneous injection of 80 MBq thallium-201 and 200 MBq iodine-123 phenylpentadecanoic acid (IPPA) during a symptom-limited stress test. Radionuclide studies were performed after 1 week of placebo treatment (baseline), 4 weeks after oral treatment with 50 mg of gallopamil t.i.d. and again after 1 week of double-blind treatment with gallopamil or placebo. As compared to baseline, initial (poststress) uptake of both tracers in poststenotic myocardial segments was significantly improved after 4 weeks of treatment with gallopamil [thallium-201, +9.0%; p < 0.001; 95% confidence interval (CI), 4.3-13.6%; IPPA, +11.8%; p = 0.003; 95% CI, 4.2-19.3%]. Poststenotic IPPA-clearance was likewise significantly increased (+28.2%; p < 0.001; 95% CI, 12.4-44.0%) indicating a considerably enhanced myocardial fatty acid oxidation after treatment. In the final double-blind phase, myocardial uptake of both tracers as well as IPPA clearance remained enhanced in the subgroup of patients receiving gallopamil and returned to baseline values in patients receiving placebo. Thus, in poststenotic myocardium, chronic treatment with gallopamil provokes an improvement of both regional myocardial perfusion (as demonstrated by an increased tracer uptake in poststress scintigrams) and regional myocardial fatty acid utilization (as demonstrated by an increased uptake and clearance of IPPA).

Algorithms↗
PubMed1991

[Papillary thyroid carcinoma in a median ectopic thyroid associated with intra-abdominal thyroid tissue].

A 17-year-old female underwent surgical removal of a painless submental lump presumed to be a median cervical cyst. Histology showed a papillary thyroid carcinoma with invasion of the surrounding connective tissue. A 99m-technetium scan, performed in preparation for a planned total thyroidectomy, demonstrated no thyroid tissue. On subsequent 123-iodine scanning there was an area of increased uptake about 3 cm above the larynx, but no normal thyroid tissue. Histological sections, obtained during further surgical exploration of the base of the tongue, showed scattered thyroid cell rests in the lingual muscles. Whole-body scanning, carried out in connection with administration of radioiodine for ablation of remaining thyroid tissue, disclosed an unexpected area of increased uptake in the epigastrium. Sonography and CT scans failed to demonstrate any corresponding morphological abnormality. Following a further dose of radioiodine 4 months later, no areas of increased uptake were noted.

Abdominal Neoplasms↗
PubMed1991

Non-invasive detection of reduced regional myocardial perfusion at rest in patients with unstable angina pectoris: increased regional 81mKr deposition following intravenous injection of 81Rb.

The present study was to investigate whether combined imaging of 81Rb and 81mKr distributions after i.v. injection of 81Rb at rest might improve the differentiation between ischemic and irreversibly damaged myocardium as compared to 201Tl scintigraphy at rest. In 21 patients who had undergone diagnostic cardiac catheterization for evaluation of chest pain, 148 MBq ultrapure 81Rb were injected i.v. at rest immediately following 201Tl scintigraphy at rest. Of 14 patients with earlier myocardial infarction, 10 patients revealed decreased regional tracer uptake of 81Rb and/or 81mKr, compared to 12 patients with regional 201Tl uptake abnormalities. In 3 patients with unstable angina pectoris, however, an evident mismatch between either the regional 201Tl or 81Rb distributions and the distribution of 81mKr was observed: in contrast to the reduced uptake of 201Tl and/or 81Rb, 81mKr activity was increased in 3 myocardial segments with normal left ventricular performance but supplied by coronary arteries with high-grade stenoses. In patients with contraindications to exercise tests (e.g. unstable angina) 81Rb/81mKr rest scintigraphy may therefore assist the differentiation between malperfused but potentially viable and irreversibly damaged myocardium.

Angina, Unstable↗
PubMed1990

Pharmacokinetics of technetium-99m-MAG3 in humans.

Technetium-99m-mercaptoacetylglycylglycylglycine (99mTc-MAG3) is introduced to replace o-iodohippurate (OIH) for renal function studies. For interpretation of clinical findings, extensive pharmacokinetic studies were performed on patients. These showed that 99mTc-MAG3, compared with OIH, has a higher plasma-protein binding, an essentially higher intravascular concentration, a smaller volume of distribution and, with practically identical biologic half-lives, a correspondingly lower clearance. Simultaneous steady-state measurements resulted in a 1.5-fold higher clearance of OIH than of 99mTc-MAG3 (n = 124). Competitive inhibition of the tubular transport system by p-aminohippurate (PAH) (20 patients) revealed a distinctly higher suppression of the 99mTc-MAG3 clearance than of OIH which indicates a lower affinity of the 99mTc complex to the tubular cell. The plasma extraction efficiencies of both agents, measured during surgery (n = 5), did not indicate an extrarenal elimination of 99mTc-MAG3. This new radiopharmaceutical is a pragmatic alternative to OIH and offers advantages not only for scintigraphic imaging but is also suited for quantitative renal function studies.

Humans↗
PubMed1989

[Effects of gallopamil on iodine-123-phenyl-pentadecanoic acid and thallium 201 uptake in patients with coronary heart disease].

Numerous experimental and clinical studies indicated that in the presence of coronary artery stenoses, myocardial thallium-201 and free fatty acid uptake in poststenotic regions is reduced during exercise. The aim of this study was to investigate the effect of the calcium antagonist gallopamil on myocardial thallium-201 and free fatty acid uptake in patients suffering from coronary artery disease. In 6 patients with angiographically proven coronary artery disease--2 patients with 1-vessel, 2 patients with 2-vessel and 2 patients with 3-vessel disease--as well as good left ventricular performance and stable, exerciseinduced angina, quantitative double-tracer scintigraphy was performed. Patients were investigated after a placebo period of 1 week, after oral gallopamil medication for 4 weeks (3 X 50 mg gallopamil daily), and after a double-blind period of 1 week. During symptom-limited exercise, 2 mCi thallium-201 and 5 mCi iodine-123 phenyl-pentadecanoic acid (IPPA) were simultaneously injected intravenously. Immediately after exercise, as well as 1 and 4 hours later, planar images were obtained in ap, 30 degrees LAO and 60 degrees LAO projections. By means of a newly developed computer algorithm, global and regional myocardial tracer uptake as well as IPPA clearance were evaluated. - Gallopamil provoked a decrease of global myocardial thallium-201 and IPPA uptake due to a reduction of myocardial oxygen consumption. Regional thallium-201 and IPPA uptake as well as myocardial IPPA clearance in poststenotic areas tended to rise following gallopamil medication. Thus, in the presence of coronary artery disease, gallopamil provokes an improvement of regional perfusion (dilatation of larger coronary arterioles) as well as an enhanced free fatty acid utilization in reversibly ischemic myocardial regions.

Angina Pectoris↗
PubMed1988

Results of liver angiography and perfusion scintigraphy do not correlate with response to hepatic artery infusion chemotherapy.

Liver angiography and liver perfusion scintigraphy with Tc-99m-labeled macroaggregated albumin (MAA) were performed in 36 patients with liver metastases from colorectal cancer prior to continuous 5-fluorouracil hepatic artery infusion (HAI) hemotherapy. Of the 26 patients showing metastases on arteriogram, five revealed increased tumor vascularisation, five had normal vascularisation, and 16 showed decreased vascularisation of the metastases relative to liver. In liver perfusion scintigraphy, 15 of the 36 patients showed increased perfusion of the metastases, four had normal perfusion, and 17 had decreased tumor perfusion. The observed differences in survival in the different groups were not statistically significant: patients survived 15 months in the group with increased tumor vascularisation, 8 months for normal vascularisation, and 14 months for decreased tumor vascularisation; survival was 28 months for the group of increased, and 13 and 14 months for the normal and decreased tumor perfusion groups respectively. Also, response rates with 80%, 40%, and 75% responders in the group of increased, normal, and decreased tumor vascularisation, respectively, and 80%, 50%, and 59% responders in the group of increased, normal, and decreased perfusion, respectively, were not significantly different. These results indicate that there is no possibility to discriminate potential responders from nonresponders by results of liver angiography or perfusion scintigraphy.

Hepatic Artery↗
PubMed1988

Technetium-99m labeled renal function and imaging agents: III. Synthesis of 99mTc-MAG3 and biodistribution of by-products.

99mTc-MAG3, a new 99mTc radiopharmaceutical with biological properties similar to o-iodohippuric acid (OIH), is expected to find wide clinical application for renal function studies. Therefore it is important to make a kit formulation available which provides reproducibly the desired product in high radiochemical yields. Some differences between the biokinetic data of kit prepared 99mTc-MAG3 and HPLC-purified 99mTc-MAG3 were reported by different authors. The subject of this paper is the isolation of the by-products which are formed with our own kits, the evaluation of their biological behaviour and the comparison with the main product 99mTc-MAG3 in rats. The results suggest that the radiochemical purity of 99mTc-MAG3-preparations should be not less than 95%.

Animals↗
PubMed1988

Technetium-99m labeled renal function and imaging agents: I. Clinical evaluation of 99mTc CO2-DADS-A (99mTc N,N'-bis-(mercaptoacetyl)-2,3-diaminopropanoate).

Animal experiments and preliminary clinical results showed that the N2S2-complex 99mTc CO2-DADS-A, which was claimed to be a potential replacement for o-I-hippurate as a renal function agent, had a lower affinity for the tubular transport system than o-I-hippurate. In order to evaluate if this finding offered the possibility of detecting decreases in tubular function with more sensitivity, or at earlier times, 6 patients in the early post-transplantation period were subjected to 53 simultaneous scintigraphic investigations with 131I o-I-hippurate and 99mTc CO2-DADS-A. The comparison of the renograms obtained with the respective agents showed that in almost all cases of acute graft rejection only o-I-hippurate yielded the typical, diagnostically useful accumulation curve which results from its high retention in the kidney parenchyma. 99mTc CO2-DADS-A did not reveal this effect. Additionally the plasma clearance of each agent was measured simultaneously under steady state conditions in nine patients. Although it was reported that relative to o-I-hippurate the analog images obtained with 99mTc CO2-DADS-A gave higher kidney-to-background ratios and the amount excreted in the urine at 30 min was slightly less, the clearance values obtained for 99mTc CO2-DADS-A were on average only 36% of those for o-I-hippurate. It is concluded that 99mTc CO2-DADS-A is not suitable as a substitute for o-I-hippurate.

Alanine↗
PubMed1988

Technetium-99m labeled renal function and imaging agents: II. Clinical evaluation of 99mTc MAG3 (99mTc mercaptoacetylglycylglycylglycine).

First clinical results indicated that among all potential 99mTc-complexes the N3S-complex 99mTc MAG3 has the biokinetic properties most similar to o-I-hippurate (OIH). A simultaneous comparison of 99mTc MAG3 and 131I OIH was conducted in a series of 48 patients. Twelve out of 18 transplant patients received simultaneously both radiopharmaceuticals for follow-up scintigraphic studies during the early post-transplantation period. In all of these double tracer studies (n = 90) the renograms obtained with 99mTc MAG3 exhibited qualitatively the same curve-shapes, compared with OIH, in cases of acute graft rejection or acute tubular necrosis. In addition, both agents were administered simultaneously to 46 of these patients and the plasma clearance values were determined under steady state conditions. The clearance data of both radio-pharmaceuticals showed a very good correlation (r = 0.95; P less than or equal to 0.05). The 99mTc MAG3/131I OIH clearance ratio showed a mean value of 0.65. Due to the high plasma protein binding of 99mTc MAG3 it is assumed not to be filtered through the glomerular membrane. Therefore we introduce for the 99mTc MAG3 clearance the term "Tubular Extraction Rate (TER)". Due to the favourable physical characteristics of 99mTc, higher activities can be administered as compared to 131I OIH. This allows the simultaneous examination of the tubular function as well as the renal perfusion. Additionally the kidney morphology is imaged with much better resolution. It is concluded that from the clinical point of view 99mTc MAG3 is a favourable replacement for OIH not only for renal imaging but also for the quantitative determination of tubular function. The acceptance will depend on the quality and on the handling of a commercially available kit formulation.

Animals↗
PubMed1986

[Bone marrow scintigraphy using radiocolloids in bone metastases. Sensitivity, specificity, reliability and indications].

The sensitivity and specificity of bone marrow scintigraphy in demonstrating skeletal metastases was examined in 40 patients with focal metastases. Radiology and MDP scintigraphy were used as reference methods. Sensitivity depends on the region of the skeleton. False negatives are the rule in parts of the skeleton containing little bone marrow. In relation to the entire bone marrow content, sensitivity is 0.64. The high proportion of false negatives (36%) in the presence of confirmed metastases and the incomplete demonstration of the bone marrow makes marrow scintigraphy unsuitable as a screening method. Occasionally lesions confined to the marrow can be demonstrated when radiographs and bone scintigrams are still negative. In advanced cases, marrow scintigraphy can demonstrate the extent of destruction of the bone marrow. Demonstration of displacement or of an 'empty bone' is evidence of invasion of the bone marrow in patients with tumours. In patients with reduced haematopoiesis of unknown origin or unidentified diffuse skeletal uptake, bone marrow scintigraphy may provide valuable information.

Adult↗
PubMed1985

[Scintigraphic imaging of benign and malignant tumors of the sympathetic nervous system with meta-iodobenzylguanidine].

The authors report on their experiences with metaiodine-benzylguanidine (MIBG) scintiscanning in a total of 36 patients. 7 of these patients had a benign pheochromocytoma, 4 a malignant one; neuroblastoma was seen in 10 patients. Scintiscan diagnosis was supplemented by measurements of irradiation exposure and attainable tumour dose. It was also shown that it is possible to mark neuroblastoma cells in cultures. The results of these studies are discussed and compared with those of other working groups. If the physiological pattern of distribution is taken into consideration, and if the proper imaging technique is adopted, MIBG scintiscan is a sensitive and highly specific method in diagnosing pheochromocytomas and neuroblastomas.

3-Iodobenzylguanidine↗
PubMed1984

[Radioiodine therapy of differentiated thyroid cancer. 10-year results of a standardized therapy in 269 patients].

Between 1969 and 1977, 269 patients submitted to thyroidectomy were treated exclusively with radioiodine according to a standardized irradiation scheme. The patients were observed during thirteen years. 195 patients were free of metastases at the time of the first therapy, whereas 74 patients had lymph node metastases or remote metastases. The survival rates of the total group were 89% (five years) and 76% (10 years), respectively. Patients with regional lymph node metastases had a ten-year survival rate of 74%. The fourty patients suffering from remote metastases had a five-year survival rate of 75% and a ten-year survival rate of 40%. Patients who were in stage T3 at the moment of diagnosis had a survival probability of 74% for five years and of 59% for eight years. None of these patients presented with remote metastases during the follow-up period. Taking into consideration these results and the small rate of complications, we are of the opinion that a routine combination therapy with external post-irradiation is not necessary.

Adenocarcinoma↗
PubMed1984

[Nuclear medicine diagnosis of malignant lymphomas].

Non-invasive and hazard-free methods for diagnosing malignant lymphomas are represented by scintigraphy with gallium 67 and by lymphoscintigraphy, especially of the retroperitoneum. These methods are particularly suitable for closely following up the course of the disease. In this article, radiopharmacology, pharmacokinetics and techniques of examination associated with these methods, are described, and typical findings are demonstrated by means of clinical case examples. Attention is also paid to radiation exposure load. The ranking of these methods within the framework of x-ray diagnostics, is also discussed.

Adult↗