Evaluation of global left ventricular myocardial function with electrocardiogram-gated multidetector computed tomography: comparison with magnetic resonance imaging

Comprehensive cardiac CT study: evaluation of coronary arteries, left ventricular function, and myocardial perfusion--is it possible?

With advances in multidetector computed tomography (MDCT) technology, the new generation of 64-slice MDCT scanners with submillimeter collimation and a faster gantry rotation allows imaging of the entire heart in a single breath-hold with excellent temporal and spatial resolution. This potentially permits a comprehensive assessment of coronary anatomy, left ventricular function, and myocardial perfusion. As will be seen in this review of the current literature regarding 16- and 64-slice MDCT, there is great promise for a comprehensive cardiac computed tomography (CT) study. The available data support the notion that CT coronary angiography may be an alternative to invasive coronary angiography in symptomatic patients with a low to intermediate likelihood of having coronary artery disease. By use of the same data acquired for CT coronary angiography, evaluation of global and regional left ventricular function and myocardial perfusion can be added to the MDCT evaluation without additional exposure to contrast medium or radiation and may provide a more conclusive cardiac workup in these patients. The potential applications and limitations of coronary stenosis detection, global and regional left ventricular function, and myocardial perfusion assessment by MDCT will be reviewed. The full potential of cardiac MDCT is just beginning to be realized.

Assessment of the right ventricular function and mass using cardiac multi-detector computed tomography in patients with chronic obstructive pulmonary disease

Objective

We wanted to assess the relationship between measurements of the right ventricular (RV) function and mass, with using cardiac multi-detector computed tomography (MDCT) and the severity of chronic obstructive pulmonary disease (COPD) as determined by the pulmonary function test (PFT).

Materials and Methods

Measurements of PFT and cardiac MDCT were obtained in 33 COPD patients. Using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, the patients were divided into three groups according to the severity of the disease: stage I (mild, n = 4), stage II (moderate, n = 15) and stage III (severe, n = 14). The RV function and the wall mass were obtained by cardiac MDCT. The results were compared among the groups using the Student-Newman-Keuls method. Pearson's correlation was used to evaluate the relationship between the right ventricular ejection fraction (RVEF) and the wall mass results with the PFT results. P-values less than 0.05 were considered statistically significant.

Results

The RVEF and mass were 47±3% and 41±2 g in stage I, 46±6% and 46±5 g in stage II, and 35±5% and 55±6 g in stage III, respectively. The RVEF was significantly lower in stage III than in stage I and II (p < 0.01). The RV mass was significantly different among the three stages, according to the disease severity of COPD (p < 0.05). The correlation was excellent between the MDCT results and forced expiratory volume in 1 sec (r = 0.797 for RVEF and r = -0.769 for RV mass) and forced expiratory volume in 1 sec to the forced vital capacity (r = 0.745 for RVEF and r = -0.718 for RV mass).

Conclusion

Our study shows that the mean RV wall mass as measured by cardiac MDCT correlates well with the COPD disease severity as determined by PFT.

The Emerging Role of Multi-Detector Computed Tomography in Heart Failure

BACKGROUND

Recent advances in cardiac multi-detector computed tomography (MDCT) technology now permits entire coronary tree evaluation in a single breath hold with submillimeter slice collimation and improved temporal resolution.

METHODS AND RESULTS

Besides excellent correlation with invasive angiogram for the detection of significant coronary occlusion, MDCT also provides reliable and reproducible data regarding various other cardiac anatomic and functional parameters that are pertinent to heart failure patients. These include left ventricular measurement (eg, ejection fraction, regional wall motion, dimensions, volumes), pulmonary vein anatomy and drainage, right ventricular function, and cardiac venous system, among many others. However, there are radiogenic and nonradiogenic risks associated with MDCT that should be considered before scanning the patients.

CONCLUSIONS

This review summarizes the existing literature of the various cardiac MDCT applications pertinent to heart failure patients.

Assessment of left ventricular volumes and ejection fraction with 16-slice multi-slice computed tomography; comparison with 2D-echocardiography

BACKGROUND

In recent years, multi-slice computed tomography (MSCT) has emerged as a rapidly expanding modality for non-invasive assessment of coronary artery disease. Simultaneously, left ventricular (LV) function can be evaluated although this is not yet a routine component of an MSCT examination. Accordingly, the purpose of the present study was to validate assessment of LV function with MSCT using 2D-echocardiography in a large cohort of patients.

METHODS

In 70 patients (57 male, 13 female), 16-slice MSCT was performed (Toshiba Aquilion 16, Japan) followed by retrospective analysis of global LV function. For these measurements, 2D-echocardiography served as the standard of reference.

RESULTS

For LV volumes, excellent correlations for both end-diastolic volume (EDV) (r=0.97) and end-systolic volume (ESV) (r=0.98) were obtained by linear regression analysis. At Bland-Altman analysis, mean differences (+/-standard deviations) of -1.4 ml+/-11.3 ml and -3.0 ml+/-7.7 ml were observed between MSCT and 2D-echocardiography for LV EDV and LV ESV respectively. As a result, LV EF was slightly overestimated with MSCT (1.7%+/-4.9%, P<0.05). Correlation between the two techniques was excellent (r=0.91).

CONCLUSION

In a large cohort of patients, an excellent correlation was observed between 16-slice MSCT and 2D-echocardiography in the evaluation of LV volumes and EF. The addition of LV function analysis to the anatomical MSCT data may potentially enhance the diagnostic and prognostic value of the technique.

Evaluation of Global and Regional Left Ventricular Function With 16-Slice Computed Tomography, Biplane Cineventriculography, and Two-Dimensional Transthoracic Echocardiography

OBJECTIVES

We sought to compare left ventricular (LV) function assessed with multislice computed tomography (MSCT), biplane cineventriculography (CVG), and transthoracic echocardiography (Echo), with magnetic resonance imaging (MRI) as the reference standard.

BACKGROUND

With the same data as acquired for noninvasive coronary angiography, MSCT enables registration of myocardial function.

METHODS

A total of 88 patients (64 men and 24 women) underwent MSCT with 16 x 0.5 mm detector collimation, CVG, and MRI, whereas Echo was retrospectively analyzed in a subset of 30 patients.

RESULTS

Regarding the ejection fraction, the agreement was significantly superior for MSCT than for CVG (+/- 10.2% vs. +/- 16.8%; p < 0.001) and Echo (+/- 11.0% vs. +/- 21.2%; p < 0.001). For the end-diastolic and end-systolic volumes, the limits of agreement with CVG (p < 0.001) and Echo (p < 0.001 and p < 0.02, respectively) were also significantly larger than with MSCT. In comparison with MSCT, CVG significantly overestimated the end-diastolic and end-systolic volumes (p < 0.001). Intraobserver analysis of MSCT yielded limits of agreement for ejection fraction (+/- 4.8%), end-diastolic volume (+/- 15.6 ml) and end-systolic volume (+/- 8.0 ml), and myocardial mass (+/- 18.2 g). The accuracy in identifying patients and myocardial segments with abnormal regional function was significantly higher with MSCT (84% and 95%) than with CVG (63% and 90%; p < 0.002 and p < 0.001), whereas MSCT and Echo were not significantly different in identifying patients with abnormal regional function.

CONCLUSIONS

Our results indicate that the assessment of global and regional LV function with MSCT is more accurate than with CVG, whereas MSCT is superior to Echo for global function. This suggests that MSCT allows reliable evaluation of global and regional LV function.

Computed tomography coronary angiography

Recent developments in computed tomography technology have made imaging of the coronary arteries possible. All the same, the rapid motion and small dimensions of the coronary vessels make coronary computed tomography angiography (coronary CTA) challenging. With the last generations of 16- and 64-slice computed tomography and adequate patient preparation (which includes lowering of the heart rate), rates of sensitivity ranging from 83% to 99% and specificity between 93% and 98% have been reported for the detection of coronary artery stenoses in comparison with invasive coronary angiography. The high negative predictive value (95% to 100%) found in these studies suggests that coronary CTA may be a useful diagnostic technique to rule out the presence of coronary stenoses in selected patients, especially those with a rather low pretest likelihood of disease. Imaging of coronary artery bypass grafts is reliable, but clinical applications can be hampered by difficulties in assessing the native coronary arteries in patients after undergoing bypass because of their often-severe calcification. The detection of in-stent restenosis is made difficult by artifacts caused by metal, especially in smaller stents. Finally, initial reports that coronary CTA allows the detection and, to a certain extent, also the characterization and quantification of noncalcified coronary arteriosclerotic plaque are interesting, but they currently do not provide sufficient data to support clinical applications in the context of risk stratification.

Visualization Techniques in Computed Tomographic Coronary Angiography

Cardiac computed tomography (CT) scans can produce enormous datasets (>3,000 images), making traditional axial image interpretation un-workable. Previously existing and new techniques including multiplanar reformats, volume rendering, maximum intensity projections, curved multiplanar reformats, and "4D" (time-resolved) methods have all been used to increase diagnostic accuracy and reduce interpretation times. The methods and applications of these techniques to cardiac anatomy will be reviewed and discussed with an eye toward practical film interpretation.

Assessment of regional left ventricular function with multidetector-row computed tomography versus magnetic resonance imaging

This study compares quantitative and qualitative information on global and regional left ventricular (LV) function obtained with multidetector-row computed tomography (MDCT) with that obtained with magnetic resonance imaging (MRI) in patients with a high prevalence of LV wall motion abnormalities. Thirty patients (19 male, 63.7+/-15.1 years) with myocardial infarction (n=12), coronary artery disease (n=9), arrhythmogenic right ventricular cardiomyopathy (n=6), and dilation cardiomyopathy (n=3) were included. Segmental LV wall motion (LV-WM) was assessed using a 4-point scale. Wall thickness measurements were calculated in diastolic and systolic short axis images. Two hundred and fifty-two out of 266 (94.7%) normal and 189 out of 214 (88.3%) segments with decreased wall motion were correctly identified by MDCT, yielding a sensitivity of 88% and specificity of 95% for identification of wall motion abnormalities. LV-WM scores were identical in 86.7% of 480 segments (kappa=0.809). MDCT had a tendency to underestimate the degree of wall motion impairment. Interobserver agreement was lower in MDCT (66.5%) than in MRI (89.1%; p<0.01). Normokinetic segments are reliably identified with MDCT. Sensitivity for detection and accurate classification of LV wall motion abnormalities need to be improved. Better temporal resolution of the CT system seems to be the most important factor for enhancing MDCT performance.

Quantitative assessment of left ventricular size and function: side-by-side comparison of real-time three-dimensional echocardiography and computed tomography with magnetic resonance reference

BACKGROUND

Cardiac CT (CCT) and real-time 3D echocardiography (RT3DE) are being used increasingly in clinical cardiology. CCT offers superb spatial and contrast resolution, resulting in excellent endocardial definition. RT3DE has the advantages of low cost, portability, and live 3D imaging without offline reconstruction. We sought to compare both CCT and RT3DE measurements of left ventricular size and function with the standard reference technique, cardiac MR (CMR).

METHODS AND RESULTS

In 31 patients, RT3DE data sets (Philips 7500) and long-axis CMR (Siemens, 1.5 T) and CCT (Toshiba, 16-slice MDCT) images were obtained on the same day without beta-blockers. All images were analyzed to obtain end-systolic and end-diastolic volumes and ejection fractions using the same rotational analysis to eliminate possible analysis-related differences. Intertechnique agreement was tested through linear regression and Bland-Altman analyses. Repeated measurements were performed to determine intraobserver and interobserver variability. Both CCT and RT3DE measurements resulted in high correlation (r2 > 0.85) compared with CMR. However, CCT significantly overestimated end-diastolic and end-systolic volumes (26 and 19 mL; P < 0.05), resulting in a small but significant bias in ejection fraction (-2.8%). RT3DE underestimated end-diastolic and end-systolic volumes only slightly (5 and 6 mL), with no significant bias in EF (0.3%; P = 0.68). The limits of agreement with CMR were comparable for the 2 techniques. The variability in the CCT measurements was roughly half of that in either RT3DE or CMR values.

CONCLUSIONS

CCT provides highly reproducible measurements of left ventricular volumes, which are significantly larger than CMR values. RT3DE measurements compared more favorably with the CMR reference, albeit with higher variability.

Multisegment and halfscan reconstruction of 16-slice computed tomography for assessment of regional and global left ventricular myocardial function

RATIONALE AND OBJECTIVES

We sought to prospectively compare multisegment and halfscan reconstruction of 16-slice computed tomography (CT) for the assessment of regional and global left ventricular myocardial function with magnetic resonance imaging (MRI) as the reference standard.

MATERIALS AND METHODS

Forty-two patients underwent CT with 16 x 0.5-mm detector collimation. Electrocardiogram-gated reconstructions were generated with multisegment reconstruction (using up to 4 segments correlated with the raw data of up to 4 heartbeats) and standard halfscan reconstruction. Steady-state free-precession cine MRI was acquired within 24 hours.

RESULTS

More normal myocardial segments were identified correctly with multisegment (95%, 620/656) compared with halfscan reconstruction (88%, 582/656) of CT (P < 0.001). Also, the accuracy (92% [657/714] vs. 87% [620/714]) and rate of nondiagnostic segments (0% vs. 5% [33/714]) were significantly better when using multisegment reconstruction (P < 0.001). The image quality with multisegment reconstruction was significantly superior to that achieved with halfscan reconstruction (P < 0.001). In the assessment of global left ventricular function, multisegment and halfscan reconstruction of CT showed high correlations for all parameters with MRI, whereas Bland-Altman analysis revealed smaller limits of agreement for assessment of myocardial mass with multisegment reconstruction (P = 0.025), but no significant differences between both reconstruction techniques in the measurement of left ventricular volumes as compared with MRI.

CONCLUSIONS

Multisegment reconstruction of 16-detector row CT improves image quality and assessment of regional wall motion compared with standard halfscan reconstruction.

Assessment of Cardiac Function Using Multidetector Row Computed Tomography

In patients with suspected or documented heart disease, a precise quantitative and qualitative assessment of cardiac function is critical for clinical diagnosis, risk stratification, management and prognosis. Cardiac CT is increasingly being used in diagnosis of coronary artery disease. Initially multi-detector row computed tomography (MDCT) was used chiefly for detecting coronary artery stenosis and assessment of cardiac morphology. Electron beam computed tomography has been shown to provide a highly accurate ejection fraction (+/-1%), with 50 ms image acquisition per image. Retrospective electrocardiographic gating allows for image reconstruction in any phase of the cardiac cycle. Thus, end systolic and end diastolic images can be produced to assess ventricular volumes and function. Despite lower temporal resolution than electron beam computed tomography, the ability of MDCT to assess ejection fraction is preserved. In the assessment of cardiac function, MDCT has been shown to be in good agreement with echocardiography, cineventriculography, single photon emission computed tomography and magnetic resonance imaging. The fast technical development of scanner hardware along with multisegmental image reconstruction has led to rapid improvement of spatial and temporal resolution and significantly faster cardiac scans. The same data that is acquired for MDCT angiography can also be used for evaluation of cardiac function. Considering contrast media application, radiation exposure, and limited temporal resolution, MDCT solely for analysis of cardiac function parameters seems not reasonable at the present time. However, because the data is already obtained during coronary evaluation, the combination of noninvasive coronary artery imaging and assessment of cardiac function with MDCT is a suitable approach to a conclusive cardiac workup in patients with suspected coronary artery disease. MDCT seems suitable for assessment of cardiac function by MDCT when results are held in comparison to magnetic resonance imaging as the reference standard. Given the radiation dose and contrast requirement, referring a patient to MDCT only for evaluation of function is not warranted, but rather adds important clinical information to the already acquired data during retrospective triggering for MDCT angiography.

MDCT Determination of Volume and Function of the Left Ventricle: Are Short-Axis Image Reformations Necessary?

OBJECTIVE

Determination of left ventricular (LV) volumes and global function parameters from MDCT data sets is usually based on short-axis reformations from primarily reconstructed axial images, which prolong postprocessing time. The aim of this study was to evaluate the feasibility of LV volumetry and global LV function assessment from axial images in comparison with short-axis image reformations.

SUBJECTS AND METHODS

This study consisted of 20 patients with either coronary artery disease or dilated cardiomyopathy. We evaluated MDCT results using cine MRI as the reference technique.

RESULTS

LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were significantly overestimated by the axial MDCT approach in comparison with volume measurements from short-axis CT image reformations. The mean LV ejection fraction (LVEF) was not significantly different (41.2% vs 42.7%). Short-axis and axial MDCT determination of LVEF revealed a systematic underestimation by a mean +/- SD of -2.1% +/- 3.6% versus -3.6% +/- 8.2%, respectively, when compared with LVEF values based on cine MRI. The interobserver variability for volume and function measurements from axial images (LVEDV = 8.5%, LVESV = 10.8%, LVEF = 9.6%) was slightly higher than those measurements from short-axis reformations (LVEDV = 7.2%, LVESV = 9.5%, LVEF = 8.7%). The mean total evaluation time was significantly shorter using axial images (14.1 +/- 3.9 min) compared with short-axis reformations (16.9 +/- 5.2 min) (p < 0.05).

CONCLUSION

Determination of LV volumes and assessment of global LV function from axial MDCT image reformations is feasible and time efficient. This approach might be a clinically useful alternative to established short-axis-based measurements in patients with normal or near-normal LV function. A progressive underestimation of LVEF with increasing LV volumes may limit the clinical applicability of the axial approach in patients with dilated cardiomyopathy.

Comparison of gated blood pool SPECT and multi-detector row computed tomography for measurements of left ventricular volumes and ejection fraction in patients with atypical chest pain: validation with radionuclide ventriculography

Gated blood pool SPECT (GBPS) is an alternative to planar radionuclide ventriculography (PRNV) and offers potential advantages. The aim of this study was to compare GBPS, multi-row detector spiral computed tomography (MDCT), and PRNV for the determination of left ventricular ejection fraction (LVEF) and left ventricular volumes (LV) in subjects with atypical chest pain.

METHOD

Twenty-three consecutive patients (14 men, 9 women; mean age 56.2 +/- 9.5 years) referred for MDCT for evaluation of atypical chest pain. All patients underwent PRNV, GBPS, and MDCT at the same day.

RESULTS

The mean LVEFs calculated with PRNA (57.3 +/- 8.6%), GBPS (55.2 +/- 6.6%), and MDCT (56 +/- 9.1%) were not statistically different (F value 0.3374, p = 0.715). Comparison of LVEFs from GBPS and MDCT yielded correlation coefficients of 0.5238 (p = 0.0178, 95% CI = 0.1057-0.7845). The correlation of LVEFs between GBPS and PRNV showed a correlation coefficient of 0.8073 (p < 0.0001, 95% CI = 0.5676-0.9209) and 0.6190 (p = 0.0036, 95% CI = 0.2431-0.8333) between MDCT and PRNV. The mean LV end-diastolic volume (EDV) calculated with GBPS (82.7 +/- 17.5 ml) was significantly lower than MDCT (106.8 +/- 18.5 ml) (p = 0.0001). The mean LV end-systolic volume (ESV) calculated with GBPS (37.2 +/- 9.6 ml) was also significantly lower than MDCT (48.1 +/- 15.8 ml) (p = 0.012). Comparison of EDV from GBPS and MDCT yielded a correlation coefficient of 0.5220 (p = 0.0182, 95% CI = 0.1033-0.7835). The correlation of ESV between GBPS and MDCT showed a correlation coefficient of 0.6642 (p = 0.0014, 95% CI = 0.3140-0.8553).

CONCLUSION

In conclusion, the LVEF, EDV, and ESV calculated by GBPS correlated significantly with those of obtained with 16-MDCT. In addition, there were no statistical differences of LVEF calculated from PRNV, GBPS, and MDCT. However, with regard to LV, EDV and ESV from GBPS revealed statistically significantly lower than those of MDCT. Also, these results should be addressed whether similar results could also be found in patients with cardiac diseases by the consequent larger population-based study.

Measurement of cardiac ventricular volumes using multidetector row computed tomography: comparison of two- and three-dimensional methods

This study compared a three-dimensional volumetric threshold-based method to a two-dimensional Simpson's rule based short-axis multiplanar method for measuring right (RV) and left ventricular (LV) volumes, stroke volumes, and ejection fraction using electrocardiography-gated multidetector computed tomography (MDCT) data sets. End-diastolic volume (EDV) and end-systolic volume (ESV) of RV and LV were measured independently and blindly by two observers from contrast-enhanced MDCT images using commercial software in 18 patients. For RV and LV the three-dimensionally calculated EDV and ESV values were smaller than those provided by two-dimensional short axis (10%, 5%, 15% and 26% differences respectively). Agreement between the two methods was found for LV (EDV/ESV: r=0.974/0.910, ICC=0.905/0.890) but not for RV (r=0.882/0.930, ICC=0.663/0.544). Measurement errors were significant only for EDV of LV using the two-dimensional method. Similar reproducibility was found for LV measurements, but the three-dimensional method provided greater reproducibility for RV measurements than the two-dimensional. The threshold value supported three-dimensional method provides reproducible cardiac ventricular volume measurements, comparable to those obtained using the short-axis Simpson based method.

Accurate estimation of global and regional cardiac function by retrospectively gated multidetector row computed tomography

Retrospective reconstruction of ECG-gated images at different parts of the cardiac cycle allows the assessment of cardiac function by multi-detector row CT (MDCT) at the time of non-invasive coronary imaging. We compared the accuracy of such measurements by MDCT to cine magnetic resonance (MR). Forty patients underwent the assessment of global and regional cardiac function by 16-slice MDCT and cine MR. Left ventricular (LV) end-diastolic and end-systolic volumes estimated by MDCT (134+/-51 and 67+/-56 ml) were similar to those by MR (137+/-57 and 70+/-60 ml, respectively; both P=NS) and strongly correlated (r=0.92 and r=0.95, respectively; both P<0.001). Consequently, LV ejection fractions by MDCT and MR were also similar (55+/-21 vs. 56+/-21%; P=NS) and highly correlated (r=0.95; P<0.001). Regional end-diastolic and end-systolic wall thicknesses by MDCT were highly correlated (r=0.84 and r=0.92, respectively; both P<0.001), but significantly lower than by MR (8.3+/-1.8 vs. 8.8+/-1.9 mm and 12.7+/-3.4 vs. 13.3+/-3.5 mm, respectively; both P<0.001). Values of regional wall thickening by MDCT and MR were similar (54+/-30 vs. 51+/-31%; P=NS) and also correlated well (r=0.91; P<0.001). Retrospectively gated MDCT can accurately estimate LV volumes, EF and regional LV wall thickening compared to cine MR.

Mutidetector-row CT and quantitative gated SPECT for the assessment of left ventricular function in small hearts: the cardiac physical phantom study using a combined SPECT/CT system

The aim of this study was to compare results of left ventricular (LV) function obtained by quantitative gated single-photon emission tomography (QGS) and multidetector-row spiral computed tomography (MDCT) with reference parameters using an electrocardiogram-gated cardiac physical phantom. The phantom study was performed using a combined SPECT/CT system. Flexible membranes formed the inner and outer walls of the simulated LV. The stroke volume was adjusted (45 mL or 58 mL) and the fixed 42-mL end-systolic volume (ESV) produced two different volume combinations. The LV function parameters were estimated by means of MDCT and QGS. Differences in true and measured volumes were compared among CT with a reconstructed image thickness of 2.5 mm and 5.0 mm and QGS volumetric values. Each scan was repeated three-times. The estimation of LV volumes using both QGS and MDCT analyses were reproducible very well. QGS overestimated ejection fraction (EF) by approximately 20%; MDCT volumetry overestimated EF by approximately 5% in each volume setting. The differences in true and measured values for EF and ESV obtained with QGS were significantly greater than obtained with MDCT.

CONCLUSION

MDCT provides a reliable estimation of functional LV parameters, whereas QGS tends to significantly overestimate the EF in small hearts.

Current and future status on cardiac computed tomography imaging for diagnosis and risk stratification

Computed tomography (CT) permits cross-sectional imaging with high spatial resolution and has, during the past years, undergone tremendous development mainly concerning the temporal resolution. By use of multidetector spiral technology, as well as electrocardiography-gated image acquisition and reconstruction techniques, 16- and 64-slice CT permits visualization of cardiac morphology and function. In this context, however, CT imaging does not play a major clinical role because other imaging methods (mainly echocardiography) usually provide all necessary information. Under certain conditions, multidetector CT also permits visualization of the coronary arteries. Detection of coronary calcification, as well as coronary CT angiography, can provide clinically useful information if applied to suitable patient groups. It is foreseeable that CT angiography will become part of the routine workup in some subsets of patients with suspected coronary artery disease, either alone or in combination with other imaging techniques. Among the limitations of cardiac CT are the requirement of a regular (and preferably low) heart rate, the associated x-ray exposure, and the need for an iodinated contrast agent for most applications. It is important to note that reliable and accurate results will require use of the most advanced CT scanner technology, optimal image quality, and sufficient experience in the acquisition and interpretation of cardiac CT data sets.

Two-phase reconstruction for the assessment of left ventricular volume and function using retrospective ECG-gated MDCT: comparison with echocardiography

OBJECTIVE

The aims of our study were to investigate the clinical feasibility of a two-phase reconstruction method based on ECG to evaluate left ventricular (LV) volume and function using cardiac MDCT and to compare these results with those from echocardiography.

SUBJECTS AND METHODS

The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction were measured using two different methods of cardiac MDCT in 19 patients who had undergone cardiac MDCT and echocardiography. The first was a two-phase reconstruction method based on retrospective ECG-triggering: The end-systolic phase was reconstructed when the reconstruction window was located halfway in the ascending T wave on ECG, and the end-diastolic phase was reconstructed when the reconstruction window was located at the starting point of the QRS complex on ECG. The second was a multiphase reconstruction method: 20 series of images were reconstructed at every 5% throughout the cardiac cycle. The LV volumes and function determined by the two reconstruction methods were compared. The results measured by cardiac MDCT were compared with those obtained by echocardiography.

RESULTS

The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction measured by the two-phase reconstruction method correlated well with those measured by the multiphase reconstruction method (r = 0.984, 0.978, 0.969, 0.969, respectively). There were no significant differences between the results of the two different reconstruction methods (p > 0.05). The LV volumes showed moderate to good correlation between cardiac MDCT and echocardiography (0.766 < r < 0.940). Ejection fraction measured by cardiac MDCT yielded a significant overestimation of 2.9% +/- 8.7% (mean +/- SD) compared with that measured by echocardiography.

CONCLUSION

A two-phase reconstruction method on cardiac MDCT is relatively simple and can provide an objective standard for reconstructing the appropriate image sets for end-diastole and end-systole without the need to review serial preview images.

Dynamic Cine Mode Imaging of the Normal Aortic Valve Using 16-Channel Multidetector Row Computed Tomography

BACKGROUND

We investigated the feasibility and image quality of dynamic cine-mode imaging of the normal aortic valve using multidetector row computed tomography (MDCT).

MATERIALS AND METHODS

We acquired contrast-enhanced retrospectively echocardiography (ECG)-gated cardiac MDCT datasets of 35 patients (mean age, 62 years; range, 53-77) who received a transoesophageal echocardiography (TOE) precedent to cardiac bypass graft surgery. Twenty data sets in 5% steps of the R-R interval were reconstructed, and data analysis was performed using a 4D software. Read-out of the MDCT data was performed in parallel and perpendicular planes, similar to TOE standard planes, by 2 independent, blinded readers using a 4-point Likert scale (best score: 4) for the following parameters: image quality of the aortic valve components, contrast media enhancement, contrast media inflow related artifacts, and ECG gating-related artifacts. The aortic valve area (AVA) was measured planimetrically and was compared between TOE and MDCT.

RESULTS

The best phase for assessing the open valve using MDCT was at 5% and the closed valve at 65% of the cardiac cycle. The mean image quality scores for cine-mode MDCT ranged between 3.26 and 3.75, with inter-reader agreements ranging between good (kappa = 0.723) and excellent (kappa = 1.00). They did not differ significantly from TOE scores for assessment of the closed and open valve. In transitional phases (close-to-open and open-to-close) TOE performed significantly better when compared with static MDCT images, whereas no significant difference was present between cine-mode presentation of MDCT and TOE. Planimetric AVA measurements correlated significantly between TOE and MDCT (Pearson correlation coefficient, r = 0.96; P < 0.0001). Contrast media inflow-related and ECG gating related artifacts were rated as slightly compromising (scores 3.24 and 3.21).

CONCLUSION

Retrospectively ECG-gated MDCT offers a noninvasive, accurate, and dynamic imaging method for quantitative and qualitative evaluation of the normal aortic valve allowing determination of morphology and function throughout the cardiac cycle. Further studies regarding assessment of diseased valves are necessary.

Comprehensive assessment of patients after coronary artery bypass grafting by 16-detector-row computed tomography

BACKGROUND

Multidetector-row computed tomography (MDCT) is a versatile modality to evaluate stenoses in native coronary arteries and bypass grafts. Acquired MDCT data can additionally be used to assess left ventricular ejection fraction (LVEF). The purpose was to use MDCT for the assessment of bypass graft and coronary artery disease combined with evaluation of LVEF.

METHODS

Twenty-five patients underwent 16-detector-row CT examination and coronary angiography. Bypass grafts and nongrafted coronary artery segments at MDCT were evaluated on eligibility, patency, and > or = 50% stenosis. The MDCT data set was used to calculate LVEF and was divided into patients with no/subendocardial/transmural myocardial infarctions (MIs).

RESULTS

Ninety vessels were evaluated: 14 arterial grafts/53 vein grafts/23 nongrafted vessels. Of 225 segments, 17 were ineligible for evaluation because of metal clips. With MDCT, patency in segments of arterial grafts/vein grafts/nongrafted vessels could be evaluated with high accuracy in 100%/100%/97% of segments. In arterial grafts, stenoses > or = 50% did not occur at angiography, which was for all eligible segments correctly diagnosed at MDCT. Stenosis > or = 50% could be correctly detected by MDCT with a sensitivity/specificity of 100%/94% for vein grafts and 100%/89% for nongrafted vessels. Negative predictive value was 100% for vein grafts and nongrafted vessels. In patients with transmural MI, MDCT revealed a significant lower LVEF as compared with patients without or with subendocardial MI (P < .05).

CONCLUSION

Comprehensive assessment of bypass grafts, nongrafted vessels, and LVEF is feasible with MDCT. Owing to the high negative predictive value this noninvasive approach may be used as gatekeeper before coronary angiography.

Left ventricular function studied with MDCT

Accurate determination of left ventricular (LV) myocardial function is fundamental for clinical diagnosis, risk stratification, and estimation of prognosis in patients with ischemic and nonischemic cardiomyopathy. Primarily, multi-detector-row spiral CT (MDCT) of the heart aimed at detecting coronary artery obstruction and cardiac morphology. Multiple studies have demonstrated that retrospectively, ECG-gated MDCT determination of LV volumes and consequently global LV function parameters is feasible in good agreement with established imaging modalities such as cineventriculography, echocardiography, and cine magnetic resonance imaging (CMR). Post-processing tools allow fast and semi-automatic determination of LV function parameters from MDCT data in analogy to known CMR evaluation approaches. Although MDCT is not considered to be first-line modality for LV function assessment, this technique provides accessory dynamic information in patients undergoing MDCT coronary angiography, contributing to combined assessment of cardiac morphology and function without need of additional radiation exposure. MDCT regional LV wall motion analysis at rest is feasible, but further improvement in temporal resolution seems mandatory to match results obtained from competing modalities. This paper will discuss the diagnostic potential of MDCT for assessment of LV function with regards to accuracy and clinical applications, as well as limitations, particularly in comparison with CMR as modality of reference.

Multislice CT coronary angiography: how to do it and what is the current clinical performance?

The introduction of multislice computed tomography (MSCT) has allowed non-invasive coronary angiography. Although widely applied, extensive information on technical details of the technique is lacking. This survey offers detailed information on patient preparation, data acquisition, reconstruction and interpretation. In addition, a summary of the available studies using MSCT for non-invasive angiography is provided. Based on pooled analysis of direct comparisons between MSCT and invasive angiography, the weighted mean sensitivity and specificity of current 16-slice MSCT for the detection of coronary artery disease are 88% and 96%, respectively. At present, the technique is particularly well suited for reliable exclusion of coronary artery disease. It is important to emphasise that MSCT only provides anatomical images, visualising the presence of atherosclerosis; information on the haemodynamic significance of these lesions (i.e. ischaemia) cannot be derived.

Technology Insight: possible applications of multislice computed tomography in clinical cardiology

With the introduction of four-slice scanners in 1999, multislice CT (MSCT) technology became available for investigative examination of the heart. Since then, MSCT technology has undergone rapid technical progress; temporal and spatial resolutions have been especially improved. The improved diagnostic image quality has led to more possible uses of MSCT being defined. At present, issues such as visualization of coronary artery bypass grafts, detection of stenoses of native coronary arteries, description of coronary anomalies, and calcium scoring, can be investigated reasonably well. Other features, such as plaque imaging and visualization of intracoronary stents, need further evaluation. A large number of factors, however, such as heart rate, atrial fibrillation, breathing artefacts and severe calcification, still influence image quality and reduce validity. In this article we provide a summary of current fields of application of cardiac MSCT. The word 'indication' is consciously avoided because official guidelines for the use of MSCT in heart examination have not yet been issued. Hopefully, prospective multicenter trials will be performed soon, providing more data with which to establish guidelines for both cardiologist and radiologist.

Assessment of cardiac function by electron-beam computed tomography

The measurement of parameters relating to the assessment of cardiac function and morphology are critically important prognostic determinates in patients with known or suspected cardiac disease, such as coronary artery disease and myocardial infarction. Similarly, the measurement of indices, such as ejection fraction and myocardial mass, are key in assessing the efficacy of therapy in patients with valvular, coronary artery and intrinsic myocardial diseases. Electron-beam computed tomography has been proven to be a reliable and accurate modality for measuring a host of parameters relating to cardiac function. This article reviews the unique technologic design of the electron-beam computed tomography scanner and specifically addresses how this technology has enabled electron-beam computed tomography to become the gold standard for the quantification of cardiac function.

Evaluation of a semiautomatic software tool for left ventricular function analysis with 16-slice computed tomography

The purpose of the study was to evaluate a semiautomatic analysis tool for assessing global left ventricular myocardial function with multislice computed tomography (MSCT). We examined 33 patients with MSCT using 16x0.5 mm detector collimation and magnetic resonance imaging (MRI) on a 1.5-T scanner. MSCT data were analyzed using semiautomatic volumetric analysis software (ANET, CSCF-001A, Toshiba). This software tool automatically creates endo- and epicardial contours that can be manually corrected on all short-axis slices at all reconstructed time points within the cardiac cycle, based on a contour-detection and density-threshold algorithm. All global left ventricular function parameters assessed with the semiautomatic MSCT software were highly correlated with the results of MRI. Bland-Altman analysis showed minor systematic overestimation of end-diastolic (10.7 ml) and end-systolic volumes (5.6 ml) and underestimation of ejection fraction (2.1%) with MSCT as compared with MRI. The post-processing time was moderately but significantly longer with the MSCT software (15.9+/-2.8 min) than necessary for MRI (14.0+/-2.5 min, P<0.01), mainly as a result of the longer time required for uploading of the MSCT datasets, which were on average 54 times larger (1.3 GByte). In conclusion, it appears feasible to accurately assess global left ventricular function with MSCT in a reasonable post-processing time using a semiautomatic software tool.

Multislice Spiral Computed Tomography of the Heart: Technique, Current Applications, and Perspective

Multislice spiral computed tomography (MSCT) is a rapidly evolving, noninvasive technique for cardiac imaging. Knowledge of the principle of electrocardiogram-gated MSCT and its limitations in clinical routine are needed to optimize image quality. Therefore, the basic technical principle including essentials of image postprocessing is described. Cardiac MSCT imaging was initially focused on coronary calcium scoring, MSCT coronary angiography, and analysis of left ventricular function. Recent studies also evaluated the ability of cardiac MSCT to visualize myocardial infarction and assess valvular morphology. In combination with experimental approaches toward the assessment of aortic valve function and myocardial viability, cardiac MSCT holds the potential for a comprehensive examination of the heart using one single examination technique.

Multislice Computed Tomography for Preoperative Evaluation of Right Ventricular Volumes and Function: Comparison With Magnetic Resonance Imaging

BACKGROUND

This study was performed to validate preoperative right ventricular measurements obtained from multislice spiral computed tomography data sets in comparison with magnetic resonance imaging.

METHODS

Before cardiac surgery, 25 patients (among them 12 patients with compromised right ventricular function) underwent contrast-enhanced retrospectively electrocardiogram-gated multislice spiral computed tomography and cine magnetic resonance imaging in a standardized fashion. Right ventricular end-diastolic, end-systolic and stroke volume, ejection fraction, and myocardial mass were calculated according to the slice summation method. Measurements obtained with both modalities were compared using Pearson's correlation coefficient (r), Student's t test for paired samples, and Bland-Altman analysis.

RESULTS

The right ventricle was completely visualized with invariably adequate image quality on all multislice spiral computed tomography and magnetic resonance images. For all measurements a close correlation between multislice spiral computed tomography and magnetic resonance imaging was found (end-diastolic volume, r = 0.93; end-systolic volume, r = 0.95; stroke volume, r = 0.91; ejection fraction, r = 0.96; mass, r = 0.94). Mean values of all measurements did not differ significantly between both modalities, and limits of agreement were in an acceptable range.

CONCLUSIONS

When compared with magnetic resonance imaging as a reference method, multislice spiral computed tomography seems to be an accurate and reliable noninvasive technique for evaluating right ventricular measurements.

Evaluation of right ventricular volume and mass using retrospective ECG-gated cardiac multidetector computed tomography: comparison with first-pass radionuclide angiography

The purposes of this study were to evaluate the right ventricular (RV) volume and mass using cardiac multidetector computed tomography (MDCT) and to compare the cardiac MDCT results with those from first-pass radionuclide angiography (FPRA). Twenty patients were evaluated for the RV end-diastolic volume (RVEDV), the RV end-systolic volume (RVESV), the RV ejection fraction (RVEF), and RV mass using cardiac MDCT with a two-phase reconstruction method based on ECG. The end-diastolic phase was reconstructed at the starting point of the QRS complex on ECG, and the end-systolic phase was reconstructed at the halfway point of the ascending T-wave on ECG. The RV mass was measured for the end-systole. The RVEF was also obtained by FPRA. The mean RVEF (47+/-7%) measured by cardiac MDCT was well correlated with that (44+/-6%) measured by FPRA (r=0.854). A significant difference in the mean RVEF was found between cardiac MDCT and FPRA (p=0.001), with an overestimation of 2.9+/-5.3% by cardiac MDCT versus FPRA. The interobserver variability was 4.4% for the RVEDV, 6.8% for the RVESV, and 7.9% for the RV mass, respectively. Cardiac MDCT is relatively simple and allows the RV volume and mass to be assessed, and the RVEF obtained by cardiac MDCT correlates well with that measured by FPRA.

Noninvasive Evaluation of the Coronary Arteries With Multislice Computed Tomography in Hypertensive Patients

Because patients with hypertension are at increased risk for coronary artery disease, early and noninvasive identification of the disease in patients with hypertension is important. Recently, multislice computed tomography (MSCT) has been demonstrated to allow both noninvasive coronary angiography and assessment of left ventricular function. The purpose of the present study therefore was to demonstrate the feasibility of this approach in patients with hypertension with known or suspected coronary artery disease and to compare the results to invasive coronary angiography and 2-dimensional echocardiography, respectively. MSCT was performed in 31 patients with confirmed hypertension. From the MSCT images, the presence of significant coronary stenoses (≥50% luminal narrowing) and regional wall motion abnormalities were evaluated and compared with invasive coronary angiography and 2-dimensional echocardiography. In addition, left ventricular ejection fraction was calculated from the MSCT images. A total of 243 (88%) coronary artery segments could be evaluated with MSCT. Sensitivity and specificity for the detection of significant coronary artery stenoses were 93% and 96%. On a per-patient basis, MSCT was accurate in 28 (90%) patients. Mean left ventricular ejection fraction was 46±14% (range, 16% to 64%). The agreement for assessing regional wall motion was 91% (kappa statistic, 0.81). In conclusion, simultaneous, noninvasive evaluation of coronary artery stenoses and left ventricular function with MSCT is accurate in patients with hypertension. This noninvasive approach may allow triage of patient treatment in terms of conservative versus invasive management.

Quantification of Functional Mitral Valve Regurgitation in Patients With Congestive Heart Failure

OBJECTIVES

We sought to determine the agreement between electron-beam computed tomography (CT) and cardiac catheterization for the quantification of mitral regurgitation and to evaluate their association with echocardiographic assessment.

MATERIAL AND METHODS

Fifty patients with congestive heart failure were examined both by electron-beam CT and catheterization to calculate mitral regurgitation volume and fraction based on the difference between the left ventricular stroke and aortic flow volume. The severity of regurgitation was also compared with visual assessment by echocardiography (grade, 0-4+).

RESULTS

The mean values for the mitral regurgitation volume and fraction did not differ significantly between electron-beam CT and catheterization (mean differences: 0.2 mL/m2 and -0.9%, P > 0.05 each, limits of agreement: -14.0 to 14.4 mL/m2 and -26.3 to 24.5%, respectively) and showed a good correlation (r = 0.79 and r = 0.76, respectively; P < 0.05 each). Good levels of correlation were observed between echocardiographic severity grading and quantitative measurements of regurgitation volume and fraction, which were somewhat better between echocardiography and electron-beam CT (rS = 0.78 and rS = 0.84, respectively; P < 0.05 each) than between echocardiography and catheterization (rS = 0.72 and rS = 0.81, respectively; P < 0.05 each).

CONCLUSION

Our results suggest that electron-beam CT allows for quantification of mitral valve regurgitation with similar accuracy as cardiac catheterization. Measurements with both modalities correlated well with the results of echocardiographic assessment.

Assessment of right ventricular function by 16-detector-row CT: comparison with magnetic resonance imaging

The purpose of this study was to determine right ventricular (RV) function from 16-detector-row CT by using two different software tools in comparison with MRI. Nineteen patients underwent cardiac CT. (1) With semiautomated contour detection software end-diastolic and end-systolic RV volumes were determined from short-axis CT reformations (MPR) created at every 10% of the RR-interval. (2) End-systolic and end-diastolic axial images were transformed to 3D to determine the volumes by using a threshold-supported reconstruction algorithm. Steady-state free-precession cine-MRI of the heart was done in short-axis orientation. RV function could not be analyzed in one patient because of sternal wire artifacts in MRI. Mean end-diastolic (155.4+/-54.6 ml) and end-systolic (79.1+/-37.0 ml) RV volumes determined with MPR correlated well with MRI [151.9+/-53.7 ml (r=0.98) and 75.0+/-36.0 ml (r=0.96), respectively (P<0.001)]. RV stroke volume (76.2+/-20.2 ml for MPR-CT, 76.9+/-20.7 ml for MRI, r=0.93) showed a good correlation and RV ejection fraction (50.8+/-8.4% for MPR-CT, 51.9+/-7.4% for MRI, r=0.74) only a moderate one. Threshold supported 3D reconstructions revealed insufficient correlations with MRI (r=0.31-0.59). MPR-based semiautomated analysis of cardiac 16 detector-row CT allows for RV functional analysis. The results correlate well with MRI findings. Threshold value-supported 3D reconstructions did not show satisfying results because of inhomogeneities of RV contrast enhancement.

Multi-detector row computed tomography of the heart: does a multi-segment reconstruction algorithm improve left ventricular volume measurements?

A multi-segment cardiac image reconstruction algorithm in multi-detector row computed tomography (MDCT) was evaluated regarding temporal resolution and determination of left ventricular (LV) volumes and global LV function. MDCT and cine magnetic resonance (CMR) imaging were performed in 12 patients with known or suspected coronary artery disease. Patients gave informed written consent for the MDCT and the CMR exam. MDCT data were reconstructed using the standard adaptive cardiac volume (ACV) algorithm as well as a multi-segment algorithm utilizing data from three, five and seven rotations. LV end-diastolic (LV-EDV) and end-systolic volumes and ejection fraction (LV-EF) were determined from short-axis image reformations and compared to CMR data. Mean temporal resolution achieved was 192+/-24 ms using the ACV algorithm and improved significantly utilizing the three, five and seven data segments to 139+/-12, 113+/-13 and 96+/-11 ms (P<0.001 for each). Mean LV-EDV was without significant differences using the ACV algorithm, the multi-segment approach and CMR imaging. Despite improved temporal resolution with multi-segment image reconstruction, end-systolic volumes were less accurately measured (mean differences 3.9+/-11.8 ml to 8.1+/-13.9 ml), resulting in a consistent underestimation of LV-EF by 2.3-5.4% in comparison to CMR imaging (Bland-Altman analysis). Multi-segment image reconstruction improves temporal resolution compared to the standard ACV algorithm, but this does not result in a benefit for determination of LV volume and function.

Evaluation of ischemic heart disease with cardiac magnetic resonance and computed tomography

Ischemic heart disease is the most common cardiac problem encountered by physicians in their daily practice. In the last few years, computed tomography and magnetic resonance have emerged as robust imaging modalities with great potential for the comprehensive evaluation of patients with this disorder. This article reviews current evidence of the applications where these techniques have demonstrated their usefulness and provides guidance for their use in the clinical management of coronary artery disease.

The use of CTA in the chest pain center: a perspective

Suitable imaging methods to reliably rule out coronary artery disease as the underlying condition might be beneficially applied in the workup of patients with acute chest pain. The temporal and spatial resolution of computed tomgraphy and electron beam computed tomography has seen continuous improvements over the past years. Current scanner generations permit relatively reliable visualization of the coronary arteries and several studies have demonstrated a high negative predictive value to rule out coronary artery stenoses. Even though applications in the context of acute coronary syndromes have not yet been specifically evaluated, it seems likely that computed tomography imaging may develop into a tool that can be integrated into the workflow in chest pain centers once appropriate studies have been performed.