Cardiac CT: coronary arteries and beyond

Computed tomography of coronary artery atherosclerosis: A review

Coronary artery atherosclerosis resulting in ischemic cardiac disease is the leading cause of mortality in the United States. In symptomatic patients, invasive diagnostic methods like catheter angiography, intravascular ultrasound, or vascular endoscopy may be used. However, for primary prevention of atherosclerotic coronary artery disease in asymptomatic patients, non-invasive methods are more commonly utilized like stress imaging, single-photon emission computed tomography (SPECT) and coronary artery calcification scoring. Coronary computed tomographic angiography (CCTA) is an excellent diagnostic tool for detection of coronary artery plaque and ability to identify resultant stenoses with an excellent negative predictive value which can potentially result in optimal exclusion of the presence of coronary artery disease. Long term follow up after a negative CCTA has repeatedly demonstrated very low incidence of future adverse coronary events, attesting its predictive value. CCTA based management is associated with improved CAD outcome in stable angina. Coronary CTA is valuable in acute chest pain evaluation in the emergency department helping in better triage. CT perfusion and CT-FFR are both very promising tools for assessment of hemodynamic significance of coronary artery stenosis.

Practical utilization of cardiac computed tomography for the success in complex coronary intervention

Percutaneous coronary intervention (PCI) for complex lesions is still technically demanding and is associated with less favorable procedural parameters such as lower success rate, longer procedural time, higher contrast volume and unexpected complications. Because the conventional angiographic analysis is limited by the inability to visualize the plaque information and the occluded segment, cardiac computed tomography has evolved as an adjunct to invasive angiography to better characterize coronary lesions to improve success rates of PCI. Adding to routine image reconstructions by coronary computed tomography angiography, the thin-slab maximum intensity projection method, which is a handy reconstruction technique on an ordinary workstation, could provide easy-to-understand images to reveal the anatomical characteristics and the lumen and plaque information simultaneously, and then assist to build an in-depth strategy for PCI. Especially in the treatment of chronic total occlusion lesion, these informations have big advantages in the visualization of the morphologies of entry and exit, the occluded segment and the distribution of calcium compared to invasive coronary angiography. Despite of the additional radiation exposure, contrast use and cost for cardiac computed tomography, the precise analysis of lesion characteristics would consequently improve the procedural success and prevent the complication in complex PCI.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Dual-source computed tomography for evaluating coronary stenosis and left ventricular function

This study aimed to evaluate the correlation between coronary stenosis and left ventricular function using dual-source computed tomography (DSCT). DSCT coronary angiography (CAG) was performed on 66 patients with coronary disease and 36 healthy volunteers. The degree of coronary stenosis, end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and myocardial mass (MM) were measured for the left ventricle. These values were compared with the results obtained by echocardiography (ECHO) and selective CAG, which were both adopted as controls. The diagnoses of coronary stenosis based on DSCT CAG and those based on selective CAG were not significantly different (P>0.05). Similarly, the values of EDV, ESV, SV or EV measured by DSCT CAG were not significantly different from thoses obtained by ECHO (P>0.05). However, significant differences were observed in the ESV, EF and SV of the severe stenosis group compared with the moderate and mild stenosis groups (both P<0.05). The values of EDV and MM significantly varied between the mild, moderate and severe stenosis groups (P<0.05). DSCT CAG is a highly accurate and highly reproducible method for evaluating the preliminary changes in cardiac function based on the variations of coronary stenosis. Significant changes were detected in the EDV and MM of the moderate stenosis group and in all parameters of the severe stenosis group.

Reliable quantification of BOLD fMRI cerebrovascular reactivity despite poor breath-hold performance

Cerebrovascular reactivity (CVR) can be mapped using BOLD fMRI to provide a clinical insight into vascular health that can be used to diagnose cerebrovascular disease. Breath-holds are a readily accessible method for producing the required arterial CO2 increases but their implementation into clinical studies is limited by concerns that patients will demonstrate highly variable performance of breath-hold challenges. This study assesses the repeatability of CVR measurements despite poor task performance, to determine if and how robust results could be achieved with breath-holds in patients. Twelve healthy volunteers were scanned at 3 T. Six functional scans were acquired, each consisting of 6 breath-hold challenges (10, 15, or 20 s duration) interleaved with periods of paced breathing. These scans simulated the varying breath-hold consistency and ability levels that may occur in patient data. Uniform ramps, time-scaled ramps, and end-tidal CO2 data were used as regressors in a general linear model in order to measure CVR at the grey matter, regional, and voxelwise level. The intraclass correlation coefficient (ICC) quantified the repeatability of the CVR measurement for each breath-hold regressor type and scale of interest across the variable task performances. The ramp regressors did not fully account for variability in breath-hold performance and did not achieve acceptable repeatability (ICC<0.4) in several regions analysed. In contrast, the end-tidal CO2 regressors resulted in "excellent" repeatability (ICC=0.82) in the average grey matter data, and resulted in acceptable repeatability in all smaller regions tested (ICC>0.4). Further analysis of intra-subject CVR variability across the brain (ICCspatial and voxelwise correlation) supported the use of end-tidal CO2 data to extract robust whole-brain CVR maps, despite variability in breath-hold performance. We conclude that the incorporation of end-tidal CO2 monitoring into scanning enables robust, repeatable measurement of CVR that makes breath-hold challenges suitable for routine clinical practice.

Reconstructions with identical filling (RIF) of the heart: a physiological approach to image reconstruction in coronary CT angiography

OBJECTIVES

To compare image quality in coronary artery computed tomography angiography (cCTA) using reconstructions with automated phase detection and Reconstructions computed with Identical Filling of the heart (RIF).

METHODS

Seventy-four patients underwent ECG-gated dual source CT (DSCT) between November 2009 and July 2010 for suspected coronary heart disease (n = 35), planning of transcatheter aortic valve replacement (n = 34) or evaluation of ventricular function (n = 5). Image data sets by the RIF formula and automated phase detection were computed and evaluated with the AHA 15-segment model and a 5-grade Likert scale (1: poor, 5: excellent quality). Subgroups regarding rhythm (sinus rhythm = SR; arrhythmia = ARR) and potential premedication were evaluated by a per-segment, per-vessel and per-patient analysis.

RESULTS

RIF significantly improved image quality in 10 of 15 coronary segments (P < 0.05). More diagnostic segments were provided by RIF regarding the entire cohort (n = 693 vs. 590, P < 0.001) and all of the subgroups (e.g. ARR: n = 143 vs. 72, P < 0.001). In arrhythmic patients (n = 19), more diagnostic vessels (e.g. LAD: n = 10 vs. 3; P < 0.014) and complete data sets (n = 7 vs. 1; P < 0.001) were produced.

CONCLUSIONS

RIF reconstruction is superior to automatic diastolic non-edited reconstructions, especially in arrhythmic patients. RIF theory provides a physiological approach for determining the optimal image reconstruction point in ECG-gated CT angiography.

KEY POINTS

Conventional CT coronary angiography suffers from numerous artefacts in patients with irregular rhythms. Coronary computed tomography angiograms (cCTA) were reconstructed with identical cardiac filling (RIF). RIF reconstructions provide improved image quality compared to non-edited standard reconstructions. RIF theory links physiology with cardiac CT.

CT radiation dose optimization and estimation: an update for radiologists

In keeping with the increasing utilization of CT examinations, the greater concern about radiation hazards from examinations has been addressed. In this regard, CT radiation dose optimization has been given a great deal of attention by radiologists, referring physicians, technologists, and physicists. Dose-saving strategies are continuously evolving in terms of imaging techniques as well as dose management. Consequently, regular updates of this issue are necessary especially for radiologists who play a pivotal role in this activity. This review article will provide an update on how we can optimize CT dose in order to maximize the benefit-to-risk ratio of this clinically useful diagnostic imaging method.

Approximations of noise covariance in multi-slice helical CT scans: impact on lung nodule size estimation

Multi-slice computed tomography (MSCT) scanners have become popular volumetric imaging tools. Deterministic and random properties of the resulting CT scans have been studied in the literature. Due to the large number of voxels in the three-dimensional (3D) volumetric dataset, full characterization of the noise covariance in MSCT scans is difficult to tackle. However, as usage of such datasets for quantitative disease diagnosis grows, so does the importance of understanding the noise properties because of their effect on the accuracy of the clinical outcome. The goal of this work is to study noise covariance in the helical MSCT volumetric dataset. We explore possible approximations to the noise covariance matrix with reduced degrees of freedom, including voxel-based variance, one-dimensional (1D) correlation, two-dimensional (2D) in-plane correlation and the noise power spectrum (NPS). We further examine the effect of various noise covariance models on the accuracy of a prewhitening matched filter nodule size estimation strategy. Our simulation results suggest that the 1D longitudinal, 2D in-plane and NPS prewhitening approaches can improve the performance of nodule size estimation algorithms. When taking into account computational costs in determining noise characterizations, the NPS model may be the most efficient approximation to the MSCT noise covariance matrix.

Comparison of global left ventricular function using 20 phases with 10-phase reconstructions in multidetector-row computed tomography

To compare the measurement of global left-ventricular (LV) function parameters of 64-slice multidetector-row computed tomography (MDCT) between 20- and 10-reconstruction phases. Fifty five patients with suspected or known coronary artery disease underwent 64-slice MDCT. LV end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were measured from MDCT data sets using threshold-based volume segmentation and reconstruction at every 5% (20 phases) and 10% (10 phases) step through the R-R interval. These global functional parameters were compared to those obtained via two-dimensional transthoracic echocardiography (2D-TTE), considering the reference standard. The required time for CT data analysis was checked. Agreement for parameters of LV global function was determined using Pearson's correlation coefficient (r) and Bland-Altman analysis. LV volumes (EDV(-5%) 87.5 ± 17.1 ml, EDV(-10%) 87.7 ± 16.3 ml; ESV(-5%) 32.4 ± 10.6 ml, ESV(-10%) 31.9 ± 9.9 ml; SV(-5%) 55.1 ± 10.5 ml, SV(-10%) 55.8 ± 9.9 ml; mean ± SD) and EF (EF(-5%) 63.4 ± 6.2%, EF(-10%) 63.9 ± 5.8%) did not differ significantly between the 20- and 10 phase reconstructions, and evidenced good to excellent correlation (r = 0.786-0.896, all P < 0.001) with the 2D-TTE results. The mean required time for CT data analysis in the 20- and 10 phase reconstructions were 15.5 ± 4.0 and 7.3 ± 2.5 min. Within MDCT, using 10-phase image reconstruction is sufficient to evaluate LV volumes and EF, and is also more time-effective than 20-phase reconstruction.

Assessment of global function of left ventricle with dual-source CT in patients with severe arrhythmia: a comparison with the use of two-dimensional transthoracic echocardiography

To evaluate the agreement between dual-source computed tomography (DSCT) and two-dimensional transthoracic echocardiography (2D-TTE) with respect to the assessment of global left ventricular (LV) function in patients with severe arrhythmia. With 2D-TTE serving as the reference method, we performed both DSCT and 2D-TTE, at an interval of less than 2 days, in 54 patients with severe arrhythmia (average heart rate difference >30 beats per min) before open heart surgery for evaluation of valvular heart disease (VHD) and coronary artery disease. DSCT was performed using retrospective electrocardiography (ECG) without dose modulation. Ten phases of the cardiac cycle were analyzed for identification of end-diastolic and end-systolic phases with ECG-editing. Pearson's correlation coefficient (r) and Bland-Altman analysis were used to determine agreement for parameters of LV global function. Correlation between DSCT and 2D-TTE measurements was good or excellent in terms of the values of the LV ejection fraction (51.0 ± 11.4% vs. 55.8 ± 11.6%; r = 0.8), LV end-diastolic volume (179.5 ± 98.6 ml vs. 152.1 ± 73.8 ml; r = 0.95), LV end-systolic volume (90.7 ± 60.7 ml vs. 69.1 ± 46.8 ml; r = 0.90), and LV stroke volume (89.0 ± 48.1 ml vs. 82.9 ± 37.3 ml; r = 0.89). Left ventricular ejection fraction measured using DSCT was less than that measured using 2D-TTE by an average of -4.8 ± 7.3%. Dual-source CT with ECG editing can provide results comparable to those of 2D-TTE for assessment of LV global function in patients with severe arrhythmia.

Quantification of Epicardial Fat by Cardiac CT Imaging

The aim of this work is to introduce and design image processing methods for the quantitative analysis of epicardial fat by using cardiac CT imaging.

Indeed, epicardial fat has recently been shown to correlate with cardiovascular disease, cardiovascular risk factors and metabolic syndrome. However, many concerns still remain about the methods for measuring epicardial fat, its regional distribution on the myocardium and the accuracy and reproducibility of the measurements.

In this paper, a method is proposed for the analysis of single-frame 3D images obtained by the standard acquisition protocol used for coronary calcium scoring. In the design of the method, much attention has been payed to the minimization of user intervention and to reproducibility issues.

In particular, the proposed method features a two step segmentation algorithm suitable for the analysis of epicardial fat. In the first step of the algorithm, an analysis of epicardial fat intensity distribution is carried out in order to define suitable thresholds for a first rough segmentation. In the second step, a variational formulation of level set methods - including a specially-designed region homogeneity energy based on Gaussian mixture models- is used to recover spatial coherence and smoothness of fat depots.

Experimental results show that the introduced method may be efficiently used for the quantification of epicardial fat.

Assessment of left ventricular ejection fraction and regional wall motion with 64-slice multidetector CT: a comparison with two-dimensional transthoracic echocardiography

The aim of this study was to compare the measurement of left ventricular ejection fraction (LVEF) and regional wall motion using 64-slice multidetector CT (MDCT) with that using two-dimensional transthoracic echocardiography (2D-TTE) in a heterogeneous patient population. In 126 patients with angina pectoris, acute myocardial infarction, chronic myocardial infarction, atypical chest pain without coronary artery disease or valvular heart disease, 64-slice MDCT was performed using retrospective electrocardiography gating without dose modulation. 20 phases of the cardiac cycle were analysed to identify the end-diastolic and end-systolic phases and to assess regional LV wall motion. For these measurements, 2D-TTE served as the reference standard. MDCT and 2D-TTE were performed within 10 days of each other. An excellent correlation between MDCT and 2D-TTE was shown for the evaluation of LVEF (59.2+/-11% vs 57.9+/-10%, respectively; r = 0.87). LVEF was slightly overestimated by MDCT, when compared with 2D-TTE, by an average of 1.4+/-5.6%. Good agreement was obtained between the use of the two techniques, with 94% of the segments scored identically on both modalities (kappa = 0.70). MDCT had a sensitivity of 97% and a specificity of 82% when compared with 2D-TTE as the reference standard. In conclusion, the use of 64-slice MDCT can provide comparable results to those using 2D-TTE for LVEF and regional wall motion assessment in a heterogeneous population.

Multislice computed tomography for comprehensive assessment of the heart in acute chest pain: a case report

Introduction

Over the last decade cardiac computed tomography emerged as a non-invasive imaging modality for the assessment of the heart and the coronary arteries. Only recently its use for patient management in the emergency department was suggested.

Case Presentation

We present an 84-year old male patient with concomitant early in-stent restenosis after coronary artery stent placement, myocardial infarction, left and right ventricular thrombi and aortic valve stenosis. Diagnoses were made on emergency cardiac computed tomography. All findings were confirmed by catheter coronary angiography, echocardiography and cardiac magnetic resonce imaging.

Conclusion

The comprehensive emergency work-up by cardiac computed tomography, illustrates the potential value of cardiac computed tomography in the emergency setting.

Cardiac spiral dual-source CT with high pitch: a feasibility study

Increase of pitch in spiral CT decreases data acquisition time; dual-source CT (DSCT) systems provide improved temporal resolution. We evaluated the combination of these two features. Measurements were performed using a commercial DSCT system equipped with prototype software allowing pitch factors from p = 0.35 to 3.0. We measured slice sensitivity profiles as a function of pitch to assess spatial resolution in the z-direction and the contrast of structures moved periodically to measure temporal resolution. Additionally we derived modulation transfer functions to provide objective parameters; both spatial and temporal resolution were essentially unchanged even at high pitch. CT of the cardiac region of three pigs was performed at p = 3.0. In vivo CT images confirmed good image quality; direct comparison with standard low-pitch phase-correlated CT image datasets showed no significant difference. For a normalized z-axis acquisition of 12 cm, the corresponding effective dose value was 2.0 mSv for the high-pitch CT protocol. We conclude that spiral DSCT imaging with a pitch of 3.0 can provide unimpaired image quality with respect to spatial and temporal resolution. Applications to cardiac and thoracic imaging with effective dose below 1 mSv are possible.

Evaluation of right ventricular function with multidetector computed tomography: comparison with magnetic resonance imaging and analysis of inter- and intraobserver variability

This study was performed to prospectively compare multidetector computed tomography (MDCT) with 16 simultaneous sections and magnetic resonance imaging (MRI) for the assessment of global right ventricular function in 50 patients. MDCT using a semiautomatic analysis tool showed good correlation with MRI for end-diastolic volume (EDV, r=0.83, p<0.001), end-systolic volume (ESV, r=0.86, p<0.001) and stroke volume (SV, r=0.74, p<0.001), but only a moderate correlation for the ejection fraction (EF, r=0.67, p<0.001). Bland Altman analysis revealed a slight, but insignificant overestimation of EDV (4.0 ml, p=0.08) and ESV (2.4 ml, p=0.07), and underestimation of EF (0.1%, p=0.92) with MDCT compared with MRI. All limits of agreement between both modalities (EF: +/-15.7%, EDV: +/-31.0 ml, ESV: +/-18.0 ml) were in a moderate but acceptable range. Interobserver variability of MDCT was not significantly different from that of MRI. For MDCT software, the post-processing time was significantly longer (19.6+/-5.8 min) than for MRI (11.8+/-2.6 min, p<0.001). Accurate assessment of right ventricular volumes by 16-detector CT is feasible but still rather time-consuming.

A technical solution to avoid partial scan artifacts in cardiac MDCT

Quantitative evaluation of cardiac image data obtained using multidetector row computed tomography (CT) is compromised by partial scan reconstructions, which improve the temporal resolution but significantly increase image-to-image CT number variations for a fixed region of interest compared to full reconstruction images. The feasibility of a new approach to solve this problem is assessed. An anthropomorphic cardiac phantom and an anesthetized pig were scanned on a dual-source CT scanner using both full and partial scan acquisition modes under different conditions. Additional scans were conducted with the electrocardiogram (ECG) signal being in synchrony with the gantry rotation. In the animal study, a simple x-ray detector was used to generate a signal once per gantry rotation. This signal was then used to pace the pig's heart. Phantom studies demonstrated that partial scan artifacts are strongly dependent on the rotational symmetry of angular projections, which is determined by the object shape and composition and its position with respect to the isocenter. The degree of partial scan artifacts also depends on the location of the region of interest with respect to highly attenuating materials (bones, iodine, etc.) within the object. Single-source partial scan images (165 ms temporal resolution) were significantly less affected by partial scan artifacts compared to dual-source partial scan images (82 ms temporal resolution). When the ECG signal was in synchrony with the gantry rotation, the same cardiac phase always corresponded to the same positions of the x-ray tube(s) and, hence, the same scattering and beam hardening geometry. As a result, the range of image-to-image CT number variations for partial scan reconstruction images acquired in synchronized mode was decreased to that achieved using full reconstruction image data. The success of the new approach, which synchronizes the ECG signal with the position of the x-ray tube(s), was demonstrated both in the phantom and animal experiments.

Optimization of cardiac MSCT contrast injection protocols: dependency of the main bolus contrast density on test bolus parameters and patients' body weight

RATIONALE AND OBJECTIVES

Our aim was to evaluate the correlation of test bolus (TB) curve parameters with main bolus (MB) contrast density for cardiac 16-slice computed tomography, and to correlate observed enhancement with patient body weight.

MATERIALS AND METHODS

Sixty patients with known or suspected coronary artery disease were included in a prospective double-blind study. Contrast material containing 300 mg iodine/mL (Iomeprol 300; Imeron 300, Bracco Imaging SpA, Milan, Italy) and 400 mg iodine/mL (Iomeprol 400; Imeron 400) was injected at a rate of 1 g of iodine/second. Contrast densities (Hounsfield units) of the MB were determined in the left cardiac system. The peak density (PD) of maximum attenuation and the area under the curve (AUC) of the TB curve were calculated for each patient. The dependency of MB contrast attenuation on these parameters and on patient body weight was evaluated.

RESULTS

Positive correlations (r = 0.52 and r = 0.56, respectively; P < .0001) were obtained between the PD and AUC of the TB curve with the mean density of the MB. Stronger correlations (r = 0.63 and r = 0.64, respectively; P < .0001) between PD and AUC of the TB curve and MB attenuation were found when patient body weight was included in the analysis.

CONCLUSIONS

Strong correlation of the PD and AUC of the TB curve with the mean density of the MB is observed when patient body weight is considered. Contrast injection protocols may be optimized, and variations of MB contrast density in the left ventricle and main coronary arteries reduced, by taking these TB parameters and the weight of the patient into account.

Intraindividual comparison of 3D coronary MR angiography and coronary CT angiography

RATIONALE AND OBJECTIVES

To compare the diagnostic value of magnetic resonance (MR) and computed tomography (CT) for the detection of coronary artery disease (CAD) with special regard to calcifications.

MATERIALS AND METHODS

Twenty-seven patients with known CAD were examined with a targeted, navigator-gated, free-breathing, steady-state free precession MR angiography sequence (repetition time = 5.6 milliseconds, echo time = 2.8 milliseconds, flip angle 110 degrees ) and 16-slice coronary CT angiography. Segment-based sensitivity, specificity, and accuracy for the detection of stenoses larger than 50% were determined as defined by the gold standard catheter coronary angiography along with the subjective image quality (Grade 1-4). The degree of calcifications in each segment was quantified using a standard calcium scoring tool.

RESULTS

Of 115 possible segments, 7% had to be excluded in MR imaging because of poor image quality. In CT, 3% were nondiagnostic because of image quality and 15% were not evaluable because of calcifications. Values for the detection of relevant coronary artery stenoses in the evaluated segments were: sensitivity: MR imaging 85% versus CT 96%; specificity: 88% versus 96%; accuracy: 87% versus. 96%. Average subjective image quality was 1.8 for MR imaging and 1.6 for CT. Of the 15% of segments that had to be excluded from CT evaluation because of calcifications, MR imaging provided the correct diagnosis segments in 67%.

CONCLUSIONS

CT provided a better image quality with superior accuracy for the detection of CAD. Despite its overall inferiority, MR imaging proved to be helpful method in interpreting coronary stenosis in severely calcified segments.

Usefulness of 40-slice multidetector row computed tomography to detect coronary disease in patients prior to cardiac valve surgery

Preoperative identification of significant coronary artery disease (CAD) in patients prior to valve surgery requires systematic invasive coronary angiography. The purpose of this current prospective study was to evaluate whether exclusion of CAD by multi-detector CT (MDCT) might potentially avoid systematic cardiac catheterization in these patients. Eighty-two patients (53 males, 62 +/- 13 years) scheduled to undergo valve surgery underwent 40-slice MDCT before invasive quantitative coronary angiography (QCA). According to QCA, 15 patients had CAD (5 one-vessel, 6 two-vessel and 4 three-vessel disease). The remaining 67 patients had no CAD. On a per-vessel basis, MDCT correctly identified 27/29 (sensitivity 93%) vessels with and excluded 277/299 vessels (specificity 93%) without CAD. On a per-patient basis, MDCT correctly identified 14/15 patients with (sensitivity 93%) and 60/67 patients without CAD (specificity 90%). Positive and negative predictive values of MDCT were 67% and 98%. Performing invasive angiography only in patients with abnormal MDCT might have avoided QCA in 60/82 (73%). MDCT could be potentially useful in the preoperative evaluation of patients with valve disease. By selecting only those patients with coronary lesions to undergo invasive coronary angiography, it could avoid cardiac catheterization in a large number of patients without CAD.