Radiomics Analysis of Clinical Myocardial Perfusion Stress SPECT Images to Identify Coronary Artery Calcification

PurposeMyocardial perfusion stress SPECT (MPSS) is an established diagnostic test for patients suspected with coronary artery disease (CAD). Meanwhile, coronary artery calcification (CAC) scoring obtained from diagnostic CT is a highly specific test, offering incremental diagnostic information in identifying patients with significant CAD yet normal MPSS scans. However, after decades of wide utilization of MPSS, CAC is not commonly reimbursed (e.g. by the CMS), nor widely deployed in community settings. We aimed to perform radiomics analysis of normal MPSS scans to investigate the potential to predict the CAC score.MethodsWe collected data from 428 patients with normal (non-ischemic) MPSS (99mTc-Sestamibi; consensus reading). A nuclear medicine physician verified iteratively reconstructed images (attenuation-corrected) to be free from fixed perfusion defects and artifactual attenuation. 3D images were automatically segmented into 4 regions of interest (ROIs), including myocardium and 3 vascular segments (LAD-LCX-RCA). We used our software package, standardized environment for radiomics analysis (SERA), to extract 487 radiomic features in compliance with the image biomarker standardization initiative (IBSI). Isotropic cubic voxels were discretized using fixed bin-number discretization (8 schemes). We first performed blind-to-outcome feature selection focusing on a priori usefulness, dynamic range, and redundancy of features. Subsequently, we performed univariate and multivariate machine learning analyses to predict CAC scores from i) selected radiomic features, ii) 10 clinical features, iii) combined radiomics + clinical features. Univariate analysis invoked Spearman correlation with Benjamini-Hotchberg false-discovery correction. The multivariate analysis incorporated stepwise linear regression, where we randomly selected a 15% test set and divided the other 85% of data into 70% training and 30% validation sets. Training started from a constant (intercept) model, iteratively adding/removing features (stepwise regression), invoking Akaike information criterion (AIC) to discourage overfitting. Validation was run similarly, except that the training output model was used as the initial model. We randomized training/validation sets 20 times, selecting the best model using log-likelihood for evaluation in the test set. Assessment in the test set was performed thoroughly by running the entire operation 50 times, subsequently employing Fisher’s method to verify the significance of independent tests.ResultsUnsupervised feature selection significantly reduced 8×487 features to 56. In univariate analysis, no feature survived FDR to directly correlate with CAC scores. Applying Fisher’s method to the multivariate regression results demonstrated combining radiomics with the clinical features to enhance the significance of the prediction model across all cardiac segments. The median absolute Pearson’s coefficient values / p-values for the three feature-pools (radiomics, clinical, combined) were: (0.15, 0.38, 0.41)/(0.1, 0.001, 0.0006) for myocardium, (0.24, 0.35, 0.41)/(0.05, 0.004, 0.0007) for LAD, (0.07, 0.24, 0.28)/(0.4, 0.06, 0.02), for LCX, and (0.06, 0.16, 0.24)/(0.4, 0.2, 0.05) for RCA, demonstrating consistently enhanced correlation and significance for combined radiomics and clinical features across all cardiac segments.ConclusionsOur standardized and statistically robust multivariate analysis demonstrated significant prediction of the CAC score for all cardiac segments when combining MPSS radiomic features with clinical features, suggesting radiomics analysis can add diagnostic or prognostic value to standard MPSS for wide clinical usage.

DISCRIMINANT ANALYSIS THROUGH FISHER’S METHOD OF THE LEVEL OF INTEREST IN TOURIST ATTRACTIONS IN INDONESIA

Penelitian ini bertujuan untuk mengelompokkan 100 tempat wisata yang ada di Indonesia kedalam daerah tempat wisata yang menarik dan tidak menarik untuk dikunjungi menggunakan software SPSS. Data tersebut dinormalkan menggunakan fungsi “sqrt” kemudian dianalisis menggunakan diskriminan fishers melalui SPSS. Data yang menjadi variabel dependen adalah keadaan menarik atau tidaknya suatu tempat wisata terhadap variabel-variabel yang mempengaruhi. Hasil yang diperoleh dari analisis ini berupa terdapatnya 50 tempat wisata yang menarik untuk dikunjungi dan 50 tempat wisata yang tidak menarik untuk dikunjungi. Fungsi diskriminan linier fisher yang terbentuk adalah. Tempat wisata yang menarik untuk dikunjungi: Y1 = 0,523X1 + (-3,610)X2 + 2,176X3 + 5,071X4 + 9,728X5 + 8,865X6 + (-0,440)X7 + 11,012X8 + 5,596X9 + 3,086X10 + (-0,881)X11 + 2,352X12 + (-1,251)X13 + 3,944X14 + 15,624X15 Dan tempat wisata yang tidak menarik untuk dikunjungi: Y2 = (-0,095)X1 + (-2,552)X2 + 2,081X3 + 3,130X4 + 6.602X5 + 5,330X6 + (-0,88)X7 + 8,333X8 + 3,276X9 + 3,907X10 + (-0,462)X11 + 2,246X12 + 0,214X13 + 3,842X14 + 9,042X15

A method to fuse multiphysics waveforms and improve predictive explosion detection: theory, experiment and performance

SUMMARY Natural and human-made sources of transient energy often emit multiple geophysical signatures that include mechanical and electromagnetic waveforms. We present a constructive method to fuse and evaluate statistics that we derive from such multiphysics waveforms that improves our capability to detect small, near-ground explosions over similar methods that consume single signature waveforms. Our method advances Fisher's Combined Probability Test (Fisher's Method) to operate under both hypotheses of a binary test on noisy data and provide researchers with the density functions required to forecast the ability of Fisher's Method to screen fused explosion signatures from noise. We apply this method against 12 d, multisignature explosion and noise records to show (1) that a fused multiphysics waveform statistic that combines radio, acoustic and seismic waveform data can identify explosions roughly 0.8 magnitude units lower than an acoustic emission, STA/LTA detector for the same detection probability and (2) that we can quantitatively predict how this fused, multiphysics statistic performs with Fisher's Method. Our work thereby offers a baseline method for predictive waveform fusion that supports multiphenomenological explosion monitoring (multiPEM) and is applicable to any binary testing problem in observational geophysics.

Testing the magnitude of correlations across experimental conditions

Comparisons between correlation coefficients are used to investigate data across multiple research fields, as they allow investigators to determine different degrees of correlation to independent variables. Such differences may be small, even with adequate sample size, but still scientifically relevant. To date, although much effort has gone into developing methods for estimating differences across correlation coefficients, adequate tools for variable sample sizes and correlational strengths have yet to be tested. The present study evaluated four different methods for detecting the difference between two correlations and tested the adequacy of each method using simulations with multiple data structures. These methods were Cohen's q, Fisher's method, linear mixed-effects models (LMEM), and an ad-hoc developed procedure that integrates bootstrap effect size estimation. Results showed that Fisher's method and the LMEM tended to reject the null hypothesis even in the presence of relevant differences between correlations and that Cohen's method was not sensitive to data structure. Bootstrap followed by effect size estimation resulted in a favorable, unbiased compromise for estimating quantitative differences between statistical associations and producing outputs that could be easily compared across studies.

Spatial distribution of interictal spikes fluctuates over time and localizes seizure onset

The location of interictal spikes is used to aid surgical planning in patients with medically refractory epilepsy; however, their spatial and temporal dynamics are poorly understood. In this study, we analysed the spatial distribution of interictal spikes over time in 20 adult and paediatric patients (12 females, mean age = 34.5 years, range = 5–58) who underwent intracranial EEG evaluation for epilepsy surgery. Interictal spikes were detected in the 24 h surrounding each seizure and spikes were clustered based on spatial location. The temporal dynamics of spike spatial distribution were calculated for each patient and the effects of sleep and seizures on these dynamics were evaluated. Finally, spike location was assessed in relation to seizure onset location. We found that spike spatial distribution fluctuated significantly over time in 14/20 patients (with a significant aggregate effect across patients, Fisher’s method: P < 0.001). A median of 12 sequential hours were required to capture 80% of the variability in spike spatial distribution. Sleep and postictal state affected the spike spatial distribution in 8/20 and 4/20 patients, respectively, with a significant aggregate effect (Fisher’s method: P < 0.001 for each). There was no evidence of pre-ictal change in the spike spatial distribution for any patient or in aggregate (Fisher’s method: P = 0.99). The electrode with the highest spike frequency and the electrode with the largest area of downstream spike propagation both localized the seizure onset zone better than predicted by chance (Wilcoxon signed-rank test: P = 0.005 and P = 0.002, respectively). In conclusion, spikes localize seizure onset. However, temporal fluctuations in spike spatial distribution, particularly in relation to sleep and post-ictal state, can confound localization. An adequate duration of intracranial recording—ideally at least 12 sequential hours—capturing both sleep and wakefulness should be obtained to sufficiently sample the interictal network.

A Working Director

This chapter talks about the completion of Four Sided Triangle, which was received as just another science-fiction programmer at the time, and marked no immediate advance in Terence Fisher's status as a director. It discusses the importance of rehearsal to Fisher, sp much that even in his lowest budgeted films, he always insisted on some time to work with the actors on the floor. It also describes how Fisher rehearsed the actors just before the cameras rolled and shot the scene immediately when he was happy with the results. The chapter recounts Fisher's method of working on a film in 1973, from the first day of shooting onward. It looks at Fisher's work in television, such as his directorial work on an episode of Colonel March of Scotland Yard in 1956, a half-hour detective series with occasional supernatural overtones.