29Prognostic safety of automatic cancellation of rest myocardial perfusion scan by machine learning: a report from multicenter REFINE SPECT registry of new generation SPECT

Background

We aimed to develop a machine learning (ML) computer score derived from stress imaging and clinical data, which indicates if the rest scan could be automatically and safely canceled in the routine stress/rest myocardial perfusion SPECT (MPS).

Methods

A total of 20414 stress/rest cases from the REFINE SPECT registry collected from 5 sites in 3 countries with Tc-99m-based MPS images, clinical data, and clinical follow-up were included in the study. All images were automatically processed at our Medical Center. The automatically generated myocardial contours were checked by experienced technologists. In total, 93 variables (26 clinical, 17 stress-test, and 50 stress-imaging variables) were used to build a LogitBoost model for prediction of adverse events (AE), including coronary revascularization, death, myocardial infarction, and unstable angina. 10-fold cross-validation was performed to separate test from validation data for the assessment of ML. The overall ML predictive performance was compared to quantitative (stress total perfusion deficit [TPD]) by the area under the receiver operating characteristic curves (AUC). ML cut-off (ML1) to simulate the decision of cancellation of the rest scan was set to result in the same % of normal scans as these determined by the normal clinical reader diagnosis on a 4-point scale in the whole population, or the same % of scans with visual summed stress scores (SSS) = 0 in the subpopulation with available SSS. A second ML cutoff (ML2) was established to achieve a 1% annual risk of AE. The annual risk of AE of the normal ML score was compared with normal clinical diagnosis and with the finding of SSS = 0.

Results

The mean follow-up interval was 4.7±1.5 years. Overall, 3542 AE were observed (3.7% annual risk). The AUC for AE was higher for ML (0.780±0.005) than for stress TPD (0.698±0.006) (p<0.001). Normal clinical diagnosis was reported in 60% cases. In 70% (14242 scans) with available segmental scores, 53% had SSS=0. ML1 and ML2 thresholds were compared with normal visual diagnosis and with SSS = 0 for AE (Figure). ML1 achieved a lower annual risk (1.5%) than normal clinical diagnosis (2.1%) or SSS = 0 (1.6% versus 2.3%) (p<0.001). The more conservative ML2 threshold with a 1% annual risk of AE resulted in a 40% canceling rate.

Figure 1

Conclusion

ML could be used to automatically cancel the rest MPS scan with the same proportion as using normal visual MPS reading, but with significantly lower AE rate in stress-only scans.

Acknowledgement/Funding

R01HL089765 from the National Heart, Lung, and Blood Institute/National Institutes of Health (NHLBI/NIH)

P6151Fully automated epicardial adipose tissue volume and density measured from non-contrast CT predict major adverse cardiovascular events in asymptomatic subjects

Background

Epicardial adipose tissue (EAT) volume and density has shown to correlate with standard markers of coronary artery disease (CAD) and may predict major adverse cardiovascular events (MACE).

Purpose

We aimed to evaluate the prognostic value of EAT volume and density measured by fully automated deep-learning software from non-contrast cardiac computed tomography (CT).

Methods

We assessed 2071 consecutive asymptomatic subjects (age 56±9 years, 59% male) from the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) trial with long-term follow-up after coronary artery calcium (CAC) measurement. EAT volume and mean density were quantified using automated deep-learning software from non-contrast cardiac CT. MACE was defined as myocardial infarction (MI), cardiac death, late (>90 days) revascularization and acute coronary syndrome (ACS). EAT volume and density were systematically compared to CAC score and atherosclerotic cardiovascular disease (ASCVD) risk score using Cox proportional hazards regression for MACE prediction.

Results

At 14±3 years, 217 subjects suffered MACE. In age-and-gender-adjusted multivariate analysis, ASCVD risk score, CAC (two-fold increase) and EAT volume (two-fold increase) were associated with increased risk of suffering MACE [Hazard Ratio (HR) (95% CI): 1.03 (1.01–1.04); 1.25 (1.19–1.30); and 1.36 (1.08–1.70) respectively, p<0.01 for all] (Figure); the corresponding Harrell's C-statistic was 0.76. The area-under-the curve from receiver-operator characteristic analysis for MACE prediction increased significantly from 0.69 to 0.77 (p<0.0001) when EAT volume and CAC were added to the current clinical standard (ASCVD, family history and obesity measures BMI and BSA). Both in men and women, increase in EAT volume was associated with increased risk of MACE, with HR 1.14 (1.06–1.22), p<0.001 in men vs. 1.15 (1.01–1.31), p=0.03 in women, for each 20 cubic centimeter increase in volume. EAT density (HU) was independently inversely associated with MACE [HR: 0.96 (0.93–0.99), p=0.01].

MACE Prediction

Conclusions

EAT volume and density measurements improve prediction of MACE in asymptomatic populations over the current clinical standard. Fully automated EAT volume and density quantification by deep-learning from non-contrast cardiac CT can provide additional prognostic value for the asymptomatic patient.

Acknowledgement/Funding

1R01HL133616, Forschungsstiftung Medizin Universitätsklinikum Erlangen, grant from Dr Miriam and Sheldon G. Adelson Medical Research Foundation

Standards for the diagnosis and management of complex regional pain syndrome: Results of a European Pain Federation task force

Background

Complex regional pain syndrome is a painful and disabling post‐traumatic primary pain disorder. Acute and chronic complex regional pain syndrome (CRPS) are major clinical challenges. In Europe, progress is hampered by significant heterogeneity in clinical practice. We sought to establish standards for the diagnosis and management of CRPS.

Methods

The European Pain Federation established a pan‐European task force of experts in CRPS who followed a four‐stage consensus challenge process to produce mandatory quality standards worded as grammatically imperative (must‐do) statements.

Results

We developed 17 standards in 8 areas of care. There are 2 standards in diagnosis, 1 in multidisciplinary care, 1 in assessment, 3 for care pathways, 1 in information and education, 4 in pain management, 3 in physical rehabilitation and 2 on distress management. The standards are presented and summarized, and their generation and consequences were discussed. Also presented are domains of practice for which no agreement on a standard could be reached. Areas of research needed to improve the validity and uptake of these standards are discussed.

Conclusion

The European Pain Federation task force present 17 standards of the diagnosis and management of CRPS for use in Europe. These are considered achievable for most countries and aspirational for a minority of countries depending on their healthcare resource and structures.

Significance

This position statement summarizes expert opinion on acceptable standards for CRPS care in Europe.

Amputation in patients with complex regional pain syndrome: a comparative study between amputees and non-amputees with intractable disease

AIMS

Amputation in intractable cases of complex regional pain syndrome (CRPS) remains controversial. The likelihood of recurrent Complex Regional Pain Syndrome (CRPS), residual and phantom limb pain and persistent disability after amputation is poorly described in the literature. The aims of this study were to compare pain, function, depression and quality of life between patients with intractable CRPS who underwent amputation and those in whom amputation was considered but not performed.

PATIENTS AND METHODS

There were 19 patients in each group, with comparable demographic details. The amputated group included 14 men and five women with a mean age of 31 years (sd 12) at the time of CRPS diagnosis. The non-amputated group consisted of 12 men and seven women and their mean age of 36.8 years (sd 8) at CRPS diagnosis. The mean time from CRPS diagnosis to (first) amputation was 5.2 years (sd 4.3) and the mean time from amputation to data collection was 6.6 years (sd 5.8). All participants completed the following questionnaires: Short-Form (SF) 36, Short Form McGill Pain questionnaire (SF-MPQ), Pain Disability Index (PDI), the Beck Depression Inventory (BDI) and a clinical demographic questionnaire.

RESULTS

The amputation group showed consistently better results compared to the non-amputation group in the following parameters: median pain intensity (VAS): 80 (inter-quartile range (IQR) 13 to 92) vs 91 (IQR 85 to 100); p = 0.007; median SF-MPQ score 28 (IQR 9 to 35) vs 35 (IQR 31 to 38), p = 0.025; median PDI: 42 (IQR 11 to 64) vs 58 (IQR 50 to 62), p = 0.031; median BDI: 19 (IQR 5 to 28) vs 27 (IQR 21 to 32), p = 0.061 (borderline significant) and in six of the eight SF-36 domains.

TAKE HOME MESSAGE

Amputation should be considered as a form of treatment for patients with intractable CRPS.

Long-term outcomes in children conceived with assisted reproductive technologies

Over five million children have been born worldwide through assisted reproductive technology (ART) and access to ART treatment is increasing yearly. Investigations of the health, disease, cognitive, developmental and behavioral outcomes in the children conceived with ART are often confounded by parental and other social, environmental and medical factors, including multiplicity, prematurity and low birth weight. Reports of the long-term health and psychosocial adjustment of children conceived with ART show generally good outcomes. Many of the major long-term conditions observed in the children may be associated with multiple gestations, preterm delivery and low birth weight, or with subfertility of the parents. Evidence in the male infants conceived with the aid of intracytoplasmic injection (ICSI) suggests an increased risk of reproductive tract anomalies such as hypospadias. Health-related outcomes of children born after cryopreservation of cleavage stage embryos are reassuring. Currently, our knowledge and understanding of the long-term health risks and/or benefits to the children conceived is incomplete. Measuring long-term outcomes is the first step to improving and optimizing health in the offspring conceived with medical and technological assistance.

Jamming, relaxation, and crystallization of a supercooled fluid in a three-dimensional lattice

Off-equilibrium dynamics of a three-dimensional lattice model with nearest- and next-nearest-neighbors exclusions is studied. At equilibrium, the model undergoes a first-order fluid-solid transition. Nonequilibrium filling, through random sequential adsorption with diffusion, creates amorphous structures and terminates at a disordered state with random closest packing density that lies in the equilibrium solid regime. The approach toward random closest packing is characterized by two distinct power-law regimes, reflecting the formation of small densely packed grains in the long-time regime of the filling process. We then study the fixed-density relaxation of these amorphous structures toward the solid phase. The route to crystallization for the high-density, deeply supercooled regime is shown to deviate from the simple grain growth proposed by classical nucleation theory. Our measurements suggest that relaxation in this regime is driven mainly by coalescence of neighboring crystallized grains which exist in the initial amorphous state.

Complex diel cycles of gene expression in coral-algal symbiosis

Circadian regulation of plant-animal endosymbioses is complicated by a diversity of internal and external cues. Here, we show that stress-related genes in corals are coupled to the circadian clock, anticipating major changes in the intracellular milieu. In this regard, numerous chaperones are "hard-wired" to the clock, effectively preparing the coral for the consequences of oxidative protein damage imposed by symbiont photosynthesis (when O(2) > 250% saturation), including synexpression of antioxidant genes being light-gated. Conversely, central metabolism appears to be regulated by the hypoxia-inducible factor system in coral. These results reveal the complexity of endosymbiosis as well as the plasticity regulation downstream of the circadian clock.

Finite-temperature liquid-quasicrystal transition in a lattice model

We consider a tiling model of the two-dimensional square lattice, where each site is tiled with one of the 16 Wang tiles. The ground states of this model are all quasiperiodic. The systems undergoes a disorder to quasiperiodicity phase transition at finite temperature. Introducing a proper order parameter, we study the system at criticality and extract the critical exponents characterizing the transition. The exponents obtained are consistent with hyperscaling.

Direct measurements of the dynamical correlation length indicate its divergence at an athermal glass transition

The supercooled N3 model exhibits an increasingly slow dynamics as density approaches the random closest packing density. Here, we present a direct measurement of the dynamical correlation function G4(r,t), showing the emergence of a growing length scale ξ(4) across which the dynamics is correlated. The correlation length measured, up to 120 lattice sites, power law diverges as the density approaches ρ(t), the density at which the fluid phase of the model is predicted to terminate. The four-point susceptibility, often used as an agent to estimate ξ(4), does not depend simply on the latter. Rather, it depends strongly on the short-range behavior of G4(r,t). Consequently, χ(4) peaks before ξ(4) reaches its maximal value. The two quantities should therefore be studied independently.

Ideal glass transition in a simple two-dimensional lattice model

We present a simple lattice model showing a glassy behavior. R matrix analysis predicts critical termination of the supercooled fluid branch at density rho(g)=0.1717. This prediction is confirmed by dynamical numerical simulations, showing power-law divergences of relaxation time tau1/2, as well as the four-susceptibility chi4 peak's location and height exactly at the predicted density. The power-law divergence of chi4 continues up to chi4 as high as 10(4). Finite-size scaling study reveals the divergence of the correlation length accompanying the transition.

Critical exponents from cluster coefficients

For a large class of repulsive interaction models, the Mayer cluster integrals can be transformed into a tridiagonal real symmetric matrix R_{mn} , whose elements converge to two constants. This allows for an effective extrapolation of the equation of state for these models. Due to a nearby (nonphysical) singularity on the negative real z axis, standard methods (e.g., Padé approximants based on the cluster integrals expansion) fail to capture the behavior of these models near the ordering transition, and, in particular, do not detect the critical point. A recent work [E. Eisenberg and A. Baram, Proc. Natl. Acad. Sci. U.S.A. 104, 5755 (2007)] has shown that the critical exponents sigma and sigma;{'} , characterizing the singularity of the density as a function of the activity, can be exactly calculated if the decay of the R matrix elements to their asymptotic constant follows a 1/n;{2} law. Here we employ renormalization group (RG) arguments to extend this result and analyze cases for which the asymptotic approach of the R matrix elements toward their limiting value is of a more general form. The relevant asymptotic correction terms (in RG sense) are identified, and we then present a corrected exact formula for the critical exponents. We identify the limits of usage of the formula and demonstrate one physical model, which is beyond its range of validity. The formula is validated numerically and then applied to analyze a number of concrete physical models.

Estimation of critical exponents from cluster coefficients and the application of this estimation to hard spheres

For a large class of repulsive interaction models, the Mayer cluster integrals can be transformed into a tridiagonal real symmetric matrix R(mn), whose elements converge to two constants with 1/n(2) correction. We find exact expressions in terms of these correction terms for the two critical exponents describing the density near the two singular termination points of the fluid phase. We apply the method to the hard-spheres model and find that the metastable fluid phase terminates at rho(t) = 0.751[5]. The density near the transition is given by rho(t)-rho approximately (z(t) - z)(sigma'), where the critical exponent is predicted to be sigma' = 0.0877[25]. Interestingly, the termination density is close to the observed glass transition; thus, the above critical behavior is expected to be associated with the onset of glassy behavior in hard spheres.

Opioids for neuropathic pain

BACKGROUND

The use of opioids for neuropathic pain remains controversial. Studies have been small, have yielded equivocal results, and have not established the long-term risk-benefit ratio of this treatment.

OBJECTIVES

To assess the efficacy and safety of opioid agonists for the treatment of neuropathic pain.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (2nd Quarter 2005), MEDLINE (1966 to June 2005), and EMBASE (1980 to 2005 Week 27) for articles in any language, and reference lists of reviews and retrieved articles.

SELECTION CRITERIA

Trials were included in which opioid agonists were given to treat central or peripheral neuropathic pain of any etiology, pain was assessed using validated instruments, and adverse events were reported. Studies in which drugs other than opioid agonists were combined with opioids or opioids were administered epidurally or intrathecally were excluded.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent investigators and included demographic variables, diagnoses, interventions, efficacy, and adverse effects.

MAIN RESULTS

Twenty-three trials met the inclusion criteria and were classified as short-term (less than 24 hours; n = 14) or intermediate-term (median = 28 days; range = eight to 70 days; n = 9). The short-term trials had contradictory results. In contrast all nine intermediate-term trials demonstrated opioid efficacy for spontaneous neuropathic pain. Meta-analysis of seven intermediate-term studies showed mean post-treatment visual analog scale scores of pain intensity after opioids to be 13 points lower on a scale from zero to 100 than after placebo (95% confidence interval -16 to -9; P < 0.00001). The most common adverse events were nausea (33% opioid versus 9% control: number needed to treat to harm (NNH) 4.2) and constipation (33% opioid versus 10% control: NNH 4.2), followed by drowsiness (29% opioid versus 12% control: NNH 6.2), dizziness (21% opioid versus 6% control: NNH 7.1), and vomiting (15% opioid versus 3% control: NNH 8.3). Where reported, 23 (11%) of 212 participants withdrew because of adverse events during opioid therapy versus nine (4%) of 202 receiving placebo.

AUTHORS' CONCLUSIONS

Short-term studies provide only equivocal evidence regarding the efficacy of opioids in reducing the intensity of neuropathic pain, whereas intermediate-term studies demonstrate significant efficacy of opioids over placebo, which is likely to be clinically important. Reported adverse events of opioids are common but not life threatening. Further randomized controlled trials are needed to establish long-term efficacy, safety (including addiction potential), and effects on quality of life.

Analysis of the ordering transition of hard disks through the Mayer cluster expansion

The available virial coefficients for the two-dimensional hard-disks model are transformed into a matrix representation of the thermodynamic potentials, which allows for an accurate description of the whole fluid phase, up to the phase transition. We find that the fluid phase terminates at the transition point, implying a second-order phase transition in accordance with the Kosterlitz-Thouless-Halperin-Nelson-Young scenario of a transition into a hexatic phase. The density and pressure at the transition are calculated from the available first ten virial coefficients, and are found to be in excellent agreement with recent Monte-Carlo calculations. Finally, we calculate the equation of state in the critical region.

Prevalence and characteristics of pain induced by percutaneous liver biopsy

Percutaneous needle liver biopsy is an important procedure for the diagnosis and evaluation of liver disease and is frequently associated with pain. In this prospective study, we investigated the prevalence and characteristics of this pain syndrome. Fifty-four subjects, who underwent liver biopsy under ultrasound guidance, received 5 mg of diazepam orally 1 h before the procedure and local infiltration with 10 mL of 2% lidocaine just before needle insertion. Outcome measures included the visual analog scale for measuring pain intensity over 24 h, pain localization on a body scheme, and the Spielberger questionnaire for measuring anxiety levels. Forty-seven (84%) of the 54 respondents reported pain 30 min after the biopsy (visual analog scale, 4.2 +/- 0.5; mean +/- SEM), and 21 (39%) reported pain at the 24-h time point. Biopsy site pain was reported by 9 subjects, right shoulder pain by 14, and pain at both sites by 24. Higher pain intensities were reported by women and by subjects with higher anxiety levels. This study indicates that liver biopsy is a painful condition in most patients. Mild anxiolytic treatment plus local anesthetic infiltration seem to produce insufficient analgesia, thus indicating that a more profound analgesic treatment is required for better control of this pain.

IMPLICATIONS

Percutaneous liver biopsy is a painful procedure in most patients. Mild anxiolytic treatment plus local anesthetic infiltration seem to produce insufficient analgesia. A more profound analgesic treatment is required for better control of this pain.

Random matrix theory for closed quantum dots with weak spin-orbit coupling

To lowest order in the coupling strength, the spin-orbit coupling in quantum dots results in a spin-dependent Aharonov-Bohm flux. This flux decouples the spin-up and spin-down random matrix theory ensembles of the quantum dot. We employ this ensemble and find significant changes in the distribution of the Coulomb blockade peak height, in particular, a decrease of the width of the distribution. The puzzling disagreement between standard random matrix theory and the experimental distributions by Patel et al. [Phys. Rev. Lett. 81, 5900 (1998)]] might possibly be attributed to these spin-orbit effects.

Coherent electron transport in a Si quantum dot dimer

We show that the coherence of charge transfer through a weakly coupled double-dot dimer can be determined by analyzing the statistics of the conductance pattern, and does not require a large phase coherence length in the host material. We present an experimental study of the charge transport through a small Si nanostructure, which contains two quantum dots. The transport through the dimer is shown to be coherent. At the same time, one of the dots is strongly coupled to the leads, and the overall transport is dominated by inelastic cotunneling processes.