Interpretation of SPECT wall motion with deep learning.

OBJECTIVES: We sought to develop a novel deep learning (DL) workflow to interpret single-photon emission computed tomography (SPECT) wall motion. BACKGROUND: Wall motion assessment with SPECT is limited by image temporal and spatial resolution. Visual interpretation of wall motion can be subjective and prone to error. Artificial intelligence (AI) may improve accuracy of wall motion assessment. METHODS: A total of 1038 patients undergoing rest electrocardiogram (ECG)-gated SPECT and echocardiography were included. Using echocardiography as truth, a DL-model (DL-model 1) was trained to predict the probability of abnormal wall motion. Of the 1038 patients, 317 were used to train a DL-model (DL-model 2) to assess regional wall motion. A 10-fold cross-validation was adopted. Diagnostic performance of DL was compared with human readers and quantitative parameters. RESULTS: The area under the receiver operating characteristic curve (AUC) and accuracy (ACC) of DL model (AUC: .82 [95% CI: .79-.85]; ACC: .88) were higher than human (AUC: .77 [95% CI: .73-.81]; ACC: .82; P < .001) and quantitative parameter (AUC: .74 [95% CI: .66-.81]; ACC: .78; P < .05). The net reclassification index (NRI) was 7.7%. The AUC and accuracy of DL model for per-segment and per-vessel territory diagnosis were also higher than human reader. The DL model generated results within 30 seconds with operable guided user interface (GUI) and therefore could provide preliminary interpretation. CONCLUSIONS: DL can be used to improve interpretation of rest SPECT wall motion as compared with current human readers and quantitative parameter diagnosis.

Study of Attenuation Correction Using a Cardiac Dynamic Phantom: Synchronized Time-Phase-Gated Attenuation Correction Method.

In cardiac nuclear medicine examinations, absorption in the body is the main factor in the degradation of the image quality. The Chang and external source methods were used to correct for absorption in the body. However, fundamental studies on attenuation correction for electrocardiogram (ECG)-synchronized CT imaging have not been performed. Therefore, we developed and improved an ECG-synchronized cardiac dynamic phantom and investigated the synchronized time-phase-gated attenuation correction (STPGAC) method using ECG-synchronized SPECT and CT images of the same time phase. Methods: As a basic study, SPECT was performed using synchronized time-phase-gated (STPG) SPECT and non-phase-gated (NPG) SPECT. The attenuation-corrected images were, first, CT images with the same time phase as the ECG waveform of the gated SPECT acquisition (with CT images with the ECG waveform of the CT acquisition as the reference); second, CT images with asynchronous ECG; third, CT images of the 75% region; and fourth, CT images of the 40% region. Results: In the analysis of cardiac function in the phantom experiment, left ventricle ejection fraction (heart rate, 11.5%-13.4%; myocardial wall, 49.8%-55.7%) in the CT images was compared with that in the STPGAC method (heart rate, 11.5%-13.3%; myocardial wall, 49.6%-55.5%), which was closer in value to that of the STPGAC method. In the phantom polar map segment analyses, none of the images showed variability (F (10,10) < 0.5, P = 0.05). All images were correlated (r = 0.824-1.00). Conclusion: In this study, we investigated the STPGAC method using a SPECT/CT system. The STPGAC method showed similar values of cardiac function analysis to the CT images, suggesting that the STPGAC method accurately reconstructed the distribution of blood flow in the myocardial region. However, the target area for attenuation correction of the heart region was smaller than that of the whole body, and changing the gated SPECT conditions and attenuation-corrected images did not affect myocardial blood flow analysis.

Remodelado del ventrículo izquierdo postinfarto: una mirada desde la perfusión miocárdica gated-SPECT / Left Ventricular Remodeling After Myocardial Infarction: A Perspective from Gated-SPECT Myocardial Perfusion Imaging

RESUMEN Introducción: El estudio gatillado de perfusión miocárdica con tomografía computarizada por emisión de fotón único, o gated-SPECT (por su denominación en inglés) es un método apropiado para cuantificar la magnitud de la escara necrótica y establecer su territorio. El análisis de pacientes con infartos de pequeña y mediana extensión que evolucionan con deterioro de la fracción de eyección ventricular izquierda (FEVI), podría arrojar luz acerca de los factores que influyen en la presencia de remodelado adverso y la consiguiente evolución a disfunción ventricular. Objetivos: a) evaluar la prevalencia de FEVI disminuida y factores asociados en una población de pacientes derivados para estudios de gated-SPECT, y b) definir la prevalencia de remodelado adverso y factores asociados en el subgrupo de pacientes con carga necrótica intermedia a baja. Material y métodos: Realizamos un análisis retrospectivo de pacientes consecutivos que se realizaron gated-SPECT durante el año 2017. Se excluyeron los pacientes con enfermedad valvular significativa o arritmias que produjeran alteración del gatillado. Se consideró remodelado adverso a la conjunción de FEVI disminuida (FEVI < 50%) y porcentaje de miocardio necrótico menor que 20 %. Resultados: Se incluyeron 1902 pacientes. La prevalencia de FEVI disminuida fue del 8 % (n =148). En el análisis multivariado, las variables independientes asociadas a disfunción ventricular fueron el género masculino (OR 2,50; IC 95% 1,30-4,90, p = 0,005), la diabetes (OR 1,83; IC 95% 1,12-3, p = 0,01), y compromiso necrótico mayor que 6,6 % (OR 39 IC 95% 25-61,28, p = 0,00001). En el subgrupo de pacientes con carga necrótica menor que 20% (n =197), la prevalencia de remodelado adverso fue del 25% (n =50). El análisis multivariado arrojó que la diabetes (OR 2,83; IC 95% 1,31 - 6,10 p = 0,007) y el género masculino (OR 5; IC 95% 1,10 - 22,9 p = 0,007) presentaron asociación independiente con el remodelado adverso. Conclusión: La gated-SPECT podría utilizarse en la valoración del remodelado adverso y factores asociados. Dicha valoración surge de la combinación de variables que no requieren un software adicional y se usan en la práctica diaria.

ABSTRACT Background: Gated single-photon emission computed tomography (gated-SPECT) myocardial perfusion imaging is a suitable technique for measuring the infarct scar size and defining its territory. Analyzing patients with small and medium myocardial infarctions that develop reduced left ventricular ejection fraction (LVEF) could provide additional information of the factors that contribute to adverse remodeling and its outcome. Objectives: a) To evaluate the prevalence of reduced LVEF and associated factors in a population of patients referred for gated-SPECT imaging, and b) to define the prevalence of adverse remodeling and associated factors in the subgroup of patients with intermediate to low necrotic burden. Methods: We conducted a retrospective analysis of consecutive patients undergoing gated-SPECT imaging during 2017. Patients with significant valvular heart disease or arrhythmias that could difficult adequate ECG gating were excluded from the study. Adverse remodeling was considered as the combination of reduced LVEF (LVEF < 50%) with percent myocardium scar < 20%. Results: A total of 1902 patients were included. The prevalence of reduced LVEF was 8% (n = 148). On multivariate analysis, the variables with independent association with ventricular dysfunction were male sex (OR 2.50; 95% CI 1.30-4.90, p = 0.005), diabetes (OR 1.83; 95% CI 1.12-3, p = 0.01), and percent myocardium scar > 6.6 % (OR 39; 95% CI 25-61.28, p = 0.00001). In the subgroup of patients with scar burden < 20 % (n = 197), the prevalence of adverse remodeling was 25 % (n = 50). On multivariate analysis, diabetes (OR 2.83; 95% CI 1.31 - 6.1 p = 0.007) and male sex (OR 5; 95% CI 1.1 - 22.9, p = 0.007) showed an independent association with adverse remodeling. Conclusion: Gated-SPECT could be used to assess adverse remodeling and its associated factors. This assessment is the result of combining variables used in daily practice which do not require any additional software.

Integración de los parámetros de remodelado, sincronía y velocidad máxima de vaciado para evaluar la función sistólica del ventrículo izquierdo / Integration of ventricular remodeling, synchrony and filling rate parameters to improve the assessment of left ventricular systolic function

Objetivos El objetivo es estudiar la relación entre los parámetros estructurales, de remodelado, de sincronía y de función sistólica del ventrículo izquierdo (VI) mediante gSPECT. Obtener los valores de corte del VI para el índice de la forma telediastólica (iFTD), el índice de la forma telesistólica (iFTS), el índice de excentricidad (iEX) y la velocidad máxima de vaciado (VMV). Desarrollar un nuevo índice para evaluar diferentes patrones de función sistólica del VI. Material y métodos Analizamos prospectivamente 238 pacientes (edad: 63,4±13 años) estudiados mediante gSPECT de esfuerzo-reposo (grupo-control, n=148; pacientes con infarto de miocardio [IM] previo, n=90). Estudio aprobado por el Comité de Ética del Hospital (PR[AG]168.2010). Resultados En el grupo-control, el índice del volumen telediastólico (iVTD) y el iEX influyeron en el iFTD (r2: 0,52, p<0,001). El iVTD, la VMV, ser varones y el iEX (r2: 0,44; p<0,001) influyeron en el iFTS. El iFTD, iFTS, la fracción de eyección VI (FEVI) y el volumen de eyección sistólica (r2: 0,62; p<0,001) influyeron en el iEX. La FEVI, la frecuencia cardíaca, el ancho de banda (AB) y la desviación estándar influyeron (r2: 0,76; p<0,001) en la VMV. Los valores de corte para iFTD, iFTS, iEX y VMV fueron 0,59, 0,42, 0,87 y −3,3 respectivamente. La VMV, el iFTS y el AB fueron los parámetros mejor relacionados con los pacientes con IM previo (AUC: 0,89), y sumados a la FEVI permitieron obtener distintos patrones de función sistólica (índice PERRS). Conclusiones Los parámetros de remodelado, sincronía y función sistólica del VI deben interpretarse simultáneamente, ya que esto permite obtener distintos patrones de función sistólica del VI (AU)

Introduction and objectives The aim of this study is to assess the relationship between structural, remodeling, synchrony, and systolic left ventricular (LV) function parameters using gated-SPECT myocardial-perfusion-images (gSPECT-MPI). In addition, obtaining the cut-off values for end-diastolic LV-shape-index (EDLVsi), end-systolic LV-shape-index (ESLVsi), ECC (eccentricity-index) and PER, and developing a new index to evaluate different patterns of the LV systolic function. Methods The study was approved by the Hospital's Ethical-Committee (PR[AG]168.2010), and all patients gave their informed consent. We analyzed prospectively 238 patients (age 63.4±13 years) who underwent stress-rest gSPECT-MPI (control-group, n=148; patients with previous myocardial infarction [MI], n=90). Results In the control group, with regard to remodeling parameters: the end-diastolic-volume-index (EDV) and the ECC were the parameters that influenced the EDLVsi (r2: 0.52, P<.001). EDV, PER, men, and the ECC were the parameters (r2: 0.44; P<.001) which influenced the ESLVsi. EDLVsi, ESLVsi, LVEF and the stroke-volume were the parameters (r2: 0.62; P<.001) which influenced the ECC. With regards to PER: LVEF, heart-rate, bandwidth, and the standard-deviation were the influencing parameters (r2: 0.76; P<.001). The cut-off values for EDLVsi, ESLVsi, ECC, and PER were 0.59, 0.42, 0.87, and 3.3, respectively. The PER, the ESLVsi and the bandwidth were the parameters related to patients with previous MI (AUC: 0.89); and they allow the assessment of different patterns of systolic function (PERRS-index: Peak-Emptying-Rate, left ventricular-Remodeling and Synchrony). Conclusions The remodeling, synchrony and the systolic function parameters of the LV should be interpreted together (PERRS-index). In this way, we obtain different patterns of LV systolic function (AU)

Integration of ventricular remodeling, synchrony and filling rate parameters to improve the assessment of left ventricular systolic function.

INTRODUCTION AND OBJECTIVES: The aim of this study is to assess the relationship between structural, remodeling, synchrony, and systolic left ventricular (LV) function parameters using gated-SPECT myocardial-perfusion-images (gSPECT-MPI). In addition, obtaining the cut-off values for end-diastolic LV-shape-index (EDLVsi), end-systolic LV-shape-index (ESLVsi), ECC (eccentricity-index) and PER, and developing a new index to evaluate different patterns of the LV systolic function. METHODS: The study was approved by the Hospital's Ethical-Committee (PR[AG]168.2010), and all patients gave their informed consent. We analyzed prospectively 238 patients (age 63.4 ±â€¯13 years) who underwent stress-rest gSPECT-MPI (control-group, n = 148; patients with previous myocardial infarction [MI], n = 90). RESULTS: In the control group, with regard to remodeling parameters: the end-diastolic-volume-index (EDV) and the ECC were the parameters that influenced the EDLVsi (r2: 0.52, p < 0.001). EDV, PER, men, and the ECC were the parameters (r2: 0.44; p < 0.001) which influenced the ESLVsi. EDLVsi, ESLVsi, LVEF and the stroke-volume were the parameters (r2: 0.62; p < 0.001) which influenced the ECC. With regards to PER: LVEF, heart-rate, bandwidth, and the standard-deviation were the influencing parameters (r2: 0.76; p < 0.001). The cut-off values for EDLVsi, ESLVsi, ECC, and PER were 0.59, 0.42, 0.87, and 3.3, respectively. The PER, the ESLVsi and the bandwidth were the parameters related to patients with previous MI (AUC: 0.89); and they allow the assessment of different patterns of systolic function (PERRS-index: peak-emptying-rate, left ventricular-remodeling and synchrony). CONCLUSIONS: The remodeling, synchrony and the systolic function parameters of the LV should be interpreted together (PERRS-index). In this way, we obtain different patterns of LV systolic function.

Case report: Myocardial perfusion gated-SPECT in pulmonary artery hypertension-the Movahed's sign.

Primary pulmonary artery hypertension (PAH) is a clinical diagnosis that requires the exclusion of other underlying causes of pulmonary hypertension (PH). Increased pulmonary artery (PA) pressure and subsequent right ventricular (RV) pressure overload often result in a flattening of the curved interventricular septum, leading to a D-shaped left ventricle (LV), as observed in echocardiographic short-axis views. A similar finding may be also observed on myocardial perfusion SPECT images, the so-called Movahed's sign. We present a clinical case of a female patient with PAH and progression of exertional dyspnea that underwent myocardial perfusion SPECT to investigate LV myocardial ischemia. The SPECT images revealed enhanced tracer uptake in the dilated right ventricle. Additionally, we observed a D-shaped LV or Movahed's sign, which may serve as a potential marker of RV pressure overload, along with a small stress-induced perfusion defect on the LV septal wall. Our findings highlight the importance of considering the presence of a D-shaped LV and signs of RV pressure overload, as they can alter the interpretation of LV perfusion deficits on SPECT images. This case report aims to emphasize the complex nature of right heart abnormalities in pathologies such as PAH and the consideration of the RV implications in myocardial SPECT images-which typically focus solely on the LV.

A new perspective on an old method: gated SPECT imaging for left ventricular contractile function assessment.

The ejection fraction (LVEF) is a commonly used marker of left ventricular function. However, because it is strongly influenced by loading conditions, it can be inaccurate in representing cardiac contractility. We therefore evaluated a gated SPECT based tool to simultaneously assess preload, afterload, and contractility. Using gated SPECT-determined ventricular volumes and arterial tension measurements, we calculated ventricular and arterial elastance (Ev and Ea), as well as end-diastolic volumes, which are surrogates for contractility, afterload, and preload, respectively. We applied this protocol to 1462 consecutive patients and assessed the ventricular function in patients with and without myocardial infarction. The median LVEF was 68% (IQR 62-74%). Patients with infarction exhibited decreased contractility (ventricular elastance of 3 mmHg/ml vs. 6 mmHg/ml), compensated by an increase of preload (end-diastolic volume of 100 ml vs. 78 ml) and a decrease in afterload (arterial elastance of 1.8 mmHg/ml vs. 2.2 ml/mmHg). These interactions yielded a preserved ejection fraction in both groups. Gated SPECT-measured volumes were consistent with values reported in the literature. In addition, the combination of nuclear imaging and arterial tension measurement accounted for not only the ejection fraction but also the loading context, providing a more accurate representation of cardiac contractility.

Prognostic Role of Diastolic Left Ventricular Mechanical Dyssynchrony by Gated Single Photon Emission Computed Tomography Myocardial Perfusion Imaging in Post-Myocardial Infarction.

Objective This study is aimed to assess the prognostic value of diastolic left ventricular mechanical dyssynchrony (LVMD) measured by gated-single photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI) in post-myocardial infarction (MI). Subjects and Methods The study was conducted on 106 post-MI from January 2015 to January 2019. First, the indices of diastolic LVMD phase standard deviation (PSD) and histogram bandwidth (HBW) of post-MI were measured using the Cardiac Emory Toolbox. Subsequently, the post-MI patients were followed up, and the primary endpoint was major adverse cardiac events (MACEs). Finally, the prognostic value of dyssynchrony parameters for MACE was analyzed by the receiver-operating characteristics curve and survival analyses. Results With the cut-off values of 55.5 degrees of PSD, the sensitivity and specificity in prediction of MACE were 75% and 80.8%, with the cut-off values of 174.5 degrees of HBW, the sensitivity and specificity were 75% and 83.3% respectively. There was a significant difference of time to MACE between groups of PSD less than 55.5 degrees and more than 55.5 degrees. PSD, HBW, and left ventricle ejection fraction (LVEF) assessed on GSPECT were significant factors in the prediction of MACE. Conclusion Diastolic LVMD parameters of PSD and HBW derived from GSPECT are significant prognostic factors in predicting MACE in post-MI patients.

Prognostic value of summed motion score assessed by gated SPECT myocardial perfusion imaging in patients with dilated cardiomyopathy.

Background: The prognosis of patients with dilated cardiomyopathy (DCM) is poor and new indicators are urgently needed to predict lethal cardiac events. This study aimed to investigate the value of summed motion score (SMS) in predicting cardiac death of DCM patients using gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Methods and results: Eighty-one patients with DCM who underwent 99mTc-MIBI gated SPECT MPI were retrospectively enrolled and were divided into cardiac death and survivor groups. The functional parameters of left ventricle including SMS were measured using quantitative gated SPECT software. During the follow-up period of 44 (25, 54) months, 14 (17.28%) cardiac deaths were observed. Compared with the survivor group, SMS was significantly higher in the cardiac death group. Multivariate cox regression analysis showed that SMS was an independent predictor for cardiac death (HR 1.34, 95% CI 1.02-1.77, P = 0.034). SMS also provided incremental prognostic value over other variables in the multivariate model as determined by likelihood ratio global chi-squared test. In the Kaplan-Meier survival analysis, the event-free survival rate was significantly lower in the high-SMS (HSMS) group than the low-SMS (LSMS) (log-rank P < 0.001). Furthermore, the area under curve (AUC) of SMS was larger than that of LVEF at the 12th month of follow-up (0.85 vs. 0.80, P = 0.045). Conclusion: SMS is an independent predictor of cardiac death in DCM patients and provides incremental prognostic value. SMS might have higher predictive value than LVEF for early cardiac death.

The Value of Left Ventricular Mechanical Dyssynchrony and Scar Burden in the Combined Assessment of Factors Associated with Cardiac Resynchronization Therapy Response in Patients with CRT-D.

BACKGROUND: Cardiac resynchronization therapy (CRT) improves the outcome in patients with heart failure (HF). However, approximately 30% of patients are nonresponsive to CRT. The aim of this study was to determine the role of the left ventricular (LV) mechanical dyssynchrony (MD) and scar burden as predictors of CRT response. METHODS: In this study, we included 56 patients with HF and the left bundle-branch block with QRS duration ≥ 150 ms who underwent CRT-D implantation. In addition to a full examination, myocardial perfusion imaging and gated blood-pool single-photon emission computed tomography were performed. Patients were grouped based on the response to CRT assessed via echocardiography (decrease in LV end-systolic volume ≥15% or/and improvement in the LV ejection fraction ≥5%). RESULTS: In total, 45 patients (80.3%) were responders and 11 (19.7%) were nonresponders to CRT. In multivariate logistic regression, LV anterior-wall standard deviation (adjusted odds ratio (OR) 1.5275; 95% confidence interval (CI) 1.1472-2.0340; p = 0.0037), summed rest score (OR 0.7299; 95% CI 0.5627-0.9469; p = 0.0178), and HF nonischemic etiology (OR 20.1425; 95% CI 1.2719-318.9961; p = 0.0331) were the independent predictors of CRT response. CONCLUSION: Scar burden and MD assessed using cardiac scintigraphy are associated with response to CRT.

Diagnostic accuracy for CZT gamma camera compared to conventional gamma camera technique with myocardial perfusion single-photon emission computed tomography: Assessment of myocardial infarction and function.

BACKGROUND: The solid-state cadmium-zinc-telluride (CZT) gamma camera for myocardial perfusion single-photon emission computed tomography (MPS) has theoretical advantages compared to the conventional gamma camera technique. This includes more sensitive detectors and better energy resolution. We aimed to explore the diagnostic performance of gated MPS with a CZT gamma camera compared to a conventional gamma camera for detection of myocardial infarct (MI) and assessment of left ventricular (LV) volumes and ejection fraction (LVEF), using cardiac magnetic resonance (CMR) as the reference method. METHODS: Seventy-three patients (26% female) with known or suspected chronic coronary syndrome were examined with gated MPS using both a CZT gamma camera and a conventional gamma camera as well as with CMR. Presence and extent of MI on MPS and late gadolinium enhancement (LGE) CMR was evaluated. For LV volumes, LVEF and LV mass, gated MPS images and cine CMR images were evaluated. RESULTS: MI was found in 42 patients on CMR. The overall sensitivity, specificity, positive and negative predictive values for the CZT and the conventional gamma camera were the same (67%, 100%, 100% and 69%). For infarct size > 3% on CMR, the sensitivity was 82% for the CZT and 73% for the conventional gamma camera, respectively. LV volumes were significantly underestimated by MPS compared to CMR (P ≤ .002 for all measures). The underestimation was slightly less pronounced for the CZT compared to the conventional gamma camera (2-10 mL, P ≤ .03 for all measures). For LVEF, however, accuracy was high for both gamma cameras. CONCLUSION: Differences between a CZT and a conventional gamma camera for detection of MI and assessment of LV volumes and LVEF are small and do not appear to be clinically significant.

The value of cardiac sympathetic activity and mechanical dyssynchrony as cardiac resynchronization therapy response predictors: comparison between patients with ischemic and non-ischemic heart failure.

BACKGROUND: Impaired cardiac sympathetic activity and mechanical dyssynchrony (MD) are associated with poor prognosis in patients with heart failure (HF) after cardiac resynchronization therapy (CRT). The study aims to assess the significance of scintigraphic evaluation of cardiac sympathetic innervation and contractility in predicting response to CRT in patients with ischemic and non-ischemic chronic HF. METHODS AND RESULTS: The study includes 58 HF patients, who were referred for CRT. Prior to CRT all patients underwent 123I-metaiodobenzylguanidine (123I-MIBG) imaging and gated myocardial perfusion imaging (MPI) using a cadmium-zinc-telluride (CZT) SPECT/CT device. At a one-year follow-up post-CRT, the delayed heart-to-mediastinum 123I-MIBG uptake ratio was an independent predictor of CRT response in non-ischemic HF patients (OR 1.469; 95% CI 1.076-2.007, p = .003). In ischemic HF patients the MD index histogram bandwidth (HBW) obtained by CZT-gated MPI had a predictive value (OR 1.06, 95% CI 1.001-1.112, p = .005) to CRT response. CONCLUSION: CRT response can be predicted by cardiac 123I-MIBG scintigraphy, specifically by the heart-to-mediastinum ratio in non-ischemic HF and by the MD index HBW in ischemic HF. These results suggest the value of a potentially useful algorithm to improve outcomes in HF patients who are candidates for CRT.

The feasibility of 18F-FDG gated positron emission tomography (PET) for left ventricular dyssynchrony assessment in comparison with 99mTc-MIBI gated single-photon emission computed tomography (SPECT) among patients with prior myocardial infarction.

Background: Phase analysis by 99mTc-MIBI gated single-photon emission computed tomography (GSPECT) has been considered to be an adequate method in the validation of left ventricular (LV) dyssynchrony. Compared with GSPECT, prior myocardial infarction patients with myocardial perfusion defects but myocardial viability usually show preserved uptake of 18F-FDG, and extensive myocardium is detected by 18F-FDG gated positron emission tomography (GPET). Thus, theoretically, it should be more accurate. The aim of this study was to investigate the feasibility of GPET for LV dyssynchrony assessment in comparison with GSPECT among infarction patients. Methods: A total of 146 patients with infarction underwent 2 consecutive days of GSPECT and GPET examinations. Quantitative gated SPECT-derived LV phase analysis was applied to GPET and GSPECT data to assess the presence of LV dyssynchrony via histogram bandwidth (BW) and phase standard deviation (SD). The correlation and agreement of BW and SD between GSPECT and GPET were examined. Factors (i.e., total perfusion defect, scar and mismatch) related to the discrepancies of LV dyssynchrony (i.e., BW and SD) in GPET and GSPECT were assessed by univariate and multivariate regression analysis. Results: A moderate correlation between GPET and GSPECT was found in the measurements of BW (r=0.554) and SD (r=0.537). Bland-Altman analysis revealed that GPET overestimated both BW and SD (20.5° and 9.5°, respectively). In addition, the BW and SD measured by GPET were still overestimated after subgroup analysis. Between GPET and GSPECT, multivariate regression analysis revealed that total perfusion defects were related to the difference in BW measurement (P<0.001), and mismatch was associated with the difference in SD measurement (P<0.01). Conclusions: In patients with infarction, GPET moderately correlated with GSPECT in assessing LV dyssynchrony. GPET overestimated both BW and SD, so these analyses should not be interchangeable in individual patients.

Effectively Detecting Left Bundle Branch Block False Defects in Myocardial Perfusion Imaging (MPI) with a Convolutional Neural Network (CNN).

Left bundle branch block (LBBB) is a frequent source of false positive MPI reports, in patients evaluated for coronary artery disease. PURPOSE: In this work, we evaluated the ability of a CNN-based solution, using transfer learning, to produce an expert-like judgment in recognizing LBBB false defects. METHODS: We collected retrospectively, MPI polar maps, of patients having small to large fixed anteroseptal perfusion defect. Images were divided into two groups. The LBBB group included patients where this defect was judged as false defect by two experts. The LAD group included patients where this defect was judged as a true defect by two experts. We used a transfer learning approach on a CNN (ResNet50V2) to classify the images into two groups. RESULTS: After 60 iterations, the reached accuracy plateau was 0.98, and the loss was 0.19 (the validation accuracy and loss were 0.91 and 0.25, respectively). A first test set of 23 images was used (11 LBBB, and 12 LAD). The empiric ROC (Receiver operating characteristic) Area was estimated at 0.98. A second test set (18x2 images) was collected after the final results. The ROC area was estimated again at 0.98. CONCLUSION: Artificial intelligence, using CNN and transfer learning, could reproduce an expert-like judgment in differentiating between LBBB false defects, and LAD real defects.

Sex-specific reference limits of left ventricular ejection fraction and volumes estimated by gated myocardial perfusion imaging for low-risk patients in China: a comparison between three quantitative algorithms.

BACKGROUND: Establishing appropriate reference value limits of left ventricular (LV) functional parameters is fundamental for the assessment of cardiac function. At present, there are no reports aimed at establishing reference limits using gated myocardial perfusion imaging (MPI) in mainland China. METHODS: A total of 175 consecutive patients who were defined as low-risk coronary artery disease patients underwent stress Technetium-99m sestamibi (99mTc-MIBI)-gated myocardial perfusion single-photon emission computed tomography (SPECT) imaging. The LV ejection fraction (EF), end-diastolic volume (EDV), and end-systolic volume (ESV) were obtained by 3 quantitative algorithms: quantitative-gated SPECT, emory cardiac toolbox, and 4-dimensional model SPECT, respectively. The threshold values were obtained using Gaussian distribution or percentiles. The influence of gender, age, and weight on cardiac functional parameters was analyzed by multiple regressions for linear models. RESULTS: For males, the lower reference limits of EF were 52%, 63%, and 58%, respectively; and the upper limits of EDV/ESV were 106/45, 152/55, and 135/55 mL, respectively. For females, the lower reference limits of EF were 58%, 66%, and 65%, respectively; and the upper limits of EDV/ESV were 73/27, 105/31, and 88/29 mL, respectively. Compared to females, males had greater cardiac volume values and lower mean EF values. Bland-Altman plots revealed that the cardiac function parameters calculated by the three quantitative algorithms were in high agreement. CONCLUSIONS: In this study, the reference limits of cardiac parameters calculated by the 3 methods based on single-center data in China were preliminarily established. The threshold values determined by three quantitative algorithms were not interchangeable but were highly correlated.

Reproducibility of global LV function and dyssynchrony parameters derived from phase analysis of gated myocardial perfusion SPECT: A multicenter comparison with core laboratory setting.

BACKGROUND: Gated myocardial perfusion scintigraphy (GMPS) phase analysis is an important tool to investigate the physiology of left ventricular (LV) dyssynchrony. We aimed to test the performance of GMPS LV function and phase analysis in different clinical settings and on a diverse population. METHODS: This is a post hoc analysis of a prospective, non-randomized, multinational, multicenter cohort study. Clinical evaluation and GMPS prior to cardiac resynchronization therapy (CRT)(baseline) and 6-month post CRT (follow-up) were done. LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV), LV ejection fraction (LVEF), LV phase standard deviation (LVPSD), and percentage of left ventricle non-viable (PLVNV) were obtained by 10 centers and compared to the core lab. RESULTS: 276 GMPS studies had all data available from individual sites and from core lab. There were no statistically significant differences between all variables except for LVPSD. When subjects with no mechanical dyssynchrony were excluded, LVPSD difference became non-significant. LVESV, LVEF, LVPSD and PLVNV had strong correlation in site against core lab comparison. Bland-Altman plots demonstrated good agreement. CONCLUSIONS: The presented correlation and agreement of LV function and dyssynchrony analysis over different sites with a diverse sample corroborate the strength of GMPS in the management of heart failure in clinical practice.

Prognostic value of absent left ventricular ejection fraction reserve with regadenoson SPECT MPI.

BACKGROUND: An absent left ventricular ejection fraction (LVEF) reserve with vasodilator stress with PET cardiac imaging has been shown to provide significant independent and incremental value to the perfusion images for prediction of future cardiovascular adverse events. However, the prognostic value of LVEF reserve has not been well characterized with SPECT myocardial perfusion imaging (MPI). METHODS: We studied 858 consecutive patients with normal and abnormal perfusion pattern with regadenoson SPECT MPI. Change in LVEF was calculated as post-stress LVEF-rest LVEF. Absent LVEF reserve was defined as a drop in LVEF by 5% or more on the post-stress images. The primary outcome was a composite of cardiac death, non-fatal myocardial infarction and late coronary revascularization. RESULTS: An absent LVEF reserve was more common in patients with abnormal vs normal MPI (31% vs 19%, P = .001). During a median follow-up of 32 months, the primary outcome was experienced by 31% of the study population. An absent LVEF reserve was not associated with an increased risk of the primary outcome in patients with normal (hazard ratio 1.1, 95% CI .4-2.7, P = .8) or abnormal (.75, .56-1.00, P = .05) MPI. There was no significant correlation between extent of ischemia and post-stress change in LVEF (Pearson r = - .072, P = .07). CONCLUSIONS: In patients undergoing regadenoson SPECT MPI, absent LVEF reserve is not associated with worse cardiac outcomes. Thus, routine reporting of both post-stress and rest LVEF measurements in this setting may not be necessary.

Clinical and gated SPECT MPI parameters associated with super-response to cardiac resynchronization therapy.

PURPOSE: We sought to evaluate the behavior of cardiac mechanical synchrony as measured by phase SD (PSD) derived from gated MPI SPECT (gSPECT) in patients with super-response after CRT and to evaluate the clinical and imaging characteristics associated with super-response. METHODS: 158 subjects were evaluated with gSPECT before and 6 months after CRT. Patients with an improvement of LVEF > 15% and NYHA class I/II or reduction in LV end-systolic volume > 30% and NYHA class I/II were labeled as super-responders (SR). RESULTS: 34 patients were classified as super-responders (22%) and had lower PSD (32° ± 17°) at 6 months after CRT compared to responders (45° ± 24°) and non-responders 46° ± 28° (P = .02 for both comparisons). Regression analysis identified predictors independently associated with super-response to CRT: absence of previous history of CAD (odds ratio 18.7; P = .002), absence of diabetes mellitus (odds ratio 13; P = .03), and history of hypertension (odds ratio .2; P = .01). CONCLUSION: LV dyssynchrony after CRT implantation, but not at baseline, was significantly better among super-responders compared to non-super-responders. The absence of diabetes, absence of CAD, and history of hypertension were independently associated with super-response after CRT.

Normal myocardial perfusion despite a very high coronary calcium score.

An exceptionally high coronary calcium score, greater than 10,000 UA, superior to any other found in the literature reviewed, was reported in an asymptomatic, adult man with hypertension, obesity and dyslipidemia, without myocardial ischemia and no significative coronary stenosis, associated to Glagov's phenomenon in the left coronary artery and an abdominal aortic aneurysm.

Prognostic value of ventricular mechanical dyssynchrony in patients with left ventricular aneurysm: A comparative study of medical and surgical treatment.

BACKGROUND: The prognostic value of left ventricular (LV) mechanical dyssynchrony (MD) in patients with LV aneurysm (LVA) is unclear. This study aimed to investigate the long-term prognostic value of LVMD in LVA patients. METHODS: 92 consecutive patients who underwent 99mTc-sestamibi-gated SPECT myocardial perfusion imaging (GSPECT) were retrospectively analyzed and followed-up for a median of 63 months (range, 1-73 months). LV function and histogram bandwidth (BW) were analyzed by QGS software. LVMD was defined by ROC analysis. Cardiac death was defined as the primary endpoint, and the composite of cardiac deaths and severe or acute heart failure (MACE) as the secondary endpoint. RESULTS: The annual cardiac mortality rate of LVA patients with LVMD and treated by surgical therapy was significantly lower than those treated by medical therapy (2.40% vs. 6.40%, P < .05) but not annual MACE rate (6.61% vs. 10.06%, P > .05). In patients without LVMD, no significant difference in survival and MACE-free survival between medical and surgical treatment. In addition, the occurrence of LVMD is related to the worsen cardiac outcome in terms of MACE and cardiac death, independent of the treatment methods. BW was an independent predictor for MACE (HR 1.010, P < .01) and LVEF (HR .928, P < .05) was an independent predictor for cardiac death in all LVA patients. CONCLUSIONS: LVA patients with LVMD might be associated with high risk for cardiac death and surgical treatment might improve cardiac survival compared to medical therapy in these patients.