Quantitative Assessment of Left Ventricular Function and Myocardial Mass: A Comparison of Coronary CT Angiography with Cardiac MRI and Echocardiography

Comparison of left ventricular mass and wall thickness between cardiac computed tomography angiography and cardiac magnetic resonance imaging using machine learning algorithms

Aims

Cardiac magnetic resonance imaging (MRI) is the gold standard in the assessment of left ventricle (LV) mass and wall thickness. In recent years, cardiac computed tomography angiography (CCTA) has gained widespread usage as an imaging modality. Despite this, limited previous investigations have specifically addressed the potential of CCTA as an alternative modality for quantitative LV assessment. The aim of this study was to compare CCTA derived LV mass and wall thickness with cardiac MRI utilizing machine learning algorithms.

Methods and results

Fifty-seven participants who underwent both CCTA and cardiac MRI were identified. LV mass and wall thickness was calculated using LV contours which were automatically placed using in-house developed machine learning models. Pearson's correlation coefficients were calculated along with Bland-Altman plots to assess the agreement between the LV mass and wall thickness per region on CCTA and cardiac MRI. Inter-observer correlations were tested using Pearson's correlation coefficient. Average LV mass and wall thickness for CCTA and cardiac MRI were 127 g, 128 g, 7, and 8 mm, respectively. Bland-Altman plots demonstrated mean differences and corresponding 95% limits of agreement of -1.26 (25.06; -27.58) and -0.57 (1.78; -2.92), for LV mass and average LV wall thickness, respectively. Mean differences and corresponding 95% limits of agreement for wall thickness per region were -0.75 (1.34; -2.83), -0.58 (2.14; -3.30), and -0.29 (3.21; -3.79) for the basal, mid, and apical regions, respectively. Inter-observer correlations were excellent.

Conclusion

Quantitative assessment of LV mass and wall thickness on CCTA using machine learning algorithms seems feasible and shows good agreement with cardiac MRI.

[Using CT to Evaluate Cardiac Function]

A comprehensive evaluation of cardiac function includes information in relation to cardiac output and systemic venous return. The heart is composed of four chambers: two atria and two ventricles, each with its own unique mechanical function. These four cardiac chambers, their valves, and the pulmonary circulation system are inter-related as they preload or afterload on each other. Cardiac dysfunction is a failure of global cardiac function, resulting in typical clinical manifestations. To investigate the underlying cause of cardiac dysfunction, a step-by-step evaluation of cardiac blood flow tracks is necessary. In this context, imaging markers showing details of the cardiac structures have an important role in assessing cardiac function. An image-based evaluation allows for investigation of function in terms of individual cardiac components. Evaluation of cardiac function using cardiac CT has recently been validated. This review aimed to discuss cardiac CT-based imaging markers for comprehensive and detailed cardiac function assessment.

Multimodality cardiovascular imaging in hypertension

PURPOSE OF THE REVIEW

Hypertension accounts for the largest proportion of cardiovascular (CV) mortality worldwide and its prevalence continues to rise. While prominent CV societies have offered strong recommendations on the management of hypertension in adults, the role of noninvasive CV imaging in the evaluation of hypertensive patients remains incompletely defined.

RECENT FINDINGS

Noninvasive imaging is a rapidly expanding field with a growing number of sophisticated and readily applicable modalities to assess how cardiac structure and function changes after periods of sustained, elevated blood pressure. Echocardiography remains the initial modality to screen these patients while developments in nuclear, computed tomography and cardiac magnetic resonance complement and expand investigations for alternative diagnoses that may complement or conflict with the diagnosis of left ventricular hypertrophy.

SUMMARY

In this review article, we summarize the application of echocardiography, nuclear imaging, cardiac computed tomography, and cardiac magnetic resonance imaging in the evaluation and management of hypertensive heart disease.

Two wrongs sometimes do make a right: errors in aortic valve stenosis assessment by same-day Doppler echocardiography and 4D flow MRI

This study aims to systematically verify if the simplified geometry and flow profile of the left ventricular outflow tract (LVOT) assumed in 2D echocardiography is appropriate while examining the utility of 4D flow MRI to assess valvular disease. This prospective study obtained same-day Doppler echocardiography and 4D flow MRI in 37 healthy volunteers (age: 51.9 ± 18.2, 20 females) and 7 aortic stenosis (AS) patients (age: 64.2 ± 9.6, 1 female). Two critical assumptions made in echocardiography for aortic valve area assessment were examined, i.e. the assumption of (1) a circular LVOT shape and (2) a flat velocity profile through the LVOT. 3D velocity and shape information obtained with 4D flow MRI was used as comparison. It was found that the LVOT area was lower (by 26.5% and 24.5%) and the velocity time integral (VTI) was higher (by 28.5% and 30.2%) with echo in the healthy and AS group, respectively. These competing errors largely cancelled out when examining individual and cohort averaged LVOT stroke volume. The LVOT area, VTI and stroke volume measured by echo and 4D flow MRI were 3.6 ± 0.7 vs. 4.9 ± 1.0 cm2 (p < 0.001), 21.2 ± 3.0 vs 15.2 ± 2.8 cm (p < 0.001), and 75.6 ± 15.6 vs 72.8 ± 14.1 ml (p = 0.3376), respectively. In the ensemble average of LVOT area and VTI, under- and over-estimation seem to compensate each other to result in a 'realistic' stroke volume. However, it is important to understand that this compensation may fail. 4D flow MRI provides a unique insight into this phenomenon.

Cardiac CT angiography: normal and pathological anatomical features-a narrative review

The normal and pathological anatomy of the heart and coronary arteries are nowadays widely developed topics and constitute a fundamental part of the cultural background of the radiologist. The introduction of cardiac ECG-gated synchronized CT scanners with an ever-increasing number of detectors and with increasingly high structural characteristics (increase in temporal resolution, increase in contrast resolution with dual-source, dual energy scanners) allows the virtual measurement of anatomical in vivo structures complying with heart rate with submillimetric precision permitting to clearly depict the normal anatomy and follow the pathologic temporal evolution. Accordingly to these considerations, cardiac computed tomography angiography (CCTA) asserts itself as a gold standard method for the anatomical evaluation of the heart and permits to evaluate, verify, measure and characterize structural pathological alterations of both congenital and acquired degenerative diseases. Accordingly, CCTA is increasingly used as a prognostic model capable of modifying the outcome of diseased patients in planning interventions and in the post-surgical/interventional follow-up. The profound knowledge of cardiac anatomy and function through highly detailed CCTA analysis is required to perform an efficient and optimal use in real-world clinical practice.

Achieving Low Radiation Dose in "One-Stop" Myocardial Computed Tomography Perfusion Imaging in Coronary Artery Disease Using 16-cm Wide Detector CT

RATIONALE AND OBJECTIVES

To investigate the feasibility of "one-stop" myocardial computed tomography perfusion (CTP) imaging (combined anatomy, perfusion, and function) in coronary artery disease using 16-cm wide detector CT, compared to conventional coronary CT angiography (CCTA).

MATERIALS AND METHODS

442 patients with suspected coronary artery disease were randomly divided into two groups. Patients in group A underwent "one-stop" CTP, whereas group B underwent conventional CCTA. Image quality of CT images was assessed. Radiation and contrast medium doses and scan time of the two groups were recorded. Group A was further divided into four subgroups according to the degree of coronary artery stenosis, for which transmural perfusion ratio (TPR) and left ventricular ejection fraction (LVEF) were measured.

RESULTS

Scan time was 73.1 ± 7.3 (s) longer in group A than in group B with 11.7% reduction of radiation dose (p < 0.001) and no significant difference in image quality was noted. Significant differences regarding the minimum TPR (F = 24.657, p < 0.001) and LVEF (χ² =36.98, p < 0.001) were observed among four subgroups. A negative correlation was found between the degree of coronary artery stenosis and TPR of the corresponding myocardial segments (r = -0.55, p < 0.001). Patients with moderate to severe arterial stenosis exhibited a decreased LVEF compared to those with normal coronary arteries (48.0% vs 56.5%, p < 0.001).

CONCLUSION

Compared to conventional CCTA, our new developed "one-stop" CTP may provide more comprehensive information on myocardial perfusion, coronary artery stenosis, and LV cardiac function with reduced radiation and contrast medium doses.

A Pilot Study of Third-Generation Dual-Source Computed Tomography for the Assessment of Global Dynamic Changes in Left Ventricular Structure and Function in a Porcine Model of Acute Myocardial Infarction

Background

First-generation and second-generation dual-source computed tomography (DSCT) are useful for analyzing left ventricle (LV) structure and function. This pilot study aimed to investigate the feasibility and role of third-generation DSCT for the evaluation of dynamic changes in LV structural and functional characteristics in a Diannan small-ear pig model of acute myocardial infarction (AMI).

Material/Methods

The model of AMI was established by balloon occlusion of the distal third of the left anterior descending (LAD) coronary artery in 14 Diannan small-eared pigs. Third-generation DSCT was performed to observe dynamic changes in LV structure and function before and after AMI was induced, with a follow-up period of 30 days.

Results

The mean structural measurements at baseline included interventricular septum thickness (8.50±0.90 mm), LV anterior wall thickness (8.40±1.30 mm), LV posterior wall thickness (7.80±1.20 mm), LV end-diastolic dimension (LVEDD) (45.00±4.90 mm), and LV end-systolic dimension (LVESD) (25.90±4.10 mm). The mean functional measurements at baseline included the LV end-diastolic volume (LVEDV) (74.62±13.54 ml), LV end-systolic volume (LVESV) (23.06±7.46 ml), LV ejection fraction (LVEF) (69.29±6.83%), LV mass (86.35±14.02 g), stroke volume (SV) (51.56±9.77 ml), and cardiac output (CO) (4.22±2.14 l/min). Trends of time-dependent changes were observed for LVESV, LVEF, SV, and CO, but not for LVEDV or LV mass.

Conclusions

Third-generation DSCT was validated as a tool for assessing dynamic changes in LV global function in a porcine model of AMI.

Use of Cardiac Imaging to Evaluate Cardiac Function and Pulmonary Hemodynamics in Patients with Heart Failure

PURPOSE OF REVIEW

Noninvasive hemodynamic assessments in patients with heart failure (HF) are essential for appropriate diagnosis and establishment of the best treatment strategies. Recently, the impact of pulmonary circulation and right ventricular function on prognosis in HF patients has drawn increasing attention. In this article, we explore the usefulness of cardiac imaging for hemodynamic assessments, mainly focusing on echocardiographic evaluation.

RECENT FINDINGS

The reliability of Doppler echocardiography as a noninvasive alternative to Swan-Ganz catheterization has been well investigated with higher than 80% accuracy for estimating pulmonary artery pressure. Strain measurement and three-dimensional echocardiography are useful for evaluating right ventricular function together with pulmonary circulation. The accuracy of analyzing left and right ventricular functions by cardiac computed tomography and cardiac magnetic resonate imaging has also been established. These modalities can provide myocardial tissue information and allow calculation of the extracellular volume fraction as well. According to the rapid improvement of technologies, cardiac imaging has become an essential tool for hemodynamic evaluation in HF management.

Technical feasibility of semiautomatic three-dimensional threshold-based cardiac computed tomography quantification of left ventricular mass

BACKGROUND

Semiautomatic three-dimensional (3-D) threshold-based cardiac computed tomography (CT) quantification has not been attempted for left ventricular mass.

OBJECTIVE

To evaluate the technical feasibility of semiautomatic 3-D threshold-based cardiac CT quantification of left ventricular mass in patients with various degrees of left ventricular hypertrophy.

MATERIALS AND METHODS

In 99 patients, cardiac CT was utilized to quantify ventricular volume and mass by using a semiautomatic 3-D threshold-based method. Left ventricular mass values were compared between the end-systole and the end-diastole. Volumetric parameters were compared among three left ventricular hypertrophy groups (definite, borderline, none). The reproducibility was assessed. The t-test, one-way analysis of variance and Pearson correlation were used.

RESULTS

There were no technical failures. The left ventricular mass between the two sessions exhibited a small mean difference of 2.3±1.1% (mean±standard deviation). The indexed mass values were significantly higher at the end-systole than at the end-diastole (71.4±42.9 g/m² vs. 65.9±43.3 g/m², P<0.001), with significant correlation (R=0.99, P<0.001). The definite group (83.5±41.3 g/m²) showed statistically significantly higher indexed mass values than the borderline and none groups (64.7±26.9 and 55.6±23.9 g/m², respectively; P<0.03), while demonstrating no statistically significant difference between the latter two groups (P>0.05). Left ventricular volume-mass and mass-volume ratios could be calculated in all three groups.

CONCLUSION

CT quantification of left ventricular mass using semiautomatic 3-D threshold-based segmentation is feasible with high reproducibility and the mass values and its ratios with ventricular volumes may be used in patients with various degrees of left ventricular hypertrophy.

Quantification in cardiovascular magnetic resonance: agreement of software from three different vendors on assessment of left ventricular function, 2D flow and parametric mapping

BACKGROUND

Quantitative results of cardiovascular magnetic resonance (CMR) image analysis influence clinical decision making. Image analysis is performed based on dedicated software. The manufacturers provide different analysis tools whose algorithms are often unknown. The aim of this study was to evaluate the impact of software on quantification of left ventricular (LV) assessment, 2D flow measurement and T1- and T2-parametric mapping.

METHODS

Thirty-one data sets of patients who underwent a CMR Scan on 1.5 T were analyzed using three different software (Circle CVI: cvi42, Siemens Healthineers: Argus, Medis: Qmass/Qflow) by one reader blinded to former results. Cine steady state free precession short axis images were analyzed regarding LV ejection fraction (EF), end-systolic and end-diastolic volume (ESV, EDV) and LV mass. Phase-contrast magnetic resonance images were evaluated for forward stroke volume (SV) and peak velocity (Vmax). Pixel-wise generated native T1- and T2-maps were used to assess T1- and T2-time. Forty-five data sets were evaluated twice (15 per software) for intraobserver analysis. Equivalence was considered if the confidence interval of a paired assessment of two sofware was within a tolerance interval defined by ±1.96 highest standard deviation obtained by intraobserver analysis.

RESULTS

For each parameter, thirty data sets could be analyzed with all three software. All three software (A/B, A/C, B/C) were considered equivalent for LV EF, EDV, ESV, mass, 2D flow SV and T2-time. Differences between software were detected in flow measurement for Vmax and in parametric mapping for T1-time. For Vmax, equivalence was given between software A and C and for T1-time equivalence was given between software B and C.

CONCLUSION

Software had no impact on quantitative results of LV assessment, T2-time and SV based on 2D flow. In contrast to that, Vmax and T1-time may be influenced by software. CMR reports should contain the name and version of the software applied for image analysis to avoid misinterpretation upon follow-up and research examinations.

TRIAL REGISTRATION

ISRCTN12210850 . Registered 14 July 2017, retrospectively registered.

Ossabaw Pigs With a PCSK9 Gain-of-Function Mutation Develop Accelerated Coronary Atherosclerotic Lesions: A Novel Model for Preclinical Studies

BACKGROUND

Ossabaw pigs are unique miniature swine with genetic predisposition to develop metabolic syndrome and coronary atherosclerosis after extended periods receiving atherogenic diets. We have hypothesized that transgenic Ossabaw swine expressing chimp PCSK9 (proprotein convertase subtilisin-like/kexin type 9) containing the D374Y gain of function would develop familial hypercholesterolemia and coronary artery plaques more rapidly than Landrace swine with the same transgene.

METHODS AND RESULTS

Ossabaw and Landrace PCSK9 gain-of-function founders were generated by Sleeping Beauty transposition and cloning. Histopathologic findings in the Ossabaw founder animal showed more advanced plaques and higher stenosis than in the Landrace founder, underscoring the Ossabaw genetic predisposition to atherosclerosis. We chose to further characterize the Ossabaw PCSK9 gain-of-function animals receiving standard or atherogenic diets in a 6-month longitudinal study using computed tomography, magnetic resonance (MR) imaging, intravascular ultrasound, and optical coherence tomography, followed by pathological analysis of atherosclerosis focused on the coronary arteries. The Ossabaw model was consistently hypercholesterolemic, with or without dietary challenge, and by 6 months had consistent and diffuse fibrofatty or fibroatheromatous plaques with necrosis, overlying fibrous caps, and calcification in up to 10% of coronary plaques.

CONCLUSIONS

The Ossabaw PCSK9 gain-of-function model provides consistent and robust disease development in a time frame that is practical for use in preclinical therapeutic evaluation to drive innovation. Although no animal model perfectly mimics the human condition, this genetic large-animal model is a novel tool for testing therapeutic interventions in the context of developing and advanced coronary artery disease.

Role of Imaging in Cardio-Oncology

OPINION STATEMENT

Recent advances in cancer treatment and research have greatly improved survival rates for patients with cancer. However, many of these cancer survivors are developing cardiac disease-most commonly heart failure as a result of this treatment. Certain chemotherapeutic agents, including anthracyclines and trastuzumab, have been linked to cardiotoxicity-induced cardiomyopathy in cancer patients. It has been reported as early as during infusion and as late as several years following treatment. Radiation therapy, particularly to the left breast, has also been linked to cardiac disease. The responsibility of cardiac monitoring has traditionally fallen on oncologists using assessment of LVEF through multigated acquisition (MUGA) scans or echocardiograms. The "formal" definition of cardiotoxicity, as a 5 to 10% decrease in LVEF from its baseline, even though not validated, is currently used by clinicians to alter treatment, but it has been recently challenged, as a possible irreversible late stage of a myocardial insult. Furthermore, it falls into the interobserver variability range of echocardiography. The growing field of medicine called cardio-oncology is based on emerging research that has shown that more advanced imaging modalities can help detect cardiotoxicity early, allowing the patient to receive treatment and avoid developing heart failure from cancer treatment. While traditional imaging still has its place in cardiac monitoring, cardiac magnetic resonance imaging is the most accurate and detailed imaging modality available to assess cardiotoxicity. Our own pilot cardiac MRI study suggests that a normal left ventricular remodeling to chemotherapy, when patients have not developed heart failure symptoms, could occur over time. Perhaps, knowing a baseline normal response could help us to define a more accurate definition of cardiotoxicity by CMR. Here, we discuss various imaging modalities and emerging techniques that can assist in detecting early signs of cardiotoxicity and thus reduce the incidence of cardiac disease in cancer survivors.