Human b-defensin-3 (HBD-3) is an antimicrobial peptide with bactericidal effects on many gram-positive and gram-negative bacteria and some yeast species and, if radiolabeled, might be used to distinguish bacterial infection from sterile inflammation. The goals of the present study were to develop methods for radiolabeling HBD-3 with 99m Tc and to perform preliminary investigations on 99m Tc-labeled HBD-3 as a means to evaluate induced infection in an animal model. To this purpose, Staphylococcus aureus-induced infection was used to evaluate the capability of 99m Tc-HBD-3 to distinguish infection from aseptic inflammation in rats. Methods: Twenty to 40 mg of recombinant HBD-3 were labeled with 99m Tc 1 hexa-coordinated with 3 molecules of CO and H 2 O and separated by a column from free 99m Tc. 99m Tc-HBD-3 was added to cultures of a bacterial suspension of S. aureus and Escherichia coli to evaluate in vitro antibacterial activity. A bacterial suspension of S. aureus and a carrageenan solution were used to induce infection and sterile inflammation, respectively, in opposite thighs of 9 adult rats. Three separate experiments were performed on groups of 3 rats each. The animals received different doses of 99m Tc-HBD-3 injected through a cannula into the jugular vein. After sacrifice of the animals, tissue samples were obtained from sites of infection, inflammation, and control muscle (left foreleg) at 1, 3, and 5 h after 99m Tc-HBD-3 administration. Tissue samples were weighed and then counted in a well-counter. Simultaneously, 1 mL of a standard solution of 99m Tc-HBD-3 corresponding to each administered dose was counted. Results: 99m Tc-HBD-3 retained antibacterial activity. Radioactivity in tissue samples from the infected sites was significantly higher than that in samples of either induced inflammation or normal control muscle (ratio, ;3:1) at 3 and 5 h after injection, whereas similar radioactivity counts were observed for tissue samples from aseptic inflammation sites and normal control muscle. Conclusion: In this investigation, 99m Tc-HBD-3 retained antibacterial activity and successfully distinguished infection from aseptic inflammation in adult rats.

LS is the more sensitive method to localize abdominal abscesses and may guide dedicated US and CT investigations to improve their diagnostic potential. Further diagnostic evolution is expected from the routine use of hybrid SPECT/CT systems.

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Here, we report a case of a 54-year-old woman affected by thyrotoxicosis, with scintigraphic evidence of a diffuse hyperfunctioning goiter and a large ectopic thyroid tissue in the thyroglossal duct remnant. The latter was apparently more active than the two lobes at 99m Tc-pertechnetate scintigraphy, mimicking a condition of preexisting increased sensitivity to thyroid-stimulating hormone stimulation. On the other hand, single-photon emission computed tomography/computed tomography has proven to be a very useful tool in demonstrating this activity to be similar to the thyroid lobes and in defining extension and anatomical relationships of the mass.

Backgound: The development of resolution recovery (RR) algorithms has made it possible to preserve good quality of cardiac images in spite of reduced number of counts during study acquisition. Objective: Our purpose was to evaluate the performance of three different software packages in the quantification of left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) from gated perfusion SPECT, applying a resolution recovery (RR) algorithm (GE Myovation Evolution), respect to cardiac MRI (cMRI) as gold standard. Methods: We retrospectively enrolled 21 patients, with suspected or known coronary heart disease. Images at rest were reconstructed by filtered back projection (FBP) and by an iterative protocol with the RR algorithm. EDV, ESV and LVEF were automatically computed employing Quantitative gated SPECT (QGS), Myometrix (MX) and Corridor 4DM (4DM). Any difference in EDV, ESV and LVEF calculation between cMRI and the three packages (with FBP and iterative reconstruction with RR) was tested using Wilcoxon or paired t-test, with assumption of normality assessed using ShapiroWilk test. Agreement between imaging reconstruction algorithms and between gated-SPECT software packages and cMRI was studied with Pearson’s (r) or Spearman’s (R) correlation coefficients and Lin’s concordance correlation coefficient (LCC). Results: Intra-software evaluation always revealed very strong correlation coefficients (R, r ≥ 0.8) and excellent LCC coefficients (LCC > 0.95), except for LCC coefficient between MX-FBP and MX-RR in EDV evaluation, nevertheless considered very good (LCC = 0.94). EDV and ESV had significantly lower value when calculated with RR algorithm respect to FBP reconstruction in QGS and MX. LVEF estimation did not show significant differences for QGSFBP, QGS-RR, MX and 4DM-RR with respect to cMRI. Results: Intra-software evaluation always revealed very strong correlation coefficients (R, r ≥ 0.8) and excellent LCC coefficients (LCC > 0.95), except for LCC coefficient between MX-FBP and MX-RR in EDV evaluation, nevertheless considered very good (LCC = 0.94). EDV and ESV had significantly lower value when calculated with RR algorithm respect to FBP reconstruction in QGS and MX. LVEF estimation did not show significant differences for QGSFBP, QGS-RR, MX and 4DM-RR with respect to cMRI. Conclusion: All reconstruction methods sistematically understimate EDV and ESV, with higher underestimation applying only the RR. No significant differences were observed between 4DM -RR and 4DM-FBP, for each parameter, when 4DM package was used.