Left ventricular ejection fraction using 64-slice CT coronary angiography and new evaluation software: initial experience

The Potential Role of Cardiac CT in the Evaluation of Patients With Known or Suspected Cardiomyopathy: From Traditional Indications to Novel Clinical Applications

After 15 years from its advent in the clinical field, coronary computed tomography (CCTA) is now widely considered as the best first-step test in patients with low-to-moderate pre-test probability of coronary artery disease. Technological innovation was of pivotal importance for the extensive clinical and scientific interest in CCTA. Recently, the advent of last generation wide-coverage CT scans paved the way for new clinical applications of this technique beyond coronary arteries anatomy evaluation. More precisely, both biventricular volume and systolic function quantification and myocardial fibrosis identification appeared to be feasible with last generation CT. In the present review we would focus on potential applications of cardiac computed tomography (CCT), beyond CCTA, for a comprehensive assessment patients with newly diagnosed cardiomyopathy, from technical requirements to novel clinical applications.

Global left ventricular function assessment by ECG-gated multi-detector CT (MDCT): revised role in relation to 2D transthoracic echocardiography

Background

An accurate and reproducible way for determining the left ventricular function is crucial to provide diagnostic and prognostic aspects of the pump activity of the heart. The MDCT of the heart can be that modality. We compared the 128 MDCT of fifty patients with their 2D echocardiography performed on the same day.

Results

Mean EF, ESV, EDV, and LV mass were 61.22 ± 9.50%, 70.23 ± 38.35, 172.22 ± 53.57, 164.63 ± 52.57 respectively on MDCT, and 61.14 ± 10.90%, 72.13 ± 32.69, 173.76 ± 62.45, 198.32 ± 72.54 respectively on echocardiography with moderate correlation in EF and good correlation in ventricular volumes (p < 0.05) using linear regression analysis. A Bland-Altman analysis showed that MDCT had slightly lower LFEF, LVESV, and LVEDV values with mean value of differences of 0.8, 2.4, and 2.28 respectively.

Conclusion

It is reasonable to use MDCT alone to assess LV function in patients already underwent coronary CT angiography.

Automated Segmentation of Left Ventricular Myocardium on Cardiac Computed Tomography Using Deep Learning

OBJECTIVE

To evaluate the accuracy of a deep learning-based automated segmentation of the left ventricle (LV) myocardium using cardiac CT.

MATERIALS AND METHODS

To develop a fully automated algorithm, 100 subjects with coronary artery disease were randomly selected as a development set (50 training / 20 validation / 30 internal test). An experienced cardiac radiologist generated the manual segmentation of the development set. The trained model was evaluated using 1000 validation set generated by an experienced technician. Visual assessment was performed to compare the manual and automatic segmentations. In a quantitative analysis, sensitivity and specificity were calculated according to the number of pixels where two three-dimensional masks of the manual and deep learning segmentations overlapped. Similarity indices, such as the Dice similarity coefficient (DSC), were used to evaluate the margin of each segmented masks.

RESULTS

The sensitivity and specificity of automated segmentation for each segment (1-16 segments) were high (85.5-100.0%). The DSC was 88.3 ± 6.2%. Among randomly selected 100 cases, all manual segmentation and deep learning masks for visual analysis were classified as very accurate to mostly accurate and there were no inaccurate cases (manual vs. deep learning: very accurate, 31 vs. 53; accurate, 64 vs. 39; mostly accurate, 15 vs. 8). The number of very accurate cases for deep learning masks was greater than that for manually segmented masks.

CONCLUSION

We present deep learning-based automatic segmentation of the LV myocardium and the results are comparable to manual segmentation data with high sensitivity, specificity, and high similarity scores.

Comparison of Echocardiography, Cardiac Magnetic Resonance, and Computed Tomographic Imaging for the Evaluation of Left Ventricular Myocardial Function: Part 1 (Global Assessment)

Assessing left ventricular function is an essential part of the cardiovascular evaluation as it plays an important role in managing the patient and predicting prognosis. Recent advances in the imaging modalities currently allow a non-invasive comprehensive assessment of cardiac mechanics and precise estimation of cardiovascular hemodynamics. In this review, we will discuss and compare the currently available techniques and novel approaches utilized by echocardiography, cardiac magnetic resonance, and computed tomography for the assessment of global left ventricular performance.

Segmentation and optical flow estimation in cardiac CT sequences based on a spatiotemporal PDM with a correction scheme and the Hermite transform

PURPOSE

The left ventricle and the myocardium are two of the most important parts of the heart used for cardiac evaluation. In this work a novel framework that combines two methods to isolate and display functional characteristics of the heart using sequences of cardiac computed tomography (CT) is proposed. A shape extraction method, which includes a new segmentation correction scheme, is performed jointly with a motion estimation approach.

METHODS

For the segmentation task we built a Spatiotemporal Point Distribution Model (STPDM) that encodes spatial and temporal variability of the heart structures. Intensity and gradient information guide the STPDM. We present a novel method to correct segmentation errors obtained with the STPDM. It consists of a deformable scheme that combines three types of image features: local histograms, gradients and binary patterns. A bio-inspired image representation model based on the Hermite transform is used for motion estimation. The segmentation allows isolating the structure of interest while the motion estimation can be used to characterize the movement of the complete heart muscle.

RESULTS

The work is evaluated with several sequences of cardiac CT. The left ventricle was used for evaluation. Several metrics were used to validate the proposed framework. The efficiency of our method is also demonstrated by comparing with other techniques.

CONCLUSION

The implemented tool can enable physicians to better identify mechanical problems. The new correction scheme substantially improves the segmentation performance. Reported results demonstrate that this work is a promising technique for heart mechanical assessment.

MDCT Derived Left Ventricular Function in Relation to Echocardiography: Validation and Revising the Role with the Evolving Technology

BACKGROUND

Coronary computed tomography angiography (CCTA) is a frequently performed examination for coronary artery disease. When performed with retrospective gating, there is an opportunity to derive functional parameters of left ventricle utilizing automated software. Complementary information, if validated with established standards, will enhance the total value of study.

OBJECTIVE

Study evaluates the usefulness of fully automated software for the assessment of left ventricular ejection fraction (LVEF) using 64-slice CCTA data and to correlate CT results with echocardiography (ECHO). Role of CT derived LV function is reviewed in the light of emerging technologies and recent developments in multidetector CT (MDCT).

MATERIALS AND METHODS

A total of 113 patients referred for MDCT CCTA for evaluation of coronary artery disease. All patients were scanned on 64 slice GE-Helical CT scanner and had an ECHO done within 1 week of the CT scan. Retrospectively electrocardiogram (ECG)-correlated image reconstruction was performed with the reconstruction at 10% R-R interval increment. Axial image sets were analyzed with advanced workstation using a program-Auto ejection fraction, Circulation: GE Medical Solutions.

RESULTS

The mean LVEF calculated by clinical ECHO was 58.6 ± 4.5% and by fully automated software based on CTA data was 58.9 ± 5.4%. The Pearson's regression analysis showed a large correlation, with a correlation coefficient of 0.503 (P < 0.001). Bland-Altman analysis showed a trend towards MDCT resulting in slightly higher values for LVEF when compared with ECHO.

CONCLUSION

The fully automated software is simple, reliable, and user-friendly, and can provide rapid assessment of LV functional parameters with good reproducibility. Despite of good correlation, fewer patients are likely to benefit, in future, from this function due to smaller number of patients undergoing CCTA with retrospective gating.

Accuracy of multi-slice computed tomography for measurement of left ventricular ejection fraction compared with cardiac magnetic resonance imaging and two-dimensional transthoracic echocardiography: a systematic review and meta-analysis

BACKGROUND

Multi-slice computed tomography (MSCT) allows non-invasive assessment of the coronary arteries and simultaneously can provide measurement of left ventricular ejection fraction (LVEF). The accuracy of newer MSCT generations (64-slice or more) for assessment of LVEF compared with magnetic resonance imaging (MRI) and two-dimensional transthoracic echocardiography (TTE) has not been evaluated in a meta-analysis.

PURPOSE

To evaluate, via a systematic literature review and meta-analysis, whether MSCT can assess LVEF with high accuracy compared with MRI and TTE.

METHODS

Electronic databases and reference lists for relevant published studies were searched. Twenty-seven eligible studies provided mean LVEF% with its standard deviation (SD) measured by MSCT versus MRI and TTE. Meta-analysis of weighted mean difference (WMD) and Bland-Altman method were used to quantify the mean difference and agreement between MSCT compared with MRI and TTE.

RESULTS

The results of combining 12 studies showed no significant difference in LVEF% between MSCT and MRI with a WMD of -0.11 (-1.48, 1.26, 95% CI), p=0.88. Bland-Altman analysis showed excellent agreement between MSCT and MRI with a bias of 0.0 (-3.7, 3.7 ± 1.96SD) with 95% CI. The results of combining 15 studies showed no significant difference in LVEF between MSCT versus TTE measurements with a WMD of 0.19 (-1.13 to 1.50; 95% CI), p=0.87. Bland-Altman analysis showed excellent agreement between MSCT and TTE with a bias of 0.3 (-4.7, 5.7 ± 1.96SD) with 95% CI.

CONCLUSION

The newer MSCT generations can provide accurate LVEF measurement compared to MRI and TTE. MSCT represents a valid technique for the combined evaluation of LVEF and coronary artery disease.

Informatics in radiology: postprocessing pitfalls in using CT for automatic and semiautomatic determination of global left ventricular function

Recent advances in technical capabilities of computed tomographic (CT) scanners, including an increasing number of detector rows, improved spatial and temporal resolution, and the development of retrospective gating, have allowed the acquisition of four-dimensional (4D) datasets of the beating heart. As a result, the heart can be visualized in different phases and CT datasets can be used to assess cardiac function. Many software packages currently exist that allow automatic or semiautomatic evaluation of left ventricular function on the basis of 4D CT datasets. The level of automation varies from extensive, completely manual segmentation by the user to fully automatic evaluation of left ventricular function without any user interaction. Although the reproducibility of functional parameter assessment is reported to be high and intersoftware variability low for larger groups of patients, significant differences can exist among measurements obtained with different software tools from the same dataset. Thus, careful review of automatically or semiautomatically obtained results is required.

Left and right ventricle assessment with Cardiac CT: validation study vs. Cardiac MR

Objectives

To compare Magnetic Resonance (MR) and Computed Tomography (CT) for the assessment of left (LV) and right (RV) ventricular functional parameters.

Methods

Seventy nine patients underwent both Cardiac CT and Cardiac MR. Images were acquired using short axis (SAX) reconstructions for CT and 2D cine b-SSFP (balanced-steady state free precession) SAX sequence for MR, and evaluated using dedicated software.

Results

CT and MR images showed good agreement: LV EF (Ejection Fraction) (52 ± 14% for CT vs. 52 ± 14% for MR; r = 0.73; p > 0.05); RV EF (47 ± 12% for CT vs. 47 ± 12% for MR; r = 0.74; p > 0.05); LV EDV (End Diastolic Volume) (74 ± 21 ml/m² for CT vs. 76 ± 25 ml/m² for MR; r = 0.59; p > 0.05); RV EDV (84 ± 25 ml/m² for CT vs. 80 ± 23 ml/m² for MR; r = 0.58; p > 0.05); LV ESV (End Systolic Volume)(37 ± 19 ml/m² for CT vs. 38 ± 23 ml/m² for MR; r = 0.76; p > 0.05); RV ESV (46 ± 21 ml/m² for CT vs. 43 ± 18 ml/m² for MR; r = 0.70; p > 0.05). Intra- and inter-observer variability were good, and the performance of CT was maintained for different EF subgroups.

Conclusions

Cardiac CT provides accurate and reproducible LV and RV volume parameters compared with MR, and can be considered as a reliable alternative for patients who are not suitable to undergo MR.

Key Points

• Cardiac-CT is able to provide Left and Right Ventricular function.

• Cardiac-CT is accurate as MR for LV and RV volume assessment.

• Cardiac-CT can provide accurate evaluation of coronary arteries and LV and RV function.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-011-2345-6) contains supplementary material, which is available to authorized users.

Automatic vs semi-automatic global cardiac function assessment using 64-row CT

OBJECTIVE

Global cardiac function assessment using multidetector CT (MDCT) is time-consuming. Therefore we sought to compare an automatic software tool with an established semi-automatic method.

METHODS

A total of 36 patients underwent CT with 64 × 0.5 mm detector collimation, and global left ventricular function was subsequently assessed by two independent blinded readers using both an automatic region-growing-based software tool (with and without manual adjustment) and an established semi-automatic software tool. We also analysed automatic motion mapping to identify end-systole.

RESULTS

The time needed for assessment using the semi-automatic approach (12:12 ± 6:19 min) was reduced by 75-85% with the automatic software tool (unadjusted, 01:34 ± 0:29 min, adjusted, 02:53 ± 1:19 min; both p<0.001). There was good correlation (r=0.89; p<0.001) for the ejection fraction (EF) between the adjusted automatic (58.6 ± 14.9%) and the semi-automatic (58.0 ± 15.3%) approaches. Also the manually adjusted automatic approach led to significantly smaller limits of agreement than the unadjusted automatic approach for end-diastolic volume (±36.4 ml vs ±58.5 ml, p>0.05). Using motion mapping to automatically identify end-systole reduced analysis time by 95% compared with the semi-automatic approach, but showed inferior precision for EF and end-systolic volume.

CONCLUSION

Automatic function assessment using MDCT with manual adjustment shows good agreement with an established semi-automatic approach, while reducing the analysis by 75% to less than 3 min. This suggests that automatic CT function assessment with manual correction may be used for fast, comfortable and reliable evaluation of global left ventricular function.

Comparison of (semi-)automatic and manually adjusted measurements of left ventricular function in dual source computed tomography using three different software tools

To assess the accuracy of (semi-)automatic measurements of left ventricular (LV) functional parameters in cardiac dual-source computed tomography (DSCT) compared to manually adjusted measurements in three different workstations. Forty patients, who underwent cardiac DSCT, were included (31 men, mean age 58 ± 14 years). Multiphase reconstructions were made with ten series at every 10% of the RR-interval. LV function analysis was performed on three different, commercially available workstations. On all three workstations, end-systolic volume (ESV), end-diastolic volume (EDV), LV ejection fraction (LVEF) and myocardial mass (MM) were calculated as automatically as possible. With the same DSCT datasets, LV functional parameters were also calculated with as many manual adjustments as needed for accurate assessment for all three software tools. For both semi-automatic as well as manual methods, time needed for evaluation was recorded. Paired t-tests were employed to calculate differences in LV functional parameters. Repeated measurements were performed to determine intra-observer and inter-observer variability. (Semi-)automatic measurements revealed a good correlation with manually adjusted measurements for Vitrea (LVEF r = 0.93, EDV r = 0.94, ESV r = 0.98 and MM r = 0.94) and Aquarius (LVEF r = 0.96, EDV r = 0.94, ESV r = 0.98 and MM r = 0.96). Also, good correlation was obtained for Circulation, except for LVEF (LVEF r = 0.45, EDV r = 0.93, ESV r = 0.92 and MM r = 0.86). However, statistically significant differences were found between (semi-)automatically and manually adjusted measurements for LVEF (P < 0.05) and ESV (P < 0.001) in Vitrea, all LV functional parameters in Circulation (P < 0.001) and EDV, ESV and MM (<0.001) in Aquarius Workstation. (Semi-)automatic measurement of LV functional parameters is feasible, but significant differences were found for at least two different functional parameters in all three workstations. Therefore, expert manual correction is recommended at all times.