Image registration for targeted MRI-guided transperineal prostate biopsy

Purpose:

To develop and evaluate image registration methodology for automated re‐identification of tumor‐suspicious foci from preprocedural MR exams during MR‐guided transperineal prostate core biopsy.

Materials and Methods:

A hierarchical approach for automated registration between planning and intra‐procedural T2‐weighted prostate MRI was developed and evaluated on the images acquired during 10 consecutive MR‐guided biopsies. Registration accuracy was quantified at image‐based landmarks and by evaluating spatial overlap for the manually segmented prostate and sub‐structures. Registration reliability was evaluated by simulating initial mis‐registration and analyzing the convergence behavior. Registration precision was characterized at the planned biopsy targets.

Results:

The total computation time was compatible with a clinical setting, being at most 2 min. Deformable registration led to a significant improvement in spatial overlap of the prostate and peripheral zone contours compared with both rigid and affine registration. Average in‐slice landmark registration error was 1.3 ± 0.5 mm. Experiments simulating initial mis‐registration resulted in an estimated average capture range of 6 mm and an average in‐slice registration precision of ±0.3 mm.

Conclusion:

Our registration approach requires minimum user interaction and is compatible with the time constraints of our interventional clinical workflow. The initial evaluation shows acceptable accuracy, reliability and consistency of the method. J. Magn. Reson. Imaging 2012;36:987–992. © 2012 Wiley Periodicals, Inc.     

Feasibility of coronary CT angiography for guidance of CABG

ObjectiveTo assess the clinical safety and effectiveness of coronary revascularization in patients who underwent coronary artery bypass grafting (CABG) based exclusively on coronary computed tomography angiography (CCTA) results.Methods53 patients (62.3 ± 7.1 years) underwent CCTA before a CABG surgery without prior invasive coronary angiography (ICA). Primary endpoints were all-cause mortality and major adverse cardiovascular events (MACE). The secondary endpoint was quality of life (QoL) assessed with the Minnesota Living with Heart Failure Questionnaire (MLHFQ). All were collected one year after the surgery.ResultsCCTA revealed multivessel coronary artery disease (CAD) in 52 patients. Indication for bypass surgery was made exclusively based on CCTA results. 136 distal anastomoses were performed. Assessment at 1 year (13.3 ± 1.4 months) was completed in 98.1% of the patients. MACE and mortality rates were 0%. The MLHFQ total score was 21.8 ± 8.7, and active lifestyle was maintained in all patients.ConclusionsIn this proof of concept prospective pilot study, we observed that non-invasive coronary angiography may provide adequate anatomic detail to guide CABG surgery. Further study of this concept is warranted.     

Study of thermal stability of p-type skutterudites DD0.7Fe3CoSb12 by Knudsen effusion mass spectrometry

The temperature and phase stability of p-type skutterudites, DD_0.7Fe₃CoSb₁₂, manufactured via various preparation techniques, all exhibiting a high ZT-level, have been studied by means of thermal analysis and Knudsen effusion mass spectrometry. The results from phase transformation measurements and characteristics of the evaporation of antimony, as the volatile element, supported by microstructure observations and by diffusion profiles are summarized and discussed in view of a full understanding of the degradation processes and knowledge of the long term operation stability of the bulk and nano-structured thermoelectrics studied. It was found out that the antimony evaporation is a complex diffusion kinetic process resulting in a stable Sb level dependent on the preparation route. The studied p-type skutterudites, DD_0.7Fe₃CoSb₁₂, have proven their long term stability in thermoelectric devices at a maximum operation temperature of 600 °C. Complementary data on the structural, physical and mechanical properties of the materials are presented as well.

Antimony vapour pressure is measured by Knudsen effusion mass spectrometry in order to assess the thermal stability of p-type DD_0.7Fe₃CoSb₁₂ thermoelectrics.     

Hollow Au@TiO2 porous electrospun nanofibers for catalytic applications

Catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles were fabricated using a combination of sol–gel chemistry and coaxial electrospinning technique. We report the fabrication of catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles (AuNPs) using a combination of sol–gel chemistry and coaxial electrospinning technique. The coaxial electrospinning involved the use of a mixture of poly(vinyl pyrrolidone) (PVP) and titania sol as the shell forming component, whereas a mixture of poly(4-vinyl pyridine) (P4VP) and pre-synthesized AuNPs constituted the core forming component. The core–shell nanofibers were calcined stepwise up to 600 °C which resulted in decomposition and removal of the organic constituents of the nanofibers. This led to the formation of porous and hollow titania nanofibers, where the catalytic AuNPs were embedded in the inner wall of the titania shell. The catalytic activity of the prepared Au@TiO₂ porous nanofibers was investigated using a model reaction of catalytic reduction of 4-nitrophenol and Congo red dye in the presence of NaBH₄. The Au@TiO₂ porous and hollow nanofibers exhibited excellent catalytic activity and recyclability, and the morphology of the nanofibers remained intact after repeated usage. The presented approach could be a promising route for immobilizing various nanosized catalysts in hollow titania supports for the design of stable catalytic systems where the added photocatalytic activity of titania could further be of significance.

Catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles were fabricated using a combination of sol–gel chemistry and coaxial electrospinning technique.     

Assessment of microRNA-related SNP effects in the 3′ untranslated region of the IL22RA2 risk locus in multiple sclerosis

Recent large-scale association studies have identified over 100 MS risk loci. One of these MS risk variants is single-nucleotide polymorphism (SNP) rs17066096, located ~14 kb downstream of IL22RA2. IL22RA2 represents a compelling MS candidate gene due to the role of IL-22 in autoimmunity; however, rs17066096 does not map into any known functional element. We assessed whether rs17066096 or a nearby proxy SNP may exert pathogenic effects by affecting microRNA-to-mRNA binding and thus IL22RA2 expression using comprehensive in silico predictions, in vitro reporter assays, and genotyping experiments in 6,722 individuals. In silico screening identified two predicted microRNA binding sites in the 3′UTR of IL22RA2 (for hsa-miR-2278 and hsa-miR-411-5p) encompassing a SNP (rs28366) in moderate linkage disequilibrium with rs17066096 (r ²?=?0.4). The binding of both microRNAs to the IL22RA2 3′UTR was confirmed in vitro, but their binding affinities were not significantly affected by rs28366. Association analyses revealed significant association of rs17066096 and MS risk in our independent German dataset (odds ratio ?=?1.15, P?=?3.48?×?10^?4), but did not indicate rs28366 to be the cause of this signal. While our study provides independent validation of the association between rs17066096 and MS risk, this signal does not appear to be caused by sequence variants affecting microRNA function.     

Sustainable oxidation of cyclohexane catalyzed by a VO(acac)2-oxalic acid tandem: the electrochemical motive of the process efficiency

Cyclohexane oxidation by H₂O₂ to cyclohexanol, cyclohexanone, and cyclohexylhydroperoxide under mild (40 °C, 1 atm) conditions is significantly enhanced in the system composed of VO(acac)₂ (starting catalyst) and small additives of oxalic acid (process promoter). In corroboration of this, several times higher yield of the desired products was obtained compared to that obtained in the acid-free process. The revealed advantage was addressed to elevate the electrical conductance G (or vice versa, decreasing the resistance, 1/G) of the reaction medium. On the other hand, the content of oxalic acid (20–30 mM) was compulsory to optimize the process parameters. The last value of concentration affords, besides the lowest 1/G, the utmost impact on pH, redox potential, and current–voltage relationships. Exceeding this level leads to an increase in 1/G of the reaction solution, ceases the impact on pH, ORP, and CV profiles, and is detrimental for the product yield. The putative mechanism of the revealed effects has been envisaged.

Cyclohexane oxidation by H₂O₂ to cyclohexanol, cyclohexanone, and cyclohexylhydroperoxide under mild (40 °C, 1 atm) conditions is significantly enhanced in the system composed of VO(acac)₂ (starting catalyst) and small additives of oxalic acid (process promoter).     

Continuum percolation of carbon nanotubes in polymeric and colloidal media

We apply continuum connectedness percolation theory to realistic carbon nanotube systems and predict how bending flexibility, length polydispersity, and attractive interactions between them influence the percolation threshold, demonstrating that it can be used as a predictive tool for designing nanotube-based composite materials. We argue that the host matrix in which the nanotubes are dispersed controls this threshold through the interactions it induces between them during processing and through the degree of connectedness that must be set by the tunneling distance of electrons, at least in the context of conductivity percolation. This provides routes to manipulate the percolation threshold and the level of conductivity in the final product. We find that the percolation threshold of carbon nanotubes is very sensitive to the degree of connectedness, to the presence of small quantities of longer rods, and to very weak attractive interactions between them. Bending flexibility or tortuosity, on the other hand, has only a fairly weak impact on the percolation threshold.     

Pathologic correlation of transperineal in-bore 3-Tesla magnetic resonance imaging-guided prostate biopsy samples with radical prostatectomy specimen

Abdominal Radiology - To determine the accuracy of in-bore transperineal 3-Tesla (T) magnetic resonance (MR) imaging-guided prostate biopsies for predicting final Gleason grades in patients who...     

Loss of complexity characterizes the heart rate response to experimental hemorrhagic shock in swine

OBJECTIVE: To improve our ability to identify physiologic deterioration caused by critical illness, we applied nonlinear and frequency-domain analytical methods to R-to-R interval (RRI) and systolic arterial pressure (SAP) time series during hemorrhagic shock. DESIGN: Prospective, randomized, controlled trial. SETTING: Animal laboratory of a government research institute. SUBJECTS: Twenty swine (weight 36.4+/-0.11 kg). INTERVENTIONS: Fixed-volume hemorrhage followed by resuscitation; off-line analysis of RRI and SAP data. MEASUREMENTS AND MAIN RESULTS: Anesthetized swine (shock group, n=12) underwent withdrawal of 30 mL/kg blood in 10 mL/kg decrements. A control group (n=8) received maintenance fluids only. Electrocardiogram and arterial pressure waveforms were acquired at 500 Hz. Eight hundred-beat data sets were analyzed at six time points: at baseline, after each blood withdrawal, after lactated Ringer's resuscitation, and after infusion of shed blood. Nonlinear methods were used to estimate the complexity (approximate entropy, sample entropy, Lempel-Ziv entropy, normalized entropy of symbol dynamics), RRI bits per word, and fractal dimension by curve lengths and by dispersion analysis of the RRI and SAP time series. Fast Fourier transformation was used to measure the high-frequency and low-frequency powers of RRI and SAP. Baroreflex sensitivity was assessed in the time domain with the sequence method. Hemorrhagic shock caused decreases in RRI complexity as quantified by approximate entropy, sample entropy, and symbol dynamics; these changes were reversed by resuscitation. Similar but statistically insignificant changes in fractal dimension by curve lengths were seen. RRI high-frequency power decreased with hemorrhagic shock-indicating withdrawal of vagal cardiac input-and was restored by resuscitation. Similar changes in baroreflex sensitivity were seen. Hemorrhagic shock did not affect SAP complexity. CONCLUSIONS: Hemorrhagic shock caused a reversible decrease in RRI complexity; these changes may be mediated by changes in vagal cardiac control. Assessment of RRI complexity may permit identification of casualties with hemorrhagic shock.     

Development and validation of a novel fusion algorithm for continuous,accurate, and automated R-wave detection and calculation of signal-derived metrics

Purpose

Previous studies have shown that heart rate complexity may be a useful indicator of patient status in the critical care environment but will require continuous, accurate, and automated R-wave detection (RWD) in the electrocardiogram (ECG). Although numerous RWD algorithms exist, accurate detection remains a challenge. The purpose of this study was to develop and validate a novel fusion algorithm (Automated Electrocardiogram Selection of Peaks, or AESOP) that combines the strengths of several well-known algorithms to provide a more reliable real-time solution to the RWD problem.

Materials and Methods

This study involved the ECGs of 108 prehospital patient records and 32 ECGs from a conscious sedated porcine model of hemorrhagic shock. The criterion standard for validation was manual verification of R waves.

Results

For 108 human ECG records, the AESOP algorithm overall outperformed each of its component algorithms. In addition, for 32 swine ECG records, AESOP achieved an R-wave sensitivity of 97.9% and a positive predictive value of 97.5%, again outperforming its component algorithms.

Conclusion

By fusing several best algorithms, AESOP uses the strengths of each algorithm to perform more robustly and reliably in real time. The AESOP algorithm will be integrated into a real-time heart rate complexity software program for decision support and triage in critically ill patients.