Myocardial Imaging Research Articles

Magnetic Resonance Myocardial Imaging in Patients With Implantable Cardiac Devices: Challenges, Techniques, and Clinical Applications.

Cardiovascular magnetic resonance imaging (MRI) in patients with cardiac implants, such as pacemakers and defibrillators, has gained importance in recent years with the development of modern cardiac implantable electronic devices. The increasing clinical need to perform MRI examinations in patients with cardiac implants has driven the development of new advanced MRI sequences to mitigate image artifacts associated with cardiac implants. More specifically, advances in imaging techniques, such as wideband late gadolinium enhancement imaging, wideband T1 mapping, and wideband perfusion, have been designed to improve image quality and examinations in patients with cardiac implants, enabling a comprehensive and more reliable diagnosis, which was previously unattainable in these patients. This review article explores recent developments and applications of wideband techniques in the field of cardiovascular MRI, offering insights into their transformative potential. Clinical applications of wideband cardiovascular MRI are highlighted, particularly in assessing myocardial viability, guiding ventricular tachycardia ablation, and characterizing myocardial tissue.

The relationship between coronary microvascular dysfunction and left ventricular longitudinal systolic function in patients with diabetes mellitus

Abstract Background Coronary microvascular dysfunction (CMD) often accompanies diabetes mellitus (DM), leading to myocardial ischemia despite normal or mildly narrowed coronary arteries (<50% stenosis). CMD causes myocardial hypoperfusion, resulting in impaired systolic function. Coronary flow reserve (CFR) serves as a marker of microvascular function, particularly in the absence of significant epicardial coronary stenosis. Myocardial contrast echocardiography (MCE) is a key tool for clinically assessing CFR. Global longitudinal strain (GLS) derived from two-dimensional speckle tracking echocardiography (2D-STE) offers early insights into left ventricular systolic dysfunction during subclinical stages but is underexplored in diabetic CMD patients. Objective This study aimed to assess myocardial microcirculatory dysfunction in diabetic patients using stress myocardial ultrasound enhancement imaging, investigate its relationship with left ventricular longitudinal systolic function, and evaluate the utility of 2D-STE in assessing left ventricular systolic function in CMD patients. The findings provide insights for early detection and prevention of left ventricular longitudinal systolic dysfunction in diabetic patients with myocardial microcirculatorydysfunction. Methods Seventy type 2 diabetic patients who underwent coronary CT or angiography within the past three months without obstructive coronary artery disease were included. Clinical data, biochemical parameters, and blood glucose levels were collected. Left ventricular longitudinal strain indices were obtained using 2D-STE, and microvascular function was assessed based on CFR measured via transthoracic stress MCE. Patients were categorized into CMD (CFR<2) and control (CFR≧2) groups, with clinical and echocardiographic parameters compared. Strain parameters included GLS at rest, GLS under stress, and ∆GLS. Correlations between these indices and CFR were analyzed. Results 1. Seventy patients, with 41 males (41.4%) and 58 females (58.6%), averaging 56.14±10.84 years, were included. The mean BMI was 25.53±3.40. Among them, 23 patients were smokers (32.8%), 41 had hypertension (58.6%), and 36 had hyperlipidemia (51.4%). 2. Patients in the CMD group had significantly shorter diabetes duration (6.59±2.18 years vs. 8.13±2.17 years) and lower glycosylated hemoglobin (7.99±1.52% vs. 8.78±1.55%) (P<0.05). No significant differences were observed in other parameters. 3. GLS and ∆GLS differed significantly between groups, while other echocardiographic parameters did not. 4. Logistic regression analysis identified GLS as an independent predictor of CMD in diabetic patients under stress. Conclusions 1. Diabetic patients with CMD exhibit lower GLS and ∆GLS under stress, indicating early reductions in left ventricular systolic function reserve. 2. 2D-STE can detect early left ventricular systolic impairment in diabetic patients.MCE quantitative analysisGLS in normal and CMD group

Feasibility of shortening scan duration of 18F-FDG myocardial metabolism imaging using a total-body PET/CT scanner

PurposeTo evaluate 18F-FDG myocardial metabolism imaging (MMI) using a total-body PET/CT scanner and explore the feasible scan duration to guide the clinical practice.MethodsA retrospective analysis was conducted on 41 patients who underwent myocardial perfusion-metabolism imaging to assess myocardial viability. The patients underwent 18F-FDG MMI with a total-body PET/CT scanner using a list-mode for 600 s. PET data were trimmed and reconstructed to simulate images of 600-s, 300-s, 120-s, 60-s, and 30-s acquisition time (G600-G30). Images among different groups were subjectively evaluated using a 5-point Likert scale. Semi-quantitative evaluation was performed using standardized uptake value (SUV), myocardial to background activity ratio (M/B), signal to noise ratio (SNR), contrast to noise ratio (CNR), contrast ratio (CR), and coefficient of variation (CV). Myocardial viability analysis included indexes of Mismatch and Scar. G600 served as the reference.ResultsSubjective visual evaluation indicated a decline in the scores of image quality with shortening scan duration. All the G600, G300, and G120 images were clinically acceptable (score ≥ 3), and their image quality scores were 4.9 ± 0.3, 4.8 ± 0.4, and 4.5 ± 0.8, respectively (P > 0.05). Moreover, as the scan duration reduced, the semi-quantitative parameters M/B, SNR, CNR, and CR decreased, while SUV and CV increased, and significant difference was observed in G300-G30 groups when comparing to G600 group (P < 0.05). For myocardial viability analysis of left ventricular and coronary segments, the Mismatch and Scar values of G300-G30 groups were almost identical to G600 group (ICC: 0.968-1.0, P < 0.001).ConclusionSufficient image quality for clinical diagnosis could be achieved at G120 for MMI using a total-body PET/CT scanner, while the image quality of G30 was acceptable for myocardial viability analysis.

Integrating Coronary Artery Assessment and Myocardial Late Enhancement Imaging With Photon-Counting Detector CT: Visualizing the Invisible.

Integrating Coronary Artery Assessment and Myocardial Late Enhancement Imaging With Photon-Counting Detector CT: Visualizing the Invisible.

Incremental prognostic value of 18F-FDG myocardial ischemic memory imaging for major adverse cardiovascular events in patients with suspected unstable angina

BackgroundThe additional prognostic value of 18F-FDG PET myocardial ischemic memory imaging for patients with suspected unstable angina (UA) is not well established. This study aimed to determine whether 18F-FDG PET imaging provides incremental prognostic information for predicting major adverse cardiac events (MACE) compared to clinical risk factors, GRACE score, and coronary artery calcium score (CACS) in suspected UA patients. MethodsIn this post-hoc analysis of a prospective study, 265 suspected UA patients (62.3% male, mean age 65.0±9.4 years) were enrolled. 18F-FDG positive was defined as focal or focal on diffuse uptake patterns. MACE included cardiovascular death, acute myocardial infarction, heart failure, rehospitalization for UA, and stroke. Multivariable Cox regression was used to identify predictors of MACE, and the incremental prognostic value of 18F-FDG PET imaging was assessed using C-index, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). ResultsOver a median follow-up of 25 months, 51 patients (19.2%) experienced MACE. 18F-FDG positive (HR=3.220, 95% CI: 1.630-6.360, P<0.001) , as well as 18F-FDG standardized uptake ratio (SUR) (HR=1.330, 95%CI: 1.131-1.564, P=0.0006) and Extent (HR=1.045, 95%CI: 1.028-1.062, P<0.0001), were independent predictors of MACE. The addition of 18F-FDG PET imaging significantly improved risk stratification beyond clinical factors, the GRACE score, and CACS, with improved C-index (0.769 vs 0.688, P=0.045), NRI (0.324, P=0.020), and IDI (0.055, P=0.027). Conclusion18F-FDG PET myocardial ischemic memory imaging significantly improves prognostic assessment for suspected UA patients, providing valuable additional risk stratification beyond clinical risk factors, GRACE score, and CACS.

Assessment of the Right Ventricle Function in Patients With Significant Tricuspid Regurgitation: A Review.

Tricuspid regurgitation (TR) is an increasingly prevalent condition, especially in older populations, and presents significant challenges due to its association with right heart failure, hospital admissions, and high mortality rates. The management of TR has evolved, with new percutaneous valve repair and replacement techniques emerging alongside traditional surgical approaches. However, accurately assessing right ventricular (RV) function-a key prognostic factor in TR-remains difficult due to the RV's unique anatomy and sensitivity to loading conditions. Current echocardiographic methods, such as Tricuspid Annular Plane Systolic Excursion (TAPSE), S' wave analysis, and RV fractional area change (FAC), offer valuable insights but have limitations, particularly regarding load dependence and incomplete assessment of RV function. Advances in 3D echocardiography and myocardial strain imaging provide more comprehensive evaluations, yet challenges persist in integrating these measures in routine clinical practice. The review highlights the importance of a multimodal approach to RV assessment in TR patients, considering both the right atrium and pulmonary artery interactions, and explores potential future tools such as myocardial work and dynamic testing to improve prognostic accuracy and patient outcomes.

Transforming Heart Failure Management: The Power of Strain Imaging, 3D Imaging, and Vortex Analysis in Echocardiography.

Heart failure (HF) remains a critical global health challenge, necessitating advancements in diagnostic and therapeutic strategies. This review explores the evolution of imaging technologies and their impact on HF management, focusing on three-dimensional echocardiography (3DE), myocardial strain imaging, and vortex dynamics imaging. Three-dimensional echocardiography enhances traditional echocardiography by providing more accurate assessments of cardiac structures, while myocardial strain imaging offers the early detection of subclinical myocardial dysfunction, crucial in conditions such as chemotherapy-induced cardiotoxicity and ischemic heart disease. Vortex dynamics imaging, a novel technique, provides insights into intracardiac flow patterns, aiding in the evaluation of left ventricular function, valve diseases, and congenital heart anomalies. The integration of these advanced imaging modalities into clinical practice facilitates personalized treatment strategies, enabling the earlier diagnosis and more precise monitoring of disease progression. The ongoing refinement of these imaging techniques holds promise for improving patient outcomes and advancing the field of precision medicine in HF care.

Epichaperome-targeted myocardial imaging by 124I-PU-H71 PET

Epichaperome-targeted myocardial imaging by 124I-PU-H71 PET

Quantitation of mitral regurgitation using positron emission tomography

BackgroundCardiac positron emission tomography (PET) offers non-invasive assessment of perfusion and left ventricular (LV) function from a single dynamic scan. However, no prior assessment of mitral regurgitation severity by PET has been presented. Application of indicator dilution techniques and gated image analyses to PET data enables calculation of forward stroke volume and total LV stroke volume. We aimed to evaluate a combination of these methods for measurement of regurgitant volume (RegVol) and fraction (RegF) using dynamic 15O-water and 11C-acetate PET in comparison to cardiovascular magnetic resonance (CMR).ResultsTwenty-one patients with severe primary mitral valve regurgitation underwent same-day dynamic PET examinations (15O-water and 11C-acetate) and CMR. PET data were reconstructed into dynamic series with short time frames during the first pass, gated 15O-water blood pool images, and gated 11C-acetate myocardial uptake images. PET-based RegVol and RegF correlated strongly with CMR (RegVol: 15O-water r = 0.94, 11C-acetate r = 0.91 and RegF: 15O-water r = 0.88, 11C-acetate r = 0.84, p < 0.001). A systematic underestimation (bias) was found for PET (RegVol: 15O-water − 11 ± 13 mL, p = 0.002, 11C-acetate − 28 ± 16 mL, p < 0.001 and RegF: 15O-water − 4 ± 6%, p = 0.01, 11C-acetate − 10 ± 7%, p < 0.001). PET measurements in patients were compared to healthy volunteers (n = 18). Mean RegVol and RegF was significantly lower in healthy volunteers compared to patients for both tracers. The accuracy of diagnosing moderately elevated regurgitant volume (> 30mL) was 95% for 15O-water and 92% for 11C-acetate.ConclusionsLV regurgitation severity quantified using cardiac PET correlated with CMR and showed high accuracy for discriminating patients from healthy volunteers.

Assessment of left ventricular myocardial systolic dysfunction in premature ovarian insufficiency patients using echocardiographic layer-specific myocardial strain imaging

BackgroundDue to the lack of oestrogen, premature ovarian insufficiency (POI) is an independent risk factor for ischaemic heart disease and overall cardiovascular disease. This study aimed to apply layer-specific myocardial strain for early quantitative evaluation of subclinical left ventricular myocardial systolic function changes in patients with POI.MethodsForty-eight newly diagnosed, untreated patients with POI (POI group) and fifty healthy female subjects matched for age, height and weight (control group) were enrolled. Standard transthoracic echocardiography was used to measure conventional parameters and layer-specific strain parameters.The layer-specific strain parameters included subendomyocardial global longitudinal strain (GLSendo), mid-layer myocardial global longitudinal strain (GLSmid), subepimyocardial global longitudinal strain (GLSepi), subendomyocardial global circumferential strain (GCSendo), mid-layer myocardial global circumferential strain (GCSmid), and subepimyocardial global circumferential strain (GCSepi). ResultsThere were no significant differences in age, body mass index (BMI), blood pressure, or left ventricular ejection fraction (LVEF) between the two groups. The end-diastolic interventricular septal thickness (IVST) was greater in the POI group (8.29 ± 1.32 vs. 7.66 ± 0.82, P = 0.008), and the POI group had lower E, E/A, and lateral e′ (all P < 0.05). As for systolic functions,the POI group had lower GLSendo, GLSmid, GLSepi, GCSendo, GCSmid, and GCSepi (all P < 0.05).The intraobserver and interobserver coefficients of GLSendo, GLSmid, GLSepi, GCSendo, GCSmid, and GCSepi were greater than 0.900. ConclusionsPOI patients with normal LVEF may suffer from subclinical left ventricular myocardial systolic dysfunction. Echocardiography of layer-specific myocardial strain could more sensitively detect subclinical impairment of left ventricular systolic function in POI patients.Graphical abstract

A novel algorithm developed using machine learning and a J-ACCESS database can estimate defect scores from myocardial perfusion single-photon emission tomography images.

Stress myocardial perfusion single-photon emission computed tomography (SPECT) imaging (MPI) has been used to diagnose and predict the prognoses of patients with coronary artery disease (CAD). An ongoing multicenter collaboration established a Japanese database (J-ACCESS) in 2001 that includes a risk model and expert interpretations. The present study aimed to develop a novel algorithm using machine learning (ML) and resources from the J-ACCESS database to aid SPECT image interpretation. We analyzed data from 1288 patients in J-ACCESS 3 and 4 databases. Three-dimensional (3D) stereoscopic images of left ventricular myocardial perfusion were reconstructed with linear transformation from the original short-axis data. Segments were extracted from U-Net, then features were extracted from each segment during the ML process. We estimated segmental scores based on weighted features obtained from fully connected layers. Correlations between segment scores interpreted by nuclear cardiology experts and estimated by ML were evaluated using a 17-segment model, summed stress (SSS), summed rest (SRS), and summed difference (SDS) scores, and ratios (%) of summed different scores (%SDS). The complete concordance rate of scores assessed by the experts and estimated by ML was 79.6%. The underestimated and overestimated rates were 10.3% and 10.0%, respectively. Associations between defect scores assessed by experts and ML were close, with correlation coefficients (r) of 0.923, 0.917, 0.842 and 0.853 for SSS, SRS, SDS, %SDS, respectively (p < 0.0001 for all). We created a new algorithm to estimate MPI scores using ML and the J-ACCESS database. This algorithm should provide accurate MPI interpretation even in facilities without specialist nuclear cardiologists, and might facilitate therapeutic decision-making and predict prognoses.

Burden of risk factors in women and men with unrecognised myocardial infarction: a systematic review and meta-analysis.

Unrecognised myocardial infarction (MI) is a MI that remains undetected in the acute phase and is associated with an unfavourable prognosis. With this systematic review and meta-analysis, we evaluated the burden of cardiovascular risk factors in individuals with unrecognised MI. We searched general population-based cohort studies diagnosing unrecognised MI by electrocardiogram or myocardial imaging up to 24 November 2023. Pooled mean differences (MD) or risk ratios (RR) with 95% confidence intervals (CI) were determined, and random-effects meta-analyses were performed. Fourteen cohort studies were included involving 200,450 individuals (mean age 62.8±9.9 years, 56.0% women), among which 4,322 (2.2%) experienced unrecognised MI (mean age 66.3±8.2 years, 47.8% women) and 4,653 (2.1%) recognised MI (mean age 68.5±7.3 years, 33.8% women). Compared to individuals without MI, those with unrecognised MI had higher body mass index (MD 0.27, 95% CI 0.16-0.39) and systolic blood pressure (MD 4.48, 95% CI 2.81-6.15), and higher prevalence of hypertension (RR 1.27, 95% CI 1.06-1.51) and diabetes mellitus (RR 1.67, 95% CI 1.36-2.06). Furthermore, individuals with unrecognised MI had lower prevalence of hypertension (RR 0.92, 95% CI 0.88-0.97) and diabetes mellitus (RR 0.80, 95% CI 0.70-0.92). Individuals with unrecognised MI are characterised by a substantial burden of metabolic risk factors. Our findings suggest insufficient recognition and management of cardiovascular risk factors among individuals with unrecognised MI.

Cardiac remodeling and inflammation detected by magnetic resonance imaging in COVID-19 survivors

BackgroundConcerns have been raised about cardiac inflammation in patients with long COVID-19, particularly those with myocardial injury during the acute phase of the disease. This study was conducted to examine myopericardial involvement, detected by cardiac magnetic resonance (CMR) imaging in patients hospitalized for COVID-19. MethodsAdult patients hospitalized with COVID-19 who presented myocardial injury or increased D-dimers were enrolled in this prospective study. All patients were invited to undergo CMR imaging examination after discharge. During follow-up, patients with nonischemic myocardial or pericardial involvement detected on the first CMR imaging examination underwent second examinations. CMR imaging findings were compared with those of a control group of healthy patients with no comorbidity. ResultsOf 180 included patients, 53 underwent CMR imaging examination. The mean age was 58.4 ± 18.3 years, and 73.6 % were male. Myocardial and pericardial LGE was reported in 43.4 % and 35.8 % of patients, respectively. Nonischemic myocardial or pericardial involvement was reported in 26 (49.1 %) patients. The prevalence of pericardial LGE was associated inversely with the interval between hospital discharge and CMR. COVID-19 survivors had higher end-systolic volume indices (ESVis) and lower left-ventricular ejection fractions than did healthy controls. Seventeen patients underwent follow-up CMR imaging; the end-diastolic volume index, ESVi, and prevalence of pericardial LGE, but not that of nonischemic LGE, were reduced. ConclusionAmong COVID-19 survivors with myocardial injury during the acute phase of the disease, the incidences of nonischemic myocardial and pericardial LGE and CMR imaging–detected signs of cardiac remodeling, partially reversed during follow-up, were high.

Myocardial Strain Imaging: Theory, Current Practice, and the Future.

Myocardial strain imaging by echocardiography or cardiac magnetic resonance (CMR) is a powerful method to diagnose cardiac disease. Strain imaging provides measures of myocardial shortening, thickening, and lengthening and can be applied to any cardiac chamber. Left ventricular (LV) global longitudinal strain by speckle-tracking echocardiography is the most widely used clinical strain parameter. Several CMR-based modalities are available and are ready to be implemented clinically. Clinical applications of strain include global longitudinal strain as a more sensitive method than ejection fraction for diagnosing mild systolic dysfunction. This applies to patients suspected of having heart failure with normal LV ejection fraction, to early systolic dysfunction in valvular disease, and when monitoring myocardial function during cancer chemotherapy. Segmental LV strain maps provide diagnostic clues in specific cardiomyopathies, when evaluating LV dyssynchrony and ischemic dysfunction. Strain imaging is a promising modality to quantify right ventricular function. Left atrial strain may be used to evaluate LV diastolic function and filling pressure.

Management of acute myocarditis: a systematic review of clinical practice guidelines and recommendations.

The management of acute myocarditis (AM) is addressed in multiple clinical guidelines. We systematically reviewed current guidelines developed by national and international medical organizations on the management of AM to aid clinical practice. Publications in MEDLINE, EMBASE and Cochrane were identified between 1 January 2013 and 12 April 2024. Additionally, the websites of relevant organizations and the Guidelines International Network, Guideline Central, and NHS knowledge and library hub were reviewed. Two reviewers independently screened titles and abstracts, two reviewers assessed the rigour of guideline development, and one reviewer extracted the recommendations. Two of the three guidelines identified showed good rigour of development. Those rigorously developed agreed on the definition of AM, sampling serum troponin as part of the workflow for AM, testing for B-type natriuretic peptides in heart failure, key diagnostic imaging in the form of cardiovascular magnetic resonance, coronary angiography to exclude significant coronary disease, indications for endomyocardial biopsy (EMB), and indications for immunosuppression and advanced treatment options. Discrepancies exist in sampling creatine kinase-myocardial bound as a marker of myocardial injury, indications for EMB, and indications for immunosuppression and treatment of uncomplicated AM. Evidence is lacking for the use of 18F-Fluorodeoxyglucose Positron Emission Tomography for myocardial imaging, exercise restriction, follow-up measures and genetic testing, and there are few high-quality randomized trials to support treatment recommendations. Recommendations for management of AM in the guidelines have largely been developed from expert opinion rather than trial data.

The Feasibility of a Model-Based Iterative Reconstruction Technique Tuned for the Myocardium on Myocardial Computed Tomography Late Enhancement.

This study evaluated the feasibility of a model-based iterative reconstruction technique (MBIR) tuned for the myocardium on myocardial computed tomography late enhancement (CT-LE). Twenty-eight patients who underwent myocardial CT-LE and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) within 1 year were retrospectively enrolled. Myocardial CT-LE was performed using a 320-row CT with low tube voltage (80 kVp). Myocardial CT-LE images were scanned 7 min after CT angiography (CTA) without additional contrast medium. All myocardial CT-LE images were reconstructed with hybrid iterative reconstruction (HIR), conventional MBIR (MBIR_cardiac), and new MBIR tuned for the myocardium (MBIR_myo). Qualitative (5-grade scale) scores and quantitative parameters (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]) were assessed as image quality. The sensitivity, specificity, and accuracy of myocardial CT-LE were evaluated at the segment level using an American Heart Association (AHA) 16-segment model, with LGE-MRI as a reference standard. These results were compared among the different CT image reconstructions. In 28 patients with 448 segments, 160 segments were diagnosed with positive by LGE-MRI. In the qualitative assessment of myocardial CT-LE, the mean image quality scores were 2.9 ± 1.2 for HIR, 3.0 ± 1.1 for MBIR_cardiac, and 4.0 ± 1.0 for MBIR_myo. MBIR_myo showed a significantly higher score than HIR (P < 0.001) and MBIR_cardiac (P = 0.018). In the quantitative image quality assessment of myocardial CT-LE, the median image SNR was 10.3 (9.1-11.1) for HIR, 10.8 (9.8-12.1) for MBIR_cardiac, and 16.8 (15.7-18.4) for MBIR_myo. The median image CNR was 3.7 (3.0-4.6) for HIR, 3.8 (3.2-5.1) for MBIR_cardiac, and 6.4 (5.0-7.7) for MBIR_myo. MBIR_myo significantly improved the SNR and CNR of CT-LE compared to HIR and MBIR_cardiac (P < 0.001). The sensitivity, specificity, and accuracy for the detection of myocardial CT-LE were 70%, 92%, and 84% for HIR; 71%, 92%, and 85% for MBIR_cardiac; and 84%, 92%, and 89% for MBIR_myo, respectively. MBIR_myo showed significantly higher image quality, sensitivity, and accuracy than the others (P < 0.05). MBIR tuned for myocardium improved image quality and diagnostic performance for myocardial CT-LE assessment.

Automatic reorientation to generate short-axis myocardial PET images

BackgroundAccurately redirecting reconstructed Positron emission tomography (PET) images into short-axis (SA) images shows great significance for subsequent clinical diagnosis. We developed a system for automatic redirection and quantitative analysis of myocardial PET images.MethodsA total of 128 patients were enrolled for 18 F-FDG PET/CT myocardial metabolic images (MMIs), including 3 image classifications: without defects, with defects, and excess uptake. The automatic reorientation system includes five modules: regional division, myocardial segmentation, ellipsoid fitting, image rotation and quantitative analysis. First, the left ventricular geometry-based canny edge detection (LVG-CED) was developed and compared with the other 5 common region segmentation algorithms, the optimized partitioning was determined based on partition success rate. Then, 9 myocardial segmentation methods and 4 ellipsoid fitting methods were combined to derive 36 cross combinations for diagnostic performance in terms of Pearson correlation coefficient (PCC), Kendall correlation coefficient (KCC), Spearman correlation coefficient (SCC), and determination coefficient. Finally, the deflection angles were computed by ellipsoid fitting and the SA images were derived by affine transformation. Furthermore, the polar maps were used for quantitative analysis of SA images, and the redirection effects of 3 different image classifications were analyzed using correlation coefficients.ResultsOn the dataset, LVG-CED outperformed other methods in the regional division module with a 100% success rate. In 36 cross combinations, PSO-FCM and LLS-SVD performed the best in terms of correlation coefficient. The linear results indicate that our algorithm (LVG-CED, PSO-FCM, and LLS-SVD) has good consistency with the reference manual method. In quantitative analysis, the similarities between our method and the reference manual method were higher than 96% at 17 segments. Moreover, our method demonstrated excellent performance in all 3 image classifications.ConclusionOur algorithm system could realize accurate automatic reorientation and quantitative analysis of PET MMIs, which is also effective for images suffering from interference.

Integrating myocardial metabolic imaging and stress myocardial contrast echocardiography to improve the diagnosis of coronary microvascular diseases in rabbits.

Persistent challenges associated with misdiagnosis and underdiagnosis of coronary microvascular disease (CMVD) necessitate the exploration of noninvasive imaging techniques to enhance diagnostic accuracy. Therefore, we aimed to integrate multimodal imaging approaches to achieve a higher diagnostic rate for CMVD using high-quality myocardial metabolism imaging (MMI) and myocardial contrast echocardiography (MCE). This combination diagnostic strategy may help address the urgent need for improved CMVD diagnosis. In this study, we established five distinct pretreatment groups, each consisting of nine male rabbit: a fasted group, a nonfasted group, a sugar load group, an acipimox group, and a combination group of nonfasted rabbits administered insulin. Moreover, positron emission tomography-computed tomography (PET/CT) scan windows were established at 30-, 60-, and 90-minute intervals. We developed 10 CMVD models and conducted a diagnosis of CMVD through an integrated analysis of MMI and MCE, including image acquisition and processing. For each heart segment, we calculated the standardized uptake value (SUV) based on body weight (SUVbw), as well as certain ratios of SUV including SUV of the heart (SUVheart) to that of the liver (SUVliver) and SUVheart to SUV of the lung (SUVlung). Additionally, we obtained three coronary SUVbw uptake values. To clarify the relationship between SUVbw uptake values and echocardiographic parameters of the myocardial contrast agent more thoroughly, we conducted a comprehensive analysis across different pretreatment protocols. Receiver operating characteristic (ROC) curve analysis was employed to evaluate the diagnostic accuracy of each parameter in the context of CMVD. In the context of MMI, the nonfasted-plus-insulin group, as observed during the 60-minute examination, exhibited a noteworthy total 18F-fluorodeoxyglucose (18F-FDG) uptake of 47.44±6.53 g/mL, which was found to be statistically different from the other groups. To ascertain the reliability of the results, two double-blind investigators independently assessed the data and achieved a good level of agreement, according to the intraclass correlation coefficient (ICC) (0.957). The SUVbw of the nonfasted-plus-insulin group exhibited a moderate correlation with the microvascular blood flow reserve (MBFR) parameters derived from the MCE examination, as evidenced by a r value of 0.686. For the diagnosis of CMVD disease, the diagnostic accuracy of the combined diagnostic method [area under the curve (AUC) =0.789; 95% confidence interval (CI): 0.705-0.873] was significantly higher than that of the MBFR (AUC =0.697; 95% CI: 0.597-0.797) and SUVbw (AUC =0.715; 95% CI: 0.622-0.807) methods (P<0.05). Our study demonstrated the feasibility of a simple premedication approach involving free feeding and intravenous insulin in producing high-quality gated heart 18F-FDG PET/CT images in adult male New Zealand white rabbits. This technique holds considerable potential for ischemic heart disease research in rabbits and can enhance CMVD diagnosis via the comprehensive assessment of myocardial metabolism and perfusion.

High-Resolution Tissue Doppler and Strain Imaging for Adult Zebrafish Myocardial Tissue Through Ultrafast High-Frequency Ultrasound Vector Doppler Estimation.

Zebrafish has been considered as an essential small-animal model for investigating the mechanism of heart regeneration. Due to the small size of zebrafish heart, high-frequency ultrasound (HFUS) imaging is often required for in vivo evaluations of its dynamic functions. Although commercial HFUS systems are available for myocardial velocity and strain measurement, only the outer myocardial region can be quantified due to the complex structure of zebrafish heart. In this study, a high-resolution 2-D myocardial tissue Doppler and strain imaging based on ultrafast HFUS imaging was developed for zebrafish heart imaging during heart regeneration. The cardiac flow region was first extracted to recognize the myocardial region, and the myocardial velocity and strain were then determined through vector Doppler estimation. Adult AB-line zebrafish was used for in vivo experiments, and cryoinjury was induced in the apical region of the heart. Both the myocardial velocity and strain of the whole ventricle after cryoinjury were directly visualized over 28 days. Myocardial velocity (during later diastolic motion) and strain, respectively, were significantly decreased (anterior wall: -2.0 mm/s and -3.3%; apical region: -2.0 mm/s and -4.5%; and posterior wall (PW): -1.7 mm/s and -4.3%) at the first three days after cryoinjury, which indicates weak myocardial beating due to heart injury. However, these all returned to the baseline values at 14 days after cryoinjury. All of the experimental results indicate that the proposed method is a useful tool for heart regeneration studies in adult zebrafish. In particular, it allows for the noninvasive evaluation of regional dynamic heart function.

A simplified approach to discriminate between healthy subjects and patients with heart failure using cardiac magnetic resonance myocardial deformation imaging.

Left ventricular global longitudinal strain (LV-GLS) shows promise as a marker to detect early heart failure (HF). This study sought to (i) establish cardiac magnetic resonance imaging (CMR)-derived LV-GLS cut-offs to differentiate healthy from HF for both acquisition-based and post-processing techniques, (ii) assess agreement, and (iii) provide a method to convert LV-GLS between both techniques. A secondary analysis of a prospective study enrolling healthy subjects (n = 19) and HF patients (n = 56) was conducted. LV-GLS was measured using fast strain-encoded imaging (fSENC) and feature tracking (FT). Receiver operating characteristic (ROC) analyses were performed to derive and evaluate LV-GLS cut-offs discriminating between healthy, HF with mild deformation impairment (DI), and HF with severe DI. Linear regression and Bland-Altman analyses assessed agreement. Cut-offs discriminating between healthy and HF were identified at -19.3% and -15.1% for fSENC and FT, respectively. Cut-offs of -15.8% (fSENC) and -10.8% (FT) further distinguished mild from severe DI. No significant differences in area under ROC curve were identified between fSENC and FT. Bland-Altman analysis revealed a bias of -4.01%, 95% CI -4.42, -3.50 for FT, considering fSENC as reference. Linear regression suggested a factor of 0.76 to rescale fSENC-derived LV-GLS to FT. Using this factor on fSENC-derived cut-offs yielded rescaled FT LV-GLS cut-offs of -14.7% (healthy vs. HF) and -12% (mild vs. severe DI). LV-GLS distinguishes healthy from HF with high accuracy. Each measurement technique requires distinct cut-offs, but rescaling factors facilitate conversion. An FT-based LV-GLS ≥ -15% simplifies HF detection in clinical routine.