Evaluation of allograft perfusion by radionuclide first-pass study in renal failure following renal transplantation.

To assess the diagnostic value of indices measured on a first-pass curve, we performed 72 radionuclide renal first-pass studies (RFP) in 21 patients during the early weeks following renal allograft transplantation. The diagnosis was based on standard clinical and biochemical data and on fine needle aspiration biopsy (FNAB) of the transplant. Aortic and renal first-pass curves were filtered using a true low-pass filter and five different indices of renal perfusion were computed, using formulae from the literature.

Mössbauer spectroscopy study of iron overloaded livers.

Absorption 57Fe Mössbauer spectra have been carried out directly on fresh or lyophylized tissues of liver with either normal iron depot or iron overload. Two types of overloading have been studied: primary iron overload due to an excessive intestinal iron absorption and secondary iron overload (hemosiderosis) produced in beta-thalassemia patients by hypertransfusional therapeutics. The Mössbauer spectra, at room temperature, 77 and 4.

Dopaminergic receptor sites in human brain: positron emission tomography.

Positron emission tomography (PET) and 11C-labeled pimozide were used to study the dopaminergic (DA) receptor sites in the human striatum by comparing the latter with the cerebellum, which lacks DA receptors. Although 11C-pimozide concentration was not different in these two brain structures up to 53 minutes after IV injection (thus implying large nonspecific binding), a significant retention of radioactivity in striatum relative to cerebellum was found in controls but not in subjects pretreated with the unlabeled competitor haloperidol. This suggests that the striatal retention seen in controls was due to specific binding of 11C-pimozide to DA receptor sites, whereas prior occupation of the receptor sites by the unlabeled competitor was achieved in pretreated subjects.

X-irradiation effect on human red cells: hemoglobin study by Mössbauer spectrometry.

This work is a study of the radioinduced transformations undergone by intraglobular hemoglobin. Mössbauer spectrometry allows us to study in a wide range of doses the effect of X rays on deoxyhemoglobin as well as on oxyhemoglobin. Using this technique we have shown large differences between these two derivatives of hemoglobin.

[Water diffusion and measurement of cerebral blood flow by C15O2 inhalation].

Measurement of local Cerebral Blood Flow (CBF) using the C15O2 continuous inhalation technique coupled with Position Emission Tomography (PET) rests on the assumption that the in vivo labelled water (H215O) of blood diffuses freely within the brain water pool. This requirement however, may be disputed: in the rhesus monkey, Eichling et al (1974) showed a linear relationship between the single-pass extraction of water (E) and CBF after intra-carotid H215O injection, such that E decreases as CBF increases. Such a limitation in water transport across the blood brain barrier has also been suggested to exist in man (Paulson, 1977).

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.

The role of positron emission tomography in the detection of pancreatic disease.

Positron emission tomography (PET) was used to assess possible pancreatic disease in 100 patients. Following injection of 10-15 mCi (370-740 MBq) of 11C-L-methionine, 4-12 transverse sections 2 cm thick were obtained. In 85 patients with a definite diagnosis (45 normal, 9 acute pancreatitis, 18 chronic pancreatitis, and 13 cancer), PET showed a sensitivity of 85.

An analytical approach to single photon emission computed tomography with the attenuation effect.

The problem of transverse plane reconstruction from an ensemble of projections is considered in its general formulation and an analytically exact solution to the attenuated tomographic operator is proposed. Such a technique, called the regularizing iterative method (RIM), allows the introduction of a priori knowledge on the size and shape of the activity distribution and in principle on the exact attenuation distribution. The relaxation factor used is so named because it provides noise filtering for a small number of iterations.

Mössbauer spectroscopy and perturbed angular correlation studies of the rare-and alkaline-earth bone uptake.

Emission Mössbauer spectra and Perturbed Angular Correlation measurements have been performed on samples of mineral bone powder labelled with 161Tb3+ or 133Ba2+ ions after either in vitro absorption or uptake by metabolic pathway. The study of these hyperfine spectra, compared with those carried out when 161Tb or 133Ba are situated in either hydroxyde lattice or phosphate one, shows that the uptake modes of rare-and alkaline-earth ions on the bone matrix are different. The rare earth ion seems to be absorbed on the surface bone in an environment of hydroxyl groups similar to the structure of a rare earth hydroxyde.

Rotating conventional gamma camera single-photon tomographic system: physical characterization.

A whole-body single-photon emission computed tomography system has been evaluated in terms of its physical performance. It consists of a standard GE 400 T maxi camera rotating on a ring stand, coupled to an Informatek Simis 3 computer system. In its standard mode of operation, 64 or 128 successive views of 64 X 64 or 128 X 64 matrices are collected at regular angular samples.

Time differential perturbed angular correlation (TDPAC) studies of the 133Ba ion uptake in bone crystals.

TDPAC measurements of the 356-81 keV gamma-ray cascade resulting from electron capture decay of 133Ba have been performed at room temperature on BaCl2 (aqueous solution and polycrystalline powder), and on samples where the 133Ba nucleus is bound to bone powder, and also to synthesised hydroxylapatite, all after absorption in vitro. As expected, the angular correlation is not perturbed in the solution. However, in the polycrystalline chloride the time dependence of the anisotropy of the cascade of 133Cs nuclide indicates that the decaying nucleus undergoes electric interactions due to different electric field gradients acting at the site of the nucleus.

Pulmonary extraction of C-11 chlorpromazine, measured by residue detection in man.

Uptake of C-11 chlorpromazine (CPZ) was measured to evaluate the nonrespiratory function of lung in patients. A multiple-indicator dilution technique was used with external detection. Following intravenous bolus injection of C-11 CPZ, with In-113m transferrin as an intravascular reference molecule, counts were recorded with a scintillation camera using two energy windows.

The physical performances of a single slice positron tomographic system and preliminary results in a clinical environment.

Metabolic phenomena can be studied and measured non-invasively using positron emitting radionuclides and a suitably adapted tomographic system. The choice of a single slice ring camera is justified by its physical performance, which is presented here and discussed. A series of measurements with geometrical phantoms and analytical simulations have been performed to determine the critical characteristics of the system.

Brain distribution and kinetics of 11C-chlorpromazine in schizophrenics: positron emission tomography studies.

The positron emitter 11C (20 minutes half-life) permits the labeling of chlorpromazine (CPZ) and the study of its distribution in humans by external counting. Trace amounts of 11C-CPZ were injected intravenously into 22 schizophrenic patients all untreated for several months with neuroleptics. The brain uptake was 6.

[11C]methionine pancreatic scanning with positron emission computed tomography.

By the use of [11C]methionine and positron computed tomography (PCT), images of the pancreas were obtained in 32 patients. The injection of between 10 and 20 mCi of this product enables four to six transverse sections to be obtained. Seventeen of the patients studied had no exocrine pancreatic disease, and in all these cases the pancreas was clearly visible.

[Tomographic study in humans of blood flow and oxygen consumption of the brain by continuous inhalation of oxygen 15. Preliminary findings in cerebral ischemic accidents].

Transverse axial tomographic imaging of regional cerebral blood flow (rCBF) and regional oxygen extraction fraction (rOEF) were obtained in 13 patients hospitalizedfor ischemic strokes (eleven middle cerebral artery territory infarcts, one capsular or pontine lacune, one transient hemispheric attack) by continuous inhalation of 15O2 and C15O2 to equilibrium and exclusive detection of the gamma rays emitted in coincidence by means of a tomograph for positron emitting agents. In the transient ischemic attack and in the case of lacune the rCBF and the rOEF images were found to be normal, and they were abnormal in all cases of middle cerebral artery territory infarcts. In recent infarcts, rOEF was always strikingly decreased in the clinically suspected area, whilst the rCBF was either decreased, normal or increased.

Installation of a compact, variable-energy cyclotron in a hospital and preliminary results obtained.

The setting up of a compact, variable-energy cyclotron within a preexisting hospital structure and the way by which have been resolved the setted technical restraints are described. Some preliminary results obtained are also given.