PubMed Health⌕ Search

Biomedical subjects

R Montz

Publications and source records attributed to R Montz.

At least 19 recordsLinked to original sources
PubMed1992

Detection of colorectal carcinomas by intraoperative RIS in addition to preoperative RIS: surgical and immunohistochemical findings.

The immunoscintigraphic detection of tumour foci less than 1 cm in diameter fails even with single photon emission tomography (SPET) owing to low contrast against background activity. In an attempt to improve detection of macroscopically invisible tumour spread, intraoperative scintimetry (IOSM) with a hand-held gamma-probe was performed in addition to SPET 24-30 and 41-48 h after injection of the technetium-99m carcinoembryonic antigen (CEA MoA) on 12 patients with colorectal carcinoma and 3 patients with different neoplastic and inflammatory diseases. Tumour specimens were measured in vitro in a gamma well counter. For comparison, the presence and amount of CEA in the tumour cells were evaluated immunohistochemically. After modification, the gamma-probe originally designed for iodine-131 was 20 times more sensitive; activities of 99mTc located close to the collimator hole were measured with absolute sensitivity of 100 cps = 2.5 kBq 99mTc. The unfavourably high background activity affected both the in vitro and in vivo analysis: SPET results had been considered positive in 8 of 15 cases. In vitro tumour/non-tumour (t/nt) ratios greater than 2.0 were found in 4 cases. In vivo IOSM resulted in t/nt ratios greater than 2.0 in only 3 patients. In most cases, there was no coincidence of elevated t/nt ratios from the different methods. A correlation was derived between positive immunoscintimetric in vitro findings and immunohistochemically proven interstitial localization of CEA in tumor cells. In conclusion, the measurement technique of IOSM seems adequate, but clinical success will depend on a more specific enrichment of MoA in tumour tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Radioimmunodiagnosis of pancreatic cancer disease.

From a theoretical point of view, immunoscintigraphy of exocrine pancreatic cancer offers itself as a promising diagnostic method. However, the actually available clinical and experimental data point out that the indication for diagnostic application in patients with pancreatic carcinoma has to be viewed more critically than in the case of, e.g., colorectal cancer disease. The quality of imaging depends on a lot of factors, such as the cellular antigen expression, the affinity of the MAbs to the corresponding antigens expressed by the cells, tumor vascularization, tumor size, and unspecific background activity as well as on labeling techniques, the kind of antibodies used, and the technical equipment. All these factors may vary from one patient to the other and from one center to the other. In summarizing the available clinical data, we have to state that immunoscintigraphy does not allow early detection of pancreatic cancer and, consequently, does not allow screening for early stages in asymptomatic patients. Even nowadays primary diagnosis and staging should be based on the imaging methods of ultrasound, CT and/or ERCP, and angiography. With respect to detection of local recurrence and especially peritoneal carcinosis, immunoscintigraphy, however, may be superior when compared to the other imaging methods. The potential clinical value for followup and as a preinvestigation to assess the probability of effective MAb treatment has still to be evaluated in prospective clinical studies. Altogether, a lot of experimental and clinical work remains to be done to introduce immunoscintigraphy of pancreatic cancer into clinical practice as a routine method.

Animals↗
PubMed1990

Detection of human collateral circulation by vasodilation-thallium-201 tomography.

Coronary arteriolar vasodilation may provoke redistribution of flow to collateral-dependent jeopardized myocardium. To assess the physiologic significance of collaterals, 80 consecutive post-infarction patients (age 58 +/- 8 years) underwent vasodilation-redistribution thallium-201 tomographic imaging after administration of 0.56 mg of intravenous dipyridamole/kg body weight. Circumferential profile analysis of thallium-201 uptake and redistribution in representative left ventricular tomograms provided quantitative assessment of transient and fixed defects and separation between periinfarctional and distant inducible hypoperfusion. Tomographic perfusion data were correlated to wall motion and collateral circulation between distinct anatomic perfusion territories. Patients were grouped according to presence (59%) or absence (41%) of angiographically visible collateral channels to jeopardized myocardium. In the presence of collaterals, distant reversible defects were larger than in absence of collaterals (p less than 0.05); the extent of combined periinfarctional and distant redistribution was also larger in collateralized patients (p less than 0.025), whereas the size of the persistent perfusion defect was similar in both groups. By prospective analysis the tomographic perfusion pattern of combined periinfarctional and distant redistribution revealed a sensitivity of 85% and a specificity of 78% for the detection of significant collateral circulation in this group of patients. Thus, using the exhausted flow reserve as a diagnostic tool, vasodilation-thallium-201 tomography has the potential to identify and quantitate collateralized myocardium in post-infarction patients and may guide diagnostic and therapeutic decision-making.

Cardiac Catheterization↗
PubMed1990

Assessment of post-infarction jeopardized myocardium by vasodilation--thallium-201 tomography: impact on risk stratification.

For the purpose of risk stratification 80 consecutive patients (mean age 58 +/- 7 years) with a chest pain syndrome after documented myocardial infarction underwent tomographic vasodilation-redistribution thallium-201 perfusion imaging, using 0.56 mg kg-1 intravenous dipyridamole. Tomograms were analysed for size and location of reversible and fixed perfusion defects and correlated to angiographic characteristics, left ventricular ejection fraction and wall motion, collateral status and 1-year prognosis, as measured by cardiac events within 12 months. No serious side-effects were noted with the diagnostic use of intravenous dipyridamole. According to the perfusion pattern three subgroups of post-infarction patients were identified: (1) by ischaemia at a distance with redistribution in non-infarct related territories (n = 48); (2) by peri-infarctional ischaemia with redistribution in the territory of the 'infarct artery' (n = 9); and (3) by exclusively fixed defects without redistribution (n = 23). Ischaemia at a distance was associated with a larger reversible defect than peri-infarctional ischaemia (P less than 0.05) and the pattern without redistribution (P less than 0.005); the fixed defect size, however, was similar in all three subgroups. In addition, the severity of coronary artery disease (Gensini score and number of diseased vessels) and the degree of collateralization was higher in the presence of a redistribution pattern (P less than 0.05), although no significant differences in global and regional function were noted as a function of thallium-201 redistribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Recovery of left ventricular function after myocardial infarction can be predicted immediately after thrombolysis by semiquantitative intracoronary thallium and technetium pyrophosphate scintigraphy.

The accuracy with which intracoronary thallium and technetium pyrophosphate scintigraphy during intracoronary thrombolysis predicts myocardial salvage was studied in 58 patients with acute myocardial infarction by comparing the acute scintigraphic findings with subsequent left ventricular function. Scintigrams obtained before and immediately after thrombolysis were interpreted by three independent observers using a scoring system. Regional wall motion in the infarct area was determined from left ventricular (LV) cine angiograms using the center-line method. Patients with mild hypokinesis (hypokinesis less than or equal to -2 SD from normal) could be distinguished from those with severe hypokinesis (hypokinesis greater than -2 SD) using the prethrombolysis thallium score with an accuracy of 83%. Accuracy using the post-thrombolysis score was 76%. When the post-thrombolysis thallium and technetium pyrophosphate scores were combined, differentiation was possible in 91% of all patients studied, and in 100% of patients with anterior myocardial infarction. Thus, analysis of combined thallium and technetium pyrophosphate scintigraphy accurately predicts recovery of LV function after thrombolysis and may be helpful in deciding whether acute percutaneous transluminal coronary angioplasty or bypass surgery should be performed after thrombolysis.

Cardiac Output↗
PubMed1988

Immunoscintigraphy with combinations of various monoclonal antibodies--studies on xenografts of human gastrointestinal carcinomas.

In order to investigate whether combinations of monoclonal antibodies (MAbs) allow a more sensitive and valid localisation of tumors by immunoscintigraphy compared to the application of single MAbs we injected 3.7 MBq/animal of various 131I-labelled MAbs (anti-CA 19-9, -CA 125, -CEA, BW 494/32, 431/31) or equivalent combinations thereof into NuNu-Balb-C mice bearing xenografts of human gastrointestinal tumors. In addition, "dose response curves" were calculated in order to evaluate the results for different total doses. As parameters we mainly used quality of the scans, fractional uptake of injected dose and tumor/blood or tumor/organ ratios. The results do not support the concept that "cocktails" of MAbs improve the results of immunoscintigraphy. In contrast, a single MAb should be used for clinical immunoscintigraphy, preferably the most appropriate one according to the results of serum determinations of the corresponding tumor-associated antigens or of immunohistochemistry. Cocktails or consecutive applications of different MAbs for immunoscintigraphy should be restricted to cases without dominant tumor-associated antigen and corresponding MAb, respectively, and to patients in whom a first trial with a first single MAb failed.

Animals↗
PubMed1988

[Radioimmunotherapy of solitary liver metastases using intratumor instillation of 131I-labeled monoclonal antibodies--initial results of a clinical study].

Solitary liver metastases (carcinoembryogenic antigen positive) in two patients suffering from colon carcinoma were multifocally injected with 131I-labelled monoclonal antibodies (131I-MAb) against the carcinoembryogenic antigen (CEA). The 131I activity in the metastases decreased biexponentially. The 131I serum concentration declined triexponentially in patient 1 and monoexponentially in patient 2. The radiation dose to the whole tumor volume amounted to 358 Sv and 762 Sv, respectively; the whole-body radiation dose was 87.5 mSv for patient 1 and 39.0 mSv for patient 2. Complications did not occur. Before treatment there had been a volume doubling time of the metastases of 1.5 and 0.9 months, respectively; this contrasts with a constant tumor volume after treatment as observed over the follow-up period of 3.5 and 2 months, respectively. The CEA serum concentration decreased after 131I-MAb instillation within 1.5 and 2.5 months to 66% and 58%, respectively, when compared with values immediately before treatment. On the basis of these results the intratumoral application of 131I-MAb appears in selected cases to be a suitable method of slowing down growth of liver metastases from gastrointestinal tumors.

Antibodies, Monoclonal↗
PubMed1987

Right ventricular ejection fraction from equilibrium krypton-81m blood pool scans: a noninvasive predictor of pulmonary arterial hypertension.

Based on the relation between the impedance to right ventricular ejection and ejection fraction of the right ventricle (RVEF) we tested the hypothesis that radionuclide RVEF correlates inversely with pulmonary artery pressure and allows the noninvasive prediction of pulmonary hypertension. A recently developed improved equilibrium right ventricular blood pool imaging technique using ultrashort-lived krypton-81m and simultaneous right heart catheterization were combined for assessment of right ventricular systolic performance in relation to right ventricular loading in a heterogeneous group of cardiopulmonary disorders. The study group included 9 patients with pulmonary artery hypertension secondary to left ventricular dysfunction, 5 with primary pulmonary hypertension, 5 with corrected tetralogy of Fallot, and 10 normal subjects. Linear regression analysis between radionuclide RVEF and simultaneously recorded hemodynamic measurements of right ventricular loading revealed a significant inverse correlation with mean PA pressure (r = -0.87; P less than 0.001), with total pulmonary resistance index (r = -0.81; P less than 0.001) and with pulmonary vascular resistance index (r = -0.78, P less than 0.01). The sensitivity and specificity of a resting RVEF less than 40% to indicate pulmonary hypertension (mean PA pressure greater than 20 mmHg) were 71% and 100%, respectively; positive and negative predictive values were 100% and 80%, respectively. Thus, radionuclide RVEF as a parameter of right ventricular systolic performance is predominantly dependent on right ventricular afterload and has the potential for the noninvasive prediction of pulmonary hypertension in a heterogeneous group of cardiopulmonary disorders.

Humans↗
PubMed1987

Tomographic myocardial perfusion scintigraphy in children with Kawasaki disease.

Myocardial infarction and stenotic coronary lesions are serious late complications in children with Kawasaki disease. For the noninvasive assessment of myocardial perfusion, dipyridamole-redistribution 201Tl emission computed tomography (ECT) was performed in seven children (age 2 8/12-8 7/12 yr) 3-20 mo after the acute stage of the disease. In all patients, coronary aneurysms had been demonstrated by cross-sectional echocardiography. The scintigrams of six children showed no significant regional reduction of myocardial thallium uptake. These children had remained asymptomatic since the acute stage of Kawasaki disease. Persistent and transient thallium defects were present in one child with documented myocardial infarction. For this patient, obstruction of corresponding coronary vessels was confirmed by contrast angiography. It is suggested, that 201Tl ECT after dipyridamole-induced vasodilation may be used as a safe alternative to invasive coronary angiography for follow-up investigations in patients with Kawasaki disease.

Child↗
PubMed1987

[Noninvasive identification of collateralized myocardium by 201 thallium tomography in vasodilation and redistribution].

Coronary arteriolar vasodilatation may provoke the redistribution of flow to collateral-dependent jeopardized myocardium. To assess the physiologic significance of collateral channels, 80 consecutive postinfarction patients (aged: 58 +/- 8 years) underwent vasodilatation/redistribution thallium-201 tomographic (SPECT) imaging using 0.56 mg dipyridamole/kg body weight. Circumferential profile analysis of redistribution and slow washout in representative left ventricular tomograms provided quantitative evaluation of transient and persistent defects and a separation between a periinfarctional and distant inducible hypoperfusion. Tomographic perfusion data were correlated to subsequent cineangiographic analysis of wall motion and to the extent of collateral circulation between two distinct anatomic perfusion areas, one of which involved the infarct zone. Patients were grouped according to the presence (59%) or absence (41%) of angiographically visible collateral channels to the jeopardized myocardium. In the presence of collaterals, distant reversible defects were larger than in the absence of collaterals (p less than 0.05); the extent of combined periinfarctional and distant redistribution was also larger in collateralized patients (p less than 0.025), whereas the size of the persistent perfusion defect was similar in both groups. In a prospective analysis, the tomographic perfusion pattern of combined periinfarctional and distant ischemia revealed a sensitivity of 85% and a specificity of 78% for the detection of significant collateral circulation in this group of patients. Thus, using the limited collateral flow reserve as a diagnostic tool, vasodilatation/redistribution thallium-201 tomography has some potential for identifying and quantifying collateral-dependent myocardium and may guide diagnostic and therapeutic decision-making.

Aged↗
PubMed1986

Development of pulmonary aneurysm in primary pulmonary hypertension: a case report.

Selected cases of severe primary pulmonary arterial hypertension and associated pulmonary vascular disease have been related to the oral ingestion of aminorex fumarate, an anorexigen obviously responsible for an epidemic of primary pulmonary hypertension in Western Europe between 1967 and 1970. This report describes a fifteen year follow-up of a female patient with aminorex fumarate related pulmonary hypertension and the uncommon finding of the formation of an excessive fusiform pulmonary trunk aneurysm in the late stage of the disease process. The progressive clinical course was followed by serial chest x-ray films and repeat right heart catheterization. The diagnosis of a main stem pulmonary artery aneurysm was noninvasively established by two-dimensional echocardiography and confirmed by contrast-enhanced computed tomography and radionuclide blood pool imaging. The patient is alive, thus no histologic correlate of this entity is available at present.

Aminorex↗
PubMed1986

[Early noninvasive detection of reperfusion and infarct by intravenous technetium 99m pyrophosphate scintigraphy following thrombolysis].

To determine whether technetium-99-pyrophosphate accumulation immediately after intravenous thrombolysis can serve as a marker of reperfusion and infarct size, 17 patients with acute myocardial infarction were studied. Immediately after thrombolysis 10 mCi of technetium-99m pyrophosphate were injected intravenously. Coronary and left ventricular angiography were then performed in all patients, revealing patent coronary arteries in 13 patients. In all patients, 0.3 and 0.5 mCi of thallium-201 were injected into the right and left coronary artery, respectively, followed by planar scintigraphy. 6 patients with patent coronary arteries and a large thallium-201 defect had massive (more than one third of the cardiac silhouette) pyrophosphate accumulation (group A), whereas 7 patients with a small or no thallium-201 defect in the presence of a patent infarct artery had either focal or no pyrophosphate accumulation (group B). In contrast, 4 patients with an occluded infarct artery showed no acute pyrophosphate uptake despite a large thallium-201 defect (group C). Emission computed tomography confirmed the planar scintigraphic data in group A patients and revealed small thallium-201 defects and focal pyrophosphate accumulation in group B patients with negative planar scintigrams. Global and regional ejection fractions in the infarct area, measured from the acute and follow-up left ventricular angiograms, were higher in group A than in group B and C patients. It is concluded that early intravenous technetium-99m pyrophosphate scintigraphy in patients with acute myocardial infarction undergoing intravenous thrombolysis may serve as an indicator of reperfusion and infarct size.

Adult↗
PubMed1986

Immunoscintigraphy and radioimmunotherapy in patients with pancreatic carcinoma.

A new monoclonal antibody (BW 494/32) labeled with 131I or 111In was used for planar and tomographic immunoscintigraphy (IS) in patients with pancreatic carcinoma. It appears that IS for pancreatic carcinoma and its metastases remains a hopeful but still difficult procedure and labeling with 111In is of advantage and results in more convincing images in the case of tumor lesions distant from liver and spleen. Attempts at radioimmunotherapy with 131I-anti-CA 19-9 and with 131I-494/32 in a patient with local recurrence of a pancreatic cancer and with large liver metastases were without success because of extremely poor blood supply to the metastatic tumor masses. Intraarterial infusion of the tracer without or with blockade and perfusion of the common hepatic artery with saline solution could not enhance the tracer uptake compared to that after intravenous infusion. High intratumoral concentrations, however, as achieved e.g. by intratumoral instillation in animal studies, represent a necessary precondition for effective beta-irradiation of tumor lesions.

Adult↗
PubMed1986

Radioimmunotherapy of xenografts of human pancreatic carcinomas--intravenous and intratumoral application of 131I-labelled monoclonal antibodies.

The effects of radioimmunotherapy were tested in xenografts of 2 different human pancreatic carcinomas comparing the intravenous and intratumoral application. On principle, intravenous injections of high doses of 131I-anti-CA 19-9 or -BW 494/32 may inhibit tumor growth. In view of the low direct radiation dose (360-2100 rad), however, other factors than direct toxic effects have to be discussed, e.g. systemic effects due to the high whole-body irradiation. Intratumoral application, however, may induce tumor regression or growth inhibition due to the high local irradiation dose. Consequently, this treatment modality might be of clinical value at least in some patients.

Animals↗
PubMed1986

[Localization and quantification of ischemic myocardial areas in the postinfarct phase by dipyridamole 201thallium emission computerized tomography].

In 41 patients with a history of an acute myocardial infarction, the location of myocardial ischemia was studied by 201Tl emission computed tomography immediately and 3 h after intravenous dipyridamole. Distant ischemia was distinguished from peri-infarctional ischemia by the presence of transient thallium defects in, or slow thallium washout from myocardium not supplied by the infarct-related coronary artery. Ischemia at a distance occurred in 13 patients and was always accompanied by peri-infarctional ischemia. Peri-infarctional ischemia without distant ischemia was observed in 15 patients. The occurrence of distant ischemia was found to be dependent on the severity of stenosis in non-infarct coronary vessels. 12 (86%) of 14 patients with non-infarct stenosis of 75% or greater had distant ischemia, but only 1 (4%) of 27 patients with a stenosis of less than 75% in another vessel. In the presence of distant ischemia, peri-infarctional ischemia was in 11 patients (85%) associated with collaterals supplying the infarct zone, whereas in 13 (87%) of the patients with peri-infarctional ischemia only, incomplete obstruction of the infarct-vessel was observed. It is concluded that, by the distinction between peri-infarctional and distant ischemia, the presence of a significant stenosis in non-infarct vessels can be non-invasively predicted from tomographic thallium scintigraphy with dipyridamole.

Angina, Unstable↗
PubMed1985

Scintigraphic evidence of the "no reflow" phenomenon in human beings after coronary thrombolysis.

To assess whether the absence of new thallium-201 uptake after successful intracoronary thrombolysis reflects a disturbance of myocardial cell function or lack of capillary reperfusion, dual isotope scintigraphic studies with thallium-201 and technetium-99m micro-albumin aggregates were performed in 16 patients with acute anterior myocardial infarction. Intracoronary thallium-201 and technetium-99m scintigraphy performed before intracoronary thrombolysis in 12 of the 16 patients resulted in identical thallium-201 and technetium-99m defect sizes. Immediately after intracoronary thrombolysis, thallium-201 and technetium-99m scintigraphy was repeated in 11 of the 12 patients. In 4 of the 11, the initial thallium and technetium scintigraphic defects were significantly reduced, and in 6 of the 11, they were only slightly reduced; there was no difference in the size of the residual defect as assessed with both radionuclides in all 10 of the 11 patients. In the eleventh patient, there was a significant reduction of the initial technetium-99m scintigraphic defect but no change in the size of the thallium-201 defect. In four other patients, scintigrams were obtained only after intracoronary thrombolysis; these revealed no difference in thallium-201 and technetium-99m defect size. In seven of eight patients restudied 2 to 4 weeks after intracoronary thrombolysis, thallium-201 and technetium-99m defect sizes were identical with those immediately after intracoronary thrombolysis; in the eighth patient there was no difference in thallium-201 and technetium-99m defect size, although such a difference had been present immediately after intracoronary thrombolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Clinical use of ultrashort-lived radionuclide krypton-81m for noninvasive analysis of right ventricular performance in normal subjects and patients with right ventricular dysfunction.

The ultrashort-lived radionuclide krypton-81m, eluted in 5% dextrose from a bedside rubidium-81m generator, was intravenously infused for rapid imaging of the right-sided heart chambers in the right anterior oblique projection adjusted for optimal right atrioventricular separation. Left-sided heart and lung background was minimized by rapid decay and efficient exhalation of krypton-81m, requiring no algorithm for background correction. A double region of interest method decreased the variability in the assessment of ejection fraction to 5%. In 10 normal subjects, 11 patients with pulmonary hypertension, 4 patients with right ventricular outflow tract obstruction and 4 patients with right ventricular infarction, right ventricular ejection fraction determined by krypton-81m equilibrium blood pool imaging ranged from 14 to 76%. The correlation between these values and those determined by cineangiography according to Simpson's rule was close: r = 0.93 for all data points (p less than 0.001), r = 0.92 for studies at rest (p less than 0.001) and r = 0.93 for exercise studies (p less than 0.001). Exercise-related changes in right ventricular function revealed a disturbed functional reserve with pulmonary hypertension and right ventricular infarction, whereas in compensated right ventricular outflow tract obstruction there was a physiologic increase in ejection fraction with exercise (p less than 0.001). Thus, equilibrium-gated right ventricular imaging using ultrashort-lived krypton-81m is a simple, accurate and reproducible method with potential for serial assessment of right ventricular ejection fraction in a variety of right ventricular anatomic and functional abnormalities, both at rest and during exercise. Advantages of this method include an extremely low radiation dose to patients and clear right atrioventricular separation without the need to correct for background activity.

Adult↗