Biomedical subjects

L Cinotti

Publications and source records attributed to L Cinotti.

At least 55 records · Page 3Linked to original sources

PubMed1988

Interpretation of the krypton-81m dynamic series: the distribution of a tidal breath.

Lung scans during cyclic breathing of krypton-81m, an isotope with a 13-s half-life, were acquired in "list mode," where both temporal and spatial information are preserved. Subjects in the left lateral decubitus position breathed with two tidal volumes at each of two frequencies. Profiles of total activity over the acquisition period were examined. They showed little effect of frequency or tidal volume on the distribution of air between dependent and non-dependent regions. Dynamic series for ensemble-averaged breaths were constructed. The regional flow per unit volume was shown to correspond to the time derivative of the regional activity of the dynamic series divided by the corresponding activity. Both the relative timing of the gas flow to different lung regions and the flow per unit volume as a function of time were obtained from the dynamic series. The dependent lung was seen to be better ventilated throughout the respiratory cycle except for brief periods at the start of inspiration and the end of expiration. Most of the dead-space gas can be construed to enter and leave the dependent lung.

Female↗

PubMed1988

[Foundation for the understanding of ventilation-perfusion ratio abnormalities].

Understanding the mismatching of ventilation and perfusion (VA/Q) is of special interest in the intensive care setting because - given a stable cardiac output and a given inspiratory oxygen fraction - it allows one to explain certain essential respiratory problems in critically ill patients, namely hypoxemia and hypercarbia. Several different methods are available today for the evaluation VA/Q mismatching. Analysis of the PCO2 and PO2 in arterial and mixed venous blood and mixed expired gas yields information about the quality and the degree of the mismatching present. Calculation of the physiologic dead space (VD/VT) and venous admixture (QVA/QT) from the PCO2 and PO2 data allow the VA/Q mismatching to be quantified according to a three-compartment model of the lung. Determination of the arterial-alveolar nitrogen partial-pressure difference permits a more precise estimation of the true right-to-left shunt as a cause of arterial hypoxemia, but the measurement of the arterial PN2 remains a delicate procedure. The multiple inert gas elimination technique permits virtually continuous ventilation-perfusion distributions to be described over the whole range of VA/Q ratios and has contributed to explaining the pathophysiological mechanisms in various pulmonary diseases. This method, however, is technically very complex and hence will remain a sophisticated investigational tool. Scintigraphic approaches allow the description of regional topographic VA/Q distributions, but their application is still difficult in the intensive care setting.

Carbon Dioxide↗

PubMed1987

[Calculation of the ventilation-perfusion ratio in the scintigraphic diagnosis of pulmonary embolism].

Ventilation perfusion scanning fails to diagnose pulmonary embolism in matched defects. In 61 patients (19 with pulmonary embolism proved by angiography, 32 with chronic obstructive lung disease and 10 with acute bacterial pneumonia) we computed the ventilation perfusion ratio (V/Q) in these matched defects, using Krypton 81 m. This analysis demonstrated that the diagnosis of pulmonary embolism could be made with a specificity of 100% when the V/Q ratio was greater than 1.2 in the matched defects. Pulmonary embolism was characterized by a perfusion defect with a high V/Q ratio, even in Laennec infarction. In contrast, the analysis excluded the diagnosis of pulmonary embolism and suggested another disease when the V/Q was less than 0.95 with a specificity of 95%. Perfusion defects in acute pneumonia always had a V/Q less than 1. The diagnosis remained difficult in chronic obstructive lung disease when pulmonary embolism was suspected on subsegmental defects. Nevertheless this could be solved in about 50% of the cases by quantitative analysis. We feel, therefore, that ventilation perfusion scanning should be quantified by V/Q analysis to improve the diagnosis of pulmonary embolism.

Adult↗

PubMed1987

Technetium-99m DTPA aerosol and gallium scanning in acquired immune deficiency syndrome.

In 11 non-smoking AIDS patients suspected of pneumocystis carinii pneumonia (PCP), the results of Tc-99m DTPA aerosol clearances, gallium scans, and arterial blood gases were compared with those of bronchoalveolar lavage (BAL). Nine patients had PCP. All had increased clearances five times higher than the normal (5.6 +/- 2.3% X min-1 vs 1.1 +/- 0.34% X min-1, N = 10, P less than 0.001), suggesting an increased alveolar permeability. Gallium scans were abnormal in six patients but normal or slightly abnormal in the three others. Four of these nine patients had normal chest x-rays. In two of these the gallium scan was abnormal, but in the two others, only the increased Tc-99m DTPA clearances showed evidence of lung disease. Two patients had normal BAL, with normal clearances and gallium scans. Four out of the nine patients with PCP were studied after treatment. Three recovered and had normal clearance and gallium scans. One still had PCP with increased clearance but normal gallium scan. Gallium scanning and Tc-99m DTPA clearance are useful for detecting lung disease in AIDS patients with suspected PCP and for prompting BAL when chest x-rays and PaO2 levels are normal. Due to its high sensitivity, a normal Tc-99m DTPA clearance could avoid BAL.

Acquired Immunodeficiency Syndrome↗

PubMed1987

Measurement of lung volume with 81Krm in a dynamic scintigram.

The meaning of 81Krm counts obtained in a dynamic series of gated lung ventilation scans was evaluated in terms of flow rate, lung volume, or the flow/volume ratio. Flow and volume signals were recorded together with scintigraphic events in 29 subjects breathing 81Krm and after its decay, 127Xe as a tracer of lung volume. Gated ventilation scans and respiratory signals were reconstructed. Statistical analyses were carried out for linear regressions between total normalized counts detected by the gamma camera and (1) flow rate, (2) lung volume and (3) flow/volume ratio. Inspiration and expiration were analysed separately. For both isotopes, the best correlation was obtained between counts and lung volume (r greater than 0.93). No correlation was obtained between counts and flow rate or flow/volume ratio. Thus, we conclude that 81Krm count variations in gated scans correlate well with tidal volume.

Humans↗

PubMed1987

Hemodynamic, gas exchange, and hormonal consequences of LBPP during PEEP ventilation.

Hemodynamic, gas exchange, and hormonal response induced by application of a 25- to 40-mmHg lower body positive pressure (LBPP), during positive end-expiratory pressure (PEEP; 14 +/- 2.5 cmH2O) were studied in nine patients with acute respiratory failure. Compared with PEEP alone, LBPP increased cardiac index (CI) from 3.57 to 4.76 l X min-1 X m-2 (P less than 0.001) in relation to changes in right atrial pressure (RAP) (11 to 16 mmHg; P less than 0.01). Cardiopulmonary blood volume (CPBV) measured in five patients increased during LBPP from 546 +/- 126 to 664 +/- 150 ml (P less than 0.01), with a positive linear relationship between changes in RAP and CPBV (r = 0.88; P less than 0.001). Venous admixture (Qva/QT) decreased with PEEP from 24 to 16% (P less than 0.001) but did not change with LBPP despite the large increase in CI, leading to a marked O2 availability increase (P less than 0.001). Although PEEP induced a significant rise in plasma norepinephrine level (NE) (from 838 +/- 97 to 1008 +/- 139 pg/ml; P less than 0.05), NE was significantly decreased by LBPP to control level (from 1,008 +/- 139 to 794 +/- 124 pg/ml; P less than 0.003). Plasma epinephrine levels were not influenced by PEEP or LBPP. Changes of plasma renin activity (PRA) paralleled those of NE. No change in plasma arginine vasopressin (AVP) was recorded. We concluded that LBPP increases venous return and CPBV and counteracts hemodynamic effects of PEEP ventilation, without significant change in Qva/QT. Mechanical ventilation with PEEP stimulates sympathetic activity and PRA apparently by a reflex neuronal mechanism, at least partially inhibited by the loading of cardiopulmonary low-pressure reflex and high-pressure baroreflex. Finally, AVP does not appear to be involved in the acute cardiovascular adaptation to PEEP.

Adult↗

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

Imaging and assessment of regional clearances of indium-111 labelled circulating immune complexes in humans.

The in vivo function of the reticulo-endothelial system in humans is currently studied by the blood clearance of 51Cr labeled RBC sensitized with IgG anti-Rh. By replacing 51Cr by 111In we developed a method which allows imaging and assessment of clearances of circulating immune complexes (CIC) by individual organs. Nine normal subjects were studied successively with 51Cr labelled CIC and 111In-labelled CIC by blood sampling and sequential imaging. Time activity curves were obtained over spleen, liver, heart lungs and kidneys. The blood clearance values were similar with 111In (T1/2 +/- SD = 23.4 min +/- 6.4 min) and 51 Cr (T1/2 = 22.9 min +/- 5.8 min). The blood clearance derived from the time activity curve obtained over the cardiac area (T1/2 = 26.6 min +/- 8.4 min) was not significantly different from that obtained by blood sampling. Most of the CIC were taken up by the spleen with a T1/2 of 20.3 min +/- 4.1 min. Although hepatic uptake was observed in all subjects, it was lower than that of the spleen and CIC were subsequently released from the liver in five of the nine patients. The spleen/liver ratio increased with time, reaching a plateau averaging 24.0 +/- 5.8 within 80 min in all subjects. CIC imaging allows, by a non-invasive procedure, the computation of CIC blood clearance and the estimation of the respective role of spleen and liver in phagocytic function.

Adult↗

PubMed1986

Regional distribution of ventilation assessed by Kr-81m scintigraphy employing temporal Fourier transform.

Temporal Fourier analysis was applied to Kr-81m ventilation scintigraphy to determine the amplitude (AMP1) and phase (PHA1) of the first harmonic of a single composite respiratory cycle and to compare regional patterns in subjects with obstructive pulmonary disease (COPD) and nonobstructed subjects. Six nonobstructed subjects, three subjects with small airway disease, six subjects with COPD, and one subject with restrictive disease were investigated. The mean value of the functional PHA1 image (PHA1m) correlated negatively with 1-second forced expiratory volume (FEV1) (r = -0.801, P less than .001), with %FEV1/FVC (r = -0.636, P less than .01) and maximum midexpiratory flow rate (FEF25-75%) (r = -0.723, P less than .002), and correlated positively with residual volume (r = 0.640, P less than .01). PHA1m values for the six subjects with COPD were significantly higher (t = 2.359, P less than .05) than for the ten nonobstructed subjects. Display of phase and amplitude functional images permits a visual evaluation of the regional distribution of ventilation to be made. Regional abnormalities of air flow were detected in obstructed subjects, and the presence of airway obstruction could be predicted. Dynamic ventilation imaging, therefore, appears to be a potentially useful noninvasive technique to assess lung impairment on a localized level.

Adult↗

PubMed1986

Exercise increases the lung clearance of inhaled technetium-99m DTPA.

The regional lung clearance of a deposited aerosol of [99mTc] diethylenetriaminepentaacetic acid was successively computed at rest and at exercise in seven nonsmoking volunteers in upright posture. The subjects were seated on a bicycle with their backs against a gamma camera. At rest there was a gradient of clearance from the apex to the base of the lung, the apical clearance being significantly higher. At exercise this regional gradient was enhanced by a large and significant increase of the apical clearances (3.40 +/- 0.63% min-1 s.d. compared with 1.82 +/- 0.75% min-1 s.d. at rest, n = 7, p less than 0.01). By contrast the changes of the basal clearances were slight and unsignificant (1.46 +/- 0.71% min-1 s.d. compared with 1.40 +/- 0.82% min-1 s.d.). This increase of the apical lung clearance could be attributed primarily to the increase of apical blood flow induced by exercise and to the subsequent increase of the permeability surface area product.

Adult↗

PubMed1985

Factor analysis of 81mKr lung ventilation studies.

Factor analysis of dynamic structures (FADS) summarizes data depending on time and space in a few elementary components. Each of them associates a time-activity curve (factor) and the spatial distribution of the corresponding events. The aim was to evaluate the patterns, the number of components, and their possible link to physiology when FADS was applied to scintigraphic images representing a composite of a 81mKr ventilation cycle. In a study of 26 patients (10 normal, 16 pathologic), components were found that represent: (1) a rapid and steeply changing ventilation factor, corresponding mainly to bases in normal subjects and whole lung fields in patients, (2) a slower expiration and shorter inspiration ventilation factor distributed throughout both lung fields in all patients, (3) a constant activity curve, with an inspiratory activity peak distributed over both lung fields and the large airways, and (4) a factor including a phase shift with respect to the first; this was found significantly more often in patients with pathology.

Factor Analysis, Statistical↗

PubMed1985

An interactive software for 81mKr pulmonary ventilation gating.

An interactive software to gate scintigraphic list-mode data collected from ventilation studies using a radioisotope of an inert gas (81mKr) has been developed. It allows the detection of end expiration and end inspiration phases in a time activity curve. It involves six phases: filtering of the curve; preselection of local extrema; validation of the preselection; choice of the parameters for the reconstruction; control of the selected cycles and display of parameters such as frequency, expiration time, breath amplitude; reconstruction of images representing the distribution of ventilation during a mean respiratory cycle. This software was tested on 116 data sets without a failure. The interactive definition and control of the selected times made the algorithm useful regardless of the count rate and the frequency. It could be adapted to gate other periodic or semiperiodic physiological phenomena.

Computers↗

PubMed1984

Regional distribution of ventilation-perfusion ratios in acute pulmonary embolism.

Regional ventilation perfusion ratios have been computed in 44 patients with acute pulmonary embolism with a gamma-camera using Krypton 81m, a short-life radionuclide delivered by inhalation and infusion. This noninvasive technique is performed during tidal breathing and can be easily repeated. High V/Q's are detected in the embolic regions and low V/Q's in the nonembolic regions with a shift of the perfusion distribution towards these low values. This pattern disappears with recovery. This technique can be used in clinical practice for diagnostic purposes.

Acute Disease↗

PubMed1984

Computation of ventilation-perfusion ratio with Kr-81m in pulmonary embolism.

Diagnostic difficulties occur in pulmonary embolism (PE) during visual analysis of ventilation-perfusion images in matched defects or in chronic obstructive lung disease (COPD). In 44 patients with angiographically confirmed PE and in 40 patients with COPD, the regional ventilation-perfusion ratios (V/Q) were therefore computed using krypton-81m for each perfusion defect, and were displayed in a functional image. In patients with PE and mismatched defects, a high V/Q (1.96) was observed. A V/Q greater than 1.25 was also found in nine of 11 patients having PE and indeterminate studies (studies with perfusion abnormalities matched by radiographic abnormalities). COPD was characterized by matched defects and low V/Q. The percentage of patients correctly classified as having PE or COPD increased from 56% when considering the match or mismatched character to 88% when based on a V/Q of 1.25 in the region of the perfusion defect. This quantitative analysis, therefore, seems useful in classifying patients with scintigraphic suspicion of PE.

Adult↗

PubMed1983

Myocardial macroaggregate uptake on successive lung perfusion scans.

In a patient with an Eisenmenger syndrome and multiple intraventricular communications, myocardial uptake of macroaggregated albumin appeared during a perfusion lung scan. This pattern can be explained by an increase of arterial pulmonary hypertension heightening the proportion of the right-to-left shunt.

Adolescent↗

PubMed1983

[Noninvasive evaluation of aortocoronary bypass graft patency with tomodensitometry and exercise myocardial scintigraphy].

The control of the patency of aortocoronary bypass grafts necessitates further coronary angiography, an invasive investigation which is difficult to perform routinely because over 60 p. cent of operated patients are asymptomatic. Non-invasive methods have been proposed for this task, including computerised axial tomography (CAT) and exercise Thallium 201 myocardial scintigraphy (EMS). The aim of this study was to assess the relative value of CAT and EMS, alone and in association, in comparison with coronary angiography. Thirty six patients (35 men, 1 woman) with a mean age of 54 years were studied. These patients had a total of 59 bypass grafts inserted an average of 23 months before investigation (20 single, 10 double, 5 triple and 1 quadruple bypass grafts). CAT scanning was performed the day before coronary angiography. Sections of the thorax 7 mm thick were recorded after intravenous injection of contrast medium. A patent graft was identified as an opacity increasing after the injection of contrast on one of the aortic walls. During coronary angiography a graft was declared to be patent when it was opacified selectively or during aortography, and when the grafted coronary artery was seen to be revascularised. The quality of the distal coronary bed was also evaluated (implantation of the graft, distal and collateral vessels). Twenty three patients (with a total of 36 grafts) also underwent EMS on the same day as CAT scanning. Normal fixation in the revascularised territory was taken as evidence of a patent graft. --Coronary angiography showed that 44/59 grafts were patent at 24 months. --CAT scanning was unable to evaluate 12/59 grafts. Thoracic metallic clips created stratified artifacts and analysis of the section was impossible (20 p. cent of CAT investigations were non-contributive); of the interpretable investigations, 40/47 grafts were correctly assessed (85 p. cent): 30/32 patent grafts and 10/15 occluded grafts. --The results of EMS were less reliable; 23/36 grafts correctly assessed (64 p. cent), 18/27 patent grafts and 5/9 occluded grafts. However, EMS provides complementary information to that provided by CAT scanning, especially with respect to the distal coronary bed. When the two methods were used together, 15/15 good surgical results (patent grafts with good distal vascularisation) and 6/8 poor results (patent grafts but poor distal vascularisation), were identified. We conclude that these two atraumatic methods, CAT scanning and EMS, which may be performed on out-patients, are valuable for the routine assessment of the patency of coronary bypass grafts. Coronary angiography could therefore be reserved for those patients in whom further surgery is being considered.

Adult↗

PubMed1983

Diagnostic value of image processing in myocardial scintigraphy.

The diagnostic value of stress myocardial analog scintigrams, and of five image-processing methods, was assessed by a decisional analysis in 96 patients undergoing coronary arteriography. The methods involved digitalization, nine-point binomial smoothing, background subtraction by linear interpolation, stationary filtering, and a combination of them. The difference between after-test probabilities of having the disease with a positive or a negative examination provided a discriminant index for different prevalences of the disease. Though the processing methods failed to improve the detection of a circumflex stenosis, the stationary filter significantly increased the diagnostic value for the detection of stenosis in a left anterior descending artery for a large range of prevalence, and in a right coronary artery at high prevalence. Thus, the filter seemed to provide a useful tool for enhancing the diagnostic value of myocardial scintigraphy.

Adult↗

PubMedDate not supplied

Extraction of functional volumes from medical dynamic volumetric data sets.

A method based on factor analysis is presented to process dynamic volumetric (t + 3D) data sets acquired for flow, excretion, or metabolic studies. It estimates a reduced number of underlying physiological kinetics and their associated spatial distributions, corresponding to functional volumes, using dedicated algorithms. The global (t + 3D) approach is shown to be superior to the conventional one, which repeats estimations on each (t + 2D) data set, obtained for each slice or projection of the volume.

Algorithms↗