PubMed Health⌕ Search

Biomedical subjects

C Raynaud

Publications and source records attributed to C Raynaud.

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

Study of the cerebral blood flow in partial epilepsy of childhood using the SPECT method.

Cerebral functional imaging methods provide information on the location of the epileptic focus in partial epilepsy of adults. We report our experience of one of these methods, single photon emission computed tomography (SPECT), in epilepsy of children. SPECT enables the regional cerebral blood flow (rCBF) to be measured, after inhalation or injection of 133-Xenon, on 5 contiguous, 20 mm thick axial sections, with a 14 mm resolution and negligible brain irradiation. In Sturge-Weber syndrome (13 patients aged 9 months to 18 years) the rCBF was reduced in the same territory as CT abnormalities suggesting ischaemia of the brain tissue lying below the pial angioma; the SPECT image facilitated the diagnosis in 3 patients with atypical CT. In hemimegalencephaly (6 patients aged 1 month to 10 years) the rCBF was extremely low in the hypertrophic hemisphere and in 1 case the SPECT image was determinant in the decision to perform hemispherectomy. In partial epilepsy with normal CT and/or MRI (42 children aged 1 to 15 years) the rCBF was abnormal in 83% of the patients, and its abnormality was located in the same area as the EEG focus in three quarters of the cases. Between seizures, the rCBF was low in 3 out of 4 cases and abnormality decreased after the seizures had ceased (6 patients explored twice); it was high in 1 out of 4 cases. Thus, in children as in adults, cerebral functional imaging provides new data which contribute to the localization and follow-up of epileptic foci.

Adolescent↗
PubMed1989

[Neonatal Proteus mirabilis septicemia and cerebral abscess. Value of the assay of antibiotics in the puncture fluid].

The authors describe a case of neonatal Proteus mirabilis septicemia accompanied by cerebral abscess formation despite the presence of therapeutically effective antibiotic levels utilised to treat the disorder. The occurrence of such brain abscesses during the course of effective antibiotic therapy raises the question of the mechanism behind their formation. Cerebritis may occur very early in the clinical course of the infection without being due to failure of antimicrobial therapy.

Anti-Bacterial Agents↗
PubMed1988

Automatic drawing of the left epicardial region of interest on thallium 201 scintigraphic images.

An algorithm has been written which automatically selects a left epicardial region of interest on 201Tl myocardial images. It accomplishes a radial search from the geometric center of the myocardium. On each of the 30 profiles, the local maximum of the 1st derivative is selected as the epicardial edge. The algorithm has been tested in 40 patients at stress and redistribution. In ten patients, conventional planar images were obtained in three views. In 30 patients conventional short axis tomographic images were obtained after reconstruction of 32 projections acquired over 180 degrees. The rate of success is 97% for both imaging modalities. This procedure is another step towards fully automated assessment of myocardial defects and redistribution.

Algorithms↗
PubMed1988

ECG gated thallium 201 myocardial images: value in detecting multivessel disease in patients on anti anginal therapy 1-3 months after myocardial infarction.

ECG gated 201Tl scintigraphy was compared to non gated images for detecting 2-3 vessel disease 1-3 months after a first uncomplicated myocardial infarction. In all, 111 patients on anti anginal treatment underwent coronary arteriography and stress thallium imaging; 39 showed single vessel disease (SVD), and 72 multivessel disease (MVD). Sensitivity of black and white analog images was 82% for SVD and 8% for MVD. Sensitivity of computerized colored static images was 87% for SVD and 33% for MVD. For gated images, sensitivity was 100% and 92% in patients with SVD and MVD respectively. Specificity for detecting MVD was 95% for black and white images, 77% for computerized colored static images, and 69% for ECG gated images. Thus, ECG gated exercise 201TL scintigraphy is useful for predicting the extent of coronary artery disease 1-3 months after myocardial infarction in patients on anti anginal therapy.

Angina Pectoris↗
PubMed1988

Non-invasive measurement of pulmonary arterial pressure: I. A haemodynamic modelling approach.

In order to monitor pulmonary arterial pressure (P) by any non-invasive imaging technique, a haemodynamic model of blood flow kinetics and wall mechanics has been developed. It is a one-dimensional model of pulsatile flow in an elastic pulmonary arterial trunk, assuming that blood is an incompressible fluid and viscous effects are negligible. The equations are P(t)-Pd = rho c2lnS(t)/Sd-1/2pw-2(t) Pd = (Sd/Ss)1/2Pp where, at any time of the ejection phase of systole, P(t), S(t) and w(t) are the pulmonary arterial pressure, cross-sectional area of the pulmonary artery and blood velocity averaged on the cross section S, respectively, PP is the pulse pressure, the difference between the peak systolic pressure and the diastolic pressure Pd; rho is blood density, c pulse wave velocity, and Ss and Sd are maximum (systolic) and minimum (diastolic) values of the cross-sectional area S. Using these equations, P(t) can be calculated if the three parameters, i.e. c, S(t) and w(t) are measured. So far, it has been impossible to measure the pulse wave velocity c non-invasively. We have investigated the calculation of c from S(t) and w(t) using the equation of continuity in the absence and presence of reflected pressure waves. The hypotheses of the haemodynamic model are discussed.

Blood Flow Velocity↗
PubMed1988

Non-invasive measurement of pulmonary arterial pressure: II. A radionuclide method.

Pulmonary artery pulse pressure (PP) and diastolic pressure (Pd) may be obtained by applying a haemodynamic model of blood flow kinetics and wall mechanics to the pulmonary artery: Pp = rho(ws/(Ss/Sd-1))2log(Ss/Sd)-1/2 rho w2s Pd = (Sd/Ss)1/2Pp where rho is blood density, ws is peak ejection velocity, and Ss and Sd are peak maximal and end diastolic cross-sectional areas of the main pulmonary artery. The different parameters of the equations were measured from radionuclide first pass and equilibrium studies. Radionuclide first pass studies were performed in 24 patients with intravenous injection of 20 mCi of 99Tcm red blood cells with a gamma camera in a 20 degrees right anterior oblique position: data were collected in list mode, i.e. a continuous sequence of spatial and temporal coordinates of each photon. Pulmonary arterial pressure was recorded simultaneously with a microtip catheter during the first pass study. Gated first pass images of the right side of the heart were reconstructed, regions of interest drawn over the right ventricle and the main pulmonary artery (MPA) and time-activity curves generated. Peak systolic (Cs) and end diastolic (Cd) counts obtained from the MPA curve were proportional to the cross sections Ss and Sd of the MPA and Ss/Sd = Cs/Cd. The diameter (D) of the pulmonary artery was calculated as the distance between the two zeros of the second derivative of a cross-sectional profile. The averaged cross-sectional area was S = pi D2/4. ECG gated blood pool studies were performed in a LAO 40 degrees position when the tracer was at equilibrium; they were processed automatically and the right ventricular end diastolic counts (EDC) converted into volume (EDV) using an aortic volume/count ratio. Right ventricular peak ejection rate (PER) was obtained from the RV time-activity curve and the instantaneous peak ejection velocity was calculated, ws = PER X EDV/S X EDC. PP and Pd were calculated in mmHg and the radionuclide method yielded pressure values that correlated reasonably with catheterisation values: PP(rad) = 0.99 PP(cath)-0.55, r = 0.84 and Pd(rad) = 0.67 Pd(cath) + 4.91, r = 0.74. We conclude that radionuclide techniques can provide a non-invasive method based on a haemodynamic model for measuring pulmonary arterial pressure.

Adult↗
PubMed1987

Early and delayed SPECT using N-isopropyl p-iodoamphetamine iodine 123 in cerebral ischemia. A prognostic index for clinical recovery.

Sixteen patients with stroke, five patients with permanent regressive ischemic neurologic deficit, and three patients with transient ischemic attacks were studied by single photon emission computed tomography performed within the first hour (early scan) and four hours (delayed scan) after injection of N-isopropyl-p-iodoamphetamine-iodine-123 (IMP). These patients were classified into three groups according to their clinical improvement three months later, and results of single photon emission computed tomography were compared with computed tomographic scan results and correlated to the clinical outcome. Regional brain hypoactivity of IMP differed in some cases between early and delayed IMP scans, showing in those cases a "redistribution" activity. The amplitude of this redistribution was significantly correlated with the clinical outcome of patients with stroke, whereas the value of hypoactivity on early IMP scan did not show such a correlation. The higher the redistribution amplitude was, the better was the clinical outcome. Comparative regional brain hypoactivity of IMP on early and delayed scans could represent a prognostic index of clinical recovery inasmuch as it gives information concerning viability of ischemic brain tissue.

Adult↗
PubMed1987

Evaluation of 3 dimensional space and time filtering on ECG gated 201Tl myocardial images.

Stress 201Tl myocardial images were obtained using a standard ECG gated acquisition protocol for 10 min per view. These images were filtered using a three dimensional space and time filter. The effects of filtering were evaluated by sectorial analysis. Comparing raw and filtered dynamic images, quantification demonstrated that filtering did not produce artefacts. A conventional static image was also obtained as the sum of the series of unfiltered dynamic images. Comparison of raw static and filtered diastolic images indicated that the latter demonstrated myocardial abnormalities more clearly (P less than 0.01) in 33 patients. Improvement in the signal to noise ratio produced by filtering made cinematic display and visual analysis possible which was not feasible with raw gated images. Clinical evaluation is in progress.

Diastole↗
PubMed1987

[Cerebral blood flow in idiopathic West syndrome: correlation with electroencephalographic findings].

Seventeen patients with idiopathic West syndrome and normal CTscan underwent a SPECT investigation. It is possible to perform this investigation in infants and children; the technical and methodological aspects are analysed. In benign infantile epileptic spasms, it showed no significant abnormality. In all the other cases, areas of hypovascularisation were observed. They predominated in the parieto-temporo-occipital areas both in the acute phase and several months or years later, and they correlated with the topography of predominating EEG abnormalities.

Amphetamines↗
PubMed1987

Amines for brain tomoscintigraphy.

Amines like N-isopropyl-p-123I-iodoamphetamine (IMP) and hydroxy 123I-iodobenzyl propyl diamine (HIPDM) associated with brain tomoscintigraphy have proved their worth for detecting ischaemic abnormalities. Even though the chemistry of their metabolism and their biodistribution are not fully understood, their application in the study of parenchymal impairment in stroke and reversible ischaemia yields additional information compared to the other methods of imaging like CT or MRI. The concept of a steady state in brain with a wash in/wash out model has been considered especially with IMP, to explain the evolution of the activity pattern with time when comparing early and delayed images. (This review leads to foresee the prognosis of of ischaemic diseases when redistribution is taken into account.)

Amphetamines↗
PubMed1986

[And if it were I...].

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed1983

[Chemical and pharmacological aspects of cerebral cellular tracers].

Among the iodophenylalkylamines studied and labelled with iodine 125 or iodine 123, N-isopropyl-iodo-amphetamin (IAMP) was selected and proposed as tracer for blood flow, a "chemical embolus" having almost 100% extraction in the brain. A new way of obtaining N-isopropyl-p-iodo-amphetamin is proposed and the easily-applied exchange reaction with iodine 125 or 123 gives a product with a radiochemical purity of more than 96% and an unexchanged radioactive iodine content of less than 1%. The pharmacokinetic study of this product in the Wistar rat showed distribution in three compartments and the appearance of a steady state by the fourth minute. The target organs are the lungs, liver and brain. The latter receives 3% of the radioactivity and the autoradiographic study shows that the early distribution in the brain for IAMP closely equals the blood flow as found by a diffusible indicator. In the first hour, the redistribution is very low and at this time although IAMP is proposed for the study of regional blood flow, it does not exactly determine the flow but rather mirrors cell activity.

Amphetamines↗
PubMed1983

Estimates of kidney volume by single photon emission tomography: a preliminary report.

Algorithms for the estimation of organ volumes have been developed which may provide whole organ volumes and which may or may not, at the operator's choice, take into account any voids which may be contained within the organ. These algorithms have been applied to the estimation of the volume of the kidneys, in normal subjects and in patients with renal disease. The dimensions of the kidneys were similar to those derived from ultrasound study measurements which were performed independently. Kidney volume should prove especially useful in the diagnosis of early graft rejection and in the diagnosis of glomerulonephritis.

Female↗
PubMed1983

Cerebral blood-flow tomography: xenon-133 compared with isopropyl-amphetamine-iodine-123: concise communication.

Tomographic maps of local cerebral blood flow (CBF) were obtained with xenon-133 and with isopropyl-amphetamine-iodine-123 (IMP) in 11 subjects: one normal, two tumor cases, and eight cerebrovascular cases. A highly sensitive four-face, rapidly rotating, single-photon emission tomograph was used. The Xe-133 flow maps are essentially based on the average Xe-133 concentration over the initial 2 min during and after an inhalation of the inert gas lasting 1 min. These maps agreed very well with the early IMP maps obtained over the initial 10 min following an i.v. bolus injection. The subsequent IMP tomograms showed a slight decrease in contrast amounting to appr. five percentage points in the CBF ratio between diseased and contralateral areas. It is concluded that Xe-133 is more practical: low cost, available on a 7-day basis, easily repeatable, quantifiable without the need for arterial sampling, and with low radiation exposure to patient and personnel. On the other hand, IMP gives an image of slightly higher resolution. It also introduces a new class of iodinated brain-seeking compounds allowing, perhaps, imaging of other functions more important than mere blood flow.

Amphetamines↗