André Constantinesco - Academia.edu (original) (raw)
Papers by André Constantinesco
Physics in Medicine and Biology, 2009
Archives internationales de physiologie et de biochimie, 1985
Time modulated field-gradient-sequences able to selectively phase encode spatial location or flow... more Time modulated field-gradient-sequences able to selectively phase encode spatial location or flow velocity in NMR signals are described. The specific phase modulation discriminates between stationary and mobile protons. The method is presented in the one dimensional case and has the following advantages: it is sensitive to flow direction and unaffected by the relaxation times.
Journal of Neuroradiology, 2005
Journal de radiologie, d'électrologie, et de médecine nucléaire, 1977
The authors present a case of intramural hematoma of the small intestines during anticoagulant tr... more The authors present a case of intramural hematoma of the small intestines during anticoagulant treatment. With reference to this case, they study the frequency, etiopathogenesis and anatomy of this hematoma and particularly look at the radiological manifestations. In this respect they distinguish three stages in the evolution. The first, when the straight X-ray of the abdomen and barium followthrough demonstrate an axial stenosis of the small intestines with dilation of the proximal loops; the second (between the 7th and 20th days) when the loop affected by the hematoma takes on a characteristic "palissade" or "spring" -like sausage appearance; finally the third (after the 3rd week), when only thickening of the haustrations persists with progressive return to normal. The radiological diagnosis is discussed, not only with intramural hematomas of the small intestines of other etiologies (traumatic, during pancreatitis, during disorders in hemostatis), but also with...
Annales de cardiologie et d'angéiologie
The total ejection fraction of the left ventricle is studied in 37 patients, most of them with co... more The total ejection fraction of the left ventricle is studied in 37 patients, most of them with coronary disease, according to two methods: contrast angiography in a single plane and angioscintigraphy (first passage and balanced), in order to compare the results according to the presence or the absence of dyskinesias. The two methods are performed in succession according to the usual views. The population is divided in two sub-groups according to the presence (17 patients) or the absence (20 patients) of segmental abnormalities. Segmental abnormalities are divided into 11 antero-apical aneurysms and 6 infero-posterior aneurysms. The correlations of the ejection fractions calculated according to the two methods and the two views, are usually satisfactory in the two sub-groups and especially as the parietal kinetics is homogeneous. In case of segmental abnormalities of the contraction, there are variations in the total ejection fractions depending on the technique and the views that ar...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
Objective: To demonstrate the feasibility of SPECT/MRI in small animal using a dual device. Mater... more Objective: To demonstrate the feasibility of SPECT/MRI in small animal using a dual device. Material and methods: A small animal pinhole camera (1.5 mm in diameter) coupled together with a dedicated low-field (0.1 T) small MR imager (imaging volume of 10 Â 10 Â 6 cm 3) was used. SPECT consisted of acquiring 48 projections after intravenous injections of 0.2 ml and 700 MBq of 99m Tc-Sestamibi and was immediately followed by MRI with 3D isotropic T 1 and T 2 weighted imaging sequences. Two adult Swiss nude mice with stereotaxic brain implanted human glioblastoma cells and maintained under isoflurane 1.5% and air 0.3 L min À1 in a warmed-up and non-magnetic imaging cell for both modalities were used in this study. Results: Fusion images of SPECT/low-field MRI were obtained with isotropic voxel resolutions of 1 Â 1 Â 1 mm 3 for SPECT and 0.5 Â 0.5 Â 0.5 mm 3 for MRI. Total acquisition time for both imaging modalities was 2.5 h. Conclusion: A low magnetic field strength of 0.1 T is a potential solution for a small animal dual imaging device combining pinhole SPECT and MRI in a single machine.
Neonatology, 1994
In this study, we used single photon emission computed tomography (SPECT) radiolabelled 99mTc HMP... more In this study, we used single photon emission computed tomography (SPECT) radiolabelled 99mTc HMPAO to assess cerebral perfusion during maturation in the neonatal period. Results of SPECT examinations in 18 newborn infants, in whom gestational age ranged form 30 to 41 weeks, and who were found to be neurologically normal in retrospect, were reviewed. The developmental changes in cerebral perfusion during the neonatal period shown by SPECT parallel findings of other methods on maturational changes of the central nervous system (neuropathological studies, positron emission tomography scan, magnetic resonance imaging). Cerebral perfusion progresses from the central part of the brain to the cerebellum, sensorimotor and then visual cortex. A close relation seems to exist between cerebral perfusion, metabolism and behavior under normal conditions in the neonatal period.
Medical & Biological Engineering & Computing, 1981
A photoconductor micrometer using a row of linear image sensors is described, which is able to de... more A photoconductor micrometer using a row of linear image sensors is described, which is able to determine the dimension of the shadow of an object transversely illuminated by a parallel beam of light. The described equipment is easily tailored to specific uses and may find appfications in variation measurement of exposed vessels, for example.
Journal of Nuclear Cardiology, 1995
ITBM-RBM, 2006
ObjectiveDevelop the methodology of data acquisition and processing for functional hepatobiliary ... more ObjectiveDevelop the methodology of data acquisition and processing for functional hepatobiliary scintigraphic imaging in normal mice.
European Surgical Research, 1977
A device for measuring the mean blood velocity (by means of a thermal equilibrium method) and the... more A device for measuring the mean blood velocity (by means of a thermal equilibrium method) and the intravascular electrical impedance, which determines the mean sectional area of the vessel, have been mounted on the same probe (french catheter 7F). The validity, of the method has been confirmed in vitro and by 100 measurements carried out in dogs and compared with flow measurements by means of the cardio-green method. The correlation coefficient is found to be 0.98.
Comptes Rendus Biologies, 2010
In vivo preclinical low field MRI monitoring of tumor growth following a suicide gene therapy in ... more In vivo preclinical low field MRI monitoring of tumor growth following a suicide gene therapy in an orthotopic mice model of human glioblastoma Contrôle par IRM bas champ in vivo de l'efficacite´d'une the´rapie ge´nique par ge`ne suicide dans un mode`le murin de glioblastome orthotopique
Clinical Nuclear Medicine, 2008
Because of its high diagnostic sensitivity in detection of unknown primary tumors, F-18 FDG PET/C... more Because of its high diagnostic sensitivity in detection of unknown primary tumors, F-18 FDG PET/CT was used in the exploration of a 51-year-old woman presenting with multiple lymphadenopathy of the hepatic hilum and several hepatic and splenic hypodensities on radiologic examinations for which malignancy was suspected. Despite the morphofunctional malignant appearance, both histologic examination and PCR analysis revealed Bartonella henselae infection. Moreover, repeat F-18 FDG PET showed disease regression during focused antibiotic therapy.
Academic Radiology, 2002
RATIONALE AND OBJECTIVES Xenon is an inert gas characterized by a nuclear halfspin and a high sol... more RATIONALE AND OBJECTIVES Xenon is an inert gas characterized by a nuclear halfspin and a high solubility in lipids. It appears to diffuse freely in biological tissues and, in particular, through the blood-brain barrier. Spin-exchange with optically pumped rubidiu mvapo rincrease sth enuclea rpolarizatio no f 129 Xe gas by several orders of magnitude above the polarization at thermal equilibrium, resulting in “hyperpolarized” (HP) xenon. HP xenon can be used as a magnetic resonance (MR) tracer because of its NMR-enhanced sensitivity combined with its high solubility. This HP tracer is a potential exogenous NMR probe for cerebral imaging studies. The purpose of this paper is to describe the preparation of this HP tracer and to demonstrate that it can be used in NMR for absolute cerebral perfusion measurements.
The knowledge of brain tissue mechanical properties is a critical issue in the head injury biomec... more The knowledge of brain tissue mechanical properties is a critical issue in the head injury biomechanics research field. Due to experimental limitations, brain tissue has been characterized in vitro, whereas its actual in vivo behavior remains poorly known. We propose the use of Magnetic Resonance Elastography as a non invasive, non destructive tool for measuring the viscoelastic properties of brain tissue. The general method and its validation versus rotational rheometry are described, and preliminary results obtained in vivo are presented.
Medecine Nucleaire-imagerie Fonctionnelle Et Metabolique, 1996
Chez 26 transplantes hepatiques, une scintigraphie hepatobiliaire ( 99m Tc-mebrofenine; 180-330 M... more Chez 26 transplantes hepatiques, une scintigraphie hepatobiliaire ( 99m Tc-mebrofenine; 180-330 MBq) a ete pratiquee en periode postoperatoire rapprochee (9,1 ± 4,3 jours). L'examen a comporte un temps angioscintigraphique et un temps fonctionnel. Chez tous les patients, le retablissement de la continuite de la voie biliaire avait ete realise par une anastomose choledococholedocienne, avec mise en place d'un drainage externe dans 13 cas. La methode des regions d'interet a permis d'etudier les variations d'activite A(t) au niveau du foie greffe: au temps angioscintigraphique pour apprecier la valeur relative des composantes arterielle et portale de la perfusion, et au temps fonctionnel pour identifier les anomalies de captation et d'excretion. L'analyse quantitative des courbes A(t) a fourni trois groupes de resultats: pour les 26 transplantes, une perfusion « normale » du greffon n'implique pas forcement une fonction de captation normale (8 cas seulem...
Pour mieux analyser la viabilite myocardiuqe, nous proposons un protocole de tomoscintigraphie sy... more Pour mieux analyser la viabilite myocardiuqe, nous proposons un protocole de tomoscintigraphie synchronisee double isotope capable d'analyser simultanement la perfusion myocardique et la cinetique parietale ventriculaire gauche. Deux traceurs sont utilises simultanement, le thallium 201 (activite moyenne 187 MBq) pour la perfusion myocardique et un marquage au technetium 99m (activite moyenne 960 MBq) pour le compartiment sanguin et la cinetique ventriculaire.
Physics in Medicine and Biology, 2009
Archives internationales de physiologie et de biochimie, 1985
Time modulated field-gradient-sequences able to selectively phase encode spatial location or flow... more Time modulated field-gradient-sequences able to selectively phase encode spatial location or flow velocity in NMR signals are described. The specific phase modulation discriminates between stationary and mobile protons. The method is presented in the one dimensional case and has the following advantages: it is sensitive to flow direction and unaffected by the relaxation times.
Journal of Neuroradiology, 2005
Journal de radiologie, d'électrologie, et de médecine nucléaire, 1977
The authors present a case of intramural hematoma of the small intestines during anticoagulant tr... more The authors present a case of intramural hematoma of the small intestines during anticoagulant treatment. With reference to this case, they study the frequency, etiopathogenesis and anatomy of this hematoma and particularly look at the radiological manifestations. In this respect they distinguish three stages in the evolution. The first, when the straight X-ray of the abdomen and barium followthrough demonstrate an axial stenosis of the small intestines with dilation of the proximal loops; the second (between the 7th and 20th days) when the loop affected by the hematoma takes on a characteristic "palissade" or "spring" -like sausage appearance; finally the third (after the 3rd week), when only thickening of the haustrations persists with progressive return to normal. The radiological diagnosis is discussed, not only with intramural hematomas of the small intestines of other etiologies (traumatic, during pancreatitis, during disorders in hemostatis), but also with...
Annales de cardiologie et d'angéiologie
The total ejection fraction of the left ventricle is studied in 37 patients, most of them with co... more The total ejection fraction of the left ventricle is studied in 37 patients, most of them with coronary disease, according to two methods: contrast angiography in a single plane and angioscintigraphy (first passage and balanced), in order to compare the results according to the presence or the absence of dyskinesias. The two methods are performed in succession according to the usual views. The population is divided in two sub-groups according to the presence (17 patients) or the absence (20 patients) of segmental abnormalities. Segmental abnormalities are divided into 11 antero-apical aneurysms and 6 infero-posterior aneurysms. The correlations of the ejection fractions calculated according to the two methods and the two views, are usually satisfactory in the two sub-groups and especially as the parietal kinetics is homogeneous. In case of segmental abnormalities of the contraction, there are variations in the total ejection fractions depending on the technique and the views that ar...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
Objective: To demonstrate the feasibility of SPECT/MRI in small animal using a dual device. Mater... more Objective: To demonstrate the feasibility of SPECT/MRI in small animal using a dual device. Material and methods: A small animal pinhole camera (1.5 mm in diameter) coupled together with a dedicated low-field (0.1 T) small MR imager (imaging volume of 10 Â 10 Â 6 cm 3) was used. SPECT consisted of acquiring 48 projections after intravenous injections of 0.2 ml and 700 MBq of 99m Tc-Sestamibi and was immediately followed by MRI with 3D isotropic T 1 and T 2 weighted imaging sequences. Two adult Swiss nude mice with stereotaxic brain implanted human glioblastoma cells and maintained under isoflurane 1.5% and air 0.3 L min À1 in a warmed-up and non-magnetic imaging cell for both modalities were used in this study. Results: Fusion images of SPECT/low-field MRI were obtained with isotropic voxel resolutions of 1 Â 1 Â 1 mm 3 for SPECT and 0.5 Â 0.5 Â 0.5 mm 3 for MRI. Total acquisition time for both imaging modalities was 2.5 h. Conclusion: A low magnetic field strength of 0.1 T is a potential solution for a small animal dual imaging device combining pinhole SPECT and MRI in a single machine.
Neonatology, 1994
In this study, we used single photon emission computed tomography (SPECT) radiolabelled 99mTc HMP... more In this study, we used single photon emission computed tomography (SPECT) radiolabelled 99mTc HMPAO to assess cerebral perfusion during maturation in the neonatal period. Results of SPECT examinations in 18 newborn infants, in whom gestational age ranged form 30 to 41 weeks, and who were found to be neurologically normal in retrospect, were reviewed. The developmental changes in cerebral perfusion during the neonatal period shown by SPECT parallel findings of other methods on maturational changes of the central nervous system (neuropathological studies, positron emission tomography scan, magnetic resonance imaging). Cerebral perfusion progresses from the central part of the brain to the cerebellum, sensorimotor and then visual cortex. A close relation seems to exist between cerebral perfusion, metabolism and behavior under normal conditions in the neonatal period.
Medical & Biological Engineering & Computing, 1981
A photoconductor micrometer using a row of linear image sensors is described, which is able to de... more A photoconductor micrometer using a row of linear image sensors is described, which is able to determine the dimension of the shadow of an object transversely illuminated by a parallel beam of light. The described equipment is easily tailored to specific uses and may find appfications in variation measurement of exposed vessels, for example.
Journal of Nuclear Cardiology, 1995
ITBM-RBM, 2006
ObjectiveDevelop the methodology of data acquisition and processing for functional hepatobiliary ... more ObjectiveDevelop the methodology of data acquisition and processing for functional hepatobiliary scintigraphic imaging in normal mice.
European Surgical Research, 1977
A device for measuring the mean blood velocity (by means of a thermal equilibrium method) and the... more A device for measuring the mean blood velocity (by means of a thermal equilibrium method) and the intravascular electrical impedance, which determines the mean sectional area of the vessel, have been mounted on the same probe (french catheter 7F). The validity, of the method has been confirmed in vitro and by 100 measurements carried out in dogs and compared with flow measurements by means of the cardio-green method. The correlation coefficient is found to be 0.98.
Comptes Rendus Biologies, 2010
In vivo preclinical low field MRI monitoring of tumor growth following a suicide gene therapy in ... more In vivo preclinical low field MRI monitoring of tumor growth following a suicide gene therapy in an orthotopic mice model of human glioblastoma Contrôle par IRM bas champ in vivo de l'efficacite´d'une the´rapie ge´nique par ge`ne suicide dans un mode`le murin de glioblastome orthotopique
Clinical Nuclear Medicine, 2008
Because of its high diagnostic sensitivity in detection of unknown primary tumors, F-18 FDG PET/C... more Because of its high diagnostic sensitivity in detection of unknown primary tumors, F-18 FDG PET/CT was used in the exploration of a 51-year-old woman presenting with multiple lymphadenopathy of the hepatic hilum and several hepatic and splenic hypodensities on radiologic examinations for which malignancy was suspected. Despite the morphofunctional malignant appearance, both histologic examination and PCR analysis revealed Bartonella henselae infection. Moreover, repeat F-18 FDG PET showed disease regression during focused antibiotic therapy.
Academic Radiology, 2002
RATIONALE AND OBJECTIVES Xenon is an inert gas characterized by a nuclear halfspin and a high sol... more RATIONALE AND OBJECTIVES Xenon is an inert gas characterized by a nuclear halfspin and a high solubility in lipids. It appears to diffuse freely in biological tissues and, in particular, through the blood-brain barrier. Spin-exchange with optically pumped rubidiu mvapo rincrease sth enuclea rpolarizatio no f 129 Xe gas by several orders of magnitude above the polarization at thermal equilibrium, resulting in “hyperpolarized” (HP) xenon. HP xenon can be used as a magnetic resonance (MR) tracer because of its NMR-enhanced sensitivity combined with its high solubility. This HP tracer is a potential exogenous NMR probe for cerebral imaging studies. The purpose of this paper is to describe the preparation of this HP tracer and to demonstrate that it can be used in NMR for absolute cerebral perfusion measurements.
The knowledge of brain tissue mechanical properties is a critical issue in the head injury biomec... more The knowledge of brain tissue mechanical properties is a critical issue in the head injury biomechanics research field. Due to experimental limitations, brain tissue has been characterized in vitro, whereas its actual in vivo behavior remains poorly known. We propose the use of Magnetic Resonance Elastography as a non invasive, non destructive tool for measuring the viscoelastic properties of brain tissue. The general method and its validation versus rotational rheometry are described, and preliminary results obtained in vivo are presented.
Medecine Nucleaire-imagerie Fonctionnelle Et Metabolique, 1996
Chez 26 transplantes hepatiques, une scintigraphie hepatobiliaire ( 99m Tc-mebrofenine; 180-330 M... more Chez 26 transplantes hepatiques, une scintigraphie hepatobiliaire ( 99m Tc-mebrofenine; 180-330 MBq) a ete pratiquee en periode postoperatoire rapprochee (9,1 ± 4,3 jours). L'examen a comporte un temps angioscintigraphique et un temps fonctionnel. Chez tous les patients, le retablissement de la continuite de la voie biliaire avait ete realise par une anastomose choledococholedocienne, avec mise en place d'un drainage externe dans 13 cas. La methode des regions d'interet a permis d'etudier les variations d'activite A(t) au niveau du foie greffe: au temps angioscintigraphique pour apprecier la valeur relative des composantes arterielle et portale de la perfusion, et au temps fonctionnel pour identifier les anomalies de captation et d'excretion. L'analyse quantitative des courbes A(t) a fourni trois groupes de resultats: pour les 26 transplantes, une perfusion « normale » du greffon n'implique pas forcement une fonction de captation normale (8 cas seulem...
Pour mieux analyser la viabilite myocardiuqe, nous proposons un protocole de tomoscintigraphie sy... more Pour mieux analyser la viabilite myocardiuqe, nous proposons un protocole de tomoscintigraphie synchronisee double isotope capable d'analyser simultanement la perfusion myocardique et la cinetique parietale ventriculaire gauche. Deux traceurs sont utilises simultanement, le thallium 201 (activite moyenne 187 MBq) pour la perfusion myocardique et un marquage au technetium 99m (activite moyenne 960 MBq) pour le compartiment sanguin et la cinetique ventriculaire.