Cross-sectional imaging of aortic infections

Aortic infections are uncommon clinical entities, but are associated with high rates of morbidity and mortality. In this review, we focus on the cross-sectional imaging appearance of aortic infections, including aortic valve endocarditis, pyogenic aortitis, mycotic aneurysm and aortic graft infections, with an emphasis on CT, MRI and PET/CT appearance. Teaching Points • Aortic infections are associated with high morbidity and mortality. • CT, MRI and FDG PET/CT play complementary roles in aortic infection imaging. • Radiologists should be vigilant for aortic infection manifestations to ensure timely diagnosis.

Treatment of Articular Cartilage Defects With Microfracture and Autologous Matrix-Induced Chondrogenesis Leads to Extensive Subchondral Bone Cyst Formation in a Sheep Model

BACKGROUND

Microfracture and the autologous matrix-induced chondrogenesis (AMIC) technique are popular for the treatment of articular cartilage defects. However, breaching of the subchondral bone plate could compromise the subchondral bone structure.

HYPOTHESIS

Microfracture and AMIC will cause deleterious effects on the subchondral bone structure.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 36 sheep received an 8-mm-diameter cartilage defect in the left medial femoral condyle. Control animals (n = 12) received no further treatment, and the rest received 5 microfracture holes either with a type I/III collagen scaffold implanted (n = 12; AMIC group) or without the collagen scaffold (n = 12; microfracture group). Macroscopic infill of defects, histology, and histomorphometry of the subchondral bone were performed at 13 and 26 weeks postoperatively, and micro-computed tomography (CT) was also performed at 26 weeks postoperatively.

RESULTS

Microfracture and AMIC resulted in subchondral bone cyst formation in 5 of 12 (42%) and 11 of 12 (92%) specimens at 13 and 26 weeks, respectively. Subchondral bone changes induced by microfracture and AMIC were characterized by an increased percentage of bone volume, increased trabecular thickness, and a decreased trabecular separation, and extended beyond the area below the defect. High numbers of osteoclasts were observed at the cyst periphery, and all cysts communicated with the microfracture holes. Cartilage repair tissue was of poor quality and quantity at both time points and rarely reached the tidemark at 13 weeks.

CONCLUSION

Microfracture technique caused bone cyst formation and induced severe pathology of the subchondral bone in a sheep model.

CLINICAL RELEVANCE

The potential of microfracture technique to induce subchondral bone pathology should be considered.

Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914

On September 14, 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.

GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4_{-0.9}^{+0.7}×10^{-22}. The inferred source-frame initial black hole masses are 14.2_{-3.7}^{+8.3}M_{⊙} and 7.5_{-2.3}^{+2.3}M_{⊙}, and the final black hole mass is 20.8_{-1.7}^{+6.1}M_{⊙}. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440_{-190}^{+180}  Mpc corresponding to a redshift of 0.09_{-0.04}^{+0.03}. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

Properties of the Binary Black Hole Merger GW150914

On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterize the properties of the source and its parameters. The data around the time of the event were analyzed coherently across the LIGO network using a suite of accurate waveform models that describe gravitational waves from a compact binary system in general relativity. GW150914 was produced by a nearly equal mass binary black hole of masses 36_{-4}^{+5}M_{⊙} and 29_{-4}^{+4}M_{⊙}; for each parameter we report the median value and the range of the 90% credible interval. The dimensionless spin magnitude of the more massive black hole is bound to be <0.7 (at 90% probability). The luminosity distance to the source is 410_{-180}^{+160}  Mpc, corresponding to a redshift 0.09_{-0.04}^{+0.03} assuming standard cosmology. The source location is constrained to an annulus section of 610  deg^{2}, primarily in the southern hemisphere. The binary merges into a black hole of mass 62_{-4}^{+4}M_{⊙} and spin 0.67_{-0.07}^{+0.05}. This black hole is significantly more massive than any other inferred from electromagnetic observations in the stellar-mass regime.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

Tests of General Relativity with GW150914

The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 10^{13}  km. In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.

Recent developments in the use of computed tomography scanners in coronary artery imaging

INTRODUCTION

Within the past decade, substantial evolution of Coronary CT Angiography (CCTA) has affected evaluation and management of coronary artery disease. In particular, technical advancement of hardware technology and image reconstruction of CT scanners have played an important role in this context making it possible to acquire abundant data with excellent temporal and spatial resolution within a shorter scan time. In addition, a concern related to the high radiation exposure in the initial noninvasive coronary artery imaging has triggered improvement in dose reduction techniques.

AREAS COVERED

In this review article, we have focused on recent technological developments in CT scanners and the impact of these developments on CCTA parameters. Expert Commentary: CCTA plays an important role in coronary artery disease management, and technical development of the CT scanners can be expected to address and remedy technical limitations.

Visceral Adiposity is a Risk Factor for Poor Prognosis in Colorectal Cancer Patients Receiving Adjuvant Chemotherapy

BACKGROUND

Studies utilizing body mass index (BMI) have failed to show a consistent relationship between obesity and survival following treatment for colorectal cancer (CRC). Computerized tomography (CT) offers a reliable alternative approach to quantify body adiposity. We hypothesized that visceral obesity may negatively impact survival in CRC patients.

AIMS AND METHODS

A retrospective review of CRC patients who received adjuvant chemotherapy at a single center during the period 2006-2009 identified from a prospectively maintained database. Visceral adiposity was determined by measuring visceral fat area (VFA) on preoperative staging CT. All patients were followed up to study completion or death.

RESULTS

Sixty-two CRC patients with a mean age of 63.2 years received adjuvant chemotherapy and had imaging available for analysis. Thirty-five patients (56.5 %) had node positive disease. Thirty-one patients (50 %) were classified viscerally obese based on staging CT. 85.4 % of the patients completed adjuvant chemotherapy and visceral obesity was not associated with increased toxicity or failure to complete treatment. After a median follow-up of 65.2 months, patients with visceral obesity had a significantly lower overall survival (OS) (54.8 % vs 87.1 %, p = 0.004) and disease-free survival (DFS) (48.4 vs 77.4 %, p = 0.007) compared with patients without visceral obesity. There was no relationship between BMI and survival. Multivariate analysis using Cox proportional hazards model showed that visceral obesity was independently associated with reduced OS (Hazard ratio = 7.0; 95 % CI 2.0-24.6; p = 0.002).

CONCLUSION

This study shows that visceral obesity increases the likelihood of a poor prognosis in CRC patients receiving adjuvant chemotherapy thus underlying the value of lifestyle interventions to minimize visceral obesity in this patient cohort.

GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses ≳30M_{⊙}, suggests a population of binary black holes with relatively high mass. This observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the Universe, could be higher than previously expected. Using the properties of GW150914, we estimate the energy density of such a background from binary black holes. In the most sensitive part of the Advanced LIGO and Advanced Virgo band for stochastic backgrounds (near 25 Hz), we predict Ω_{GW}(f=25  Hz)=1.1_{-0.9}^{+2.7}×10^{-9} with 90% confidence. This prediction is robustly demonstrated for a variety of formation scenarios with different parameters. The differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. We conclude that this background is potentially measurable by the Advanced LIGO and Advanced Virgo detectors operating at their projected final sensitivity.

GW150914: The Advanced LIGO Detectors in the Era of First Discoveries

Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With a strain sensitivity of 10^{-23}/sqrt[Hz] at 100 Hz, the product of observable volume and measurement time exceeded that of all previous runs within the first 16 days of coincident observation. On September 14, 2015, the Advanced LIGO detectors observed a transient gravitational-wave signal determined to be the coalescence of two black holes [B. P. Abbott et al., Phys. Rev. Lett. 116, 061102 (2016)], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 in coincidence by the two detectors. Here, we present the main features of the detectors that enabled this observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver another factor of 3 improvement in the signal-to-noise ratio for binary black hole systems similar in mass to GW150914.

Water Use and Management in the Bakken Shale Oil Play in North Dakota

Oil and natural gas development in the Bakken shale play of North Dakota has grown substantially since 2008. This study provides a comprehensive overview and analysis of water quantity and management impacts from this development by (1) estimating water demand for hydraulic fracturing in the Bakken from 2008 to 2012; (2) compiling volume estimates for maintenance water, or brine dilution water; (3) calculating water intensities normalized by the amount of oil produced, or estimated ultimate recovery (EUR); (4) estimating domestic water demand associated with the large oil services population; (5) analyzing the change in wastewater volumes from 2005 to 2012; and (6) examining existing water sources used to meet demand. Water use for hydraulic fracturing in the North Dakota Bakken grew 5-fold from 770 million gallons in 2008 to 4.3 billion gallons in 2012. First-year wastewater volumes grew in parallel, from an annual average of 1,135,000 gallons per well in 2008 to 2,905,000 gallons in 2012, exceeding the mean volume of water used in hydraulic fracturing and surpassing typical 4-year wastewater totals for the Barnett, Denver, and Marcellus basins. Surprisingly, domestic water demand from the temporary oilfield services population in the region may be comparable to the regional water demand from hydraulic fracturing activities. Existing groundwater resources are inadequate to meet the demand for hydraulic fracturing, but there appear to be adequate surface water resources, provided that access is available.

Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

Diagnostic accuracy of standard axial 64-slice chest CT compared to cardiac MRI for the detection of cardiomyopathies

OBJECTIVE

To assess the diagnostic accuracy of standard axial chest CT compared with cardiac MRI for cardiomyopathies.

METHODS

The standard axial 64-slice chest CTs of 49 patients with cardiomyopathies and 27 controls were blindly assessed for the presence of a cardiomyopathy by two independent readers. Qualitative and quantitative analysis included assessment of: (i) interatrial septal thickness, (ii) left atrial diameter, (iii) myocardial hypertrophy, thinning or fat, (iv) myocardial and papillary muscle calcification, (v) papillary muscle thickness, (vi) calcified coronary artery segments, (vii) left ventricular (LV) diameter, (viii) interventricular septal thickness and (ix) right ventricular diameters. Cardiac MRI was the gold standard.

RESULTS

There were 21 (42.9%) dilated, 16 (32.7%) hypertrophic, 8 (16.3%) ischaemic and 4 other (8.2%) (LV non-compaction × 2, amyloid, idiopathic restrictive) patients with cardiomyopathies. An LV diameter of 47 mm, interventricular septal thickness of 14 mm and coronary artery/papillary muscle calcification on axial chest CT best distinguished dilated, hypertrophic and ischaemic cardiomyopathies from controls, respectively; kappa = 0.45 (moderate interobserver agreement). The sensitivity (95% confidence interval), specificity, positive- and negative-predictive values (95% confidence interval) and diagnostic accuracy of chest CT in diagnosing cardiomyopathies were 68% (52-83), 100%, 100%, 66% (55-85) and 80%, respectively.

CONCLUSION

Cardiomyopathies may be detected on standard chest CT with good sensitivity and high specificity.

ADVANCES IN KNOWLEDGE

It is useful to assess for an underlying cardiomyopathy on standard chest CT, especially in a patient with unexplained dyspnoea.

ICU director data: using data to assess value, inform local change, and relate to the external world

Improving value within critical care remains a priority because it represents a significant portion of health-care spending, faces high rates of adverse events, and inconsistently delivers evidence-based practices. ICU directors are increasingly required to understand all aspects of the value provided by their units to inform local improvement efforts and relate effectively to external parties. A clear understanding of the overall process of measuring quality and value as well as the strengths, limitations, and potential application of individual metrics is critical to supporting this charge. In this review, we provide a conceptual framework for understanding value metrics, describe an approach to developing a value measurement program, and summarize common metrics to characterize ICU value. We first summarize how ICU value can be represented as a function of outcomes and costs. We expand this equation and relate it to both the classic structure-process-outcome framework for quality assessment and the Institute of Medicine's six aims of health care. We then describe how ICU leaders can develop their own value measurement process by identifying target areas, selecting appropriate measures, acquiring the necessary data, analyzing the data, and disseminating the findings. Within this measurement process, we summarize common metrics that can be used to characterize ICU value. As health care, in general, and critical care, in particular, changes and data become more available, it is increasingly important for ICU leaders to understand how to effectively acquire, evaluate, and apply data to improve the value of care provided to patients.

Beyond HIV microbicides: multipurpose prevention technology products

Multipurpose prevention technologies (MPTs) that aim to simultaneously prevent unintended pregnancy, HIV-1 infection and other sexually transmitted infections are among the most innovative and complex products currently in development within women's sexual and reproductive health care. In this review article, MPTs are placed within the wider context of combination products, combination drug products and multi-indication products. The current MPT product landscape is mapped and assessed with reference to existing products for the corresponding single indications, before identifying the gaps in the current MPT product pipeline and highlighting priority products and challenges moving forward.

Idiopathic pulmonary fibrosis with emphysema: evidence of synergy among emphysema and idiopathic pulmonary fibrosis in smokers

BACKGROUND

Emphysema and fibrosis, typically the idiopathic pulmonary fibrosis (IPF) form of usual interstitial pneumonia (UIP), can co-exist as combined pulmonary fibrosis emphysema (CPFE). It is unknown whether there is a pathobiologic basis for CPFE beyond the coexistence of fibrosis and emphysema. The aim of this study was to ascertain radiologic differences in severity of fibrosis and emphysema in smokers with IPF versus other forms of UIP.

METHODS

Computed tomography thorax images were prospectively rescored in retrospectively identified smokers (minimum 5-pack-year history) with radiologic UIP (any etiology). Radiologic severity (emphysema/fibrosis/reticulation) was scored in consensus by two radiologists, blinded to clinical details, across 5 lung regional levels, and then correlated with clinical data.

RESULTS

For the whole cohort (IPF, n=102; non-IPF UIP [mainly rheumatoid arthritis/asbestosis/scleroderma], n=30), IPF and non-IPF UIP smokers were similar regarding pack-year, age, gender, and lung function (P>.1). IPF smokers had greater whole lung fibrosis and reticulation scores (P<.04 in all cases). CPFE was present in n=61 (IPF, n=49; non-IPF UIP, n=12). Compared with smokers with non-IPF CPFE, smokers with IPF and emphysema (IPFE) were similar regarding confounders (P>.1). There were significantly greater regional reticulation severity (P=.009), cumulative emphysema severity (P=.04), and cumulative reticulation severity (P<.001) scores in IPFE versus non-IPF CPFE.

CONCLUSIONS

When controlled for confounders, smokers with IPFE have worse radiologic CPFE than other smokers with non-IPF UIP and emphysema, suggesting an interactive synergy among IPF, emphysema, and smoking, with more extensive emphysema due to either inherent susceptibility and/or traction effects. IPFE should be considered separately from other CPFE in future work. It is currently unknown whether CPFE is a distinct pathobiologic entity; therefore, we identified subjects with radiologic UIP (any etiology) who had been similarly exposed to smoke, and asked whether there are differences in the extent/severity of radiologic fibrosis and/or emphysema in those with IPF versus individuals with non-IPF UIP. Although relevant confounders were similar, IPF smokers had greater whole lung fibrosis and reticulation scores than smokers with secondary forms of UIP, and in the CPFE subgroup, smokers with IPF/emphysema had worse radiologic CPFE findings than smokers with non-IPF UIP/emphysema. It is shown for the first time that relevant confounding variables do not explain the observed excess radiologic severity of emphysema and fibrosis in smokers with IPF compared with smokers with non-IPF UIP, lending support to the hypothesis that there is a pathobiologic mechanism or synergy involved in IPF with emphysema that is distinct from the mere co-existence of UIP and emphysematous processes.