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Biomedical subjects

J Maublant

Publications and source records attributed to J Maublant.

At least 37 records · Page 2Linked to original sources
PubMed1991

Comparison of the myocardial distributions of 201Tl and 99Tcm-MIBI on SPECT images.

The distributions of 201Tl and 99Tcm-MIBI on stress images were quantitatively measured in a series of 15 patients presenting with documented coronary artery disease. Following two sequential, one-week apart, peak-exercise injections of either 74 MBq of 201Tl or 370 MBq of 99Tcm-MIBI, tomographic views of the myocardium were reconstructed and two thick, central short-axis sections were divided into nine sectors. A sector was considered as showing a defect if its relative activity was lower than 30, 40, 50 or 60% of the highest level of activity in the 18 sectors. Results demonstrate that there were more defects with 201Tl than with 99Tcm-MIBI. However, the difference disappeared if the inferior wall was not included. These results suggest that depth attenuation could be, at least partly, responsible for the higher rate of positive results observed in single photon emission computed tomography with 201Tl than with 99Tcm-MIBI.

Adult↗
PubMed1991

Comparative effects of APSAC and rt-PA on infarct size and left ventricular function in acute myocardial infarction. A multicenter randomized study.

BACKGROUND: Recombinant tissue-type plasminogen activator (rt-PA or alteplase) and anisoylated plasminogen streptokinase activator complex (APSAC or anistreplase) have been demonstrated to limit infarct size significantly and to preserve left ventricular function when injected soon after acute myocardial infarction. However, as yet, the efficacy and safety of these two thrombolytic agents have not been directly compared in one trial; this was the aim of this study. METHODS AND RESULTS: One hundred eighty-three patients suffering from a first acute myocardial infarction were randomly allocated to either APSAC (30 units over 5 minutes) or single-chain rt-PA (100 mg over a 3-hour period) within 4 hours of the onset of symptoms. Global and regional left ventricular function were assessed from contrast angiography an average of 5.3 +/- 2.3 days after initial therapy. Radionuclide angiography and thallium-201 single-photon emission computerized tomography were performed before hospital discharge. Infarct size was assessed by single-photon emission computerized tomography and expressed in percentage of the total myocardial volume. Ninety patients received APSAC and 93 received rt-PA within a mean period of 172 +/- 52 minutes after the onset of symptoms. The two groups were similar in age, location of the acute myocardial infarction, Killip class, and time of randomization. The patency rate of the infarct-related artery was 72% in the APSAC group and 76% in the rt-PA group (NS). Initial and predischarge left ventricular ejection fraction as well as infarct size were similar in both therapeutic groups (0.50 +/- 0.14 versus 0.52 +/- 0.12 for initial and 0.48 +/- 0.10 versus 0.47 +/- 0.10 for predischarge ejection fraction, 11 +/- 7% versus 9 +/- 7% for infarct size, respectively, for APSAC- and rt-PA-treated patients). Bleeding complications requiring blood transfusion occurred in one APSAC patient and in two rt-PA patients. One patient in the rt-PA group died of a massive intracranial hemorrhage. At the end of the 3-week follow-up period, five APSAC patients (5.5%) and seven rt-PA patients (7.5%) had died. CONCLUSIONS: The early infusion of APSAC or rt-PA in acute myocardial infarction produced a similar patency rate, limitation of infarct size, and preservation of left ventricular systolic function with an equivalent rate of bleeding complications.

Anistreplase↗
PubMed1990

[Isotopes and myocardial ischemia].

Single photon emission computed tomography (SPECT) is superior to conventional radionuclide scintigraphy. The most widely used marker is thallium-201, despite the fact that it is not exclusively flow-dependent. Thallium-201 SPECT can be performed in patients at rest, during exercise followed by a redistribution study, under dipyridamole or nitrate infusion, or combined with spasm provocation test. When performed at rest, it is helpful to diagnose and, above all, quantify a myocardial infarction. Under nitrate infusion, it delineates the viable muscle remaining around the infarct. During exercise or under dipyridamole infusion, it is more effective than any other non-invasive method in detecting myocardial ischaemia (sensitivity 95%, specificity 90%). Following surgical revascularization, a normal exercise SPECT indicates a functional aorto-coronary bypass in 80% of the cases. It is a good method to detect post-angioplasty restenosis (sensitivity 82%, specificity 86%, negative predictive value 93%). Like all paraclinical examinations, SPECT has its limitations: left bundle branch block, reverse redistribution, non-ischaemic (i.e. dilated or hypertrophic) cardiopathies.

Coronary Disease↗
PubMed1989

[Detection of coronary restenosis using myocardial tomoscintigraphy with thallium 201. A series of 85 cases].

UNLABELLED: After a successful coronary angioplasty (less than 50 p. 100 residual stenosis and no complication), can restenosis be detected by a non-invasive method? We tested the value of stress thallium 201 myocardial scintigraphy by comparing this method with clinical angina and the conventional exercise-induced angina test. The study was prospective and involved 85 patients (74 men, 11 women; mean age 54.7 years, range 33-78 years). Sixty patients were suffering from angina, 13 had post-infarction angina and 12 had mild necrosis. Angioplasty had been performed on a single vessel (LAD in 57 cases, right in 18 cases and CX in 10 cases). After 6.4 +/- 1.8 months, all patients were re-evaluated under treatment, undergoing successively an exercise test, a stress and recovery myocardial scintigraphy and a coronary angiography. Restenosis was defined as a more than 50 p. 100 reduction of diameter on two orthogonal planes and was observed in 22 cases (26 p. 100). 19 patients were suffering from angina, 12 had restenosis, 10 were asymptomatic but had restenosis. Eighteen exercise tests were pathological; 10 corresponded to restenosis and 12 were normal in spite of restenosis. Myocardial scintigraphy was regarded as positive when, outside a necrotic territory, a lack of uptake at stress was reversible or became worse at redistribution. 27 tests were positive, 18 corresponded to restenosis, 4 were normal in spite of restenosis. The diagnostic values of the three methods were compared: (Table: see text). CONCLUSIONS: (1) stress myocardial scintigraphy has the best sensitivity and specificity; (2) if it is negative, restenosis is very unlikely; (3) coronary angiography may be performed only in case of symptoms and/or of positive stress scintigraphy.

Adult↗
PubMed1987

[Tomoscintigraphy of the myocardium labelled with thallium-201. Value in the quantification and prognosis of myocardial infarction].

Myocardial thallium 201 tomography was performed in 112 patients admitted to hospital in the acute stage of a first myocardial infarction. Our quantification method for the myocardial lacuna, validated by animal studies, is described. The necrotic mass evaluated is compared with enzymatic (CPK) (r = 0.89) and angiographic (r = 0.78) quantitative assessments. Thallium 201 tomographic quantification has an unquestionable prognostic value. Thus, among patients whose infarcted mass represented more than 25% of the total myocardial mass, 71% died or developed severe heart failure. Conversely, 93% of patients with a small infarct (less than 20% of total myocardial mass) were asymptomatic on a 24-month follow-up. Myocardial thallium 201 tomography provides a reasonable quantification of the infarct. Its prognostic value seems to be satisfactory.

Adult↗
PubMed1983

Quantification of infarct size in the dog by thallium-201 single photon emission transaxial tomography (SPETT).

In a series of 12 dogs having an acute experimental anterior myocardial infarct, the size of the infarct was measured using, successively, single photon emission transaxial tomography (SPETT) with thallium-201, conventional planar scintigraphy of the anatomic slices, and planimetry of these slices after nitroblue-tetrazolium (NBT) staining. The tomographic views were obtained after processing of projection images collected during the rotation of a scintillation camera around the animals. A correlation of 0.86 was obtained between SPETT and NBT staining for the whole series, and a value of 0.94 was observed when only the transmural infarcts were considered. These results suggest that SPETT of the myocardium labelled with thallium-201 should allow a reliable, rapid and atraumatic estimation of the infarct size.

Animals↗
PubMed1983

Feasibility of gated single-photon emission transaxial tomography of the cardiac blood pool.

A procedure for gated single-photon emission transaxial tomography of the cardiac blood pool using a commercially available rotating camera and a computer is described. During image acquisition, the end-diastolic and end-systolic frames are retained after each of the 16 angular steps of the rotation of the camera around the anterior side of the patient's chest. Complete acquisition takes 25 minutes; 10 more minutes are required for the reconstruction and processing of the sections. One set of images is oriented transaxially; the other set includes vertical sections obtained by rotation around a vertical axis passing through the center of the left ventricular cavity. Results from the planar and tomographic examinations were in good agreement for most of the 18 patients who underwent both studies, although more inferior abnormalities were detected with tomography.

Coronary Circulation↗
PubMed1983

Gold-195m, an ultra-short-lived generator-produced radionuclide: clinical application in sequential first pass ventriculography.

Gold 195m (Au-195m) has a half-life of 30.5 sec and can be produced at the bedside from the parent mercury-195m (T 1/2 = 41.6 hr). The generator produced sterile pyrogen-free Au-195m with mercury breakthrough of 0.75 +/- 0.09 (s.e.m.) muCi per mCi of Au-195m. Approximately 20 to 25 mCi of Au-195m was produced per elution from a generator containing 155 mCi of Hg-195m. We compared first-pass resting Tc-99m angiograms with Au-195m angiograms in 28 patients. The correlation coefficient between the two studies was 0.92 over an ejection-fraction range from 0.22 to 0.83. In addition, we tested the reproducibility of Au-195m first-pass angiograms by performing two studies 3 min apart. In 25 patients with ejection fractions ranging from 0.20 to 0.78, the correlation coefficient between such pairs was 0.93. The nuclide is reliably and reproducibly produced, and its short half-life allows the performance of background-free sequential first-transit studies with unusually low radiation exposure to the patient.

Gold Radioisotopes↗
PubMed1983

Effects of pindolol on the heart rate in the conscious dog with chronic atrioventricular block and the distribution of blood mass in the anesthetized dog.

The intrinsic sympathomimetic activity (ISA) of the adrenergic beta-blocker pindolol was studied by comparing its effects with those of propranolol in two experimental models: In the non-anesthetized dog with atrio-ventricular block created at least two months previously, propranolol at 0.078, 0.156 and 0.312 mg/kg depressed idioventricular automaticity without affecting atrial rate. Pindolol at 0.5 mg/kg raised atrial rate but left idioventricular rate unchanged. Beta-blockers depress the ventricular adrenergic tone which is strong in this model. With pindolol, this effect is offset by its ISA. Two successive injections of Thallium-201 enable variations in blood mass distribution caused by an agent administered between them to be studied. Isoprenaline increased blood flow in heart and skeletal muscles at the expense of lungs and kidneys. Pindolol (0.1 and 0.2 mg/kg) did not modify coronary blood flow, but increased muscular blood flow.

Anesthesia, General↗
PubMed1982

Emission computed tomography vs perfusion scanning in lung disease.

Emission computed tomography has achieved considerable credibility in thallium-201 cardiac imaging and in brain imaging studies. To date the procedure has had only limited application in the study of other organs. In the present study traditional perfusion lung scans were compared with horizontal, sagittal and frontal tomograms in 30 patients. Preliminary results showed agreement between the two methods in most cases. Tomography, however, gave more precise information about the site and extent of areas of deficient lung perfusion. In a small number of cases tomography also revealed defect not seen on conventional scans. In patients with cardiomegaly in whom conventional scanning data were difficult to assess, tomography proved enlightening.

Humans↗
PubMed1982

Multi-organ functional imaging with thallium-201: a new noninvasive method for rapid assessment of vasoactive drugs.

A new method for rapid and noninvasive assessment of vasoactive drugs is described, using scintigraphic imaging with thallium-201 in anesthetized dogs. The scintigraphic images were processed to evaluate the effects of the vasoactive agents studied upon the biodistribution of thallium-201 in the whole body of dogs. The calculation of the functional parameter was based upon the comparison of the cell by cell increase of the tracor uptake following two different injections: the first in the basal state, the second after treatment with a vasoactive drug. Six drugs were tested and their effects evaluated in heart, liver, lungs, kidneys, and skeletal muscles. The most marked effects on myocardium were observed with dipyridamole and the ionophore grisorixin, two coronary vasodilators, which induced a strong increase in the TI-201 myocardial uptake (168.9 +/- 31.6% and 194.9 +/- 34.2% respectively). The results obtained in the other organs with all the drugs tested were in accord with their known hemodynamic properties, and so confirm the usefulness of this method.

Animals↗
PubMed1982

A comparison between conventional scintigraphy and emission tomography with thallium-201 in the detection of myocardial infarction: concise communication.

We have compared emission tomography and conventional scintigraphy with thallium-201 in a series including 15 normal subjects and 64 patients showing transmural myocardial necrosis in various locations, fully documented by clinical, electrocardiographic, and enzymatic evidence. The reconstruction was derived from 32 projection images collected around the left side of the patient's chest by a rotating scintillation camera. The conventional views and the transverse, frontal, and sagittal sections were interpreted independently by two observers. The final calculated sensitivity was 89% with conventional scintigraphy and 98% with emission tomography, and the specificity was 93% in the two cases. Thus, emission tomography provides a better sensitivity and also a better interobserver agreement than conventional scintigraphy in the detection of transmural myocardial necrosis with thallium-201.

Humans↗
PubMed1982

Myocardial imaging in dogs treated with grisorixin: relationship between thallium-201 uptake and coronary blood flow.

Thallium-201 myocardial imaging was performed in dogs after pretreatment with grisorixin, which appeared to increase the myocardial uptake of Tl-201. This effect of grisorixin was found to be dose dependent, with an optimal dose of 60 microgram/kg. The myocardial-to-background ratio, which was 1.92 in the control dogs, rose to 4.45. The increase in the absolute myocardial uptake was demonstrated in guinea pigs that received Tl-201 after similar pretreatment with grisorixin. In the animals treated with 500 microgram/kg, the uptake of Tl-201 by the heart was 35% over the control value. With 60 microgram/kg grisorixin, the coronary blood flow increased from 40 to 176 ml/min 5 min after the injection. This dose, optimal for imaging, induced the maximum vasodilator effect with only a very slight concomitant increase in the left-ventricular pressure and myocardial contractility. Above 60 microgram/kg, grisorixin appeared to be a potent inotropic agent, whereas below this dose it showed only coronary vasodilator properties. Some evidence for an ionophore effect of this compound was found in dogs pretreated with 60 microgram/kg. In these the radionuclide was injected when the coronary vasodilatation had become insignificant, but a significant improvement of the M/B ratio was still evident.

Animals↗
PubMed1982

Hemodynamic effects of grisorixin, a monocarboxylic ionophore.

The cardiovascular effects of grisorixin, a monocarboxylic ionophore, were studied in anesthetized dogs. At low doses, up to 60 micrograms/kg, grisorixin showed potent coronary vasodilator properties without marked effects on other cardiac parameters. The maximum increase in CBF was observed with the 60 micrograms/kg dose (+390%). With higher doses (125-500 micrograms/kg), the coronary vasodilation was more persistent and concomitant with strong inotropic and hypertensive effects. Pretreatment with a beta-blocking agent (propranolol 2 mg/kg) partly reduced the grisorixin-induced effects. The increase in CBF was lowered in the dogs receiving 60 micrograms/kg and shortened in those receiving 500 micrograms/kg while the rise in contractility was considerably reduced but not abolished; the hypertensive effect was almost not affected by pretreatment with propranolol. In no case was the myocardial oxygen consumption increased in proportion to cardiac work. It is suggested that like other ionophores such as monensin, grisorixin acts partly through a release of catecholamines but also by a nonadrenergic mechanism involving modifications in intra- and extracellular ionic concentrations.

Animals↗
PubMed1981

Automatic construction of pulmonary functional images.

Dynamic study of regional ventilation of Xenon-133 with a gamma camera requires the medical interpretation of many analog scintigraphic images and time-consuming curve analysis. We have developed a program for the immediate creation of two functionally digitalized images by minicomputer which collects the data from the whole study. These images are constructed by assigning a value to each pont which depends upon the dynamic phenomenon. The program automatically computes the working files of the dynamic acquisition, performs the background subtraction, and delineates the boundaries of the lungs using isoactivity lines. Then the functional images of transit time and clearance of the radioactive gas in the alveoli are reconstructed. This processing takes less than 1 min and allows both time sharing and enhancement of interpretation.

Computers↗
PubMed1981

Myocardial emission tomography with thallium-201. Value of multiple and orthogonal sections in the study of the myocardial infarction.

The usefulness of transverse, sagittal, and frontal tomographic images was assessed in the study of the myocardium labelled with thallium-201. In a series of 20 patients with myocardial infarcts in various locations documented by clinical, electrocardiographical, and biochemical data in 15 cases and uncertain diagnosis in 5 cases, the sections reconstructed from 32 views obtained with a rotating scintillation camera were compared to the conventional views. Quantitatively, the mean myocardium-to-background activity ratio improved significantly from 1.60 to 2.57 (p less than 0.001); qualitatively, the presence, site, and size of the defect were more easily determined on the sections and generally showed a sharp contrast to the normal tissue; transverse sections enabled us to explore the anterior infarcts, but sagittal or frontal views were required for inferior locations. The tomographic exploration was normal in only patient whose diagnosis was uncertain. These results suggest that three-dimensional emission tomography can improve both detection and quantification of the myocardial infarct.

Humans↗