Unexpected primary bone lymphoma / Linfoma óseo primario inesperado

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Evaluation of a crossed fused renal ectopia in a paediatric patient using 99mTc-DMSA SPECT/CT / Ectopia renal cruzada con fusión en un paciente pediátrico evaluado con 99mTc-DMSA SPECT/TC

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Self-sealing capacity of vial stoppers after multiple needle punctures.

OBJECTIVE: To evaluate the self-sealing capacity of vial stoppers in two common radiopharmaceuticals after more than 10 needle punctures. METHODS: Assessment of self-sealing capacity was performed according to the self-sealing capacity test described in United States Pharmacopeial Convention (USP) General Chapter <381>. Groups of 10 vials of technetium (Tc)-99m sulfur colloid and Tc-99m tetrofosmin were tested for maintenance of self-sealing capacity following 10 punctures with 22-, 20-, and 18-gauge needles. Each vial was sequentially retested after additional sets of 10 punctures until failure of self-sealing capacity or until a total of 100 punctures, whichever came first. RESULTS: The median number of needle punctures with maintenance of self-sealing ability before failure for 22-, 20-, and 18-gauge needles was >100 (range all >100), >100 (all >100), and 60 (30-90), respectively, for sulfur colloid and >100 (all >100), >100 (50 to >100), and 50 (20-70), respectively, for tetrofosmin. Incidentally, coring particles were observed frequently in vials after many punctures with 18-gauge needles, but infrequently with 20-gauge and rarely with 22-gauge needles. CONCLUSION: Vial stoppers in two radiopharmaceutical products demonstrated robust self-sealing capacity, substantially exceeding the USP standard of 10 punctures with a 21-gauge needle. Coring particles were frequently observed after many punctures when using larger-bore needles but rarely when using smaller-bore needles. Under conditions commonly used, failure of self-sealing capacity and generation of coring particles are not anticipated to be problems encountered when puncturing vial stoppers of these two products substantially more than 10 times.

Radiolabelling of egg meals for gastric emptying studies: a comparison of 99mTc sulfur and 99mTc stannous colloids.

OBJECTIVES: To establish whether 99mTc stannous (Tc-Sn) colloid is a suitable alternative to 99mTc sulfur (Tc-S) colloid for gastrointestinal studies, we compared the per cent binding to egg solids (%BS) and radiochemical purity (RCP) of both colloids in digesting media. METHODS: Egg white and yolk containing colloids were cooked separately and mashed. Samples of 4-5 g were digested over 2-3 h (37 degrees C) in excess simulated gastric juice (SGJ: 15 ml of 0.1 M HCl and 0.5 g.l-1 pepsin) or water, centrifuged, imaged with a gamma camera and the %BS computed. RCP was determined in aspirates taken from these preparations and from solutions of colloid added directly to SGJ. RESULTS: The %BS in egg white after 3 h in SGJ for both colloids were similar: Tc-Sn, 62+/-8 (n=12); Tc-S, 61+/-6 (n=8), but markedly lower than 95% (the often quoted literature value). Egg yolk was digested more rapidly than egg white: %BS after 2 h in SGJ for Tc-Sn colloid was 55+/-10 (n=5) in the yolk, compared to 77+/-4 (n=5) in the white (P<0.01). The RCP for Tc-S colloid alone in SGJ was >94% over 3 h but for Tc-Sn colloid was as low as 14%. For egg white, the RCP in SGJ was 91-96% for Tc-S and 80-91% for Tc-Sn. For egg yolk the RCPs in SGJ were similar for both colloids (>90%). The RCP in water digesting egg white or yolk containing either colloid was always lower than in the corresponding SGJ aspirates, indicating a leakage of small amounts of non-colloidal 99mTc. CONCLUSIONS: Although 99mTc-Sn almost completely dissociates in SGJ, once cooked in egg it is digested similarly to 99mTc-S. Variations in the size of digesting egg fragments and in SGJ composition can reconcile the lower %BS values obtained with previously reported higher results. 99mTc-Sn colloid cooked in egg appears suitable for gastrointestinal studies.

[The stability of solid food labeled with different radiopharmaceuticals for studying gastric emptying]. / Estabilidad de alimento sólido marcado con diferentes radiofármacos para vaciamiento gástrico.

OBJECTIVE: Sulfur colloid 99mTc-SC, the radiopharmaceutical of choice for solid gastric emptying studies, is not available in our country. It has led us to assess the solid binding stability of seven alternative radiopharmaceuticals that could present adequate fixation to it a priori. MATERIALS AND METHOD: The stability of labelled solid food with seven colloidal 99mTc-radiopharmaceuticals of different sizes and nature (MAA, tin colloid, rhenium sulphide macrocolloid, albumin microcolloid, sulfur nanocolloid, albumin nanocolloid and rhenium sulfur nanocolloid) has been studied by measuring their dissociated activity after two hours digestion in simulated gastric fluid (kept 120' in agitation, in HCl 0.1 M at 37). The survey also assesses radiopharmaceutical labelling stability after two hours digestion in identical conditions by measuring their radiochemical purity in ITLC. RESULTS: In these conditions, MAA, rhenium sulphide macrocolloid, albumin microcolloid and albumin microcolloid present the best behaviour, with an activity linked to food over 90 % of the previously fixed activity. CONCLUSIONS: According to the results, there is no relationship between the radiopharmaceutical size and nature and the stability of its binding to the solid food. Because rhenium sulphide macrocolloid is no longer manufactured and the other three radiopharmaceuticals which have a binding stability to the solid food over 90 % do not include digestive explorations amongst their indications, nowadays, there is a serious legal limitation to carry out this type of studies in our country.

Induced sputum derives from the central airways: confirmation using a radiolabeled aerosol bolus delivery technique.

Indirect evidence suggests that induced sputum derives from the surfaces of the bronchial airways. To confirm this experimentally, we employed a radiolabeled aerosol bolus delivery technique that preferentially deposits aerosol in the central airways in humans. We hypothesized that there would be significantly more radioactivity recovered in an induced sputum sample, and greater airways clearance of radiolabeled particles, immediately after a central versus peripheral airways deposition. Ten healthy volunteers underwent radiolabeled aerosol deposition ((99m)Tc sulfur colloid particles) to the central and peripheral airways on separate occasions followed immediately by induced sputum or no sputum (control), while seated in front of a gamma camera. Radioactivity was measured in the selected sputum sample, processed cell pellet, and supernatant fraction. Significantly more radioactivity was present in all portions of the sputum sample after central versus peripheral airways deposition (i.e., selected sample: 15,607 counts +/- 2,985 versus 943 counts +/- 298, p = 0.001). Clearance from the whole lung was significantly greater 40 min after central versus peripheral airways deposition (48 +/- 3% versus 5 +/- 1%, p = 0.0001). Compared with control, induced sputum greatly enhanced clearance after central deposition (48 +/- 3% versus 11 +/- 6%, p = 0.0001), but not after peripheral deposition (5 +/- 1% versus 3 +/- 0.8%). These results provide direct evidence that induced sputum derives from the central airways with little or no contribution from the peripheral airways.

Inhibition of needlestick-induced simulated viremia by local measures.

BACKGROUND: The possibility of confinement of simulated retrovirus to the inoculation site after needlestick injuries to enhance chances of local intervention and function of lymphaticovenous communications was investigated. METHODS: Using the canine model, technetium-99 m sulfur colloid particles were injected subcutaneously and into the vein and lymphatics. Blood and lymph were collected at a higher level from the femoral vein and the major lymphatic. Flow rates, particle arrival times, concentrations, and other variables were evaluated for 45 minutes by gamma counting. A tourniquet was used to slow dissemination after subcutaneous injection. RESULTS: After subcutaneous inoculation, particles arrived in the blood at 2.81 +/- 0.54 minutes and in the lymph at 6.0 +/- 1.47 minutes. Application of a tourniquet delayed appearance in the blood to 7.11 +/- 1.5 minutes and in the lymph to 40.0 +/- 5.1 minutes. Concentration of particles in lymph was 1,000 times higher than in the blood. Flux values were comparable in both pathways, but accumulation patterns were different. After intravenous injection, particles arrived in lymph at 25.4 +/- 6.44 minutes. After intralymphatic injection particles arrived in the blood within 4 seconds. CONCLUSIONS: There are functional lymphaticovenous communications at the peripheral level. The period between virus inoculation and blood and lymph invasion may be extended by application of a tourniquet; therefore, time could be gained for local intervention.

[Effect of fever on gastric emptying and on serum gastrin levels]. / Efecto de la fiebre sobre el vaciamiento gástrico y los niveles séricos de gastrina.

We studied the effect of fever on gastric emptying and serum gastrin 17 levels. 8 patients with fever and normal gastric emptying were selected. Blood samples were obtained for measuring serum gastrin 17. We used Tc99m scintiscanning to measure gastric emptying. Differences between fever and normal temperature were significant. Gastric emptying in fever was 118 +/- 54 minutes and 55 +/- 22 minutes for normal temperature (p less than .01). Serum gastrin was 47.7 +/- 13 pg/ml in normal temperature and with febrile patients was 30 +/- 5.7 pg/ml (p less than .002). We conclude that fever retards gastric emptying, perhaps independently of serum gastrin level.

Technetium-99m radiochemical assay by rapid filtration: a superior alternative to chromatography.

A new method for simultaneously measuring radiochemical purity and estimated lung trapping of colloidal technetium-99m (99mTc) radiopharmaceuticals is described. The method employs a small filtration device comprised of two stacked membrane filters, differing in membrane composition and in pore size, situated over a filtrate collection vial. Specifically, an 8-microns pore polycarbonate membrane filter is situated above a 0.22-microns pore mixed-cellulose-esters membrane filter. For assay, a diluted aliquot of radiopharmaceutical is passed through the filtration device. Technetium-99m radioactivity on the membranes and in the vial is then measured. The polycarbonate filter traps and quantitates lung-capillary-occluding particles. The mixed-cellulose-esters filter traps and quantitates radiocolloid particles irrespective of relative size. The filtrate contains free pertechnetate. Within 4 min, this method yields results that compare well with those achieved by conventional techniques. The method works equally well for large colloidal particles [( 99mTc]stannous colloid), intermediate-size particles [( 99mTc]sulfur colloid), and small-size particles [( 99mTc] antimony trisulfide colloid).

Technique for aerosol deposition restricted to the nose in beagle dogs.

A method was developed for exposing the nasal cavity of beagle dogs to a radiolabeled aerosol without exposure of the remainder of the respiratory tract. Deposition efficiency, using a test aerosol of 2.0-micron particles of 99mTc-sulfur colloid delivered to the nose, was 15 +/- 2% (mean +/- SE) of inhaled activity. Gamma camera imaging showed that maximum deposition occurred in the anterior third of the nasal cavity, which contained 78 +/- 4% (mean +/- SE) of the total deposited radioactivity. The middle-third of the nasal cavity received 13 +/- 3% and the posterior third 9 +/- 2% of the deposited radioactivity. Aerosol deposition in regions of the respiratory tract below the larynx was not detectable.

An evaluation of methods for sizing radiocolloidal particles.

Technetium-99m-labelled colloids covering the entire spectrum of particle size were prepared from commercial kits (antimony colloid, sulphur colloid, tin colloid) or by chemical (excess aluminium) or thermal modification of sulphur colloid (heating time of 30 min). Particle size measurements were obtained using electron microscopy and/or a laser light scattering technique. The results for antimony colloid agreed reasonably well for both techniques with a range of 3 to 25 nm. However, standard sulphur colloid had a smaller size (220 nm) when measured by electron microscopy in comparison to the larger size (390 nm) obtained with the light scattering method. This discrepancy was felt to be due to artefacts created by electron microscopy. These artefacts (drying and sublimation) were avoided by the laser light scattering techniques which has the advantage of being non-destructive and of quickly sizing particles while still in solution. The larger colloidal particles were sulphur colloid doped with aluminium ions (1000 nm) and the tin colloid (2500 nm) which were sized by electron microscopy and laser light scattering respectively.

Formation of labelled colloid in 99Tcm-DMSA due to the presence of bactericidal fluid.

The possibility that traces of bactericidal fluid in 99Tcm-DMSA could lead to the formation of labelled colloid, was explored. In vitro investigations were undertaken using ultracentrifugation techniques and photon correlation spectroscopy. The latter showed that both contaminated and uncontaminated DMSA contained colloidal (or particulate) material. However the presence of 10 microliters bactericidal fluid as contaminant was shown by ultracentrifugation to result in labelling of this colloidal material when 99Tcm was added to DMSA. Studies in a normal volunteer confirmed the results of the in vitro studies, in that significant liver and spleen uptake was observed after the administration of contaminated 99Tcm-DMSA.