[en] The purpose of this was the modification of labelled autologous red blood cells in vivo/in vitro. Evaluation consisted in different combinations of Tc-99m radiopharmaceuticals as pyrophosphate (PYP) and stannous chloride (SnCl2), anticoagulants as heparin and acid-citrate-dextrose (ACD), and oxidant agents as hydrogen peroxide (H2O2) and sodium hypochlorite (NaClO); factorial block design was carried out to determinate which one brings a better yield of labelling, and more advantages of availability. Results showed that all tested combinations were above 90% labelled; variance analysis indicated significant difference between the two radiopharmaceuticals (P<0.05), being higher percent of labelling with PYP than SnCl2, and PYP-ACD-NaClO the best combination. It was demonstrated that the procedure is safe because hemocultives realized during the labelling process were all negative, evidencing no bacterial contamination. There were significant erythrocyte-shape modifications, too. Due to low costs and good availability of H2O2 as oxidant agent there were no statistic significant differences between the use of H2O2 or NaClO, the modification PYP-ACD-H2O2 will be used as scintigraphic test for deep vein thrombosis

[en] Some factors affecting the biodistribution of radiopharmaceuticals in patients are discussed. These include concomitant drug therapy, contamination of radiopharmaceuticals during dispensing or injection into the patient, prior administration of diagnostic contrast media and prior administration of another radiopharmaceutical. (UK)

[en] Graphical analysis (GA) is an efficient method for estimating total tissue distribution volume (V_T) from positron emission tomography (PET) uptake data. The original GA produces a negative bias in V_T in the presence of noise. Estimates of V_T using other GA forms have less bias but less precision. Here, we show how the bias terms are related between the GA methods and how using an instrumental variable (IV) can also reduce bias. Results are based on simulations of a two-compartment model with V_T's ranging from 10.5 to 64 mL/cm₃ and from PET image data with the tracer (¹¹C)DASB ((¹¹C)-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl) benzonitrile). Four estimates of V_T (or distribution volume ratio (DVR) using a reference tissue) can be easily computed from different formulations of GA including the IV. As noise affects the estimates from all four differently, they generally do not provide the same estimates. By taking the median value of the four estimates, we can decrease the bias and reduce the effect of large values contributing to noisy images. The variance of the four estimates can serve as a guide to the reliability of the median estimate. This may provide a general method for the generation of parametric images with little bias and good precision.

[en] An improved quantitative immuno chemical determination of tyrosine hydroxylase brain concentrations was designed by using direct transfer into nitro-cellulose from 20 μm thick brain sections followed by immuno-detection and quantitative radioautography

[en] Bone scintigrams are usually obtained for evaluation of skeletal abnormalities; soft-tissue abnormalities are often an unexpected finding. However, the recognition of specific conditions with extraskeletal accumulation of bone-seeking radiopharmaceuticals greatly enhances the diagnostic value of the study. Several examples of abnormal nonosseous uptake in both neoplastic and nonneoplastic processes involving the brain, lung, heart, breast, bowel, liver, spleen, skeletal muscle, kidney, and bladder are presented. Examples of artifactual uptake in the soft tissues are also described. Causes for nonosseous accumulation are discussed.21 references

[en] Published in summary form only

[en] SPECT imaging with ¹²³I-labeled methyl 3β-(4-iodophenyl)tropane-2β-carboxylate ([¹²³I]β-CIT) in nonhuman primates has shown brain striatal activity, which primarily reflects binding to the dopamine transporter. The biodistribution and calculated radiation-absorbed doses of [¹²³]β-CIT administered to eight healthy subjects were measured with attention to the accurate determination of organ time-activity data. Whole-body transmission images were obtained with a scanning line source for attenuation correction of the emission images. Following administration of 92.5 ± 22.2 MBq (2.5 ± 0.6 mCi) of [¹²³I]β-CIT, subjects were imaged with a whole-body imager every 30 min for 3 hr, every 60 min for the next 3 hr and at 12, 24 and 38 hr postinjection. Regional body conjugate counts were converted to microcuries of activity, with a calibration factor determined in a separate experiment using a distributed source of ¹²³I. The peak brain uptake represented 14% of the injected dose, with 2% of the activity approximately overlying the striatal region. Highest radiation-absorbed doses were to the lung (0.1 mGy/MBq, 0.38 rads/mCi), liver (0.087 mGy/MBq, 0.32 rads/mCi) and lower large intestine (0.053 mGy/MBq, 0.20 rads/mCi). Iodine-123-β-CIT is a promising SPECT agent for imaging of the dopamine transporter in humans with favorable dosimetry and high brain uptake. 18 refs., 4 figs., 5 tabs

[en] The authors have synthesized a number of fluorine-containing compounds of two known muscarinic receptor ligand classes and evaluated these analogs for subtype selectivity using the NOVASCREEN tissue subtype assays. Fluorine-containing analogs of the antagonist quinuclidinyl benzilate (QNB) were prepared in a stereoselective manner and the various isomers were found to display differing affinities in the tissue subtype assays. Fluorine-containing analogs of the agonist 3-(3-(alkylthio)-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridine [TZTP] were also prepared and observed to display differences in subtype selectivity. Biodistribution studies have been conducted with some of these analogs to study in vivo selectivity

[en] Published in summary form only

[en] Blood-brain barrier (BBB) passage of the flow tracer ethylenediylbis-L-cysteine diethylester (bicisate, ECD) was measured repeatedly in five patients by means of the intravenous (i.v.) double-indicator technique using ²⁴Na⁺ as an intravascular cotracer. After i.v. injection, the arterial concentration curve of ^99m T_c-bicisate was delayed and dispersed compared with that of the intravascular cotracer, presumably due to lung retention of the flow tracer. The corrected cerebral venous output curves were fitted using a three-compartment model with four parameters. At resting cerebral blood flow (CBF) values, the unidirectional brain extraction was 0.57 ± 0.05, the permeability-surface area product for passage from blood to brain (PS₁) was 0.48 ± 0.07 ml/g/min, and the distribution volume for bicisate was 0.74 ± 0.20 (mean ± SD). In a single patient, BBB transport after i.v. injection of bicisate was compared with that of a similar flow tracer, d,l-hexamethylpropyleneamine oxime (HM-PAO), and similar values were found for the two tracers. In 19 rats, the brain extraction of bicisate was measured by means of the intracarotid double-indicator technique. The brain extraction was measured at resting, decreased, and increased CBF values. Low CBF values were obtained by hyperventilation and high values by hypercapnia. The degree of backflux of tracer from brain to blood was evaluated by means of the three-compartment model and was found to be negligible in these experiments. The brain extraction was 0.70 ± 0.1 and PS₁ was 0.94 ± 0.27 ml/g/min. During hypercapnia, CBF increased from 0.77 to 1.09 ml/g/min, leading to a significant decrease in brain extraction, from 0.70 to 0.56. During hyperventilation, CBF decreased from 0.77 to 0.54 ml/g/min, leading to a significant increase in brain extraction, from 0.70 to 0.74. PS₁ remained constant despite changes in CBF or bolus size. 12 refs., 5 figs., 3 tabs