Background: The prevalence of ischemia on nuclear myocardial perfusion imaging(MPI) has been decreasing. Recent research has questioned the benefit of invasive revascularization for patients with moderate to severe is...Background: The prevalence of ischemia on nuclear myocardial perfusion imaging(MPI) has been decreasing. Recent research has questioned the benefit of invasive revascularization for patients with moderate to severe ischemia. We hypothesized that patients with moderate to severe ischemia could routinely undergo successful revascularization.Methods: We analyzed data from 544 patients who underwent an MPI at a single academic Veterans Affairs Medical Center. Patients with moderate to severe ischemia, defined as a summed difference score(SDS) 8 or greater, were compared to the rest of the cohort.Results: Of the total cohort(n=544), 39 patients had MPI studies with resultant moderate to severe ischemia. Patients with ischemia were more likely to develop coronary artery disease(74.4% versus 38.8%, P<0.0001) and have successful revascularization(38.5% versus 4.0%, P<0.0001) during the following year. Revascularization was attempted in 31 patients with moderate to severe ischemia, though only 15(47%) of these attempts were successful. Ischemia was predictive of myocardial infarction(5.1% versus 0.8%, P=0.01) within 1 year.Conclusion: Moderate to severe ischemia is an uncommon finding in a contemporary nuclear laboratory. Among patients with ischemia, revascularization is typically attempted but is frequently unsuccessful.Trial registration: This trial does not appear on a registry as it is neither randomized nor prospective.展开更多
Objective:To observe the effects of Chinese drugs for supplementing qi,nourishing yin and activating blood circulation on the myocardial perfusion in acute myocardial infarction(AMI) patients after revascularization.M...Objective:To observe the effects of Chinese drugs for supplementing qi,nourishing yin and activating blood circulation on the myocardial perfusion in acute myocardial infarction(AMI) patients after revascularization.Methods:Eighty patients with anterior or inferior ventricular wall AMI,who had received revascularization by intravenous thrombolysis or coronary bypass,were randomized into the treated group and the control group equally,both treated with conventional Western medical treatment,but combined,r...展开更多
Objective To evaluate the clinical value of myocardial perfusion imaging with dual-source dual-energy CT and a contrast agent at a low concentration in the diagnosis of myocardial infarction in the elderly.Methods One...Objective To evaluate the clinical value of myocardial perfusion imaging with dual-source dual-energy CT and a contrast agent at a low concentration in the diagnosis of myocardial infarction in the elderly.Methods Onestop cardiac imaging with dual-source CT was conducted in 138 elderly patients diagnosed with myocardial infarction between October 2015 and May 2016.The展开更多
BACKGROUND Liver transplant(LT)patients have become older and sicker.The rate of post-LT major adverse cardiovascular events(MACE)has increased,and this in turn raises 30-d post-LT mortality.Noninvasive cardiac stress...BACKGROUND Liver transplant(LT)patients have become older and sicker.The rate of post-LT major adverse cardiovascular events(MACE)has increased,and this in turn raises 30-d post-LT mortality.Noninvasive cardiac stress testing loses accuracy when applied to pre-LT cirrhotic patients.AIM To assess the feasibility and accuracy of a machine learning model used to predict post-LT MACE in a regional cohort.METHODS This retrospective cohort study involved 575 LT patients from a Southern Brazilian academic center.We developed a predictive model for post-LT MACE(defined as a composite outcome of stroke,new-onset heart failure,severe arrhythmia,and myocardial infarction)using the extreme gradient boosting(XGBoost)machine learning model.We addressed missing data(below 20%)for relevant variables using the k-nearest neighbor imputation method,calculating the mean from the ten nearest neighbors for each case.The modeling dataset included 83 features,encompassing patient and laboratory data,cirrhosis complications,and pre-LT cardiac assessments.Model performance was assessed using the area under the receiver operating characteristic curve(AUROC).We also employed Shapley additive explanations(SHAP)to interpret feature impacts.The dataset was split into training(75%)and testing(25%)sets.Calibration was evaluated using the Brier score.We followed Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis guidelines for reporting.Scikit-learn and SHAP in Python 3 were used for all analyses.The supplementary material includes code for model development and a user-friendly online MACE prediction calculator.RESULTS Of the 537 included patients,23(4.46%)developed in-hospital MACE,with a mean age at transplantation of 52.9 years.The majority,66.1%,were male.The XGBoost model achieved an impressive AUROC of 0.89 during the training stage.This model exhibited accuracy,precision,recall,and F1-score values of 0.84,0.85,0.80,and 0.79,respectively.Calibration,as assessed by the Brier score,indicated excellent model calibration with a score of 0.07.Furthermore,SHAP values highlighted the significance of certain variables in predicting postoperative MACE,with negative noninvasive cardiac stress testing,use of nonselective beta-blockers,direct bilirubin levels,blood type O,and dynamic alterations on myocardial perfusion scintigraphy being the most influential factors at the cohort-wide level.These results highlight the predictive capability of our XGBoost model in assessing the risk of post-LT MACE,making it a valuable tool for clinical practice.CONCLUSION Our study successfully assessed the feasibility and accuracy of the XGBoost machine learning model in predicting post-LT MACE,using both cardiovascular and hepatic variables.The model demonstrated impressive performance,aligning with literature findings,and exhibited excellent calibration.Notably,our cautious approach to prevent overfitting and data leakage suggests the stability of results when applied to prospective data,reinforcing the model’s value as a reliable tool for predicting post-LT MACE in clinical practice.展开更多
Introduction: During the pharmacological stress test with dipyridamole, a normal hemodynamic response is slightly reduced blood pressure and raised heart rate (HR). However, sometimes the HR response is reduced. This ...Introduction: During the pharmacological stress test with dipyridamole, a normal hemodynamic response is slightly reduced blood pressure and raised heart rate (HR). However, sometimes the HR response is reduced. This study investigated the relationship between the HR response during the dipyridamole stress test and the severity of the perfusion defects using Thallium 201 myocardial perfusion imaging. Methods: We enrolled 50 patients undergoing dipyridamole stress at the nuclear cardiology Lab, Main University Hospital of Alexandria. Standard dipyridamole protocol (infusion over 4 min) and standard thallium 201 protocol (2 min after dipyridamole infusion) were followed. If the heart rate (HR) ratio (peak HR/rest HR) was 1.20 or less, it was considered a reduced response. Total perfusion defect (TPD), summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) for myocardial perfusion<span style="white-space:normal;font-family:;" "=""> </span><span style="white-space:normal;font-family:;" "="">were calculated. Patients with reduced HR response and normal HR responses were compared and independent predictors of reduced HR response were determined. Results: About 56% of patients had reduced HR response;which included a high number of patients with a history of dyslipidemia and diabetes mellitus. The reduced HR response group showed lower SSS, SRS. The analysis showed that the independent predictors of reduced HR response were rest HR, SSS, and diabetes mellitus. Conclusions: Reduction in the HR response during the dipyridamole-induced stress test is related to the severity of perfusion defect, diabetes mellitus, and Dyslipidemia.</span>展开更多
Objective: SPECT data from myocardial perfusion imaging (MPI) are normally displayed as a set of three slices orthogonal to the left ventricular (LV) long axis. For data presentation, the images are orientated about t...Objective: SPECT data from myocardial perfusion imaging (MPI) are normally displayed as a set of three slices orthogonal to the left ventricular (LV) long axis. For data presentation, the images are orientated about the LV long axis. Therefore, radial slices provide a suitable alternative to standard orthogonal slices, with the advantage of requiring fewer slices to adequately represent the data. In this study, a semi-automatic method is developed for displaying MPI SPECT data as a set of radial slices orientated about the LV axis. The aim is to reduce the number of slices viewed without loss of information and independently from the heart size. Method: Standard short axis slices, orientated perpendicular to the LV axis, are utilized.The skeleton of the segmented myocardium is found and the true LV axis is determined in each central long slice. The LV axis of the whole volume is determined by aligning the axes of all slices. Result: Radial slices centered about this axis were generated by integration over a sector equal to the resolution of the imaging system which was of the order of 1.2 cm. Therefore, assuming a mean LV diameter of 8 cm, 20 slices were sufficient to represent a non-gated study. Gated information could be adequately displayed with 4 slices integrated over an angle of 45. Conclusion: A semi-automatic method for generating radial slices from SPECT MPI short axis slices has been developed.展开更多
BACKGROUND The prevalence of type 2 diabetes(T2D)has been increasing dramatically in recent decades,and 47.5%of T2D patients will die of cardiovascular disease.Thallium-201 myocardial perfusion scan(MPS)is a precise a...BACKGROUND The prevalence of type 2 diabetes(T2D)has been increasing dramatically in recent decades,and 47.5%of T2D patients will die of cardiovascular disease.Thallium-201 myocardial perfusion scan(MPS)is a precise and noninvasive method to detect coronary artery disease(CAD).Most previous studies used traditional logistic regression(LGR)to evaluate the risks for abnormal CAD.Rapidly developing machine learning(Mach-L)techniques could potentially outperform LGR in capturing non-linear relationships.AIM To aims were:(1)Compare the accuracy of Mach-L methods and LGR;and(2)Found the most important factors for abnormal TMPS.METHODS 556 T2D were enrolled in the study(287 men and 269 women).Demographic and biochemistry data were used as independent variables and the sum of stressed score derived from MPS scan was the dependent variable.Subjects with a MPS score≥9 were defined as abnormal.In addition to traditional LGR,classification and regression tree(CART),random forest,Naïve Bayes,and eXtreme gradient boosting were also applied.Sensitivity,specificity,accuracy and area under the receiver operation curve were used to evaluate the respective accuracy of LGR and Mach-L methods.RESULTS Except for CART,the other Mach-L methods outperformed LGR,with gender,body mass index,age,low-density lipoprotein cholesterol,glycated hemoglobin and smoking emerging as the most important factors to predict abnormal MPS.CONCLUSION Four Mach-L methods are found to outperform LGR in predicting abnormal TMPS in Chinese T2D,with the most important risk factors being gender,body mass index,age,low-density lipoprotein cholesterol,glycated hemoglobin and smoking.展开更多
It is not rare for acute coronary syndrome(ACS)patients to present with symptoms that are atypical,rather than chest pain.It is sometimes difficult to achieve a definitive diagnosis of ACS for such patients who presen...It is not rare for acute coronary syndrome(ACS)patients to present with symptoms that are atypical,rather than chest pain.It is sometimes difficult to achieve a definitive diagnosis of ACS for such patients who present with atypical symptoms,normal initial biomarkers of myocardial necrosis,and normal or nondiagnostic electrocardiograms(ECGs).Although cardiac CT allows for assessments of coronary artery stenosis as well as myocardial perfusion defect in patients with suspected ACS,it requires ECG gating and is usually performed with high-performance multislice CT for highly probable ACS patients.However,several recent reports have stated that ACS is detectable by myocardial perfusion defects even on routine non-ECG-gated contrast-enhanced CT.A growing number of contrast-enhanced CT scans are now being performed in emergency departments in search of pathologies responsible for a patient’s presenting symptoms.In order to avoid inappropriate management for this life-threatening event,clinicians should be aware that myocardial perfusion defect is more commonly detectable even on routine non-ECG-gated contrast-enhanced CT performed in search of other pathologies.展开更多
文摘Background: The prevalence of ischemia on nuclear myocardial perfusion imaging(MPI) has been decreasing. Recent research has questioned the benefit of invasive revascularization for patients with moderate to severe ischemia. We hypothesized that patients with moderate to severe ischemia could routinely undergo successful revascularization.Methods: We analyzed data from 544 patients who underwent an MPI at a single academic Veterans Affairs Medical Center. Patients with moderate to severe ischemia, defined as a summed difference score(SDS) 8 or greater, were compared to the rest of the cohort.Results: Of the total cohort(n=544), 39 patients had MPI studies with resultant moderate to severe ischemia. Patients with ischemia were more likely to develop coronary artery disease(74.4% versus 38.8%, P<0.0001) and have successful revascularization(38.5% versus 4.0%, P<0.0001) during the following year. Revascularization was attempted in 31 patients with moderate to severe ischemia, though only 15(47%) of these attempts were successful. Ischemia was predictive of myocardial infarction(5.1% versus 0.8%, P=0.01) within 1 year.Conclusion: Moderate to severe ischemia is an uncommon finding in a contemporary nuclear laboratory. Among patients with ischemia, revascularization is typically attempted but is frequently unsuccessful.Trial registration: This trial does not appear on a registry as it is neither randomized nor prospective.
基金Supported by the National Key Technologies Research and Development Program of China during the 10th Five-Year Plan Period(No.2003BA712A11)
文摘Objective:To observe the effects of Chinese drugs for supplementing qi,nourishing yin and activating blood circulation on the myocardial perfusion in acute myocardial infarction(AMI) patients after revascularization.Methods:Eighty patients with anterior or inferior ventricular wall AMI,who had received revascularization by intravenous thrombolysis or coronary bypass,were randomized into the treated group and the control group equally,both treated with conventional Western medical treatment,but combined,r...
文摘Objective To evaluate the clinical value of myocardial perfusion imaging with dual-source dual-energy CT and a contrast agent at a low concentration in the diagnosis of myocardial infarction in the elderly.Methods Onestop cardiac imaging with dual-source CT was conducted in 138 elderly patients diagnosed with myocardial infarction between October 2015 and May 2016.The
文摘BACKGROUND Liver transplant(LT)patients have become older and sicker.The rate of post-LT major adverse cardiovascular events(MACE)has increased,and this in turn raises 30-d post-LT mortality.Noninvasive cardiac stress testing loses accuracy when applied to pre-LT cirrhotic patients.AIM To assess the feasibility and accuracy of a machine learning model used to predict post-LT MACE in a regional cohort.METHODS This retrospective cohort study involved 575 LT patients from a Southern Brazilian academic center.We developed a predictive model for post-LT MACE(defined as a composite outcome of stroke,new-onset heart failure,severe arrhythmia,and myocardial infarction)using the extreme gradient boosting(XGBoost)machine learning model.We addressed missing data(below 20%)for relevant variables using the k-nearest neighbor imputation method,calculating the mean from the ten nearest neighbors for each case.The modeling dataset included 83 features,encompassing patient and laboratory data,cirrhosis complications,and pre-LT cardiac assessments.Model performance was assessed using the area under the receiver operating characteristic curve(AUROC).We also employed Shapley additive explanations(SHAP)to interpret feature impacts.The dataset was split into training(75%)and testing(25%)sets.Calibration was evaluated using the Brier score.We followed Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis guidelines for reporting.Scikit-learn and SHAP in Python 3 were used for all analyses.The supplementary material includes code for model development and a user-friendly online MACE prediction calculator.RESULTS Of the 537 included patients,23(4.46%)developed in-hospital MACE,with a mean age at transplantation of 52.9 years.The majority,66.1%,were male.The XGBoost model achieved an impressive AUROC of 0.89 during the training stage.This model exhibited accuracy,precision,recall,and F1-score values of 0.84,0.85,0.80,and 0.79,respectively.Calibration,as assessed by the Brier score,indicated excellent model calibration with a score of 0.07.Furthermore,SHAP values highlighted the significance of certain variables in predicting postoperative MACE,with negative noninvasive cardiac stress testing,use of nonselective beta-blockers,direct bilirubin levels,blood type O,and dynamic alterations on myocardial perfusion scintigraphy being the most influential factors at the cohort-wide level.These results highlight the predictive capability of our XGBoost model in assessing the risk of post-LT MACE,making it a valuable tool for clinical practice.CONCLUSION Our study successfully assessed the feasibility and accuracy of the XGBoost machine learning model in predicting post-LT MACE,using both cardiovascular and hepatic variables.The model demonstrated impressive performance,aligning with literature findings,and exhibited excellent calibration.Notably,our cautious approach to prevent overfitting and data leakage suggests the stability of results when applied to prospective data,reinforcing the model’s value as a reliable tool for predicting post-LT MACE in clinical practice.
文摘Introduction: During the pharmacological stress test with dipyridamole, a normal hemodynamic response is slightly reduced blood pressure and raised heart rate (HR). However, sometimes the HR response is reduced. This study investigated the relationship between the HR response during the dipyridamole stress test and the severity of the perfusion defects using Thallium 201 myocardial perfusion imaging. Methods: We enrolled 50 patients undergoing dipyridamole stress at the nuclear cardiology Lab, Main University Hospital of Alexandria. Standard dipyridamole protocol (infusion over 4 min) and standard thallium 201 protocol (2 min after dipyridamole infusion) were followed. If the heart rate (HR) ratio (peak HR/rest HR) was 1.20 or less, it was considered a reduced response. Total perfusion defect (TPD), summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) for myocardial perfusion<span style="white-space:normal;font-family:;" "=""> </span><span style="white-space:normal;font-family:;" "="">were calculated. Patients with reduced HR response and normal HR responses were compared and independent predictors of reduced HR response were determined. Results: About 56% of patients had reduced HR response;which included a high number of patients with a history of dyslipidemia and diabetes mellitus. The reduced HR response group showed lower SSS, SRS. The analysis showed that the independent predictors of reduced HR response were rest HR, SSS, and diabetes mellitus. Conclusions: Reduction in the HR response during the dipyridamole-induced stress test is related to the severity of perfusion defect, diabetes mellitus, and Dyslipidemia.</span>
文摘Objective: SPECT data from myocardial perfusion imaging (MPI) are normally displayed as a set of three slices orthogonal to the left ventricular (LV) long axis. For data presentation, the images are orientated about the LV long axis. Therefore, radial slices provide a suitable alternative to standard orthogonal slices, with the advantage of requiring fewer slices to adequately represent the data. In this study, a semi-automatic method is developed for displaying MPI SPECT data as a set of radial slices orientated about the LV axis. The aim is to reduce the number of slices viewed without loss of information and independently from the heart size. Method: Standard short axis slices, orientated perpendicular to the LV axis, are utilized.The skeleton of the segmented myocardium is found and the true LV axis is determined in each central long slice. The LV axis of the whole volume is determined by aligning the axes of all slices. Result: Radial slices centered about this axis were generated by integration over a sector equal to the resolution of the imaging system which was of the order of 1.2 cm. Therefore, assuming a mean LV diameter of 8 cm, 20 slices were sufficient to represent a non-gated study. Gated information could be adequately displayed with 4 slices integrated over an angle of 45. Conclusion: A semi-automatic method for generating radial slices from SPECT MPI short axis slices has been developed.
基金The study was reviewed and approved by the Cardinal Tien Hospital Institutional Review Board(Approval No.CTH-102-2-5-024).
文摘BACKGROUND The prevalence of type 2 diabetes(T2D)has been increasing dramatically in recent decades,and 47.5%of T2D patients will die of cardiovascular disease.Thallium-201 myocardial perfusion scan(MPS)is a precise and noninvasive method to detect coronary artery disease(CAD).Most previous studies used traditional logistic regression(LGR)to evaluate the risks for abnormal CAD.Rapidly developing machine learning(Mach-L)techniques could potentially outperform LGR in capturing non-linear relationships.AIM To aims were:(1)Compare the accuracy of Mach-L methods and LGR;and(2)Found the most important factors for abnormal TMPS.METHODS 556 T2D were enrolled in the study(287 men and 269 women).Demographic and biochemistry data were used as independent variables and the sum of stressed score derived from MPS scan was the dependent variable.Subjects with a MPS score≥9 were defined as abnormal.In addition to traditional LGR,classification and regression tree(CART),random forest,Naïve Bayes,and eXtreme gradient boosting were also applied.Sensitivity,specificity,accuracy and area under the receiver operation curve were used to evaluate the respective accuracy of LGR and Mach-L methods.RESULTS Except for CART,the other Mach-L methods outperformed LGR,with gender,body mass index,age,low-density lipoprotein cholesterol,glycated hemoglobin and smoking emerging as the most important factors to predict abnormal MPS.CONCLUSION Four Mach-L methods are found to outperform LGR in predicting abnormal TMPS in Chinese T2D,with the most important risk factors being gender,body mass index,age,low-density lipoprotein cholesterol,glycated hemoglobin and smoking.
文摘It is not rare for acute coronary syndrome(ACS)patients to present with symptoms that are atypical,rather than chest pain.It is sometimes difficult to achieve a definitive diagnosis of ACS for such patients who present with atypical symptoms,normal initial biomarkers of myocardial necrosis,and normal or nondiagnostic electrocardiograms(ECGs).Although cardiac CT allows for assessments of coronary artery stenosis as well as myocardial perfusion defect in patients with suspected ACS,it requires ECG gating and is usually performed with high-performance multislice CT for highly probable ACS patients.However,several recent reports have stated that ACS is detectable by myocardial perfusion defects even on routine non-ECG-gated contrast-enhanced CT.A growing number of contrast-enhanced CT scans are now being performed in emergency departments in search of pathologies responsible for a patient’s presenting symptoms.In order to avoid inappropriate management for this life-threatening event,clinicians should be aware that myocardial perfusion defect is more commonly detectable even on routine non-ECG-gated contrast-enhanced CT performed in search of other pathologies.
