Quantification of global left ventricular function: comparison of multidetector computed tomography and magnetic resonance imaging. a meta-analysis and review of the current literature

Recommendations for Multimodality Cardiovascular Imaging of Patients with Hypertrophic Cardiomyopathy: An Update from the American Society of Echocardiography, in Collaboration with the American Society of Nuclear Cardiology, the Society for Cardiovascular Magnetic Resonance, and the Society of Cardiovascular Computed Tomography

Hypertrophic cardiomyopathy (HCM) is defined by the presence of left ventricular hypertrophy in the absence of other potentially causative cardiac, systemic, syndromic, or metabolic diseases. Symptoms can be related to a range of pathophysiologic mechanisms including left ventricular outflow tract obstruction with or without significant mitral regurgitation, diastolic dysfunction with heart failure with preserved and heart failure with reduced ejection fraction, autonomic dysfunction, ischemia, and arrhythmias. Appropriate understanding and utilization of multimodality imaging is fundamental to accurate diagnosis as well as longitudinal care of patients with HCM. Resting and stress imaging provide comprehensive and complementary information to help clarify mechanism(s) responsible for symptoms such that appropriate and timely treatment strategies may be implemented. Advanced imaging is relied upon to guide certain treatment options including septal reduction therapy and mitral valve repair. Using both clinical and imaging parameters, enhanced algorithms for sudden cardiac death risk stratification facilitate selection of HCM patients most likely to benefit from implantable cardioverter-defibrillators.

Clinical utility of early postoperative cardiac multidetector computed tomography after coronary artery bypass grafting

We evaluated the clinical utility of early postoperative cardiac computed tomography (CT) for evaluating left ventricular (LV) function and predicting prognosis in patients who had undergone coronary artery bypass grafting (CABG). Of the 205 patients who underwent CABG from March 2011 to December 2014, 136 underwent early postoperative cardiac CT (within 30 days after CABG) and were enrolled as the study population. The baseline and postoperative follow-up echocardiographic findings, major adverse cardiac events (MACE), and death were recorded for a follow-up period (mean, 5.9 ± 1.1 years). Functional cardiac CT parameters were compared to echocardiographic measurements. The associations between cardiac CT findings and functional recovery and prognosis were evaluated by logistic regression analyses. The LVEF measured via cardiac CT was significantly higher (56.2 ± 11.5% vs. 61.9 ± 12.9%; p = 0.0002) compared to those via early postoperative echocardiography, but the wall motion score index (WMSI) was not significantly different (1.23 ± 0.33 vs. 1.21 ± 0.28, p = 0.5041) between the two methods. During the follow-up period, 17 patients (12.5%) died and 40 (29.4%) developed MACE. Both the LVEF and WMSI measured with early postoperative echocardiography (p = 0.0202 and odds ratio [OR] = 5.0171, p = 0.0039, respectively), and cardiac CT (OR = 0.9625, p = 0.0091 and OR = 14.3605, p = 0.0001, respectively) predicted MACE OR = 0.9630, but only the WMSI, measured using cardiac CT, predicted all-cause death (OR = 10.6017, p = 0.0035). In CABG patients, LVEF and the WMSI measured with early postoperative cardiac CT were comparable with echocardiography and predicted the development of MACE and all-cause death.

Electrocardiography-gated cardiac CT angiography can differentiate brachycephalic dogs with and without pulmonary valve stenosis and findings differ from transthoracic echocardiography

Pulmonary valve stenosis (PS) is one of the most commonly diagnosed congenital heart defects in dogs. Currently, transthoracic echocardiography (TTE) is the standard modality used to evaluate PS. Image acquisition by TTE can be challenging in some brachycephalic breeds of dogs. The use of echocardiographic-gated CT angiography (ECG-gated CTA) in veterinary medicine is limited. This retrospective method comparison study investigated right and left ventricular outflow diameters by sedated ECG-gated CTA and unsedated TTE in 14 brachycephalic dogs with PS and 12 brachycephalic dogs without PS. Measurements of ventricular outflow structures were made in early systole and end diastole for both modalities and then compared for significance between systolic and diastolic phases, as well as between the two modalities. Ratios of the pulmonary trunk diameter to the aorta at different locations (aortic valve, aortic annulus, and ascending aorta) and in different planes (transverse, sagittal) were compared between dogs with PS and without PS, as well as within dogs, by both TTE and ECG-gated CTA. Transthoracic echocardiography and ECG-gated CTA both detected significantly greater pulmonary trunk to aorta ratios in dogs with PS at all aortic locations (P < 0.05). Pulmonary valve to aortic valve ratios were significantly smaller in dogs with PS (P < 0.05). Pulmonary trunk to aorta and pulmonary valve to aorta ratios were achieved with good anatomic detail using ECG-gated CTA. Ratios of the pulmonary trunk and pulmonary valve relative to the aorta may be useful to evaluate for PS using a modality that is underutilized for cardiac assessment.

Nongated Cardiac Computed Tomographic Angiograms for Detection of Embolic Sources in Acute Ischemic Stroke

Background and Purpose—

We assessed the feasibility of obtaining diagnostic quality images of the heart and thoracic aorta by extending the z axis coverage of a non–ECG-gated computed tomographic angiogram performed in the primary evaluation of acute stroke without increasing the contrast dose.

Methods—

Twenty consecutive patients with acute ischemic stroke within the 4.5 hours of symptom onset were prospectively recruited. We increased the longitudinal coverage to the domes of the diaphragm to include the heart. Contrast administration (Omnipaque 350) remained unchanged (injected at 3–4 mL/s; total 60–80 mL, triggered by bolus tracking). Images of the heart and aorta, reconstructed at 5 mm slice thickness in 3 orthogonal planes, were read by a radiologist and cardiologist, findings conveyed to the treating neurologist, and correlated with the transthoracic or transesophageal echocardiogram performed within the next 24 hours.

Results—

Of 20 patients studied, 3 (15%) had abnormal findings: a left ventricular thrombus, a Stanford type A aortic dissection, and a thrombus of the left atrial appendage. Both thrombi were confirmed by transesophageal echocardiography, and anticoagulation was started urgently the following day. None of the patients developed contrast-induced nephropathy on follow-up. The radiation dose was slightly increased from a mean of 4.26 mSV (range, 3.88–4.70 mSV) to 5.17 (range, 3.95 to 6.25 mSV).

Conclusions—

Including the heart and ascending aorta in a routine non–ECG-gated computed tomographic angiogram enhances an existing imaging modality, with no increased incidence of contrast-induced nephropathy and minimal increase in radiation dose. This may help in the detection of high-risk cardiac and aortic sources of embolism in acute stroke patients.

Bias associated with left ventricular quantification by multimodality imaging: a systematic review and meta-analysis

Purpose

Cardiac MR (CMR) is the gold standard for left ventricular (LV) quantification. However, two-dimensional echocardiography (2DE) is the most common approach, and both three-dimensional echocardiography (3DE) and multidetector CT (MDCT) are increasingly available. The clinical significance and interchangeability of these modalities remains under-investigated. Therefore, we undertook a systemic review to evaluate the accuracy and absolute bias in LV quantification of all the commonly available non-invasive imaging modalities (2DE, CE-2DE, 3DE, MDCT) compared to cardiac MR (CMR).

Methods

Studies were included that reported LV echocardiographic (2DE, CE-2DE, 3DE) and/or MDCT measurements compared to CMR. Only modern CMR (SSFP sequences) was considered. Studies involving small sample size (<10 patients) and unusual cardiac geometry (ie, congenital heart diseases) were excluded. We evaluated LV end-diastolic volume (LVEDV), end-systolic volume (LVESV) and ejection fraction (LVEF).

Results

1604 articles were initially considered: 65 studies were included (total of 4032 scans (echo, CT, MRI) performed in 2888 patients). Compared to CMR, significant biased underestimation of LV volumes with 2DE was seen (LVEDV—33.30 mL, LVESV −16.20 mL, p<0.0001). This difference was reduced but remained significant with CE-2DE (LVEDV −18.05, p<0.0001) and 3DE (LVEDV −14.41, p<0.001), while MDCT values were similar to CMR (LVEDV −1.20, p=0.43; LVESV −0.13, p=0.91). However, excellent agreement for echocardiographic LVEF evaluation (2DE LVEF 0.78–1.01%, p=0.37) was observed, especially with 3DE (LVEF 0.14%, p=0.88).

Conclusions

Comparing imaging modalities to CMR as reference standard, 3DE had the highest accuracy in LVEF estimation: 2DE and 3DE-derived LV volumes were significantly underestimated. Newer generation CT showed excellent accuracy for LV volumes.

Korean guidelines for the appropriate use of cardiac CT

The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease.

Left ventricular function and volume with coronary CT angiography improves risk stratification and identification of patients at risk for incident mortality: results from 7758 patients in the prospective multinational CONFIRM observational cohort study

PURPOSE

To assess whether gradations of left ventricular (LV) ejection fraction (LVEF) and volumes measured with coronary computed tomography (CT) would augment risk stratification and discrimination for incident mortality.

MATERIALS AND METHODS

This study was approved by the institutional review board, and informed consent was obtained when required. Subjects without known coronary artery disease (CAD) who underwent cardiac CT angiography with quantitative LV measurements were categorized according to LVEF (≥ 55%, 45%-54.9%, 35%-44.9%, or <35%). LV end-systolic volume (LVESV) and LV end-diastolic volume (LVEDV) were classified as normal (≥ 90 mL) or abnormal (≥ 200 mL). CAD extent and severity was categorized as none, nonobstructive, obstructive (≥ 50%), one-vessel, two-vessel, and three-vessel or left main disease. LVEF and volumes were assessed for risk prediction and discrimination of future mortality by using Cox hazards model and receiver operating characteristic curve analysis, respectively.

RESULTS

During a follow-up of 2.0 years ± 0.9, 7758 patients (mean age, 58.5 years ± 13.0; 4220 male patients [54.4%]) were studied. At multivariable analysis, worsening LVEF was independently associated with mortality for moderately (hazard ratio = 3.14, P < .001) and severely (hazard ratio = 5.19, P < .001) abnormal ejection fraction. LVEF demonstrated improved discrimination for mortality (Az = 0.816) when compared with CAD risk factors alone (Az = 0.781) or CAD risk factors plus extent and severity. At multivariable analysis of a subgroup of 3706 individuals, abnormal LVEDV (hazard ratio = 4.02) and LVESV (hazard ratio = 6.46) helped predict mortality (P < .001). Similarly, LVESV and LVEDV demonstrated improved discrimination when compared with CAD risk factors or CAD extent and severity (P < .05).

CONCLUSION

LV dysfunction and volumes measured with cardiac CT angiography augment risk prediction and discrimination for future mortality.

Sex-specific biatrial volumetric measurements obtained with use of multidetector computed tomography in subjects with and without coronary artery disease

Atrial volumetric measurement has proven clinical implications. Advances in cardiac imaging, notably the precision enabled by multidetector computed tomography (MDCT), herald the need for new criteria of what constitutes normal volumetric measurements. With use of 64-slice MDCT, we compared the atrial volumes in healthy individuals with those in individuals with coronary artery disease. By means of manual segmentation, we measured biatrial volume in 686 participants who underwent retrospective electrocardiographic-gated MDCT angiographic evaluation. The study population included a control group of 203 persons with no cardiac abnormalities, and a study group of 483 patients with obstructive coronary artery disease. All variables were compared between men and women and between the groups. We found a significant difference in left atrial end-systolic and end-diastolic volumes between men and women in the control group (P <0.05); however, right atrial volumes were similar. In comparison with the entire control group, the coronary artery disease group had significantly higher left atrial volume, significantly lower right atrial stroke volume, and significantly lower biatrial ejection fraction, except for left atrial ejection fraction in men. Right atrial volume and left atrial stroke volume were not significantly different. The results imply that a sex-specific reference value is necessary for left atrial volumetric evaluation, and that left atrial volume and biatrial ejection fraction (excluding left atrial ejection fraction in men) might be useful during diagnosis and prognosis in patients who have coronary artery disease.

Meta-analysis of global left ventricular function comparing multidetector computed tomography with cardiac magnetic resonance imaging

We compare the diagnostic accuracy of multidetector row computed tomography (MDCT) to cardiac magnetic resonance imaging (CMR) for evaluating global left ventricular function. We systematically searched PubMed, CINAHL, Cochrane CENTRAL, Scopus, and the Web of Science databases for studies published between 1966 to January 2013 that compared left ventricle (LV) volumes, ejection fraction (EF) and LV mass measured by MDCT and CMR. We performed meta-analyses and used random-effects model with inverse variance weighting test to determine the overall bias and limits of agreement of LV end-diastolic volume, end-systolic volume, stroke volume, and EF measured by MDCT and CMR. Furthermore, subgroup analyses were performed to compare 16-slice and 64-slice MDCT with CMR. Two study authors independently reviewed the 90 articles originally identified and selected 27 studies (n = 831) for analysis. Excellent correlation and a linear relation were seen between MDCT and CMR for LV end-diastolic volume (r = 0.93; p <0.001), LV end-systolic volume (r = 0.95; p <0.001), LV stroke volume (r = 0.85; p <0.001), LV ejection fraction (r = 0.93; p <0.001), and LV mass (r = 0.86; p <0.001). Subgroup analyses showed strong positive correlations for both 16- and 64-slice MDCT. In conclusion, although not the first-line test for LV function assessment in most patients, when appropriate, retrospectively gated MDCT provides an accurate and valid assessment of LV function compared with CMR.

Head-to-head comparison of left ventricular function assessment with 64-row computed tomography, biplane left cineventriculography, and both 2- and 3-dimensional transthoracic echocardiography: comparison with magnetic resonance imaging as the reference standard

OBJECTIVES

This study was designed to compare the accuracy of 64-row contrast computed tomography (CT), invasive cineventriculography (CVG), 2-dimensional echocardiography (2D Echo), and 3-dimensional echocardiography (3D Echo) for left ventricular (LV) function assessment with magnetic resonance imaging (MRI).

BACKGROUND

Cardiac function is an important determinant of therapy and is a major predictor for long-term survival in patients with coronary artery disease. A number of methods are available for assessment of function, but there are limited data on the comparison between these multiple methods in the same patients.

METHODS

A total of 36 patients prospectively underwent 64-row CT, CVG, 2D Echo, 3D Echo, and MRI (as the reference standard). Global and regional LV wall motion and ejection fraction (EF) were measured. In addition, assessment of interobserver agreement was performed.

RESULTS

For the global EF, Bland-Altman analysis showed significantly higher agreement between CT and MRI (p < 0.005, 95% confidence interval: ±14.2%) than for CVG (±20.2%) and 3D Echo (±21.2%). Only CVG (59.5 ± 13.9%, p = 0.03) significantly overestimated EF in comparison with MRI (55.6 ± 16.0%). CT showed significantly better agreement for stroke volume than 2D Echo, 3D Echo, and CVG. In comparison with MRI, CVG-but not CT-significantly overestimated the end-diastolic volume (p < 0.001), whereas 2D Echo and 3D Echo significantly underestimated the EDV (p < 0.05). There was no significant difference in diagnostic accuracy (range: 76% to 88%) for regional LV function assessment between the 4 methods when compared with MRI. Interobserver agreement for EF showed high intraclass correlation for 64-row CT, MRI, 2D Echo, and 3D Echo (intraclass correlation coefficient >0.8), whereas agreement was lower for CVG (intraclass correlation coefficient = 0.58).

CONCLUSIONS

64-row CT may be more accurate than CVG, 2D Echo, and 3D Echo in comparison with MRI as the reference standard for assessment of global LV function.

Assessment of left ventricular parameters in orthotopic heart transplant recipients using dual-source CT and contrast-enhanced echocardiography: comparison with MRI

OBJECTIVES

To establish the accuracy and reliability of cardiac dual-source CT (DSCT) and two-dimensional contrast-enhanced echocardiography (CE-Echo) in estimating left ventricular (LV) parameters with respect to cardiac magnetic resonance imaging (CMR) as the reference standard.

METHODS

Twenty-five consecutive heart transplant recipients (20 male, mean age 62.7±10.4 years, mean time since transplantation 8.1±5.9 years) were prospectively recruited. Two blinded readers independently assessed LV ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volume (SV) for each patient after manual tracing of the endo- and epicardial contours in DSCT, CE-Echo and CMR cine images. Student's t-test for paired samples for differences, and Bland and Altman plots and Lin's concordance-correlation coefficients (CCC) for agreement were calculated.

RESULTS

There was no statistical difference between left ventricular parameters determined by DSCT and CMR. CE-Echo resulted in significant underestimation of left ventricular volumes (mean difference EDV: 15.94±14.19 ml and 17.1±17.06 ml, ESV: 8.5±9.3 and 7.32±9.14 ml with respect to DSCT and CMR), and overestimation of EF compared with the cross-sectional imaging modalities (3.78±8.47% and 2.14±8.35% with respect to DSCT and CMR). Concordance correlation coefficients for LV parameters using DSCT and CMR were higher (CCC≥0.75) than CCC values observed between CE-Echo and DSCT- or CMR-derived data (CCC≥0.54 and CCC≥0.49, respectively). Interobserver agreement was higher for DSCT and CMR values (CCC≥0.72 and CCC≥0.87, respectively).

CONCLUSION

In orthotopic heart transplantation cardiac DSCT allows accurate and reliable estimation of LV parameters compared with CMR, whereas CE-Echo seems to be insufficient to obtain precise measurements.

Assessment of global left ventricular function with dual-source computed tomography in patients with valvular heart disease

BACKGROUND

Left ventricular (LV) function is a vital parameter for prognosis, therapy guidance, and follow-up of cardiovascular disease. Dual-source computed tomography (DSCT) provides an accurate analysis of global LV function.

PURPOSE

To assess the performance of DSCT in the determination of global LV functional parameters in comparison with cardiovascular magnetic resonance (CMR) and two-dimensional transthoracic echocardiography (2D-TTE) in patients with valvular heart disease (VHD).

MATERIAL AND METHODS

A total of 111 patients (58 men, mean age 49.9 years) with known VHD and who underwent DSCT, 2D-TTE, and CMR a period of 2 weeks before undergoing valve surgery were included in this study. LV end-systolic volume (ESV), end-diastolic volume (EDV), stroke volume (SV), and ejection fraction (EF) were calculated by DSCT using the threshold-based technique, by 2D-TTE using a modified Simpson's method, and by CMR using Simpson's method. Agreement for parameters of LV global function was determined with the Pearson's correlation coefficient (r) and Bland-Altman analysis. All the DSCT and CMR data-sets were assessed independently by two readers.

RESULTS

Fifty of the total 111 patients had aortic VHD, 29 patients had mitral VHD, and 32 patients had mixed aortic and mitral VHD. An excellent inter-observer agreement was seen for the assessment of global LV function using DSCT (r = 0.910-0.983) and CMR (r = 0.854-0.965). An excellent or good correlation (r = 0.93, 0.95, 0.87, and 0.71, respectively, P < 0.001) was noted between the DSCT and 2D-TTE values for EDV, ESV, SV, and EF. EDV (33.7 mL, P < 0.001), ESV (12.1 mL, P < 0.001), SV (21.2 mL, P < 0.001), and EF (1.6%, P = 0.019) were significantly overestimated by DSCT when compared with 2D-TTE. An excellent correlation (r = 0.96, 0.97, 0.91, and 0.94, respectively, P < 0.001) between DSCT and CMR was seen in the evaluation of EDV, ESV, SV, and EF. EDV (15.9 mL, P < 0.001), ESV (7.3 mL, P < 0.001), and SV (8.5 mL, P < 0.001) were significantly underestimated, but EF (1.1%, P = 0.002) was significantly overestimated by DSCT when compared with CMR.

CONCLUSION

Our study showed that DSCT measurements of global LV function using the threshold-based technique were highly reproducible and compared more favorably with CMR measurements using Simpson's method than those of 2D-TTE using the modified Simpson's method. DSCT enables accurate quantification of global LV function in patients with VHD.

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.

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.

Accuracy of different reconstruction intervals to quantify left ventricular function and mass in cardiac computed tomography examinations

PURPOSE

To compare the accuracy of cardiac dual-source CT (DSCT) reconstructions obtained at 5% and 10% of the cardiac cycle and MRI for quantifying global left ventricular (LV) function and mass in heart transplant recipients.

MATERIAL AND METHODS

We prospectively included 23 heart transplant recipients (21 male, mean age 60±11.7 years) who underwent cardiac DSCT and MRI examinations. We compared LV parameters on cardiac DSCT reconstructions obtained at 5% (0%-95%) and 10% (0%-90%) intervals of the cardiac cycle and on double-oblique short-axis MR images. We determined ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and myocardial mass using commercially available semiautomated segmentation analysis software for DSCT datasets and conventional manual contour tracing for MR studies.

RESULTS

Using different reconstruction intervals to quantify LV parameters at DSCT resulted in non-significant differences (P>.05). Compared to MRI, DSCT slightly overestimated LV-EDV, ESV, and mass when both 5% (11.5±25.1ml, 6.8±10.9ml, and 28.3±21.6g, respectively) and 10% (mean difference 15.3±26.3ml, 7.4±11.5ml, and 29.3±18.7g, respectively) reconstruction intervals were used. DSCT and MRI estimates of EF and SV were not significantly different.

CONCLUSION

In heart transplant recipients, DSCT allows reliable quantification of LV function and mass compared with MRI, even using 10% interval reconstructions.

Effects of propranolol on the left ventricular volume of normal subjects during CT coronary angiography

OBJECTIVE

The purpose of this study is to determine the effects of propranolol on the left ventricular (LV) volume during CT coronary angiography.

MATERIALS AND METHODS

The LV volume of 252 normal Chinese subjects (126 subjects with propranolol medication and 126 age- and gender-matched Chinese subjects without medication) was estimated using 64 slices multi-detector CT (MDCT). The heart rate difference was analyzed by the logistic linear regression model with variables that included gender, age, body height, body weight, systolic blood pressure (SBP), diastolic blood pressure (DBP) and the dosage of propranolol. The following global LV functional parameters were calculated: the real-end diastolic volume (EDV), the real-end systolic volume (ESV) and the real-ejection fraction (EF).

RESULTS

The female subjects had a greater decrease of heart rate after taking propranolol. The difference of heart rate was negatively correlated with the dosage of propranolol. The real-EDV, the real-ESV and the real-EF ranged from 48.1 to 109 mL/m², 6.1 to 57.1 mL/m² and 41% to 88%, respectively. There was no significant difference in the SBP and DBP between the groups without and with propranolol medication (123 ± 17 and 80 ± 10 mmHg; 120 ± 14 and 80 ± 11 mmHg, respectively). The real-EDV showed no significant difference between these two groups, but the real-ESV and real-EF showed significant differences between these two groups (69.4 ± 9.3 and 70.6 ± 8.9 mL/m²; 23.5 ± 5.7 and 25.6 ± 3.7 mL/m², 66.5 ± 5.1% and 63.5 ± 4.6%, respectively).

CONCLUSION

The difference of heart rate is significantly influenced by gender and the dosage of propranolol. Propranolol will also increase the ESV, which contributes to a decreased EF, while the SBP, DBP and EDV are not statistically changed.

Quantification of aortic regurgitant fraction and volume with multi-detector computed tomography comparison with echocardiography

RATIONALE AND OBJECTIVES

Evaluate quantification of the aortic regurgitant fraction and volume with computed tomography (CT).

MATERIALS AND METHODS

Fifty-three patients with aortic regurgitation (AR) and 29 controls were examined with 64-multi-detector CT coronary angiography and transthoracic echocardiography (TTE). A dedicated software algorithm employing three-dimensional segmentation of left ventricle (LV) and right ventricle (RV) volumes and LV mass was applied. AR volume and fraction was calculated based on RV and LV stroke volumes (SV) and compared with echocardiography. The aortic regurgitant orifice area (ROA) was measured by CT.

RESULTS

A good correlation of the AR fraction and AR volume determined by CT compared to echocardiography was found for mild, moderate, and severe AR with 14.2% ± 9, 28.8% ± 8, and 57.9% ± 9 (r = 0.95, P < .001) for AR fraction, and 15.7 mL ± 11.33 mL ± 14, and 98.9 mL ± 36 for AR volume (r = 0.92, P < .0001), respectively. CT correctly classified severity of AR in 93% of patients based of AR-fraction, and in 89% based on AR volume. The sensitivity and specificity of CT were 98% and specificity 90.3%. The specificity improved to 97%, if the ROA by CT was added as diagnostic criterion.

CONCLUSION

Aortic regurgitation fraction and volume can be accurately quantified from CT coronary angiography datasets. These parameters can assist clinical management, e.g. in case of pending cardiac surgery decision.

Nonobstructive coronary artery disease as detected by 64-detector row cardiac computed tomographic angiography is associated with increased left ventricular mass

BACKGROUND

Cardiac computed tomographic angiography (CCTA) permits simultaneous assessment of coronary artery disease (CAD) and left ventricular mass (LVM). While increased LVM predicts mortality and is associated with obstructive CAD, the relationship of LVM with non-obstructive CAD is unknown.

METHODS

We evaluated 212 consecutive patients undergoing 64-detector row CCTA at 2 sites without evident cardiovascular disease or obstructive (≥70%) CAD by CCTA. LVM was measured by CCTA using Simpson's method of disks and indexed to body surface area (LVMI) and height to the allometric power of 2.7(LVM/ht2.7). CCTAs were evaluated by scoring a modified AHA 16-segment coronary artery model for none = 0 (0% stenosis), mild = 1 (1-49% stenosis) or moderate = 2 (50-69% stenosis). Overall CAD plaque burden was estimated by summing scores across all segments for a segment stenosis score (SSS, max = 32).

RESULTS

The mean age was 53.3 ± 12.8 with 52% female, 48% hypertensive, and 7.4% diabetic. The mean LVM was 109 ± 32.5 g; 58.5% had any coronary artery plaque. In multivariable linear regression, SSS was significantly associated with increased LVM, LVMI and LVM/ht2.7. LVM increased by 2.0 g for every 1-point increase in SSS (95% CI 0.06-3.4, p = 0.006). Agatston scores provided no additional predictive value for increased LVM above and beyond SSS.

CONCLUSION

Non-obstructive CAD visualized by CCTA is associated with increased LVM independent of effects of clinical risk factors and calcium scoring. Whether addition of LVM to stenosis assessment in patients undergoing CCTA enhances risk prediction of future CAD events warrants investigation.

Ischemic stroke: etiologic work-up with multidetector CT of heart and extra- and intracranial arteries

PURPOSE

To assess the potential of a single-session multidetector computed tomography (CT) protocol, as compared with established methods, for the etiologic work-up of acute ischemic stroke.

MATERIALS AND METHODS

Patients found to have recently experienced an ischemic stroke were recruited for this prospective study after institutional review board approval was obtained. Each patient was scheduled for two evaluation strategies: (a) a standard approach involving transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE), duplex ultrasonography (US) of the neck vessels, and magnetic resonance (MR) angiography of the neck and brain vessels; and (b) a protocol involving single-session multidetector CT of the heart, neck, and brain vessels. The authors sought to determine the major etiologic factors of stroke, including cardiac sources of embolism and atheroma of the aortic arch and the extra- and intracranial vessels, by using both strategies.

RESULTS

Multidetector CT, MR imaging, and duplex US were performed in 46 patients, 39 of whom also underwent TEE. The sensitivity and specificity of multidetector CT were 72% (18 of 25 cases) and 95% (20 of 21 cases), respectively, for detection of cardiac sources and 100% (24 of 24 cases) and 91% (20 of 22 cases), respectively, for detection of major arterial atheroma. For the 46 cases of stroke, the final etiologic classifications determined by using the standard combination approach were cardiac sources in 20 (44%) cases, major arterial atheroma in nine (20%), multiple sources in four (9%), and cryptogenic sources in 13 (28%). Multidetector CT facilitated correct etiologic classification for 38 (83%) of the 46 patients.

CONCLUSION

Multidetector CT is a promising tool for etiologic assessment of ischemic stroke, although the identification of minor cardiac sources with this examination requires the establishment of robust criteria.

Reperfusion injury components and manifestations determined by cardiovascular MR and MDCT imaging

Advances in magnetic resonance (MR) and computed tomography (CT) imaging have improved visualization of acute and scar infarct. Over the past decade, there have been and continues to be many significant technical advancements in cardiac MR and multi-detector computed tomography (MDCT) technologies. The strength of MR imaging relies on a variety of pulse sequences and the ability to noninvasively provide information on myocardial structure, function and perfusion in a single imaging session. The recent technical developments may also allow CT technologies to rise to the forefront for evaluating clinical ischemic heart disease. Components of reperfusion injury including myocardial edema, hemorrhage, calcium deposition and microvascular obstruction (MO) have been demonstrated using MR and CT technologies. MR imaging can be used serially and noninvasively in assessing acute and chronic consequences of reperfusion injury because there is no radiation exposure or administration of radioactive materials. MDCT is better suited for assessing coronary artery stenosis and as an alternative technique for assessing viability in patients where MR imaging is contraindicated. Changes in left ventricular (LV) volumes and function measured on cine MR are directly related to infarct size measured on delayed contrast enhanced images. Recent MR studies found that transmural infarct, MO and peri-infarct zone are excellent predictors of poor post-infarct recovery and mortality. Recent MR studies provided ample evidence that growth factor genes and stem cells delivered locally have beneficial effects on myocardial viability, perfusion and function. The significance of deposited calcium in acute infarct detected on MDCT requires further studies. Cardiac MR and MDCT imaging have the potential for assessing reperfusion injury components and manifestations.

Semi-automatic assessment of global left ventricular function and left ventricular parameters with dual-source computed tomography: comparison with invasive angiography

This study assesses the global left ventricular function and volumes using dual-source computed tomography (DSCT) with improved temporal resolution (83 ms) by use of a semi-automatic software tool in comparison to invasive angiography (IVA). One hundred patients scheduled for invasive coronary angiography because of suspected or known coronary artery disease (80 men; 20 women, mean age 62 +/- 10 years) were additionally examined by DSCT. Global left ventricular function (LVF), left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), and stroke volume (SV) were calculated by the use of semi-automatic post-processing software and results compared with those of IVA. Bland-Altman analysis revealed a good concordance between DSCT and IVA in terms of LVF: Pearson's r 0.78, confidence interval [CI] 0.68-0.86, P < 0.0001, bias 7.1% +/- 9.1%. The same was true for LVESV (Pearson's r 0.78, CI 0.67-0.85, P < 0.0001, bias 15.0 +/- 21.0 ml), whereas the agreement for LVEDV and SV was only moderate (LVEDV: Pearson's r 0.59, CI 0.43-0.72, P < 0.0001, bias 13.0 +/- 18.1 ml; SV: Pearson's r 0.47, CI 0.28-0.62, P < 0.0001, bias -1.4 +/- 28.4 ml). Semi-automatic evaluation of left ventricular parameters with DSCT revealed good correlation for LVF and LVESV, whereas LVEDV and SV showed only a moderate correlation. Moreover, LVF is systematically underestimated by DSCT.

Diagnosing coronary artery disease in women: an update on cardiac imaging modalities

Coronary heart disease (CHD) remains the leading cause of death in women. However, there are multiple challenges to the diagnosis of CHD in women, including: 1) women perceive their risk of CHD to be lower than it truly is, 2) women frequently present with atypical cardiac symptoms, 3) traditional stress tests have lower accuracy in women than in men, 4) women have a lower frequency of obstructive CHD detected at angiography than do men, and 5) a high percentage of women without obstructive CHD by invasive angiography have recurrent chest pain. Given the increasing number of options and complexity of noninvasive testing for CHD, it is important for women's health care providers to select the best test for a given patient. Newer imaging modalities such as cardiac computed tomography and magnetic resonance imaging offer speed, convenience, and high diagnostic accuracy in women. The goal of this article is to provide practitioners with an overview of the conventional diagnostic tests and to compare these with the newer imaging modalities. The appropriate application of diagnostic tests should allow practitioners to identify accurately and reassure those patients who are at low risk while targeting those who have preclinical or symptomatic atherosclerosis so that they can receive aggressive medical therapy, referral to cardiovascular specialists, or both.

[Technological advances in cardiac CT]

The SFR-SFC presents guidelines dedicated to cardiac and coronary imaging using CT in the area of indications, technological requirement including both hardware and software, patient conditioning, CT protocols and related results concerning radiation dose, image quality and diagnostic value. These guidelines are based either on up-dated medical literature proofs and/or on expert consensus.

Quantitative evaluation of regional left ventricular function by multidetector computed tomography

OBJECTIVE

: Because most contemporary workstations offer quantitative analysis of regional function by multidetector computed tomography, we aimed to establish typical values for normal, hypokinetic, and akinetic regions, and to establish optimal thresholds to differentiate between normal and abnormal values.

METHODS

: For 33 patients, quantitative regional functional parameters were compared with visual analysis by both multidetector computed tomography and echocardiography. Normal values were established to normalize for segmental variability. Optimal thresholds were established to differentiate between normal and abnormal segments by receiver operating characteristic analysis.

RESULTS

: Akinetic, hypokinetic, and normokinetic segments demonstrated significant differences (P < 0.0001) for end-systolic thickness (mean [95% confidence interval], 9.4 [4.5-14.3], 11.7 [7.2-16.2], and 14.3 mm [8.2-20.3 mm]), respectively; thickening, 24% [-22% to 71%], 45% [-16% to 106%], and 82% [10%-154%]), respectively; and motion, 3.5 [-2.0 to 8.9], 6.1 [-0.2 to 12.4], and 8.5 mm [1.8-15.3 mm], respectively). Thickening performed best with area under the curve of 0.87 and sensitivity equal to specificity of 82%. Intraobserver variability was good, but interobserver variability was only moderate.

CONCLUSIONS

: Quantification of regional myocardial function can be performed to assist the physician in mapping left ventricular function.

[Quantification of left ventricular function and mass in dual-source CT (DSCT).]

OBJECTIVES

To evaluate the interobserver agreement in quantifying left ventricular function and mass and to assess the accuracy of conventional manual contour tracing compared to semiautomatic segmentation analysis software.

MATERIAL AND METHODS

Twenty consecutive subjects who underwent cardiac DSCT with retrospective ECG-gating were included. Two different multiphase image reconstructions were done in 5% steps throughout the entire cardiac cycle (0-95% of the R-R interval) with effective slice thickness of 1mm in the axial plane and 8mm in the short-axis orientation. Left ventricular function and mass were calculated by two independent observers, tracing endocardial and epicardial borders manually and using a semiautomatic software tool (Circulation II, Siemens). Ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), cardiac output (CO), and myocardial mass were evaluated by two independent observers blind to each other's assessments. The interobserver agreement and the reliability of the different segmentation methods were calculated. The time required for manual contouring and semiautomatic contour tracing was also registered.

RESULTS

We found an excellent correlation (r>0.94; p<0.05) between the two independent observers for the quantification of left ventricular function and mass. Left ventricular functional parameters derived from semiautomatic contour software and conventional manual tracing method were not significantly different (p>0.05). The semiautomatic contour detection algorithm overestimated LV mass significantly compared with the manual contouring method (mean difference 29.45+/-1.64g; p<0.05). The time needed to calculate these parameters with the semiautomatic tool was significantly lower (248.85+/-99.8s) than with manual contouring (452.7+/-73.92s) (p<0.05).

CONCLUSIONS

Interobserver agreement for quantifying left ventricular function and mass using DSCT is excellent. Despite overestimating left ventricular mass, the semiautomatic software tool allows cardíac parameters to be quantified with the same reliability as the conventional manual method in half the time.

Aortic stenosis: evaluation with multidetector CT angiography and MR imaging

Aortic valvular stenosis (AS) is the most common valve disease which results in the need for a valve replacement. Although a Doppler echocardiography is the current reference imaging method, the multidetector computerized tomograpghy (MDCT) and magnetic resonance imaging (MRI) have recently emerged as a promising method for noninvasive valve imaging. In this study, we briefly describe the usefulness and comparative merits of the MDCT and MRI for the evaluation of AS in terms of valvular morphology (as the causes of AS), quantification of aortic valve area, pressure gradient of flow (for assessment severity of AS), and the evaluation of the ascending aorta and cardiac function (as the secondary effects of AS). The familiarity with the MDCT and MRI features of AS is considered to be helpful for the accurate diagnosis and proper management of patients with a poor acoustic window.