Phase Histogram Research Articles

Determinants of left ventricular mechanical dyssynchrony in patients submitted to myocardial perfusion imaging: A cardiac CZT study

BackgroundAn interaction between coronary anatomy, myocardial perfusion, and left ventricular (LV) functional parameters in the development of mechanical LV dyssynchrony (LVD) has been suggested. This study examined the correlates of LVD in a large sample size of patients with known or suspected coronary artery disease (CAD) using cadmium-zinc-telluride camera. MethodsSix-hundred and fifty-seven consecutive patients who underwent myocardial perfusion imaging (MPI) and coronary angiography were included. Coronary stenosis >70% was considered significant. LV perfusion and functional parameters were computed from MPI images. The presence of significant LVD was evaluated by phase standard deviation and histogram bandwidth. Results415/657 (63%) patients had significant CAD. LVD was present in 247 (38%) patients and was associated with the presence of a higher CAD burden (P < .001), more impaired measures of LV perfusion (P < .001), contractile function (P < .001), and larger LV volumes (P < .001). By multivariate analysis, the LV end-systolic volume index (P < .001) and ischemic burden (P < .001) were the strongest predictors of LVD independent of CAD extent and LV systolic dysfunction. ConclusionsLVD is frequent in patients undergoing MPI for suspected or known CAD. Its presence is independent of CAD burden and LV systolic dysfunction, but is dependent on the presence of myocardial perfusion abnormalities and LV end-systolic volume.

Reference values for left ventricular systolic synchrony according to phase analysis of ECG-gated myocardial perfusion SPECT.

The aim of this study was to define reference values for left ventricular systolic synchrony and for the volume parameters of the left ventricle using myocardial perfusion SPECT-derived phase analysis method. We evaluated data of 433 patients who underwent myocardial perfusion SPECT/CT during January 2012-February 2013 in Kuopio University Hospital. The final study population consisted of 52 patients (aged 42-84years) who met the criteria: (1) no previously diagnosed cardiac disease, (2) normal ECG at rest, (3) no advanced coronary artery disease in CT and 4) normal myocardial perfusion in stress/rest myocardial perfusion SPECT/CT. The severity of mechanical dyssynchrony was assessed by phase analysis of gated myocardial SPECT at stress stage after pharmacological exercise and at rest using Quantitative Gated SPECT (QGS) software. Volume parameters of the left ventricle were also assessed. The phase histogram bandwidth at rest was 28.0 [63.7] degrees (median [95th percentile]). The standard deviation of phase histogram at rest was 7.8 [26.5] degrees. Entropy at the rest study was 54.0 [63.7] %. All left ventricular dyssynchrony parameters were statistically significantly higher at stress compared to rest. There were no statistically significant differences in dyssynchrony values between men and women. In volume parameters, reference values in male were expectedly higher than in female. Cardiac output did not differ significantly between genders. In subjects without signs of cardiac diseases, the left ventricular systolic function is well synchronized. Phase analysis measurement does not depend on gender, age, BMI or blood pressure, but the values of dyssynchrony parameters increase during pharmacological stress.

Left ventricular systolic synchrony of patients with hypertensive heart failure but preserved ejection fraction and its impact on left ventricular function

Objective To investigate the systolic synchrony of the left ventricle in patients with left ventricular hypertrophy (LVH) or with heart failure but preserved ejection fraction (HF-PEF), and to evaluate the impact of systolic dyssynchrony on left ventricular function. Methods During June 2011 to May 2014, a total of 352 patients(160 males, 192 females, average age: (67.6±7.8)years) with essential hypertension (EH) were enrolled in this retrospective study. Ultrasonic and G-MPI were performed for assessment of left ventricular remodeling and systolic synchrony and the results were statistically analyzed by one-way analysis of variance and χ2 test. Relationship between BNP and synchronic parameters as well as other clinical factors were analyzed by partial correlation analysis. Results The EH patients were divided into hypertension group (n=182), LVH group (n=74) and HF-PEF group (n=96). In comparison to hypertension group, significant LVH developed in LVH and HF-PEF groups although the LVEF was still preserved. The LVMI of the 3 groups were (94.4±10.1), (121.1±9.8) and (123.2±10.9) g/m2, respectively(F=8.66, P 0.05). Diastolic dysfunction was identified in LVH and HF-PEF groups with significantly reduced E/A ratio (1.19±0.23, 0.80±0.28, 0.67±0.17; F=13.46, P<0.05). Remarkable left ventricular systolic dyssynchrony with phase histogram bandwidth (PHB) of (88.4±8.6)° and phase standard deviation (PSD) of (23.6±1.9)° and increased BNP of (228.4±69.7) ng/L were revealed in HF-PEF group. The BNP in HF-PEF group was significantly higher than that in LVH group((92.5±13.6) ng/L; q=8.63, P<0.05). Positive correlation was found between BNP level and PHB, PSD, LVMI, respectively (r=0.277-0.331, all P<0.05). Conclusion Left ventricular systolic dyssynchrony is concomitant with HF-PEF patients induced by EH, and this dyssynchrony might be one of the factors leading to diastolic dysfunction. Key words: Heart failure; Hypertension; Stroke volume; Tomography, emission-computed, single-photon; Ultrasonography; MIBI

Image retrieval based on exponent moments descriptor and localized angular phase histogram

Multiple feature extraction and combination is one of the most important issues in the content-based image retrieval (CBIR). In this paper, we propose a new content-based image retrieval method based on an efficient combination of shape and texture features. As its shape features, exponent moments descriptor (EMD), which has many desirable properties such as expression efficiency, robustness to noise, geometric invariance, fast computation etc., is adopted in RGB color space. As its texture features, localized angular phase histogram (LAPH) of the intensity component, which is robust to illumination, scaling, and image blurring, is used in hue saturation intensity (HSI) color space. The combination of above shape and texture information provides a robust feature set for color image retrieval. Experimental results on well known databases show significant improvements in retrieval rates using the proposed method compared with some current state-of-the-art approaches.

Prevalence and predictors of left intraventricular dyssynchrony determined by phase analysis in patients undergoing gatedSPECT myocardial perfusion imaging.

Left ventricular dyssynchrony (LVD) is an independent predictor of adverse cardiovascular events, death, and progression to heart failure. Myocardial perfusion imaging (MPI) with ECG-gated single-photon emission computed tomography (SPECT) can be used to diagnose LVD rapidly and automatically using phase analysis (PA). The objective of this study was to evaluate the prevalence and predictors of LVD in patients undergoing MPI. Clinical, electrocardiographic, and scintigraphic data from 1000 patients who underwent MPI with ECG-gated SPECT over a period of 1year were analyzed retrospectively. TheEmoryCardiac Toolboxsoftware was used for PA, and LVD was diagnosed based on the following criteria: standard deviation of LV phase distribution ≥43° and/or phase histogram ≥140° in the resting and/or stress phase of the examination. Several variables were evaluated using univariate and multivariate analyses. The prevalence of LVD in the study population was 6.5%, and the average age was 63.6±12years. The variables significantly associated with LVD were male gender, obesity, hypertension, diabetes, dyslipidemia, coronary artery disease (CAD), QRS interval ≥120ms, LV dysfunction, and myocardial perfusion defects (especially fixed defects) on MPI. Although the PA parameters were greater at rest, both phases could be used for diagnosis. Multivariate analysis revealed that the variables significantly associated with LVD were male sex, obesity, history of CAD, and QRS interval ≥120ms. The overall prevalence of LVD was 6.5% in patients undergoing MPI in this study, and it reached 42% in the presence of certain risk factors.

Normal values of cardiac mechanical synchrony parameters using gated myocardial perfusion single-photon emission computed tomography: Impact of population and study protocol

Purpose of the Study:Normal values of cardiac mechanical synchrony parameters in gated myocardial perfusion single-photon emission computed tomography (GMPS) are well established in literature from the Western population. The aim of the study is to establish normal values of mechanical synchrony with GMPS in Indian population and to find out whether it differs significantly from established values.Procedure:We retrospectively analyzed 1 day low-dose stress/high-dose rest GMPS studies of 120 patients (sixty males, 52 ± 11.7 years) with low pretest likelihood of coronary artery disease and having normal GMPS study. In GMPS, first-harmonic fast Fourier transform was used to extract a phase array using commercially available software. Phase standard deviation (PSD) and phase histogram bandwidth (PHB) were used to quantify cardiac mechanical dyssynchrony.Results:The values obtained were as follows, PSD: In men, 14.3 ± 4.7 (stress) and 8.9 ± 2.9 (rest), in women 11 ± 4 (stress) and 7.7 ± 2.7 (rest), and PHB: In men, 40.1 ± 11.9 (stress) and 30.6 ± 7.6 (rest), in women, 34.7 ± 12.6 (stress) and 25.3 ± 8.6 (rest). The value of PSD and PHB was significantly less in Indian population as compared with established values in literature. We also observed that synchrony indices derived from the low-dose stress studies are higher than high-dose rest studies.Conclusions:The value of synchrony parameters differs significantly according to population and methodology suggesting that specific population and methodology-based normal database for assessment of cardiac mechanical dyssynchrony should be established.

Hypovascular hepatic nodules at gadoxetic acid-enhanced MRI: whole-lesion hepatobiliary phase histogram metrics for prediction of progression to arterial-enhancing hepatocellular carcinoma.

To explore whole-lesion histogram analysis of the hepatobiliary phase (HBP) defect in indeterminate hypovascular liver lesions for predicting progression to arterial-enhancing hepatocellular carcinoma (HCC). Twenty patients undergoing gadoxetic acid-enhanced MRI for HCC screening with 12° and 25° flip angle (FA) HBP acquisitions demonstrating an indeterminate lesion showing HBP hypointensity but no arterial enhancement were included. Volumes-of-interest were placed on HBP defects, from which histogram metrics were obtained. Associations between these metrics and progression to arterial-enhancing HCC on follow-up imaging were investigated. Lesions were also assessed for the presence of a signal abnormality on conventional sequences. 40% of lesions progressed to arterial-enhancing HCC; 60% were stable at ≥6 months follow-up. Neither T2-hyperintensity increased diffusion signal nor portal/equilibrium phase washout was different between progressing and nonprogressing lesions (p = 1.0). Among direct signal intensity-based measures (overall mean; mean of bottom 10th, 10-25th, and 25-50th percentiles), area-under-the-curve (AUC) for prediction of progression to arterial-enhancing HCC was consistently higher at 25° (range 0.619-0.657) than at 12° (range 0.512-0.548). However, at both FAs, the four measures with highest AUC were measures related to lesion texture and heterogeneity [standard deviation (SD), coefficient of variation (CV), skewness, and entropy], having AUC of 0.655-0.750 at 12° and 0.686-0.800 at 25. The metric with highest AUC at 12° was SD (AUC = 0.750) and at 25° was CV (AUC = 0.800). Whole-lesion histogram HBP measures of indeterminate hypovascular liver lesions may help predict progression to arterial-enhancing HCC by reflecting greater lesion heterogeneity, particularly at higher FA. Larger studies are therefore warranted.

Predictors of ventricular remodelling in patients with reperfused acute myocardial infarction and left ventricular dysfunction candidates for bone marrow cell therapy: insights from the BONAMI trial.

Few data are available regarding the relation of left ventricular (LV) mechanical dyssynchrony to remodelling after acute myocardial infarction (MI) and stem cell therapy. We evaluated the 1-year time course of both LV mechanical dyssynchrony and remodelling in patients enrolled in the BONAMI trial, a randomized, multicenter controlled trial assessing cell therapy in patients with reperfused MI. Patients with acute MI and ejection fraction (EF) ≤ 45% were randomized to cell therapy or to control and underwent thallium single-photon emission computed tomography (SPECT), radionuclide angiography, and echocardiography at baseline, 3months, and 1year. Eighty-three patients with a comprehensive 1-year follow-up were included. LV dyssynchrony was assessed by the standard deviation (SD) of the LV phase histogram using radionuclide angiography. Remodelling was defined as a 20% increase in LV end-systolic volume index (LVESVI) at 1year. At baseline, LVEF, wall motion score index, and perfusion defect size were significantly impaired in the 43 patients (52%) with LV remodelling (all p < 0.001), without significant increase in LV mechanical dyssynchrony. During follow-up, there was a progressive increase in LV SD (p = 0.01). Baseline independent predictors of LV remodelling were perfusion SPECT defect size (p = 0.001), LVEF (p = 0.01) and a history of hypertension (p = 0.043). Bone marrow cell therapy did not affect the time-course of LV remodelling and dyssynchrony. LV remodelling 1year after reperfused MI is associated with progressive LV dyssynchrony and is related to baseline infarct size and ejection fraction, without impact of cell therapy on this process.

Abstract 13754: Scar Burden and Left Ventricular Dyssynchrony on Myocardial Perfusion Imaging as Predictors of Antitachycardia Pacing Responsiveness in the Treatment of Ventricular Tachycardia

Background: Antitachycardia pacing (ATP) is the primary treatment for sustained ventricular tachycardia (VT), resulting in a reduction in ICD shocks. Patients who fail ATP have increased mortality compared to ATP responders. Myocardial scarring by cMR and left ventricular dysynchrony (LVD) by nuclear imaging are associated with a higher risk for VT. We hypothesized that scar and dyssynchrony can predict response to ATP. Methods: We identified 119 patients with sustained VT from 2008-2012, who received ICD therapy with preprogrammed ATP delivery and had a single photon emission computed tomography (SPECT) myocardial perfusion study. Semi-quantitative visual scoring with a 17-segment model was used and the summed stress, rest and difference scores were calculated to measure abnormal myocardium, scar and ischemia. LVD was measured in gated studies (n=59), using the established phase analysis (PA) methodology. Phase standard deviation (PSD) and histogram bandwidth (HBW) were compared between groups using chi-square analysis. Results: Of 119 patients (105 men, mean age: 75.8±18.2y), 82 (68%) had successful ATP. Normal myocardial perfusion was more commonly found in ATP-responders (10.5% vs. 19.8%, p=0.29). There was no difference in the presence of ischemia between the two groups. Phase SD (13.5±6.2 vs. 9.0±5.4, p=0.009) and HBW (54.5±27.1 vs. 37.9±25.2, p = 0.03) were significantly higher among ATP responders. In both a univariate and multivariate logistic regression analysis phase SD (OR, 95% CI: 1.85, 1.09-3.15, p=0.02) was an independent predictor of ATP success. Conclusions: LV dyssynchrony but not scar burden was associated with ATP responsiveness. These results are hypothesis generating for a role of LV dyssynchrony in the prediction of ATP responsiveness.

Left ventricular systolic synchrony assessed by phase analysis of gated myocardial perfusion imaging in patients with old myocardial infarction

To assess the left ventricular (LV) systolic synchrony by phase analysis of gated myocardial perfusion imaging (GMPI) with SPECT/CT in patients with old myocardial infarction (OMI) and further to identify independent predictors for LV dyssynchrony. Seventy-six OMI patients and seventy-four healthy volunteers (control group) underwent resting GMPI from October 2010 to September 2013 in our hospital were included in this study. The left ventricular systolic synchrony parameters including phase histogram bandwidth (BW) and phase standard deviation (SD) were obtained by Cedars-Sinai quantitative gated SPECT (QGS) phase analysis technique, and LV cardiac function was also measured. The extent of myocardial perfusion defect was analyzed by the Quantitative Perfusion SPECT (QPS) software. The value of BW and SD were compared between OMI and the control groups, between LVEF ≤ 35% and LVEF > 35% groups in OMI patients. Dyssynchrony was defined when the BW exceeded the abnormality threshold derived from a normal control group (threshold = x ± 2s for normal BW). (1) The BW ((91.3 ± 58.6)° vs. (37.2 ± 11.7)°) and SD ((27.3 ± 20.8)° vs. (11.8 ± 5.4)°) were significantly higher and the LVEF was significantly lower in OMI group than in the normal control group (all P < 0.01). In addition, BW ((136.0 ± 52.9)° vs. (51.0 ± 24.0)°) and SD ((38.7 ± 21.3)° vs. (17.1 ± 14.0)°) were significantly higher in patients with LVEF ≤ 35% than in patients with LVEF > 35% (all P < 0.001). (2) Dyssynchrony (BW > 60.6°) prevalence was 57.9% (44/76) in OMI patients. Compared with the synchrony group, LVEF was significantly lower, while the left ventricular end-diastolic volume, end-systolic volume, summed motion score, summed thickening score and extent were significantly higher in dyssynchrony group (all P < 0.001). (3) Additionally, dyssynchrony prevalence was significantly higher in patients with LVEF ≤ 35% compared with patients with LVEF > 35% (91.7% (33/36) vs. 27.5% (11/40), P < 0.001). (4) Pearson correlation analysis showed that LVEF was negatively correlated with BW (r = -0.807, P < 0.001). (5) Multivariate logistic regression analysis revealed that the extent of myocardial perfusion defect was an independent predictor for dyssynchrony in OMI patients (OR = 1.076, 95% CI: 1.015-1.141, P = 0.015). GMPI phase analysis can reliably reflect left ventricular systolic synchrony. The left ventricular systolic dyssynchrony in OMI patients is significantly increased. Left ventricular dyssynchrony is closely related to LVEF. The extent of myocardial perfusion defect (Extent) is an independent predictor for left ventricular systolic dyssynchrony in OMI patients.

Robust rigid coherent point drift algorithm based on outlier suppression and its application in image matching

The typical probability based point pattern matching method is coherent point drift (CPD) algorithm, which treats one point set as centroids of a Gaussian mixture model, and then fits it to the other. It uses the expectation maximization framework, where the point correspondences and transformation parameters are updated alternately. However, the anti-outlier performance of CPD is not robust enough as outliers have always been involved in the operation until the CPD converges. Hence, an automatic outlier suppression (AOS) mechanism is proposed. First, outliers are judged by a matching probability matrix. Then, transformation parameters are fitted using accurate matching point sets. Finally, the Gaussian centroids are forced to move coherently by this transformation model. AOS-CPD can efficiently improve the anti-outlier performance of rigid CPD. Furthermore, CPD is applied to image matching. A new local changing information descriptor-relative phase histogram (RPH) is designed and RPH-AOS-CPD is proposed to embed RPH measurement into AOS-CPD as a constraint condition. RPH-AOS-CPD makes full use of grayscale information besides having an excellent anti-outlier performance. The experimental results based on both synthetic and real data indicate that compared with other algorithms, AOS-CPD is more robust to outliers and RPH-AOS-CPD offers a good practicability and accuracy in image matching applications.

Does perfusion pattern influence stress-induced changes in left ventricular mechanical dyssynchrony on thallium-201-gated SPECT myocardial perfusion imaging?

BackgroundThe relationship between perfusion pattern and stress-induced changes in left ventricular mechanical dyssynchrony (LVMD) on stress-rest thallium-201-gated SPECT myocardial perfusion imaging (Tl-201 SPECT MPI) is not clear. The aim of the study is to assess the relation of perfusion pattern with stress-induced changes in LVMD on Tl-201 MPI. MethodsData of 194 patients who underwent exercise-rest Tl-201 MPI between January to December 2012 at our institute was retrospectively evaluated. Institute Ethical committee approval was obtained. Fifty patients who underwent Tl-201 MPI for suspected CAD and had normal LV perfusion and function on MPI were taken as normal group. Patients with perfusion abnormalities (n = 144) were divided into three groups: ischemia (n = 66), infarct (n = 32), and mixed group (n = 46; ischemia and infarct both). Summed stress score, summed rest score, summed difference score (SDS), and LV ejection fraction (EF) were evaluated. Two LVMD parameters, phase standard deviation (PSD) and phase histogram bandwidth (PHB), were assessed in post-stress and rest MPI images. ΔPSD (post-stress PSD − rest PSD) and ΔPHB (post-stress PHB − rest PHB) were calculated to measure stress-induced changes in LVMD. ResultsIn all the groups, mean post-stress LVMD parameters were lower as compared to LVMD parameters at rest. Post-stress PSD was significantly lower than rest PSD in all groups. Similar trend was noted with PHB values also, but it was statistically significant in the normal and ischemia group only. Post-stress worsening of at least one of the LVMD parameters was noted in 28 patients and all these patients had perfusion abnormalities. But on subgroup analysis, no difference was found in proportion of patients showing post-stress worsening of LVMD between ischemia (13.6%), infarct (25%), and mixed (23.6%) groups. No significant correlation was found between ΔPSD/ΔPHB and ΔLVEF/SDS in any group. ConclusionLV mechanical dyssynchrony parameters are smaller in post-exercise stress as compared to rest on Tl-201 MPI, regardless of perfusion pattern. Stress-induced worsening of LV dyssynchrony was observed only in patients with perfusion abnormalities, but this is not related to the type of perfusion abnormality.

Diagnostic Value of Vasodilator-Induced Left Ventricular Dyssynchrony as Assessed by Phase Analysis to Detect Multivessel Coronary Artery Disease

Purpose: Phase analysis was recently developed to allow left ventricular(LV)mechanical dyssynchrony to be assessed by gated single-photon emission computed tomography(SPECT) . However, few studies have analyzed LV dyssynchrony during pharmacological stress and at rest by applying phase analysis to detect multivessel coronary artery disease(CAD)using the SyncTool TM . Methods: Adenosine triphosphate(ATP)loading electrocardiogram-gated 99m Tc-sestamibi SPECT was performed on 180 patients with suspected or known CAD. LV dyssynchrony was evaluated using the SyncTool TM ; the phase standard deviation(SD)and histogram bandwidth were derived. Results: The summed stress score(SSS) , summed difference score(SDS) , post-stress increase in phase SD, and histogram bandwidth were greater in 78 patients with multivessel CAD than in 102 patients with insignificant or single-vessel CAD. In the detection of multivessel CAD, SSS of >9 and SDS of >5 showed sensitivities of 74% and 74%,and specificities of 71% and 78% respectively, whereas an increase in phase SD>8.3°and in histogram bandwidth >16°after ATP loading had sensitivities of 62% and 74% and specificities of 77% and 68%, respectively. A multivariate logistic analysis revealed that the identification of multivessel CAD was superior with the combination of a post-ATP increase in phase SD, increase in histogram bandwidth, and SDS(sensitivity 82%, specificity 76%, chi-square=80.0)than with SDS alone (sensitivity 74%, specificity 78%, chi-square=58.9) . Conclusion: The addition of ATP-induced LV dyssynchrony parameters to conventional perfusion analysis enabled the superior identification of patients with multivessel CAD.

Histogram of gradient phases: a new local descriptor for face recognition

Gradient‐based local descriptors have received more attention these years and have been successfully used in many applications such as human detection and face recognition. The advantages of the local descriptors are the resistance to the local geometric and photometric errors and the robustness to the expression variations. In this paper, the authors propose a new local descriptor called the histogram of gradient phases (HGP), which has some intriguing properties compared with the existing local descriptors such as the histogram of orientated gradients and DAISY for face recognition under the unconstrained conditions. In contrast with the histogram of the oriented gradient descriptor, the orientation histogram is computed from the estimated gradient phase distributions instead of weighting the votes of the gradient magnitudes. In this paper, the phase distributions are estimated by means of the gradient phases and the variances are decided by the estimated gradient signal‐to‐noise ratios of the pixels in a local region. The HGP descriptor which takes the confidence of the gradient phase into account is more discriminative and less sensitive to the normalisation process than most local descriptors, which significantly degrade without a proper normalisation. The simulation results show that the proposed HGP descriptor achieves a better performance and is more robust than the existing local descriptors.

Assessment of left ventricular mechanical dyssynchrony by phase analysis of gated-SPECT myocardial perfusion imaging and tissue Doppler imaging: Comparison between QGS and ECTb software packages

BackgroundRecently, the phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has become feasible via several software packages for the evaluation of left ventricular mechanical dyssynchrony. We compared two quantitative software packages, quantitative gated SPECT (QGS) and Emory cardiac toolbox (ECTb), with tissue Doppler imaging (TDI) as the conventional method for the evaluation of left ventricular mechanical dyssynchrony. Methods and ResultsThirty-one patients with severe heart failure (ejection fraction ≤35%) and regular heart rhythm, who referred for gated-SPECT MPI, were enrolled. TDI was performed within 3 days after MPI. Dyssynchrony parameters derived from gated-SPECT MPI were analyzed by QGS and ECTb and were compared with the Yu index and septal-lateral wall delay measured by TDI. QGS and ECTb showed a good correlation for assessment of phase histogram bandwidth (PHB) and phase standard deviation (PSD) (r = 0.664 and r = 0.731, P < .001, respectively). However, the mean value of PHB and PSD by ECTb was significantly higher than that of QGS. No significant correlation was found between ECTb and QGS and the Yu index. Nevertheless, PHB, PSD, and entropy derived from QGS revealed a significant (r = 0.424, r = 0.478, r = 0.543, respectively; P < .02) correlation with septal-lateral wall delay. ConclusionDespite a good correlation between QGS and ECTb software packages, different normal cut-off values of PSD and PHB should be defined for each software package. There was only a modest correlation between phase analysis of gated-SPECT MPI and TDI data, especially in the population of heart failure patients with both narrow and wide QRS complex.

Clinical usefulness of a novel program "Heart Function View" for evaluating cardiac function from gated myocardial perfusion SPECT.

To investigate clinical usefulness of a novel program "Heart Function View (HFV)" for evaluating left ventricular (LV) function from myocardial perfusion SPECT (MPS), we compared LV functional parameters (F(x)) calculated by HFV with those obtained by the other similar programs QGS and cardioGRAF or by ultrasound echocardiography (UCG) and examined their correlations with clinical markers of heart failure: plasma BNP concentrations (BNPs) and exercise capacity. Studied patients (n = 60) underwent technetium-99m tetrofosmin quantitative gated MPS including treadmill exercise for examining heart disease. Myocardial stress images were acquired 30 min after the first tracer injection during maximal exercise. Three hours later, the second tracer was injected, and resting images were acquired. LV systolic F(x) [ejection fraction (EF), peak ejection rate (PER)] and diastolic F(x) [first third filling fraction (1/3FF), first third filling rate (1/3FR), peak filling rate (PFR), time to PFR (TPF)] were analyzed, and phase standard deviation (SD) and histogram bandwidth were obtained by phase analysis. LV end-diastolic volume (EDV), end-systolic volume (ESV) and EF obtained from HFV were well correlated with those from QGS, cardioGRAF and UCG. A diastolic parameter Doppler E/e' from UCG was significantly with PFR from HFV. There were good correlations between LVEDV, LVESV, LVEF, PER, PFR, 1/3FR, TPF and 1/3FF from HFV and those from cardioGRAF. LVEF, PER, 1/3FR, and PFR were significantly correlated with plasma BNP concentrations. In patients with non-ischemic heart disease (n = 42), phase SD and histogram bandwidth were correlated negatively with exercise capacity or PFR. HFV-derived LVF(x) are correlated with LVF(x) from the other programs or UCG, or with the clinical markers of heart failure and are thus useful in the functional assessment for patients with heart disease.

Clinical value of gated MPI phase histogram in patients with chronic total occlusive coronary artery disease

Objective To evaluate the clinical value of phase diagrams in G-MPI for patients with chronic total occlusive coronary artery disease (CTO).Methods Twenty-one CTO patients (all males,average age:56.6 years,age range:37-77 years) from CTO Club of China in 2012 were retrospectively analyzed.99Tcm-MIBI myocardial perfusion and 18F-FDG myocardial metabolic imaging were performed.Patients were divided into normal group with LVEF＞60％ (n=11) and abnormal group with LVEF≤60％ (n=10).Differences of LVEF,perfusion/metabolic deficit and synchrony were compared by two-sample t test or Wilcoxon rank sum test.Correlations between LVEF and synchrony were analyzed by linear correlation analysis in all CTO patients.The synchrony parameters included peak phase,phase standard deviation (SD),phase histogram bandwidth,skewness and kurtosis.Results The history of occlusion for the 21 patients ranged from 3 to 60 months.In all CTO patients,the phase SD and bandwidth were higher than the healthy reference values:((30.8±28.3)°vs (14.2±5.1)°,t=3.09; (58.1±39.4)° vs (38.7±11.8)°,t=2.61,both P＜0.05).LVEF was negatively correlated with the phase SD and bandwidth (r=-0.785,-0.883,both P＜0.01) but positively correlated with phase histogram skewness and kurtosis (r=0.755,0.666,both P＜0.01).Higher LVEF value was shown in normal group than that in group((69.3±4.7)％ vs (44.7±13.0)％,t=-5.65,P＜ 0.01).The perfusion deficit in normal group (4.0％) was lower than that in abnormal group (16.0％) (Z=-2.23,P＜0.05) while the metabolic deficit of the two groups was similar (Z=-1.82,P＞0.05).The phase SD and bandwidth were lower in normal group than those in abnormal group ((18.7±19.0)° vs (44.2± 31.6)°,t=2.21; (36.4±12.7)° vs (82.1±45.4)°,t=3.08,both P＜0.05) and skewness and kurosis were higher in normal group than those in abnormal group (5.11 ± 0.75 vs 3.55 ± 1.05,t =-3.89 ; 30.77± 10.49 vs 15.66±10.12,t=-3.35,both P＜0.01).Conclusions The left ventricle synchrony was significantly worse in patients with CTO than that in normal individuals.The phase histogram could be used to estimate the the contractile function of left ventricle in the patients with CTO. Key words: Coronary disease; Gated myocardial perfusion imaging; Tomography, emission-computed, single-photon ; Tomography, emission-computed; Deoxyglucose; MIBI

Hybrid ensemble of classifiers for logo and trademark symbols recognition

Abstract The paper presents a hybrid ensemble of diverse classifiers for logo and trademark symbols recognition. The proposed ensemble is composed of four types of different member classifiers. The first one compares color distribution of the logo patterns and is responsible for sifting out images of different color distribution. The second of the classifiers is based on the structural tensor recognition of local phase histograms. A proposed modification in this module consists of tensor computation in the space of the morphological scale-space. Thanks to this, more discriminative histograms describing global shapes are obtained. Next in the chain, is a novel member classifier that joins the Hausdorff distance with the correspondence measure of the log-polar patches computed around the corner points. This sparse classifier allows reliable comparison of even highly deformed patterns. The last member classifier relies on the statistical affine moment invariants which describe global shapes. However, a real advantage is obtained by joining the aforementioned base classifiers into a hybrid ensemble of classifiers, as proposed in this paper. Thanks to this a more accurate response and generalizing properties are obtained at reasonable computational requirements. Experimental results show good recognition accuracy even for the highly deformed logo patterns, as well as fair generalization properties which support human search and logo assessment tasks.

Prognostic value of left ventricular mechanical dyssynchrony by phase analysis in patients with non-ischemic cardiomyopathy with ejection fraction 35-50% and QRS < 150 ms

BackgroundLeft ventricular mechanical dyssynchrony (LVMD) by phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a useful tool for predicting response to cardiac resynchronization therapy and has prognostic value. While most of the studies were done on patients with ischemic cardiomyopathy or those with LV ejection fraction (EF) < 35%, there are little data on the prognostic value of LVMD in patients with non-ischemic cardiomyopathy (NICM), particularly those with mildly decreased systolic function and narrow or intermediate QRS duration. Methods and ResultsFrom the stress SPECT-MPI database at Cleveland Clinic, we identified 324 consecutive patients (mean age 62 ± 13 years, 62% male, 36% diabetics) with NICM, LVEF 35-50% (median [Q1,Q3] 45 [41,49]), and QRS < 150 ms (13% with QRS 120-149 ms). LVMD was determined from gated stress images and expressed as phase standard deviation (SD) and histogram BW (% R-R cycle). For easier graphical illustration, patients were divided into tertiles of LVMD. All-cause death was the primary endpoint and determined using the Social Security Death Index. Cox proportional hazard model was performed to determine the independent predictive value of LVMD, and next Cox models for incremental value. After a mean follow-up time of 1,689 days, 86 (26.5%) of patients died. These patients were older, had more diabetes, more use of diuretics, with wider QRS duration, and with a trend for higher phase SD and BW. After adjusting for age, hypertension, diabetes, aspirin, beta-blockers, diuretics, QRS, and EF, phase SD was an independent predictor of all-cause mortality with hazard ratio [95% CI] 1.97 [1.06,3.66] for the highest tertile, and added incremental prognostic value (P = .025). Similar findings were obtained using histogram BW. ConclusionIn patients with NICM, EF 35-50%, and QRS < 150 ms, increased LVMD on peak stress SPECT was an independent predictor of all-cause mortality. The utility and applicability of such findings in clinical practice need further evaluation in larger and prospective studies.

Usefulness of Phase Analysis to Differentiate Ischemic and Non-Ischemic Etiologies of Left Ventricular Systolic Dysfunction in Patients With Heart Failure

The detection of significant coronary artery disease (CAD) in patients with heart failure (HF) from left ventricular (LV) systolic dysfunction is crucial. We evaluated the usefulness of LV mechanical dyssynchrony as assessed by phase analysis compared with conventional gated single-photon emission computed tomography to identify ischemic etiology in patients with HF. Forty-one consecutive patients who were initially admitted to hospital due to HF resulting from systolic dysfunction were evaluated. All patients underwent cardiac catheterization. LV mechanical dyssynchrony was evaluated using SyncTool™ to obtain the phase SD and histogram bandwidth. The changes in phase SD and histogram bandwidth with stress were calculated. The summed stress score, summed difference score, and changes in phase SD and histogram bandwidth with stress were greater in 26 patients with CAD than in 15 patients without CAD (P=0.001 and P=0.01). On multivariate analysis a phase SD of >14° (odds ratio [OR], 16.7) and a summed stress score of >17 (OR, 8.0) best differentiated LV dysfunction of ischemic and non-ischemic etiologies, with a sensitivity of 89% and a specificity of 87% (χ(2)=20), compared with summed stress score only (sensitivity, 46%; specificity, 87%; χ(2)=4.5). The addition of phase analysis to conventional perfusion analysis enables better differentiation of the etiology of HF in patients with systolic dysfunction.