Functional parameters of the left ventricle: comparison of cardiac MRI and cardiac CT in a large population

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

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

Evaluation of the CT imaging findings in patients newly diagnosed with chronic thromboembolic pulmonary hypertension

PURPOSE

The aim of this study was to evaluate the vascular and parenchymal CT imaging findings, including vessel and cardiac chamber diameter measurements, in patients newly diagnosed with chronic thromboembolic pulmonary hypertension (CTEPH). The CT imaging findings were correlated with hemodynamic measurements and patient outcome.

METHODS

Vascular and parenchymal CT findings were assessed on retrospectively ECG-gated MDCT angiography scans in 76 patients newly diagnosed with CTEPH. The diameters of the right and left ventricle (dRV, dLV), the right and left atrium (dRA, dLA), the ascending aorta (dAA), the right and left pulmonary arteries (drPA, dlPA), and the main pulmonary artery (dPA) were measured on axial CT scans. The CT imaging findings were correlated with demographic and hemodynamic data and adverse patient outcome due to right heart failure (RHF).

RESULTS

The majority of patients showed chronic PE, mosaic perfusion, disparity in segmental vessel size, parenchymal densities, bronchial dilatation, and bronchial collaterals in CT. Mean pulmonary artery pressure (mPAP) was not significantly different in patients with and those without chronic PE, mosaic perfusion, disparity in segmental vessel size, parenchymal densities, bronchial dilatation, and bronchial collaterals. Mean PAP showed significant correlations with the CT metrics of dRV/dLV ratio, dRA, dRV, dPA and dPA/dAA ratio, but no correlation with the central thrombi score. By backward linear regression, the dPA/dAA ratio independently correlated with mPAP. Patients who died of RHF tended to have a higher frequency of exclusively chronic peripheral PE and greater dRV/dLV ratios on presenting CT scans compared with survivors.

CONCLUSION

The majority of patients newly diagnosed with CTEPH show vascular signs of chronic PE, mosaic perfusion, parenchymal densities, disparity in segmental vessel size, bronchial dilatation, and bronchial collaterals on presenting CT scans. Particularly CTEPH patients with exclusively chronic peripheral PE and increased dRV/dLV ratios seem to be at risk of adverse outcome due to RHF.

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

Background

The purpose of this study was to compare the left ventricular parameters obtained from multi-detector row computed tomography (MDCT) studies with two-dimensional echocardiography (2DE), and magnetic resonance imaging (MRI), which is accepted as the gold standard in the evaluation of left ventricular functions. The study also aimed to evaluate whether or not there is a relationship between the MR-Argus and CMR tools software programs which are used in post-process calculations of data obtained by MRI.

Material/Methods

Forty patients with an average age of 51.4±14.9 years who had been scanned with cardiac MDCT were evaluated with cardiac MRI and 2DE. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), cardiac output (CO), and myocardial mass values calculated by MDCT, MRI, and 2DE were compared with each other. Two different MR software programs were used to compare left ventricular functions. The CMR tools LV tutorials method is accepted as the gold standard because it can be used in three-dimensional functional evaluation. The Pearson Correlation and Bland-Altman analysis were performed to compare the results from the two MR methods (MR-Argus and CMR tools) and the results from both the MDCT and the 2DE with the CMR tools results.

Results

Strong positive correlations for EF values were found between the MDCT and CMR tools (r=0.702 p<0.001), and between the MR-Argus and CMR tools (r=0.746 p<0.001). The correlation between the 2DE and CMR tools (r=0.449 p<0.004), however, was only moderate. Similar results were obtained for the other parameters. The strongest correlation for ESV, EDV, and EF was between the two MR software programs. The correlation coefficient between the MDCT and CMR tools is close to the correlation coefficient between the two software programs. While the correlation between 2DE and CMR tools was satisfactory for ESV, EDV, and CO values, it was at a moderate level for the other parameters.

Conclusions

Left ventricular functional analysis can be performed easily and reliably with cardiac MDCT used for coronary artery evaluation and it also gives more accurate results than 2DE.

CT for evaluation of myocardial cell therapy in heart failure: a comparison with CMR imaging

OBJECTIVES

The aim of this study was to use multidetector computed tomography (MDCT) to assess therapeutic effects of myocardial regenerative cell therapies.

BACKGROUND

Cell transplantation is being widely investigated as a potential therapy in heart failure. Noninvasive imaging techniques are frequently used to investigate therapeutic effects of cell therapies in the preclinical and clinical settings. Previous studies have shown that cardiac MDCT can accurately quantify myocardial scar tissue and determine left ventricular (LV) volumes and ejection fraction (LVEF).

METHODS

Twenty-two minipigs were randomized to intramyocardial injection of phosphate-buffered saline (placebo, n = 9) or 200 million mesenchymal stem cells (MSC, n = 13) 12 weeks after myocardial infarction (MI). Cardiac magnetic resonance and MDCT acquisitions were performed before randomization (12 weeks after MI induction) and at the study endpoint 24 weeks after MI induction. None of the animals received medication to control the intrinsic heart rate during first-pass acquisitions for assessment of LV volumes and LVEF. Delayed-enhancement MDCT imaging was performed 10 min after contrast delivery. Two blinded observers analyzed MDCT acquisitions.

RESULTS

MDCT demonstrated that MSC therapy resulted in a reduction of infarct size from 14.3 ± 1.2% to 10.3 ± 1.5% of LV mass (p = 0.005), whereas infarct size increased in nontreated animals (from 13.8 ± 1.3% to 16.5 ± 1.5%; p = 0.02) (placebo vs. MSC; p = 0.003). Both observers had excellent agreement for infarct size (r = 0.96; p < 0.001). LVEF increased from 32.6 ± 2.2% to 36.9 ± 2.7% in MSC-treated animals (p = 0.03) and decreased in placebo animals (from 33.3 ± 1.4% to 29.1 ± 1.5%; p = 0.01; at week 24: placebo vs. MSC; p = 0.02). Infarct size, end-diastolic LV volume, and LVEF assessed by MDCT compared favorably with those assessed by cardiac magnetic resonance acquisitions (r = 0.70, r = 0.82, and r = 0.902, respectively; p < 0.001).

CONCLUSIONS

This study demonstrated that cardiac MDCT can be used to evaluate infarct size, LV volumes, and LVEF after intramyocardial-delivered MSC therapy. These findings support the use of cardiac MDCT in preclinical and clinical studies for novel myocardial therapies.

Clinical indications for cardiac computed tomography. From the Working Group of the Cardiac Radiology Section of the Italian Society of Medical Radiology (SIRM)

Cardiac computed tomography (CCT) has grown as a useful means in different clinical contexts. Technological development has progressively extended the indications for CCT while reducing the required radiation dose. Even today there is little documentation from the main international scientific societies describing the proper use and clinical indications of CCT; in particular, there are no complete guidelines. This document reflects the position of the Working Group of the Cardiac Radiology Section of the Italian Society of Radiology concerning the indications for CCT.

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.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Key Points

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

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

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

Electronic supplementary material

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

Incremental Prognostic Value of Cardiac Computed Tomography in Coronary Artery Disease Using CONFIRM

Background—

Large multicenter studies validating the prognostic value of coronary computed tomographic angiography (CCTA) and left ventricular ejection fraction (LVEF) are lacking. We sought to confirm the independent and incremental prognostic value of coronary artery disease (CAD) severity measured using 64-slice CCTA over LVEF and clinical variables.

Methods and Results—

A large international multicenter registry (CONFIRM Registry) was queried, and CCTA patients with LVEF data on CCTA were screened. Patients with a history of myocardial infarction, coronary revascularization, or cardiac transplantation were excluded. The National Cholesterol Education Program-Adult Treatment Panel III risk was calculated for each patient, and CCTA was evaluated for CAD severity (normal, nonobstructive, non–high-risk, or high-risk CAD) and LVEF <50%. Patients were followed for an end point of all-cause mortality; 27 125 patients underwent CCTA at 12 participating centers, with a total of 14 064 patients meeting the analysis criteria. Follow-up was available for 13 966 (99.3%) patients (mean follow-up of 22.5 months; 95% confidence interval, 22.3 to 22.7 months). All-cause mortality (271 deaths) occurred in 0.65% of patients without coronary atherosclerosis, 1.99% of patients with nonobstructive CAD, 2.90% of patients with non–high-risk CAD, and 4.95% for patients with high-risk CAD. Multivariable analysis confirmed that LVEF <50% (hazard ratio, 2.74; 95% confidence interval, 2.12 to 3.51) and CAD severity (hazard ratio,1.58; 95% confidence interval, 1.42 to 1.76) were predictors of all-cause mortality, and CAD severity had incremental value over LVEF and clinical variables.

Conclusions—

Our results demonstrate that CCTA measures of CAD severity and LVEF have independent prognostic value. Incorporation of CAD severity provides incremental value for predicting all-cause death over routine clinical predictors and LVEF in patients with suspected obstructive CAD.

[Exclusion of coronary artery disease using cardiac CT. What impact do CT results have on patient management?]

Rapid advancement of multidetector head computed tomography (MDCT) during the past 10 years has facilitated noninvasive evaluation of CAD (coronary artery disease). Since the introduction of 320-row technology, examination of the whole heart in a single heart beat with diagnostic quality has become feasible. Direct imaging of vessel morphology, a high sensitivity for CAD above 96%, and low requirements of patient compliance represent advantages over other imaging modalities, such as MRI (magnetic resonance imaging), scintigraphy, and echocardiography. In some cases radiation exposure can be reduced to an effective dose below 1 mSV.Current data suggest that cardiac CT represents a more effective diagnostic tool than treadmill testing in order to decide whether cardiac catheterization is indicated. Treadmill testing has been an integral procedure of cardiac examinations for decades, although sensitivity for detecting CAD is as low as 70%.Cardiac CT represents a rather new modality and is almost exclusively performed in diagnostic imaging centers. Innovative concepts in the evaluation of CAD including CT are expected. Some authors propose cardiac CT as a major diagnostic tool for the exclusion of CAD. MRI, scintigraphy, or echocardiography in combination with a stress test remain important procedures in order to evaluate the hemodynamic relevance of coronary artery stenosis. Treadmill testing prior to cardiac CT has become questionable.The future role of cardiac CT in CAD in "change of management" concepts is promising. In order to optimize decisions of patient management on the basis of a cardiac CT examinations, awareness of current data is mandatory for the referring clinician and the performing radiological department.