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Biomedical subjects

B Danet

Publications and source records attributed to B Danet.

7 recordsLinked to original sources
PubMed1990

[A simulation method for studying scintillation camera collimators].

This paper presents a computer simulation of photon interaction with collimator septa, which allows the point spread function of scintillation camera collimators to be calculated. The method simulates photon attenuation along their propagation direction in a determinist way. Using this simulation, the spatial resolution, geometric efficiency and penetration index of collimators may be easily assessed. Results obtained with this method are presented and compared with those obtained from standard formulae. We show the usefulness of the simulation which precisely accounts for effects of septum penetration. Measurements performed on two collimators with 131I and 99Tcm point sources provide results consistent with those obtained from the simulation method. In conclusion we show that this method is an accurate tool to assist conception of collimators for nuclear medicine.

Computer Simulation↗
PubMed1989

Human brain and spinal cord scan after intracerebroventricular administration of iodine-123 morphine.

[123I]iodomorphine (IMPH) was administered intracerebroventriculary (i.c.v.) in eight patients treated by i.c.v. morphinotherapy (i.c.v.m.). Scans obtained by gamma-scintigraphy over 1 h post-injection showed only a slight diffusion of IMPH beyond the ventricular system, particular attention being paid to the spinal cord. These data agree well with induced i.c.v.m. analgesia (mean latency 20 min) and biological results such as HPLC assay of morphine in the lumbar cerebrospinal fluid, supporting the action of morphine only on the central opiate receptors.

Brain↗
PubMed1988

[Quantitative renal scintigraphy with technetium-labelled dimercaptosuccinic acid in children].

Separate measurement of renal function is essential in children with urinary tract disease. This can be done satisfactorily by means of kidney scintigraphy with technetium 99m-labelled dimercaptosuccinic acid. A retrospective study of the records of 415 children, which comprised renal function tests, radiology and scintigraphy, confirmed the value of the radioisotope technique. Graphs of height, kidney uptake and kidney uptake density in relation to age were established, showing highly significant correlations with renal function tests and intravenous urography results, but many dissociations were encountered. Separate renal function evaluation by radioisotope scintigraphy seems to be more reliable than evaluation extrapolated from measurement of the cortical areas at intravenous urography. In vesico-ureteral reflux scintigraphy makes it possible to detect reflux nephropathy at an earlier stage than with other methods.

Age Factors↗
PubMed1986

Utility of caudal view in pelvic bone imaging.

Bone imaging of the lower pelvis often is impaired by the radioactivity of the bladder. The caudal view produces an image that clearly distinguishes the bladder from the bones. Thus, it is helpful in patients with bony lesions of the lower and anterior pelvis. The caudal view examination is completed by a backward tilting of the camera head that clarifies this distinction.

False Negative Reactions↗
PubMed1985

Measurement of cerebral circulation time in man.

A simple, inexpensive method for measuring the cerebral circulation time (CCT) was developed. The CCT was considered to be equal to the time that an intravenously injected bolus of sodium pertechnetate Tc 99m took to go from the subclavian artery to the posterior venous confluence. The dilution curves were externally recorded at these two vessels. Particular attention was given to the curve treatment. The computer programmes were specially conceived in order to detect and, if possible, correct the experimental curve defects. Several reliability criteria were also defined in order to test the validity of each measurement. From a physiological point of view, the CCT is equal to the ratio of the global cerebral blood volume to the global cerebral blood flow. Thus, it can be widely applied in clinical research. For example, in a study of the relationship between CCT and age, sex and light cerebrovascular impairment, the technique was sensitive enough to discriminate between healthy subjects and patients suffering from-transient ischemic attack, or regressive stroke, and to show the action of a drug on the cerebral circulation in such patients.

Adult↗
PubMed1976

[Influence of pressure and duration of perfusion on functional properties and hemodynamics of isolated kidneys from dogs (author's transl)].

1. Changes in functional properties and hemodynamics of isolated kidneys were analysed with special regard to pressure and duration of perfusion. Observations were compared between pairs of kidneys taken from the same animal and placed in identical experimental situations, but respectively perfused at a pressure level of either 100 mm Hg or 160 mm Hg. 2. A method using 133Xenon wash-out to measure renal blood flow, suppressing early recirculation, is described. 3. Changes in functional properties were towards decreases of glomerular filtration and tubular transfer. Hemodynamic changes proceeded from decreases of total and regional renal vascular resistance. Both functional properties and hemodynamic changes were larger as the duration of the pressure of the perfusion became greater. 4. Renal blood flow was different when measured with an electromagnetic flowmeter and by the 133Xenon wash-out technique. Practical applications, theoretical basis and results of the latter method are criticized. 5. Possible mechanisms by which high perfusion pressure hastens and increases functional and hemodynamic changes of isolated kidneys are discussed.

Animals↗