Ramune Aleksyniene

Parathyroid hormone PTH(1-34) increases the volume, mineral content, and mechanical properties of regenerated mineralizing tissue after distraction osteogenesis in rabbits

Background and purpose Parathyroid hormone (PTH) has attracted considerable interest as a bone anabolic agent. Recently, it has been suggested that PTH can also enhance bone repair after fracture and distraction osteogenesis. We analyzed bone density and strength of the newly regenerated mineralized tissue after intermittent treatment with PTH in rabbits, which undergo Haversian bone remodeling similar to that in humans. Methods 72 New Zealand White rabbits underwent tibial mid-diaphyseal osteotomy and the callus was distracted 1 mm/day for 10 days. The rabbits were divided into 3 groups, which received injections of PTH 25 µg/kg/day for 30 days, saline for 10 days and PTH 25 µg/kg/day for 20 days, or saline for 30 days. At the end of the study, the rabbits were killed and the bone density was evaluated with DEXA. The mechanical bone strength was determined by use of a 3-point bending test. Results In the 2 PTH-treated groups the regenerate callus ultimate load was 33% and 30% higher, absorbed energy was 100% and 65% higher, BMC was 61% and 60% higher, and callus tissue volume was 179% and 197% higher than for the control group. Interpretation We found that treatment with PTH during distraction osteogenesis resulted in substantially higher mineralized tissue volume, mineral content, and bending strength. This suggests that treatment with PTH may benefit new bone formation during distraction osteogenesis and could form a basis for clinical application of this therapy in humans.

Observer agreement of treatment responses on planar bone scintigraphy in prostate cancer patients: importance of the lesion assessment method.

Purpose The aim of this study was to assess observer agreement on the evaluation of treatment responses of bone metastases by bone scintigraphy (BS) using different scoring methods in prostate cancer patients. Patients and methods Sixty-three paired BS from 55 patients were included. BS was performed before and after more than 12 weeks of anticancer treatment. A panel of experienced nuclear medicine physicians from several institutions evaluated treatment response using three different methods: (a) standard clinical assessment, (b) MD Anderson criteria, and (c) Prostate Cancer Working Group 2 (PCWG-2) criteria. All methods were based on the evaluation of paired before–after bone scans. Results Readers were able to classify the presence of bone metastases at baseline with a high level of agreement [Cohen’s &kgr;=0.94, 95% confidence interval (CI) 0.82–1.00]. Observer agreement on bone response by PCWG-2 criteria showed considerable agreement (Cohen’s &kgr;=0.84, 95% CI: 0.69–0.99). Evaluation using standard clinical assessment and MD Anderson criteria showed moderate agreement (0.52, 95% CI: 0.36–0.69 and 0.64, 95% CI: 0.48–0.79, respectively). There was considerable variation among readers for regional lesion count on individual scans, with limits of agreement of −10 to 10 lesions or more for the majority of anatomical regions, including the thorax, spine, and pelvis. Conclusion Observer agreement on treatment response by BS varied notably across methods. Optimal agreement was achieved by the PCWG-2 criteria. Variation in the classification of treatment response of bone metastases may have a significant impact on clinical decision-making, emphasizing the need for a uniform approach, including during clinical practice. Response assessment by lesion counting on repeated BS without access to previous scans cannot be recommended.

No benefit of a proximal stem centralizer in cementing of a femoral prosthesis in human cadavers.

Background and purpose A proximal stem centralizer may be beneficial regarding cementing pressures, cement penetration, and stem alignment. We measured these parameters when cementing a mat-surfaced femoral component with and without the use of a proximal stem centralizer. Material and methods 8 femoral prostheses with proximal centralizers and 8 femoral prostheses without proximal centralizers were cemented according to third-generation cementing technique in 8 pairs of embalmed cadaveric femora. We recorded intramedullary pressures (peak levels, the area under the pressure curves and mean pressure) with 6 pressure transducers during stem cementation. Computer tomographic scanning of specimens was performed to evaluate stem alignment after surgery. Thickness of the cement mantle, cement penetration, and stem centralization at the metaphyseal part of the femur were measured on cross sections using stereology. Results There were no statistically significant differences in measured pressure and cement penetration values between the groups. There was similar cement distribution around the stems; however, in using a proximal centralizer, the cement mantle tended to be thinner laterally. Moreover, we found a larger variation in stem alignment on lateral projection in the proximal centralizer group. Interpretation No benefits regarding intramedullary pressures and cement penetration were obtained from cementation of a straight stem with a proximal stem centralizer. However, there was an increased risk of inferior stem positioning in the reamed medullary cavity using the centralizing device.

Differential Contributions of Specimen Types, Culturing, and 16S rRNA Sequencing in Diagnosis of Prosthetic Joint Infections.

ABSTRACT Prosthetic joint failure is mainly caused by infection, aseptic failure (AF), and mechanical problems. Infection detection has been improved with modified culture methods and molecular diagnostics. However, comparisons between modified and conventional microbiology methods are difficult due to variations in specimen sampling. In this prospective, multidisciplinary study of hip or knee prosthetic failures, we assessed the contributions of different specimen types, extended culture incubations, and 16S rRNA sequencing for diagnosing prosthetic joint infections (PJI). Project specimens included joint fluid (JF), bone biopsy specimens (BB), soft-tissue biopsy specimens (STB), and swabs (SW) from the prosthesis, collected in situ, and sonication fluid collected from prosthetic components (PC). Specimens were cultured for 6 (conventional) or 14 days, and 16S rRNA sequencing was performed at study completion. Of the 156 patients enrolled, 111 underwent 114 surgical revisions (cases) due to indications of either PJI (n = 43) or AF (n = 71). Conventional tissue biopsy cultures confirmed PJI in 28/43 (65%) cases and refuted AF in 3/71 (4%) cases; one case was not evaluable. Based on these results, minor diagnostic adjustments were made. Fourteen-day cultures of JF, STB, and PC specimens confirmed PJI in 39/42 (93%) cases, and 16S rRNA sequencing confirmed PJI in 33/42 (83%) cases. One PJI case was confirmed with 16S rRNA sequencing alone and five with cultures of project specimens alone. These findings indicated that JF, STB, and PC specimen cultures qualified as an optimal diagnostic set. The contribution of sequencing to diagnosis of PJI may depend on patient selection; this hypothesis requires further investigation.

Effect of Recent Contrast-Enhanced CT and Patient Age on Image Quality of Thyroid Scintigraphy

Purpose of the Report When thyroid scintigraphy (TS) is performed after contrast-enhanced CT (CE-CT), tracer uptake of 99mTcO4 in the thyroid gland can be inhibited by free iodide. Currently, it is recommended to postpone TS until 4 to 8 weeks after CE-CT, but few data exist to support this recommendation. The purpose was to investigate the effect of CE-CT and other variables for the diagnostic quality of TS. Patients and Methods This retrospective study included 196 patients subjected to TS less than 3 months after a CE-CT (median, 66 days). Patients with elevated thyroid-stimulating hormone (>4.5 mIU/L) or suspected thyroiditis were excluded. Logistic regression was used to calculate the probability of a TS of diagnostic quality with the variables days since CE-CT, age, thyroid-stimulating hormone, and kidney function (eGFR). Results Days since CT and age were highly significant (P < 0.001) predictors for diagnostic TS. The probability of diagnostic quality TS after CE-CT increased with time and reached approximately 70% to 80% 6 to 8 weeks after CE-CT. Analysis of age-specific populations showed age to be a strong independent factor. Conclusions Our findings are in consensus with the currently recommended interval of 6 to 8 weeks between CE-CT and TS. However, our results indicate that patient age should be taken into account, and we suggest the following delay from CE-CT to TS: 4 weeks for patients aged younger than 50 years, 6 weeks for patients aged 50 to 60 years, and 8 weeks for patients aged older than 60 years.

Influence of a Recent Contrast-Enhanced CT on Image Quality of Thyroid Scintigraphy: A retrospective Study of 197 Patients

Aim: Inflammatory bowel disease (IBD) is defined as a chronic relapsing idiopathic inflammation of the gastrointestinal tract. The two main clinical forms of this disease family are Crohn’s Disease (CD) and Ulcerative Colitis (UC). IBD affects an estimated 3.6 million individuals in Europe and North America. To date it is thought that IBD is the result of continual activation of the mucosal immune system. In order to better understand this disease family an in-house developed animal model was implemented and characterized with [18F]FDG (used to illustrate the increased glucose consumption associated with inflammatory processes) and also with TSPO 18 kDa radioligand [18F]DPA-714, an established radiotracer for the study of inflammation within the central nervous system. Materials and Methods: Colonic inflammation was induced in male Wistar rats weighing between 200-250 g by rectal administration of trinitrobenzenesulfonic acid (TNBS) at 4cm from the anal orifice. Control animals were administered, 0.9% aq. sodium chloride analogously. A Siemens Inveon PET/CT tomograph, dedicated to small animals, was used to acquire [18F]FDG images on day 7 post TNBS administration and [18F]DPA714 images the following day. Rats were then sacrificed by an i.v. injection of pentobarbital, and then the lower intestine was extracted and analyzed by immunohistochemistry to determine macrophage infiltration and the presence of TSPO. Results: PET image analysis clearly shows an important accumulation of both radiotracers within the intestinal walls of treated animals in comparison to control animals. Mean levels of [18F]FDG uptake in treated and control animals were 1.20 ± 0.56 %ID/cc and 0.43 ± 0.18 %ID/cc, respectively. Comparable results were found when using [18F]DPA-714, with mean level of uptake in treated and control animals of 1.21 ± 0.62 %ID/cc and 0.46 ± 0.23 %ID/cc, respectively. Immunohistochemistry analysis revealed a higher presence of macrophages in TNBS treated animals. Expression of TSPO was largely increased in the treated animals, when compared to the controls animals, and mainly localized in macrophages cells. Conclusion: Preliminary results seem to indicate that [18F]DPA-714 is an adapted tracer for the study of inflammation of IBD in our animal model. Beyond this, data demonstrating that [18F]DPA-714 could be used to characterize and quantify the level of inflammation during the disease evolution, within the TNBS treated animals, will also be presented. OP366 Surface displayed SNAP-tag as a novel tool for study of Grampositive bacterial infections. B. Mills, V. Steele, J. C. A. Luckett, R. O. Awais, P. Duncanson, V. Griffiths, A. Cockayne, M. Xu, I. Correa, A. C. Perkins, P. Williams, P. Hill; School of Molecular Medical Sciences, University of Nottingham, Nottingham, UNITED KINGDOM, Radiological and Imaging Sciences, University of Nottingham, Nottingham, UNITED KINGDOM, School of Biological and Chemical Sciences, Queen Mary University of London, London, UNITED KINGDOM, New England Biolabs, Inc, Ipswich, ME, UNITED STATES, School of Biosciences, University of Nottingham, Nottingham, UNITED KINGDOM. Introduction: The design of specific probes for in vivo molecular imaging of microbial infections remains one of the greatest challenges to overcome before useful, functional data can be obtained. An increasingly attractive approach for probe design is to express a ligand-binding protein within a cell, which may then covalently bind specific synthetic ligands with attached imaging moieties. One such labelling system is the commercially available SNAP-tag. SNAP-tag specifically and covalently binds O2-benzylguanine (BG) compounds, which may have fluorophores or other functional elements attached at the 4’ position of their benzyl ring. We have designed a BG ligand labelled with Tc, suitable for SPECT imaging. We propose to utilise this technology for the imaging of Staphylococcal infection in vivo with the view to investigate bacterial pathogenicity and to visualise the effect potential antimicrobials may have on bacterial load. Methods: The SNAP-tag gene was codon optimised for expression in the Gram positive bacterium Staphylococcus aureus and fused with an N-terminal spa secretion leader sequence and a Cterminal spa cell-wall anchoring domain. The N-terminal fusion directs the expressed SNAP-tag towards the cell exterior where the C-terminal domain is recognised by the cell-wall sorting enzyme sortase A, covalently anchoring SNAPtag in such a way that the ligand binding domain decorates the cell surface. A novel 99m Tc-HYNIC–NH-BG ligand for SPECT imaging was prepared by coupling BG to HYNIC and radiolabelling with NaTcO4 in the presence of tricine as co-ligand. Radiochemical yields >99% were obtained. nanoSPECT-CT imaging will be used to assess the functional data produced by using SNAP-tag expressing S. aureus cells in in vivo infection models. Results: We have demonstrated that SNAP-tag was expressed and exported to the cell wall where it was covalently anchored. Deletion of the sortase A enzyme prevented attachment of the SNAP-tag to the cell wall, as determined by Western blot. Once situated within the cell wall, SNAP-tag was functional and able to specifically bind cell-impermeable fluorescent BG ligands and our synthesised precursor HYNIC-NH2-BG ligand, as determined by confocal microscopy and fluorometry assay. Pilot in vivo studies for fluorescence optical imaging and nanoSPECT-CT imaging with the novel 99m Tc-HYNIC-NH-BG ligand are currently under development to visualise S. aureus infections in mouse models. Conclusions: This approach should allow a higher sensitivity to be achieved when investigating bacterial infections in real time compared to current molecular imaging techniques, thus allowing bacterial virulence and the potential effects of new antimicrobials to be assessed. OP367 Dual imaging of lipopolysaccharides (LPS) by SPECT-CT and Confocal Microscopy. M. Moreau, V. Duheron, B. Collin, W. Sali, C. Bernhard, C. Goze, T. Gautier, J. Pais de Barros, V. Deckert, F. Brunotte, L. Lagrost, F. Denat; ICMUB UMR CNRS 6302, Dijon, FRANCE, INSERM UMR866, Dijon, FRANCE, Centre Georges-François Leclerc, Dijon, FRANCE, Centre Hospitalier Universitaire, Dijon, FRANCE. Introduction: Lipopolysaccharides (LPS) or endotoxins are found inserted in the outer membrane of Gram-negative bacterias. Their appearance in blood stream triggers a massive secretion of pro-inflammatory cytokines in mammals. A controlled response allows the neutralization and elimination of LPS, whereas an excessive inflammatory response leads to severe circulatory and respiratory defects. It is the endotoxemic shock or septic shock that can leads to death. Many approaches are used to study LPS, including labeling with radiochemicals (3H, 125I, 99mTc or 51Cr) or with fluorophores (FITC, Alexa488, Bodipy). Bimodality is attracting more and more interest in the field of molecular imaging since the combination of two different techniques may provide complementary information, thus improving the accuracy of diagnosis. Combining nuclear modalities (PET or SPECT) with optical imaging is of particular interest, and the similar sensitivities of the two techniques allows to fuse the signaling moieties into a unique molecule, called monomolecular multimodality imaging agent (MOMIA), ensuring a same biodistribution of the two probes. Method: A recently described bimodal probe, namely DOTA-Bodipy-NCS, has been covalently attached to LPS. The integrity of the LPS after labeling procedure was checked by SDS-PAGE electrophoresis and βhydroxymyristate titration (BHM). Pro-inflammatory activity of LPS was assessed by quantification of cytokines released by differentiated THP-1 cells. This bioconjugate was then radiometallated for SPECT-CT biodistribution imaging. Results: DOTABodipy-LPS was metallated with 111In to yield a high specific activity (600 MBq.mg1), with a radiochemical purity >98 % after purification. Biodistribution of the radiolabeled compound was then evaluated in vivo in WT mice by SPECT-CT imaging. Radiolabeled LPS is rapidly eliminated from the bloodstream and accumulates in spleen and liver. Liver slices were then analyzed by confocal microscopy, and specific fluorescent signals in the cytoplasm of hepatocytes were detected, confirming the accumulation of 111In-DOTA-Bodipy-LPS in the liver. Conclusion: These results demonstrate the efficiency of the conjugation process of our bimodal probe. It made it possible to perform both non-invasive SPECT and ex vivo fluorescence imaging of LPS biodistribution, underlining its liver uptake for further detoxification. The 111In-DOTA-Bodipy-LPS probe arises here as a relevant tool to identify key components of LPS detoxification in vivo paving the way to therapeutic issues in the field of sepsis. Acknowlegement: Support was provided by the CNRS, the University of Burgundy, the Conseil Régional de Bourgogne. O P _ M o nd ay S178 Eur J Nucl Med Mol Imaging (2013) 40 (Suppl 2):S89–S567Affibody molecules constitute a class of small (7 kDa) scaffold proteins that can be engineered to have excellent tumor targeting properties. High reabsorption in kidneys complicates development of ...