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Biomedical subjects

W E Adam

Publications and source records attributed to W E Adam.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Stress testing of long-term type I diabetic patients with radionuclide ventriculography].

Left ventricular function was assessed by means of radionuclide ventriculography in 42 patients with long-standing (13 +/- 5 yrs) insulin-dependent diabetes mellitus and in eleven healthy age matched control subjects. Only diabetics were included in the study without diabetes related cardiac risk factors such as hypertension and CAD in order to evaluate diabetes specific changes of cardiac function. No differences were seen between diabetics and controls concerning heart rate and functional parameters of left ventricle in systole and diastole. The rapid filling period was not prolonged. According to our radionuclide data there is no evidence of diabetes related impairment of ventricular function in young patients with long-standing type-1-diabetes mellitus.

Adult↗
PubMed1989

The contraction fraction (CF) in myocardial studies with technetium-99m-isonitrile (MIBI)--correlations with radionuclide ventriculography and infarct size measured by SPECT.

Criteria for the detection of coronary artery disease in nuclear cardiology include visualization of perfusion defects and functional impairment of contraction. The purpose of this study is to combine both methods in one procedure with the new myocardial perfusion tracer, 99mTc-methoxy-isobutyl-isonitril (MIBI), reducing time and radiation burden to the patient. Following an uncomplicated recovery, ten patients with first myocardial infarction participated in this study. Radionuclide ventriculography (RNV) was performed at rest and during exercise. Within 2-3 days, 370 MBq 99mTc-MIBI were injected and SPECT acquisition commenced 1 h later. Data processing included a scar image in polar coordinates. Areas of significantly reduced tracer uptake were expressed as a percentage of the total myocardial area. Directly following SPECT, resting and maximum exercise gated planar LAO images were recorded and the contraction was quantified. The concept of the contraction fraction (CF) rested on the end systolic change in count distribution: their increase in density and their centripetal concentration. For comparison, geometrical inner edge detection techniques were also applied. All algorithms for describing an EF equivalent were verified by computer simulations, showing a perfect correlation over a wide range of preset EFs. When applied to the patient studies only the non geometric methods revealed a good correlation with the ejection fraction (EF) obtained by RNV, and with the infarct size measured by SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1989

[Quantitative image analysis in nuclear cardiology as a decision aid in addition to visual assessment of findings].

Quantitative analysis of nuclear cardiology procedures has stimulated tremendous work in the past and will continue to do so in the future. The impact on routine patient care has grown at a slower pace and should be assessed separately for tissue perfusion and for myocardial contraction. The current status will be presented, focusing on patients with coronary heart disease. In the preinfarct period myocardial scintigraphy with thallium-201 and emission computer tomography (ECT) is the preferred method. The procedure for quantitation includes transfer of all data into a standard polar map and comparing the numbers with a normal, gender-matched data base. The result reveals areas of reduced tracer uptake, color-coded according to the level of significance. Interpretation of these colored polar maps might appear simple, but in fact requires a substantial amount of knowledge to avoid overinterpretation of the results. This has led us to a restricted use of this quantitative tool: following an initial step of reading the original data in terms of short and long axes slices of the left myocardium, the polar map is utilized for verification and for suggestions of any additional lesions. This has to be confirmed by a second reading of the slices, and only this last step defines the lesions to be reported. Quantitation used in this dialectic approach avoids inclusion of artefacts, and at the same time is useful experience for trainees. Furthermore, it allows easy presentation during the clinical conference and statistical analysis of groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1989

Quantification of amplitude images of gated radionuclide heart studies: a new universal method.

Absolute quantification in nuclear medicine is difficult because of the individual shape, size, and position of human organs. In this study, a general data processing procedure is presented that allows inter-individual comparison and definition of normal count density pattern of unevenly shaped scintigraphic structures. This new method is demonstrated on Fourier amplitude images of gated heart studies. The information contained in the original irregularly shaped left ventricular amplitude scans was transformed into a standard sized circle by interpolating the radiant profiles of varying length from the original left ventricular ROI into the radii of the standard circle using 720, 360, 180, and 72 sampling angles. Retransformation of the individual left ventricular amplitude image from the standard circle area is feasible with only approximately 1% error with the 180, 360, or 720 sampling steps. As a first application of this new method 20 normal amplitude studies were transferred into the standard circle, which allowed the definition of a statistically normal reference image against which individual left ventricular amplitude images may be compared for documenting areas of significantly depressed amplitudes quantitatively. This simple and unique approach may be applied to most organ-related scans such as brain, kidneys, lung, and liver both in planar and tomographic studies to first create a normal reference image and second, to quantify the significance of locally increased or decreased activity in routine scans automatically.

Heart↗
PubMed1989

[Quantification of the myocardial scar with technetium-99m-isonitrile (MIBI) in emission computerized tomography (SPECT)--comparison with serial creatine kinase determinations and radionuclide ventriculography].

Estimation of the size of myocardial infarction is of major interest for clinical patient management and a simple and reliable method is still searched for. In this study the potential of the new myocardial perfusion tracer, Technetium-99m (Tc-99m) methoxy-isobutyl-isonitril (MIBI) combined with emission computertomography (SPECT), is tested vs. the standard procedures of serial plasma creatine kinase (CK) measurements and radionuclide ventriculography (RNV). In 10 patients with first myocardial infarction, integral values for CK were obtained during the acute phase. Following three weeks of uncomplicated recovery the patient was referred for both types of myocardial imaging within four days. 370 MBq Tc-99m-MIBI were injected with the patient supine and at rest. One hour later SPECT acquisition commenced. The reconstructed slices were rearranged to long and short axes slices, which served to calculate a functional "scar image" in polar coordinates. The color-coded areas of significantly reduced tracer uptake were expressed in percent of the total myocardial area. RNV was performed with the patient supine and at rest, the left anterior oblique angle being optimized for septum visualization. Infarct localizations were antero-apical (three), anterolateral (two), postero-lateral (one), and posterior (four).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Studies of myocardial metabolism using P-31-NMR spectroscopy and a simple heart perfusion model of slaughtered animals--an approach to avoiding in vivo animal experiments].

In research cardiology large numbers of in vivo animal experiments, mostly with dogs or pigs, are necessary. It was the aim of this study to test a simple in vitro perfusion heart model from swine harvested in the slaughterhouse as a potential substitute for in vivo animal studies. 32 unselected hearts of slaughterhouse swine after 10 to 15 min of warm ischemia were subjected to reperfusion with warm oxygenized blood and were examined for mechanical recovery, which occurred in 56%, increasing to 95% if primarily using only hearts that were in relaxation. In 21 of selected relaxed heart models the energy phosphate pattern as an index of viability was measured by P-31 MRS on a 4.7 Tesla NMR tomograph in 37 experimental runs with the following perfusion protocols: 1) immediate cardioplegia with cold Bretschneider or Collins solution, transportation under cooling, MRS after approximately 1 h; 2) immediate cardioplegia, transportation, reperfusion with oxygenated warm blood, MRS; 3) immediate blood perfusion with genuine fresh arterial blood from the slaughterhouse, cold plegia perfusion, transportation, MRS; 4) immediate blood perfusion with transportation MRS; 4) immediate blood perfusion with genuinefresh arterial blood, cold plegia perfusion, transportation, reperfusion with oxygenated warm blood, MRS during reperfusion; 5) An experimental pig heart was made plegic in vivo and reperfused with oxygenated warm blood during MRS as reference.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1988

The Schilling test cannot be replaced by an absorption test with unlabeled vitamin B12.

It was the purpose of this study to evaluate the diagnostic usefulness of an oral absorption test using nonlabeled Vit B12 suggested by a commercial distributor as an alternative for the more expensive Schilling test (ST). Plasma levels of Vit B12 were measured with a commercial kit before and 4 h after oral administration of 1 mg Vit B12 in 32 normals, in 16 patients with normal ST, and in 14 patients with abnormal ST for determination of sensitivity and specificity with the ST as golden standard. In normals, a mean of 767 +/- 404 pg/ml before and 1096 +/- 776 pg/ml after oral Vit B12 with a mean increase of 331 +/- 453 pg/ml was measured. Because of the obvious large variation, no meaningful range for normal absorption could be established. In the two patient subsets, there was no Gaussian distribution of the results, with a meridian of Vit B12 increase after absorption of 142 pg/ml, range 27-2668 pg/ml, in the group with normal ST and a meridian of 244 pg/ml ranging from 40 to 2453 pg/ml in the group with abnormal ST. Statistical nonparametric analysis did not reveal any difference between the two groups. Assuming a minimum required increase of 100 pg/ml, as suggested by the kit distributor, a sensitivity of only 27% and a specificity of 75% was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Radionuclide ventriculography (equilibrium gated blood pool scanning)--its present clinical position and recent developments.

Myocardial scanning (MS) and radionuclide ventriculography (RNV) are the foundation of nuclear cardiology. These procedures aim in two completely different directions: RNV tries to image heart motion, that is, mechanical (pump) function, and therefore belongs to the group of first-order functional imaging (FI, imaging mechanical function), whereas MS is based on myocardial metabolism, and therefore can be attributed to third-order functional imaging (metabolism). This statement is relevant for the assessment of the clinical position of RNV: Third-order (metabolism) functional imaging is the domain of nuclear medicine (NM), whereas first-order FI has to face the competition of alternative noninvasive procedures such as ultrasound (US), digital subtraction angiography (DSA), computer tomography (CT), and nuclear magnetic resonance (NMR). The domain of RNV includes stages two (acute infarction) and three (postinfarction period) of coronary arterial disease (CAD). The advantageous combination of quantitative data on global, left ventricular (LV) function and imaging of regional motion ensures the superiority of RNV over US. However, RNV is inferior to MS in physical examinations in the preinfarction stage of CAD, whereas US is clearly inferior to both NM procedures. Recent progress could be attained by gated SPECT (GASPECT). A proposal is presented for simplification of this time-consuming procedure. Technetium-labeled isonitriles offer the chance for the combination of "perfusion-motion" imaging of the myocardium. However, even standard RNV offers new possibilities. The multitude of parameters produced by quantitation has not yet been exploited completely. This can be done by discriminant analysis. The computer finds out an optimal subset from the whole set of parameters for the solution of a significant clinical problem. The software "learns" to find the "label" of a special pathognomonic entity. This computer work is supported by a relational data bank (Oracle) and an optical disk. Two examples for the effectiveness of the computer in problem solving are presented. It is concluded that RNV, even in the very competitive class of first-order functional imaging, enjoys a preferred position. The future indeed seems brighter because labeled isonitriles offer the chance for the combination of perfusion-motion imaging of the myocardium.

Coronary Disease↗
PubMed1988

Long term inotropic effects of flecainide and propafenone.

This study was undertaken to evaluate the effect of flecainie (Fle) and propafenone (Pro) on rest and exercise myocardial contractility after prolonged oral administration. Standardized, fully automated, gated radionuclide angiograms at rest and during maximum exercise were performed single blinded and prospectively in 19 patients before and after oral treatment with either 150 mg b.i.d. of Fle or 150 mg t.i.d. of Pro. The left ventricular ejection fraction (EF%) as a hemodynamic indicator presented as follows: (Table: see text) In general, there was no significant effect of either drug on resting ventricular function. In only one patient of the Fle group with decreased baseline function did the left ventricular EF fall from 40% to 29%. During exercise, ventricular performance showed deterioration in the Pro group, but, interestingly, improvement in the Fle group. As a result of these opposite changes, the effect of the two drugs on the exercise response of ventricular function was significantly different (P less than 0.05). This study thus gives first evidence that no significant cardiodepressive effects are to be expected after prolonged application of Fle or Pro in normal hearts. There might even be a mild beneficial effect on exercise performance after Fle.

Administration, Oral↗
PubMed1988

Differentiation between infarction and cardiomyopathy in left bundle branch block by parametric radionuclide imaging.

In LBBB the diagnosis of the underlying disease, i.e. infarction (MI) or cardiomyopathy (CMP), is still a challenge. In this study, the usefulness of radionuclide ventriculography (RNV) for solving this problem noninvasively was tested. The hypothesis was that quantitation of the space-time sequence of left ventricular (LV) contraction by Fourier analysis may differentiate among MI, CMP, and LBBB-specific wall motion abnormalities (WMA). Forty-seven patients (pts) with LBBB were divided into 3 groups: 1) 20 pts with MI, 2) 7 pts with CMP, 3) 20 pts without MI or CMP. Regional parametric amplitude and phase data of eight LV sectors were calculated and expressed in standard deviation units (SDU) of normal. Out of the many regional data only the values of the mean amplitude and the standard deviation of the mean phase shift showed high discriminative power for separating the three groups, with an average squared canonic correlation of 0.5 and a Wilks lambda of 0.22, respectively. In other words, 17 of 20 pts in group 1, 6 of 7 pts in group 2, and 19 of 20 pts in group 3 were truly diagnosed by RNV alone. Such a separation also seems reasonable physiologically, since the mean amplitude reflects global left ventricular function and standard deviation of phase is a measure of time homogeneity of contraction. Furthermore, there was a significant septal phase delay of -4.92 +/- 5.3 SDU in 15 pts with septal MI compared to group 3 pts, who had a subtle premature septal motion of +0.75 +/- 2.64 SDU, whereas the septal amplitude was not different and slightly decreased in both.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Radionuclide ventriculography and hemodynamic evaluation by right heart catheterization with exercise for assessing the functional significance of coronary artery stenoses. A comparative study.

A series of 13 patients with significant coronary stenoses but without prior myocardial infarction were simultaneously studied by right heart catheterization and radionuclide ventriculography to determine the extent to which abnormal responses in left ventricular ejection fraction and wall motion to maximum exercise are paralleled by abnormal left ventricular filling pressures. The correlations of the filling pressure as evaluated by the diastolic pulmonary artery pressure with both the exercise ejection fraction and the rest-to-exercise change in ejection fraction were high (r = -0.89, P less than 0.01 and r = -0.76, P less than 0.01, respectively). In addition, the filling-pressure response to stress separated the patients into distinct radionuclide categories. All the 7 patients with grossly abnormal filling pressures (P greater than or equal to 30 mmHg) developed regional wall motion abnormalities with exercise as evaluated by visual interpretation or quantitative phase analysis. These patients also had a decrease in ejection fraction from rest to exercise ranging from -9% to -32% together with an exercise ejection fraction below 50%. Conversely, these abnormalities were never found in patients with filling pressures below this threshold level. The data suggest that radionuclide ventriculography and measurement of left ventricular filling pressure with exercise yield corresponding results when assessing the functional significance of coronary stenoses in normotensive patients without prior myocardial infarction and normal global left ventricular function at rest.

Blood Pressure↗
PubMed1987

Tumor scintigraphy with 131I anti CEA monoclonal antibodies and F(ab')2 in colorectal cancer.

In 14 patients with proven local recurrence of colorectal cancer or metastases in liver and/or lungs, the sensitivity (SE) in detecting tumor sites was estimated in a single-blind study using conventional planar whole body scintigraphy. Nine patients received F(ab')2 and five received MAB by intravenous infusion over 30 min with a dose of 40-200 MBq after skin testing and thyroid blocking, scanning was performed 1-7 days later. All but one patient had elevated plasma CEA levels with a mean of 25.5 +/- 31.9 ng/ml. The scans were interpreted by two independent observers. In five of the nine patients receiving F(ab')2, the tumor site could be visualized, yielding a sensitivity of 55%. No tumor sites were identified with MAB. The highest tumor uptake was recorded in a patient with additional ovarian cancer with the activity accumulating in the ovarian cancer. The optimum time for imaging was 3 or 4 days after injection. There was no correlation between positive imaging and plasma CEA levels which ranged from 1.9 ng/ml to 100 ng/ml in the positive cases. The thyroid uptake on the sixth day was 0.68% +/- 0.2% of the total dose given despite thyroid blocking. Bone uptake of 131I was also observed, this was mild in four patients, moderate in three but high in one patient, especially on days one to four. Thus, only anti-CEA F(ab')2 seem to be of clinical interest for further evaluation in localizing colorectal cancer. Regarding the still low sensitivity of 55%, further improvement can be expected by gaining experience, using more appropriate isotopes such as 111In and SPECT. The estimated radiation side effects on thyroid and bone marrow are only modest.

Aged↗
PubMed1987

A general comparison of functional imaging in nuclear medicine with other modalities.

New (noninvasive) diagnostic procedures in medicine (ultrasound [US], digital subtraction angiography [DSA], computed tomography [CT], nuclear magnetic resonance [NMR]) create a need for a review of the clinical utility of functional imaging in nuclear medicine. A general approach that is valid for all imaging procedures is not possible. For this reason, an individual assessment for each class of functional imaging is necessary, taking into account the complexity and sophistication of the various imaging procedures. This leads to a hierarchical order: first order functional imaging: imaging of organ motion (heart, lungs, blood); second order functional imaging: imaging of excretory function (kidneys, liver); and third and fourth order functional imaging: imaging of metabolism (except excretory function). First order functional imaging is possible fundamentally, although with limitations in detail, by all modalities. Second order functional imaging is not possible with US. Third and fourth order functional imaging is a privilege of nuclear medicine alone. Up to now, NMR has not proven clinically useful to produce metabolic images in its true sense. This is due to the fact that the signals used are too weak to provide metabolic information with satisfactory local resolution, even after administration of nonradioactive isotopes. First and second order functional imaging of nonradioactive procedures face severe disadvantages, including difficulties in performing stress investigations, which are essential for coronary heart disease, limited capability for true quantitative information (eg, kidney clearance in mL/min), side effects of contrast media and paramagnetic substances, and high costs. Therefore, nuclear medicine functional imaging turns out to be in a favorable clinical position, even in the presence of the competitive diagnostic modalities that have been developed in recent years.

Brain Neoplasms↗
PubMed1987

Phase mapping from left ventricular radionuclide ventriculograms: interobserver reliability and accuracy of the programme.

Phase analysis of data from radionuclide ventriculograms is known to provide space-time information on the mechanical emptying of pixels located in the ventricular regions. It could therefore perhaps be useful for detecting abnormal sequences of contraction of the ventricles as well as to localize sites of premature electromechanical action. The phase programme used in this investigation is designed to trace the electromechanical action of the ventricles from colour-coded phase images (first harmonic Fourier transform), not only visually from a cinematic representation, but particularly from a data output of x, y coordinates and phase angles of sites chosen as they empty in the ventricular regions. Six healthy baboons were subjected to conventional radionuclide ventriculography, performed hourly for the duration of 11 h under anaesthesia. The programme was used by two independent observers to map the progression of emptying for each of the thus acquired 66 left ventricular phase images. The interobserver reliability and the accuracy achieved in mapping normal contraction patterns was found to be good. Abnormalities which appeared during the prolonged anaesthesia and which were confirmed with 12 lead electrocardiography were likewise detected consistently.

Animals↗
PubMed1987

Effect of right ventricular hypertrophy on cardiac performance and the relation between right ventricular systolic peak pressure and end-systolic volume.

To investigate the role of hypertrophy of the right ventricle upon right heart performance and the significance of the peak systolic pressure/end-systolic volume (P/V) ratio in terms of right ventricular systolic performance, simultaneous measurements of radionuclide ventriculograms and central hemodynamics were done in 32 patients with chronic obstructive pulmonary disease. In 26 of the patients (80%) technically adequate two-dimensional echocardiograms could be performed. In the subset of patients with increased (greater than or equal to 6 mm) right ventricular end-diastolic wall thickness no relationship between pulmonary artery pressure and right ventricular ejection fraction (RVEF) existed in comparison with the remaining patients. P/V indices and cardiac output were not decreased. Considering the patients, whose P/V ratio did not increase from rest to exercise, RVEF decreased highly significantly more than in the remaining patients. The ratio of wall thickness and end-diastolic radius as determinant of peak systolic stress was significantly decreased in these patients compared with the remaining patients. In the patients with right ventricular hypertrophy despite significantly higher values of pulmonary artery pressures and resistances, the afterload in terms of systolic wall stress is markedly reduced. We conclude that in the hypertrophic state, right ventricular performance is not impaired despite decreased RVEF values. In the patients whose P/V ratio does not increase from rest to exercise, an inappropriate high peak systolic wall stress may exist both due to inadequate wall thickness and increased diameter of the right ventricle. The role of P/V in terms of prognosis and development of decompensated right heart failure remains undetermined.

Biomechanical Phenomena↗
PubMed1987

Quantitative bone scintigraphy in patients with hyperparathyroidism.

Laboratory tests, including the determination of parathormone in serum, and x-ray examinations are often of limited value in diagnosing hyperparathyroidism (HPT). In this study, bone scintigraphy was carried out in 15 patients with proven HPT (primary and secondary in patients with chronic renal disease) and 25 normal subjects, to evaluate quantitatively increased bone metabolism. The count density ratios bone to soft tissue (D/S-index) were calculated. In normal, this D/S index averaged 3.66 +/- 0.94 and was significantly (p less than 0.001) different to that of HPT-patients averaging 6.37 +/- 1.64. The quantitative evaluation shows a sensitivity of 73%, a specificity of 100% and an accuracy of 90% for detecting HPT (based on the sample values). Discriminant analysis can be applied to calculate the probability of the presence of HPT (primary and secondary) as a function of the measured D/S index.

Bone Diseases, Metabolic↗