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M Faraggi

Publications and source records attributed to M Faraggi.

At least 55 records · Page 3Linked to original sources
PubMed1995

Comparison between factor analysis of dynamic structures and Fourier analysis in detection of segmental wall motion abnormalities: a clinical evaluation.

To evaluate Factor Analysis of Dynamic Structures (FADS) versus or in association with other methods, a protocol was set up including as 'gold standard' investigation the left ventricular angiography (LVA) and processing by Fourier Analysis (FA), and FADS with different variants. To refine the diagnosis of Regional Wall Motion Abnormalities (RWMA), processing was done on a sectorial basis for more accurate spatial localization and functional description. 53 patients were studied (8 normal, 45 with coronary artery disease). FADS gave better results than FA on a sectorial basis. Total agreement between FADS and LVA was obtained in 208/265 (78%), while FA was in agreement with LVA in only 167/265 segments (63%). Globally, FADS was significantly better than FA (Z-test: p < 0.05). When only the diagnosis of maximal abnormality was considered, FA and FADS are statistically equivalent. The superiority of FADS vs FA is more obvious in the diagnosis of hypokinesia. Most FA discrepancies corresponded to underestimation of WMA.

Adult↗
PubMed1995

Modelling of the relationship between cell dimensions and mean electron dose delivered to the cell nucleus: application to five radionuclides used in nuclear medicine.

The mean dose delivered to the cell nucleus by electron emissions of 99Tcm, 123I, 111In, 67Ga and 201Tl was evaluated at the subcellular level. Models were applied assuming uniform distributions of radioactivity throughout the nucleus, the cytoplasm or the cell membrane, allowing computation of the total absorbed fraction, phi and S-values to the cell nucleus as a function of cell dimensions. The graphs of phi plotted according to cell dimensions show that the dose to the cell nucleus strongly depends on the subcellular distribution of radioactivity, the nucleus radius Rnucl and the cytoplasmic thickness e. For a nuclear distribution, phi ranges from 0.1 to 0.35 for the radionuclides studied and S from 0.049 cGy Bq-1 s-1 to 5.503 cGy Bq-1 s-1. In the case of a cell membrane localization, the maximum is obtained for 123I (phi = 0.016). For a cytoplasmic distribution, the maximum is obtained for 201Tl with a value of 0.036. To ease future calculations, third-degree polynomials have been separately fitted to the relationship between the mean absorbed dose to the nucleus for activity accumulated in the nucleus, cytoplasm or surface of the cell membrane. We found a good agreement between our computations and the values obtained by the polynomials. The relative difference between the two methods is always less than 0.7%, 2.8% and 4.5% respectively for nuclear, cell membrane and cytoplasmic distributions.

Cell Membrane↗
PubMed1995

[Diagnostic value of myocardial thallium stress scintigraphy in the detection of coronary artery disease in patients undergoing chronic hemodialysis].

Atherosclerotic heart disease is the leading cause of death in patients with end stage renal disease, but its non invasive detection remains difficult because of a low efficacy of exercise testing. The aim of the study was to evaluate diagnostic accuracy of thallium myocardial imaging after dipyridamole combined with exercise. Forty two chronic dialysis patients (34 men, 8 women) aged 55 +/- 11 years (range: 36 to 75) without symptom of angina nor myocardial infarction were studied. In each patient, an echocardiography, a myocardial scintigraphy with dipyridamole combined with symptom-limited exercise, and coronarography were performed. A coronary heart disease was diagnosed by coronarography in 10 patients (4.5 and 1 respectively with 1, 2 and 3 vessels diseased). Echocardiography detected a left ventricular hypertrophy (LVH) in 26 patients and a regional asynergia in 14 patients. A positive scintigraphy was present in 11 patients. Three false-positive and 2 false-negative on scintigraphy were noted. Sensibility, specificity, positive predictive value and negative predictive value were respectively evaluated at 80, 73, 73 and 93%. All the five patients with either false-positive or false-negative scintigraphy exhibited a LVH. CONCLUSION. In chronic dialysis patients, coronary heart disease may be detected by thallium myocardial imaging after dipyridamole combined with exercise.

Adult↗
PubMed1994

Somatostatin receptor scintigraphy in forty-eight patients with the Zollinger-Ellison syndrome. GRESZE: Groupe d'Etude du Syndrome de Zollinger-Ellison.

In patients with the Zollinger-Ellison syndrome, which is either sporadic or integrated into multiple endocrine neoplasia type 1, accurate localization of all the tumours is difficult and may have therapeutic implications. In an attempt to improve this localization, somatostatin receptor scintigraphy using [111In-DTPA-D-Phe1]-octreotide was performed prospectively in 48 consecutive patients with the Zollinger-Ellison syndrome. Thirty of them had the sporadic type of this disease. Scintigraphic data were compared with data obtained by conventional imaging methods, and also, in 32 selected patients, with those obtained by endoscopic ultrasonography. Somatostatin receptor scintigraphy showed abnormal tracer uptake in 39 patients (81%), in whom it correctly identified 50 of the 60 tumoral sites (83%) previously localized by the other imaging methods. In 17 patients (35%) somatostatin receptor scintigraphy disclosed abnormal tracer uptake at 18 different tumoral sites: 14 were located in the abdomen, including four in the liver and eight in the duodenopancreatic area, and four outside the abdomen, including two in the mediastinum. Six of the ten tumoral sites which were not correctly identified by somatostatin receptor scintigraphy were located in the duodenopancreatic area. However, in the 20 patients for whom conventional techniques failed to visualize any tumour in the duodenopancreatic area, somatostatin receptor scintigraphy was positive in ten (50%) whereas endoscopic ultrasonography was only positive in five (25%). In our patients with the Zollinger-Ellison syndrome, somatostatin receptor scintigraphy appeared to be a useful new addition to the battery of tests used for tumour detection.

Bone Neoplasms↗
PubMed1994

Functional evaluation of normal and ischemic kidney by means of gadolinium-DOTA enhanced TurboFLASH MR imaging: a preliminary comparison with 99Tc-MAG3 dynamic scintigraphy.

The functional value of TurboFLASH MR imaging in the assessment of dynamic contrast enhancement and renal perfusion anomalies was evaluated in seven patients, who also underwent renal scintigraphy in baseline conditions. The basal renograms obtained from MAG-3 scintigraphy (mercapto acetyl triglycine, MAG3-S) and from Gd-DOTA-enhanced turboFLASH MRI were compared. After hydration, the protocol used consisted in breath-hold coronal turboFLASH acquisitions after IV bolus of Gd-DOTA (4 s every 20 s during 10 min) for MRI, and IV bolus of 370 MBq of 99mTc-MAG3 followed by 60 frames of 1 s and then 120 frames of 10 s for MAG3-S. Relative renal functions were computed for both methods by calculation of the integral of the uptake phase between the first and the second minute. Renograms exhibited 10 normal and 4 ischemic kidneys. There was a close correlation between the contrast enhancement of MRI and isotopic uptake in normal and ischemic kidneys. Global renograms of MRI correlated with MAG3-S (r = .82, p < .001) with similar curve shape and time to peak. Relative renal function of the right and left kidney were closely correlated in all patients (r = .98, p < .001), although there was a tendency for MR to overestimate MAG3-S evaluation in kidneys with severe basal dysfunction. Enhanced turboFLASH provides noninvasive assessment of renal perfusion in patients with renovascular disease. Accurate renograms are obtained with dynamic-enhanced MRI, but the relative renal function seems to be overestimated in low values of ischemic kidneys, and needs further comparative evaluation.

Adult↗
PubMed1994

Myocardial sarcoidosis. Clinical value of technetium-99m sestamibi tomoscintigraphy.

STUDY OBJECTIVE: The presence of defects on rest thallium 201 myocardial scintigraphy, reversible after dipyridamole infusion, was already demonstrated in myocardial localization of sarcoidosis. The present study compared the respective efficiency of a new tracer of myocardial blood flow, 99mTc sestamibi (sestamibi), vs thallium 201 (TI) for the diagnosis and follow-up of myocardial sarcoidosis. METHODS: Quantitative single photon emission computed tomography (SPECT) was performed in 37 consecutive patients with confirmed sarcoidosis and clinical suspicion of myocardial localization. Three successive scans were performed in all patients within the same day: rest TI SPECT, rest sestamibi SPECT, and dipyridamole sestamibi SPECT. Thirteen patients were reinvestigated after 3 months of corticosteroid therapy. The size and intensity of the defects were compared using a computerized quantitative analysis of bull's eye. RESULTS: At rest, sestamibi SPECT is more sensitive than TI, demonstrating significantly larger defects (28.1 +/- 13.2% vs 17.2 +/- 12.8% of bull's eye area, p < 0.001) and detecting abnormalities in seven more patients (24 vs 17). All patients with abnormal TI scans also had sestamibi abnormalities. After dipyridamole infusion, sestamibi defects decreased significantly (28.1 +/- 13.2% vs 15.2 +/- 12.3%, p < 0.001). This improvement correlated with the evolution of sestamibi SPECT performed in the 13 patients reinvestigated after corticosteroid therapy (r = 0.85, p < 0.001). CONCLUSIONS: We conclude that sestamibi SPECT is suitable for the diagnosis of myocardial sarcoidosis and represents an objective tool for the follow-up. The improvement after vasodilatation supports the hypothesis of reversible abnormalities in most of these patients and accurately predicts corticosteroid efficiency.

Adult↗
PubMed1994

[Postinfarction hibernating myocardium].

The detection of hibernating myocardium after infarction is important because it justifies the discussion concerning the revascularisation of infarcted zones irrigated by occluded or severely stenosed vessels, but with an adequate collateral circulation to allow hibernation. The detection of hibernating myocardium is particularly important in patients without the classical indications for revascularisation, such as residual spontaneous ischaemia or ischaemia provoked by exercise or pharmacological stress testing. All techniques currently in use tend to overestimate the size of the necrosed, fibrous scar, compared with the amount of viable myocardium. Improved regional myocardial function after revascularisation is the most convincing proof of hibernating myocardium but it can only be obtained retrospectively. The detection of a reserve of contractility in the necrosed territory by an inotropic stimulus is well adapted to the demonstration of stunned myocardium but this method has not been proved in hibernating myocardium. Thallium scintigraphy is certainly useful in the prospective diagnosis of hibernating myocardium but the protocol of examination should be adapted to this specific problem. There is little available data concerning the evaluation of hibernating myocardium by positron emission tomography: the technical advantages of this method in assessing myocardial viability should enable a more accurate evaluation of post-infarction hibernating myocardium. Adequate revascularisation of necrosed territories depends on a deeper understanding and more precise prospective assessment of postinfarction hibernating myocardium.

Humans↗
PubMed1994

The influence of tracer localization on the electron dose rate delivered to the cell nucleus.

UNLABELLED: The radiation dose rate delivered by electron emissions of 99mTc, 123I, 111In, 67Ga and 201Tl was evaluated at the subcellular level. METHODS: Spherical models of sources were used to simulate various cellular localizations of radionuclides. These models were applied to large lymphocytes, assuming uniform distributions of radioactivity throughout the nucleus, the cytoplasm or the cell membrane surface. RESULTS: The graphs of the absorbed dose rate plotted according to the distance from the center of the cell show that the dose rate strongly depends on the subcellular distribution of the radioisotope. The absorbed dose rate D(0) at the center of the cell delivered by a constant cellular radioactivity of 99mTc, 123I, 111In, 67Ga and 201Tl is respectively 94, 21, 18, 74 and 76 times higher if the radioactivity is localized within the cell nucleus than if it is situated only on the cell membrane. D(0) for subcellular localizations was compared to D(0) obtained by assuming uniform distribution of radioactivity throughout the cell. This latter assumption may underestimate the dose rate from 2.8- to 3.2-fold if the tracer is exclusively localized within the nucleus or overestimate from 4.3- to 30-fold if the tracer is localized within the cytoplasm or on the cell membrane, depending on the radionuclide. CONCLUSION: Such findings show that the localization of radiopharmaceuticals at the subcellular level plays a crucial role in determining the actual dose delivered to the cell nucleus in diagnostic nuclear medicine procedures.

Cell Membrane↗
PubMed1993

[Contribution of antimyosin antibody myocardial scintigraphy in the diagnosis of acute myocarditis].

The authors report three cases of acute myocarditis: the first patient was a 23 year old woman treated for tuberculosis who presented with rapidly progressive congestive cardiac failure. The second patient was a 52 year old man with atypical chest pain and the third was a 55 year old woman presenting as an acute myocardial infarction. In all three cases, a positive antimyosin antibody myocardial scintigraphy supported the presumptive diagnosis. The authors review the principles of the method and its potential indications, antimyosin antibody scintigraphy being able to demonstrate recent myocardial necrosis but not to identify the cause. The sensitivity of the technique is high (83 to 100% according to the series) but the specificity is much lower (about 55%) compared with endomyocardial biopsy, an investigation which is specific but not very sensitive. Modifications of the antibody and the radioactive tracer used at present should improve the diagnostic value of the technique in the near future.

Acute Disease↗
PubMed1992

Long range electron transfer along an alpha-helix.

The many observations of long range electron transfer in proteins raises the question of whether a protein's structure can influence the rate or path of such transfers, and if so, then how. To answer these questions requires information on which of the various structural elements composing proteins support long range electron transfer. In this report, we present evidence for long range electron transfer along the alpha-helix of a synthetic leucine zipper dimer. We also present electron transfer rate data obtained with other helical peptides.

Amino Acid Sequence↗
PubMed1992

[Myocardial thallium scintigraphy after administration of dipyridamole. Application to the diagnosis and evaluation of coronary insufficiency].

Myocardial thallium scintigraphy performed after intravenous injection of dipyridamole is a non-invasive method to diagnose and evaluate coronary disease. It can be used as an alternative to postexercise scintigraphy, both methods having similar sensitivity and specificity. The dipyridamole test is contraindicated in patients with a history of bronchospasm and uncontrolled angina pectoris. Close clinical and electrocardiographic monitoring is required. The wide use of tomographic techniques has notably improved this examination.

Administration, Oral↗
PubMed1992

Myocardial viability in patients with Q wave myocardial infarction and no residual ischemia.

BACKGROUND: Coronary revascularization in patients with persistent angina after myocardial infarction reduces the incidence of recurrent angina pectoris and myocardial infarction and improves left ventricular function. The results of revascularization after a Q wave myocardial infarction when there is no residual ischemia may depend on myocardial viability. METHODS AND RESULTS: To determine whether there was viable myocardium in the infarct area in the absence of clinical and scintigraphic evidence of myocardial ischemia, 15 asymptomatic patients with a Q wave myocardial infarction, no redistribution on stress 201Tl test, and single-vessel disease (greater than 70% stenosis) with persistent anterograde blood flow were randomized to percutaneous transluminal coronary artery angioplasty (PTCA) or conservative medical treatment. After 2 months of follow-up, mean coronary blood flow measured by Doppler catheter in the infarct-related artery was higher in the PTCA treatment group (33 +/- 6 ml/min, n = 8) than in the conservative treatment group (16 +/- 4 ml/min, n = 7; p less than 0.05 between groups). The 201Tl pathological-to-normal ratios measured on postexercise images did not change in patients treated conservatively during the follow-up period (delta = +1.1 +/- 2.2%; NS from baseline) but increased significantly in patients treated by PTCA (delta = +8.5 +/- 2.3%; p less than 0.01 from baseline; p less than 0.05 between groups). Segmental wall motion improved on left ventricular angiography 2 months after PTCA (delta = +11.5 +/- 2.2%; p less than 0.001 from baseline) significantly more than in the conservative treatment group (delta = +4.1 +/- 1.4%; p less than 0.05 between both groups). Improvements of 201Tl ratios and segmental wall motion indexes correlated significantly (r = 0.73, p = 0.002). The mild improvement of global left ventricular ejection fraction measured in the PTCA treatment group did not differ significantly from changes in the conservative treatment group. CONCLUSIONS: Successful angioplasty of the stenotic infarct artery in patients with a Q wave myocardial infarction and no residual ischemia improved coronary flow, 201Tl uptake in the infarct area, and regional wall motion. Therefore, myocardial viability may last several weeks, as long as residual blood flow persists in the infarct-related artery. Optimal assessment of viability by imaging techniques should identify patients who are most likely to benefit from revascularization.

Angioplasty, Balloon, Coronary↗
PubMed1991

Long range electron transfer between tyrosine and tryptophan in hen egg-white lysozyme.

The azide, dibromide and dichloride radicals oxidize one or more tryptophan side chains in hen egg-white lysozyme. The indolyl radical produced in this second-order 1-electron oxidation subsequently oxidizes a tyrosine side chain to the phenoxy radical in an intramolecular reaction with a rate constant of 130 +/- 10 s-1 at pH 7, 25 degrees C. The final indolyl and phenoxy equilibrium mixture then decays with a t1/2 approximately 2 s. The faster intramolecular reaction exhibits a pH dependence; on decreasing the pH from 9 the first-order rate constant increases to a maximum near pH 5.4 and then declines as the pH is lowered further. In contrast, the first-order rate constant for the intramolecular electron transfer between the tyrosine and tryptophan of the peptide trpH-pro-tyrOH remains unchanged between approx. pH 11 and 6.5 and then increases as the pH is lowered further. This difference in the observed pH dependence suggests that changes in structure or ionization state influence the protein electron transfer rate. We also discuss the radiation inactivation of lysozyme in light of these observations.

Animals↗
PubMed1991

Role of technetium 99m methoxyisobutylisonitrile single photon emission tomography in the evaluation of thrombolysis in acute myocardial infarction before and after admission to hospital. Multicenter Study Group "Etude MIBI (EMIBI)".

To investigate initial perfusion status in acute myocardial infarction, methoxyisobutylisonitrile (MIBI) was administered by the rescue physicians. Thirty-nine patients received the radiopharmaceutical at home or upon arrival at the hospital. Diagnosis was confirmed in 30 patients, and 19 emergency thrombolyses were performed. Initial single photon emission tomography (SPET) analysis was constantly abnormal in confirmed myocardial infarction sometimes before direct electrocardiographic signs. MIBI-SPET was normal in non-coronary syndromes. MIBI uptake improved after thrombolysis (P less than 0.001) but also after heparin therapy (P less than 0.05). SPET improvement demonstrated myocardial salvage earlier than wall motion studies. MIBI administration at the patient's home allowed very early perfusion imaging when thrombolysis was performed at home. MIBI-SPET has the potential use of comparing thrombolytic agents or at home versus in hospital thrombolysis.

Ambulances↗
PubMed1991

[Pre-hospital and hospital thrombolytic therapy of acute myocardial infarction. Evaluation of initial myocardial ischemia and its reversibility by methoxy isobutyl isonitrile computed tomographic scintigraphy].

In order to assess initial myocardial perfusion, 20 mCi of Tc 99m MIBI were administered to 39 patients with suspected myocardial infarction less than 6 hours old. The injection was given on admission to the coronary care unit (n = 19) or by the emergency ambulance service at the patient's house (n = 20). For immediate availability, this myocardial tracer was labelled throughout the 24 hour period for 1 month and distributed to 4 emergency ambulance teams. The diagnosis of acute myocardial infarction was confirmed in 30 cases and 19 thrombolytic therapies were started either at home or on hospital admission. Myocardial scintigraphy was abnormal in all cases with confirmed infarction, in some cases before the ECG changes, and the results correlated perfectly with those of early angiography (36 hours). Repeat myocardial scintigraphy performed at 72 hours was used to assess response to therapy. The fixation of MIBI increased significantly after thrombolysis (p less than 0.001) but also after heparin alone (p less than 0.05). The scintigraphic improvement demonstrated the presence of viable myocardium at an earlier stage than analysis of wall notion but the presence of a stable defect at 72 hours did not indicate absence of viability. MIBI tomoscintigraphy is a non-invasive method for evaluating the benefits of thrombolytic therapy. It could be used to compare the efficacy of different thrombolytic agents or to appreciate the value of pre-hospital thrombolytic therapy with respect to thrombolysis started on hospital admission.

Aged↗
PubMed1991

[Detection of coronary disease before valve surgery. Contribution of myocardial scintigraphy with dipyridamole].

The detection of coronary disease before valve surgery remains difficult in the absence of coronary arteriography. The contribution of myocardial scintigraphy with dipyridamole (MS-DP) was studied in 34 consecutive patients with valve disease (11 mitral and 23 aortic) with a mean age of 63 +/- 11 years having undergone coronary arteriography before valve surgery. Coronary arteriography was performed because of angina (21 cases) or age (women greater than 50, men greater than 40). Positive criteria of coronary disease were the presence of at least one frank and clearly visible fault of myocardial perfusion (MS-DP positive) and at least one stenosis of greater than 70 per cent by coronary arteriography. Coronary disease existed in 13 patients (38 per cent). Ten patients (29 per cent) had a positive MS-DP. The sensitivity and specificity of MS-DP in detecting coronary disease were 69 per cent and 95 per cent respectively. Its positive predictive value was 90 per cent. MS-DP was negative in all asymptomatic patients (19 per cent of them having coronary disease) and in 11 symptomatic patients (18 per cent of them having coronary disease). The low positive predictive value of angina (52 per cent) increased to 90 per cent when combined with a positive MS-DP. Because of relatively low sensitivity, basing indications for coronary arteriography before valve surgery on the results of MS-DP cannot be advised.

Adult↗
PubMed1990

Intramolecular long-range electron transfer in the hemerythrin monomer: a pulse radiolysis study.

The single sulfhydryl group (Cys-50) of the methemerythrin from Phascolosoma gouldii reacts with 5,5'dithiobis(2-nitrobenzoic acid) to form a mixed disulfide. The pulse radiolytically generated formate radical reduces this mixed disulfide to its radical anion. In turn, the disulfide radical anion reduces the protein two-iron center over a nominal distance of 13 A. The rate constant for this intramolecular electron transfer is approximately 15 s-1 at room temperature, pH 7. Between the two redox centers there is an equilibrium driving force of 0.78 V, measured by differential pulsed polarography.

Animals↗