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Biomedical subjects

F J Bonte

Publications and source records attributed to F J Bonte.

At least 55 records · Page 3Linked to original sources
PubMed1983

Single-proton tomographic study of regional cerebral blood flow in epilepsy. A preliminary report.

Regional cerebral blood flow (rCBF) may be measured with a single-photon-emission computed tomograph (SPECT) after inhalation of xenon 133. Our SPECT studies of rCBF in a group of 18 patients with seizure disorders, when compared with studies in 32 normal control subjects, have shown enhanced flow to an active seizure focus and ischemia of brain areas in certain subjects between seizures. Thus, SPECT determination of rCBF has demonstrated a number of findings recently observed with positron-emission tomography and may become a useful modality in the study of patients who have epilepsy.

Adolescent↗
PubMed1983

A comparison of infarct identification with technetium-99m pyrophosphate and staining with triphenyl tetrazolium chloride.

The topographic relationship between the uptake of technetium-99m pyrophosphate (PPi) and myocardial infarction delineated by 2,3,5-triphenyl tetrazolium chloride (TTC) was studied in a canine model of permanent coronary occlusion (24-48 hr). Photographs of TTC staining and scintigraphic images of PPi uptake were planimetered for infarct area. In addition, narrow tissue samples (3 X 10 mm) were taken on both sides of the TTC border and counted for PPi uptake. A significant correlation (p less than 0.001) was found between area of PPi uptake and area of myocardium unstained by TTC (r = 0.84 in epicardium and r = 0.91 in endocardium). The slope relating PPi to TTC for all infarcts was 1.01 +/- 0.11, indicating that variations in infarct size were followed equally by the two techniques. Tissue counting showed the ratio of PPi activity just inside the infarct to activity just outside the infarct to be 9.2 +/- 0.6 (mean +/- s.e.m.). Thus, PPi is distributed topographically in a manner identical to the distribution of irreversibly injured myocardium as delineated by TTC.

Animals↗
PubMed1982

Attenuation compensation in single-photon emission tomography: a comparative evaluation.

Attenuation of photons in single-photon emission tomography (SPECT) makes three-dimensional reconstruction of unknown radioactivity distributions a mathematically intractable problem. Approaches to approximate SPECT reconstruction range from ignoring the effect of photon attenuation to incorporating assumed attenuation coefficients into an iterative reconstruction procedure. We have developed a computer-based simulation method to assess the relative effectiveness of attenuation compensation procedures. The method was used to study four procedures for myocardial SPECT using an infarct-avid radiopharmaceutical, Tc-99m stannous pyrophosphate. Reconstructions were evaluated by two criteria: overall (sum-of-squares) accuracy, and accuracy of lesion sizing. For moderate- to high-contrast studies there were no significant differences among the reconstructions by either evaluation criterion; for low contrast ratios the iterative method produced lower sum-of-squares criterion; for low contrast ratios the iterative method produced lower sum-of-squares error. We conclude that the additional expense of the iterative method is not justified under the conditions of this study. The approach used here is a convenient tool for evaluating specific SPECT reconstruction alternatives.

Humans↗
PubMed1981

Recent advances in nuclear cardiology. 1. "Hot-spot" and "cold-spot" myocardial scintigraphy.

Nuclear cardiology is a comparatively new field of cardiovascular medicine in which technologic advances have provided relatively noninvasive means of evaluating cardiovascular abnormalities. The purpose of this two-part review is to emphasize some important recent advances and to place in perspective the advantages and disadvantages of those new techniques that are particularly useful clinically.

Coronary Disease↗
PubMed1981

Recent advances in nuclear cardiology. 2. Dynamic myocardial scintigraphy.

Nuclear cardiology, a developing subspeciality of cardiology and nuclear medicine, has experienced rapid growth during the past five years. Important advances in "hot-spot" and "cold-spot" myocardial scintigraphy for measurement of myocardial perfusion and detection of myocardial infarction are discussed in part 1 of this article, beginning on page 55. Part 2 concludes the discussion with an update on dynamic myocardial imaging.

Coronary Disease↗
PubMed1981

Quantitation of experimental canine infarct size using multipinhole single-photon tomography.

A four-pinhole longitudinal tomographic system, with collimator and software, was developed for a standard-field portable scintillation camera. This system was used with technetium--99m pyrophosphate (Tc-PPi) to quantify the volume of infarcted myocardium in 27 dogs with experimental myocardial infarcts. These were induced by ligation of the left anterior descending (LAD) or the circumflex coronary artery. Tomographic estimations of scintigraphic infarct size agreed well with postmortem findings when the circumflex group (r = 0.87) and LAD group (r = 0.83) were considered separately, but the correlation fell when the groups were pooled (r = 0.73). Whereas multipinhole tomography extends Tc-PPi infarct sizing capability in animals to include posterior and subendocardial infarcts as well as anterior lesions, the tomographic sections contain enough blur artifacts to lower the sizing accuracy of the method. The main advantage of the technique may well be its ability to aid in detection and location of small myocardial infarcts.

Animals↗
PubMed1981

Quantitation of experimental canine infarct size with multipinhole and rotating-slanthole tomography.

Myocardial infarct size was estimated by three methods in a canine model, using Tc-99m pyrophosphate at 24 and 48 hr after coronary ligation. A gamma camera provided anterior, LAO, and lateral views, and was then fitted with multipinhole (MPH) and rotating-slanthole (RSH) collimators for tomographic studies, processed by computer to display frontal sections of the chest. Infarct weight was measured postmortem for comparison. All transmural infarcts were detected by all three imaging techniques. RSH tomography was superior to both MPH tomography and planar imaging for the detection of nontransmural infarction. Infarcts as small as 1.0 g were detected. Estimates of infarct volume measured from RSH slices showed an excellent correlation with infarct weight (r = 0.89) and were reproducible within acceptable limits. Estimates on infarct volume measured from MPH slices demonstrated a significantly poorer correlation with infarct weight (r = 0.48, p less than 0.01). Both tomographic techniques may improve infarct visualization by suppressing overlying activity and increasing contrast between infarct and background, but both produce significant blur artifacts that hamper their utilization by inexperienced observers.

Animals↗
PubMed1981

Simultaneous display of gated technetium-99m stannous pyrophosphate and gated blood-pool scintigrams.

We have developed a method by which any two sets of R-wave-synchronized radionuclide images may be registered, color-coded, and displayed in cinematic fashion so that the image sets are superimposed and shown simultaneously in contrasting colors. The technique has been applied to technetium-99m stannous pyrophosphate (Tc-99m PPi) and equilibrium blood-pool images. Gated Tc-99m PPi and gated blood-pool image sets (16 frames per cardiac cycle) were acquired in identical projections. Image sets were then registered, if necessary, and color-coded by a computer algorithm. Our initial experience suggests that this overlay technique may be of value to: (a) detect right ventricular infarction with greater precision; (b) provide a better estimate of anatomic location and circumferential extent of Tc-99m PPi myocardial uptake relative to the ventricular blood pool; and (c) distinguish between segmental contraction abnormalities caused by recent infarction (identified by abnormal Tc-99m PPi uptake) and segmental contraction abnormalities caused by ischemia or previous myocardial infarction.

Adult↗
PubMed1981

Effect of coronary blood flow and site of injection on Tc-99m PPi detection of early canine myocardial infarcts.

The effect of blood flow and site of injection on Tc-99m PPi uptake in acute myocardial infarction was studied in a group of 24 dogs. Temporary (3 hr) and permanent LAO occlusion models were used. Animals with the temporary occlusions showed scintigraphic visualization of the infarcts and reversal of the normal epito-endocardial Tc-99m PPi ratio in contrast to those with permanent coronary occlusions. The data demonstrate that early (within 3 hr) experimental canine myocardial infarcts can be detected with Tc-99m PPi if reflow to the area of infarction is provided. Delayed development of abnormal Tc-99m PPi scintigrams with acute infarction is related primarily to the initial lack of adequate blood flow to the damaged tissue, with subsequent development of adequate collateral flow allowing delivery and uptake of sufficient amount of the radiopharmaceutical for in vivo scintigraphic detection of the damaged area(s).

Animals↗
PubMed1980

Radionuclide evaluation of cardiac trauma.

Radionuclides were first used in the evaluation of myocardial trauma as a noninvasive means to detect hemopericardium. At present an important use is in the diagnosis of myocardial contusion, which can be difficult to recognize clinically, and often has nonspecific EKG and enzyme alterations. Technetium-99m pyrophosphate scintigraphy has been shown to be of significant value in confirming this diagnosis. Myocardial scintigrams are helpful in determining the degree of damage produced by penetrating wounds of the heart and can also detect electrical injury to the heart from accidental shock or cardioversion. In addition, multiple gated blood pool scans can determine the hemodynamic significance of mycardial trauma and evaluate for late sequelae such as aneurysm formation.

Contusions↗
PubMed1980

Pathophysiologic considerations and clinicopathological correlates of technetium-99m stannous pyrophosphate myocardial scintigraphy.

99mTc-PYP myocardial scintigrams represent a means to detect and localize acute myocardial necrosis. These scintigrams are expected to be abnormal with acute myocardial infarcts of at least 3 grams in weight if serial imaging is utilized and proper attention to technique is provided. Any etiology of myocardial necrosis may produce abnormal 99mTc-PYP scintigrams if the damage is relatively localized and includes at least 3 grams of tissue. It is possible to accurately size acute anterior and anterolateral transmural myocardial infarcts using area or 2 dimensional measurements. Further development in imaging cameras and computer techniques allowing three dimensional reconstruction of myocardial infarcts with this and similar imaging techniques may allow relatively precise quantitation of other types of myocardial infarcts. The "doughnut" and "persistently abnormal" 99mTc-PYP scintigrams appear to have anatomic and prognostic significance at least in subsets of patients studied, but larger numbers of individuals need to be evaluated before final conclusions regarding their ultimate prognostic significance can be reached.

Animals↗
PubMed1980

Localization of anti-mitochondrial antibody in experimental canine myocardial infarcts.

Alterations in cell and subcellular membrane integrity occur during evolving ischemic myocardial injury. We tested the hypothesis that an antibody against human liver mitochondria [anti-mitochondrial antibody developing in a patient with primary biliary cirrhosis] could identify altered cell membrane integrity in experimental canine myocardial infarcts. The proximal left anterior descending coronary arteries of 12 dogs were ligated and 1 hr later 131I-labeled F(ab')2 fragments from either a control human IgG (6 dogs) or anti-mitochondrial IgG (6 dogs) were injected. The 131I-labeled F(ab')2 anti-mitochondrial fragments concentrated maximally in the central infarct subendocardium [infarct-to-normal ratio of 9.2 +/- 3.5 (mean +/- SD) vs. 4.6 +/- 3.3 for control F(ab')2 IgG, P < 0.05]. There was also 1 1/2- to 2-fold greater anti-mitochondrial antibody F(ab')2 accumulation in the central infarct epicardium and the peripheral infarct subendocardium and subepicardium. Thus, an anti-mitochondrial antibody obtained from a patient with primary biliary cirrhosis concentrates in irreversibly damaged myocardium after experimental canine myocardial infarction. Presumably this occurs because of altered cell membrane integrity, which allows exposure of mitochondria to the anti-mitochondrial antibody. The F(ab')2 fragments of anti-mitochondrial antibodies labeled with suitable radionuclides should allow noninvasive scintigraphic detection of experimental acute myocardial infarcts.

Animals↗
PubMed1980

Acute subendocardial myocardial infarction: its detection by Tc-99m stannous pyrophosphate myocardial scintigraphy.

Sixty-two patients hospitalized because of prolonged chest pain and initial electrocardiographic (ECG) changes of ST depression and T-wave inversion suggestive of acute subendocardial myocardial infarction were evaluated to determine the ability of Tc-99m-stannous pyrophosphate mycardial scintigraphy to detect the presence or absence of acute subendocardial myocardial necrosis. Three groups of patients were designated. Group A consisted of eight patients (13%) who developed reduction of R-waves of more than 25% or new Q-waves broader than 0.03 seconds; of these patients with acute transmural myocardial infarction, all had well-localized, abnormal scintigrams. Group B consisted of 30 patients with ECG changes and subsequent enzymatic documentation, including elevated serum creatine kinase-B levels as determined by radioimmunoassay, of the presence of acute subendocardial myocardial infarction. Of these, 27 had abnormal scintigrams, including 18 with well-localized patterns and nine with "poorly localized" patterns. Group C consisted of 24 patients (39%) with chest pain, but without enzymatic documentation of the presence of acute myocardial infarction (acute coronary insufficiency). Eight of these had abnormal scintigrams, including one with a well-localized pattern and seven with "poorly localized" patterns. In four of the latter, the scintigrams were "persistently positive" several weeks to months after a previous myocardial infarct. Serial myocardial imaging will be necessary to identify such patients.

Adult↗