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Leipzig, Germany

Apostolova I.,Charite - Medical University of Berlin | Wiemker R.,Philips | Paulus T.,Philips | Kabus S.,Philips | And 8 more authors.
European Radiology | Year: 2010

Objective: We evaluate a fully data-driven method for the combined recovery and motion blur correction of small solitary pulmonary nodules (SPNs) in F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT). Methods: The SPN was segmented in the low-dose CT using a variable Hounsfield threshold and morphological constraints. The combined effect of limited spatial resolution and motion blur in the SPN's PET image was then modelled by an effective Gaussian point-spread function (psf). Both isotropic and non-isotropic psfs were used. To validate the method, PET/CT measurements of the NEMA/IEC spheres phantom were performed. The method was applied to 50 unselected SPNs ≥30 mm from routine patient care. Results: Recovery of standardised uptake value (SUV) in the phantom image was significantly improved by combined recovery and motion blur correction compared with recoveryonly correction, particularly with the non-isotropic model (residual average error 10%). In the patient images, automated segmentation and fit of the effective psf worked properly in all cases. Volume-equivalent diameter ranged from 4.9 to 27.8 mm. Uncorrected maximum SUV ranged from 0.9 to 13.3. Compared with recoveryonly correction, combined correction with the non-isotropic model resulted in a 'relevant' (≥30%) SUV increase in 47 SPNs (94%). Conclusions: Correction of both recovery and motion blur is mandatory for accurate SUV quantification of SPNs. © European Society of Radiology 2010. Source

De Souza Albernaz M.,Federal University of Rio de Janeiro | Ospina C.A.,Brazilian Nanotechnology National Laboratory | Rossi A.M.,Brazilian Center for Research in Physics (CBPF) | Santos-Oliveira R.,Institute of Radiopharmacy | Santos-Oliveira R.,Brazilian Nuclear Engineering Institute (IEN)
Artificial Cells, Nanomedicine and Biotechnology | Year: 2014

The use of nanoparticles is under intense investigation. The possible advantages proposed by these systems are very impressive and the results may be quite schemer. In this scenario, the association of nanoparticles with radioactive materials (radionuclide) may be the most important step since the discovery of radioactive for nuclear medicine and radiopharmacy, especially for cancer targeting and therapy. In this study, we developed radiolabelled nanoparticles of hydroxyapatite with technetium 99m for bone cancer imaging. The results demonstrated that it is possible to label nanoparticles of hydroxyapatite, and due to its physicochemical properties is possible to develop nano-radiopharmaceutical for bone imaging. © 2014 Informa Healthcare USA, Inc. Source

Hildebrand H.,Institute of Resource Ecology | Franke K.,Institute of Radiopharmacy
Journal of Nanoparticle Research | Year: 2012

Nanoparticle (NP) tracking in complex media is still a challenge since NP concentrations are expected to be low compared to elemental background levels as it can be found in environmental matrices. This study presents a new method for radiolabeling of commercial silver nanopowder (Ag 0-NPs, dp<100 nm) with 110mAg radionuclides (t 1/2 = 249.9 days) that provide an adequate time frame for particle detection, localization, and tracking under various experimental conditions. The radiolabeling procedure insures high efficiency, stability, and consistency of important particle properties such as size and morphology. Detection of Ag 0-NP in concentrations as low as 125 ng kg -1 could be reached. For the first time, an appropriate tool for life-cycle studies of commercial Ag 0-NPs is provided without changing chemical composition of thematerial. This is of great importance e.g., for research in the field of nanotoxicology. © Springer Science+Business Media B.V. 2012. Source

Torigian D.A.,University of Pennsylvania | Lopez R.F.,HHUU Virgen del Rocvo | Alapati S.,University of Pennsylvania | Bodapati G.,University of Pennsylvania | And 4 more authors.
Hellenic Journal of Nuclear Medicine | Year: 2011

Our aim was to assess feasibility and performance of novel semi-automated image analysis software called ROVER to quantify metabolically active volume (MAV), maximum standardized uptake value-maximum (SUV max), 3D partial volume corrected mean SUV (cSUV mean), and 3D partial volume corrected mean MVP (cMVP mean) of spinal bone marrow metastases on fluorine-18 fluorodeoxyglucose-positron emission tomography/computerized tomography ( 18F-FDG-PET/CT). We retrospectively studied 16 subjects with 31 spinal metastases on FDG-PET/CT and MRI. Manual and ROVER determinations of lesional MAV and SUV max, and repeated ROVER measurements of MAV, SUV max, cSUV mean and cMVP mean were made. Bland-Altman and correlation analyses were performed to assess reproducibility and agreement. Our results showed that analyses of repeated ROVER measurements revealed MAV mean difference (D)=-0.03±0.53cc (95%CI(-0.22, 0.16)), lower limit of agreement (LLOA)=-1.07cc, and upper limit of agreement (ULOA)=1.01cc; SUV max D=0.00±0.00 with LOAs=000; cSUV mean D=-0.01±0.39 (95%CI(-0.15, 0.13)), LLOA=-0.76, and ULOA=0.75; cMVP mean D=-0.52±4.78cc (95%CI(-2.23, 1.23)), LLOA=-9.89cc, and ULOA=8.86cc. Comparisons between ROVER and manual measurements revealed volume D= -0.39±1.37cc (95%CI (-0.89, 0.11)), LLOA=-3.08cc, and ULOA=2.30cc; SUV max D=0.00±0.00 with LOAs=000. Mean percent increase in lesional SUV mean and MVP max followinq partial volume correction using ROVER was 84.25±36.00% and 84.45+35.94%, respectively. In conclusion, it is feasible to estimate MAV, SUV max, cSUV mean, and cMVP mean of spinal bone marrow metastases from 18F-FDG-PET/CT quickly and easily with good reproducibility via ROVER software. Partial volume correction is imperative, as uncorrected SUV mean and MVP mean are significantly underestimated, even for large lesions. This novel approach has great potential for practical, accurate, and precise combined structural-functional PET quantification of disease before and after therapeutic intervention. Source

Ansurudeen I.,TU Dresden | Ansurudeen I.,Karolinska Institutet | Pietzsch J.,Institute of Radiopharmacy | Graessler J.,TU Dresden | And 4 more authors.
American Journal of Hypertension | Year: 2010

Background: Serum aldosterone is a causative factor for various metabolic and cardiovascular disorders. Low-density lipoprotein (LDL) is a major cholesterol source for aldosterone steroidogenesis; however, the effect of oxidative modification of LDL on aldosterone release is not known. We studied the effect of hypochlorite-oxidized LDL (oxLDL) on adrenal aldosterone secretion.MethodsLDL (native LDL (natLDL)) was obtained from healthy volunteers and oxidatively modified in vitro. NCI-H295R cells were stimulated with natLDL and oxLDL, and the aldosterone release was quantified by radioimmunoassay. Molecular changes were studied with western blot analysis and quantitative RT-PCR analysis.ResultsNatLDL and oxLDL caused dose-dependent increase in aldosterone release up to threefold. However, the stimulatory effects of modified LDL on aldosterone secretion decreased with increasing degree of LDL oxidation. 24-h incubations with natLDL, mild- and medium-oxidized LDL sensitized the adrenocortical cells to subsequent angiotensin II (Ang II) stimulations by 2.9-, 2.8-, and 2.5-folds, respectively. Heavily oxidized LDL did not sensitize the cells to Ang II stimulations to a similar extent. At the molecular level, the ERK pathway was activated within a minute by both natLDL and oxLDL; however, oxLDL showed a stronger (2.75-fold at 1 and 15min) and longer (15min) activation of ERK than natLDL (twofold).ConclusionsThis study demonstrates the following: (i) both natLDL and hypochlorite-oxidized LDL utilize ERK pathway to mediate aldosterone release; (ii) mildly oxidized LDL sensitizes the adrenocortical cells to further stimulations by Ang II similar to natLDL that may have a role in pathological processes; (iii) extensive LDL oxidation counteracts adrenocortical aldosterone release. © 2010 American Journal of Hypertension, Ltd. Source

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