[en] The positive diagnosis of bone infection may be difficult, particularly when protheses have been implanted. Nuclear medicine offers different methods to visualize focal infection. C de Labriolle-Vaylet presents them, insisting on their uptake mechanism, which explains their advantages, but also their limits. (author). 1 fig., refs

[en] Published in summary form only

[en] The radiation dose rate delivered by electron emissions of ^99mTc, ¹²³I, ¹¹¹In, ⁶⁷Ga and ²⁰¹Tl was evaluated at the subcellular level. 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. 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(O) 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(O) for subcellular localizations was compared to D(O) 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. 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. 27 refs., 4 figs., 4 tabs

[en] Published in summary form only

[en] This study evaluated the morphological and functional status of HMPAO-Tc^99m labelled leukocytes, and studied the labelling homogeneity using a micro-autoradiographic method. The results confirmed that the labelled cells were in good functional state and presented no morphological damage. A significant labelling heterogeneity was observed

[en] Defects of fixation can be observed on bone scintigraphy of the thorax in patients with lung cancer. One extensive form is reported in one case of Pancoast -Tobias syndrome with a complete disappearance of 3 ribs and 2 hemivertebrae due to tumoral invasion which was evident on CT scan. In the second case, a solitary defect was discovered in the right median part of the sternum, adjacent to the tumor, while the CT scan did not show any abnormality of the sternum. This observation raises the question of the mechanism of some cold lesions which may be due to compression of vessels supplying blood to the bone, rather than to tumoral invasion or metastases

[en] Short communication

[en] Full text of publication follows. Purpose: a 3D-Personalized Monte Carlo Dosimetry (PMCD) was developed for treatment planning in nuclear medicine. The method was applied to Selective Internal Radiation Therapy (SIRT) using ⁹⁰Y-microspheres for unresectable hepatic cancers. Methods: The PMCD method was evaluated for 20 patients treated for hepatic metastases or hepatocellular carcinoma at the European Hospital Georges Pompidou (Paris). First, regions of interest were outlined on the patient CT images. Using the OEDIPE software, patient-specific voxel phantoms were created. ^99mTc-MAA SPECT data were then used to generate 3D-matrices of cumulated activity. Absorbed doses and Biologically Effective Dose (BED) were calculated at the voxel scale using the MCNPX Monte Carlo transport code. Finally, OEDIPE was used to determine the maximum injectable activity (MIA) for tolerance criteria on organs at risk (OARs), i.e. the lungs and non tumoral liver (NTL). Tolerance criteria based on mean absorbed doses, mean BED, Dose-Volume Histograms (DVHs) or BED-Volume Histograms (BVHs) were considered. Those MIAs were compared to the Partition Model with tolerance criteria on mean absorbed doses, which is a conventional method applied in clinical practice. Results: compared to Partition Model recommendations, performing dosimetry using the PMCD method enables to increase the activity prescription while ensuring OARs' radiation protection. Moreover, tolerance criteria based on DVHs allow us to enhance treatment planning efficiency by taking advantage of the parallel characteristic of the liver and the lungs, whose functions are not impaired if the level of irradiation to a fraction of the organ is kept sufficiently low. Finally, multi-cycle treatments based on tolerance criteria on mean BED and BVHs, were considered to go further in the dose optimization, taking into account biological considerations such as cell repair or radiosensitivity. Conclusion: besides its feasibility and applicability in clinical routine, the interest of a personalized Monte Carlo dosimetry for treatment planning in SIRT was confirmed from those patient studies. Finally, the PMCD is a general purpose method that could be used to perform treatment planning and dosimetry for different therapies and isotopes in nuclear medicine. (authors)

[en] Short communication

[en] Owing to the lack of a reference technique and of an international cobalamin (vitamin B12) standard, and the large discrepancy between laboratory norms, the authors performed a multicentric study to compare five RIA kits usually used. First, classical tests were used to evaluate the analytical performances of each kit. Results did not demonstrate any superiority of one kit over another. Secondly, B12 values were classified among three categories (low, normal and high) characterized by laboratory and then manufacturer norms. The concordance between these two ''judgments'' was evaluated with the Kappa coefficient. In addition, the Kappa index proved that the norms supplied by the manufacturer were better than those of laboratories. But mean Kappa coefficient established for each norm gave us an insatisfactory result. Third, clinical informations allowed to improve the classification of the patients. New limits were defined for each technique and should be tested further, routinely in each laboratory. (author)