Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography

Can ECG-gated MDCT be considered an obligatory step to plan and manage a new chest-pain unit?

The recent improvements in multi-detector computed tomography technology and its application in cardiac field allow to consider this non-invasive imaging technique as a promising comprehensive method for detecting significant coronary stenoses in a chest-pain unit. The possibility to use the ECG-synchronisation acquisition protocol, normally limited to the cardiac volume, for the entire thoracic vascular system should have the remarkable potential to reduce invasive and non-invasive procedures actually used to investigate acute chest pain and the number of unnecessary hospital admissions without reducing appropriate admissions in patients with chest pain.

Triage of patients with suspected coronary artery disease using multislice computed tomography

RATIONALE AND OBJECTIVES

Several studies have shown that multislice computed tomography (MSCT) has a high sensitivity and specificity for detecting coronary artery stenoses. The aim of the present study was to investigate whether MSCT can reliably triage patients with suspected coronary artery disease (CAD) to coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), or no revascularization.

MATERIALS AND METHODS

A total of 123 patients with suspected CAD who were referred for conventional coronary angiography (CATH) additionally underwent MSCT (16*0.5 mm detector collimation). Therapeutic decisions made on the basis of CATH and MSCT strictly following current guidelines for treatment of CAD were compared with decisions made by a cardiac surgeon and an interventional cardiologist. Only MSCTs with at least adequate image quality in all coronary segments were included in the analysis (94/123).

RESULTS

Decisions made on the basis of MSCT and CATH according to guidelines did not differ significantly (agreement of 88%, 82 of 94, P = .319). The therapeutic decisions made by the interventional cardiologist and the cardiac surgeon based on CATH differed significantly (overall agreement of 79%, 74 of 94 cases, P < .001; cardiologist: 78% PCI and 22% CABG versus surgeon: 38% PCI and 62% CABG), whereas there was 100% agreement regarding decisions for or against invasive treatment.

CONCLUSIONS

MSCT shows good agreement with CATH in triaging patients with suspected CAD to CABG, PCI, or no revascularization. The choice of revascularization procedure is significantly more strongly influenced by whether an interventional cardiologist or a cardiac surgeon makes the decision than by the diagnostic test on which the decision is based.

Image Quality and Reconstruction Intervals of Dual-Source CT Coronary Angiography

PURPOSE

To evaluate reconstruction intervals and image quality in dual-source computed tomography (DSCT) coronary angiography for optimal placement of the ECG-pulsing window.

MATERIALS AND METHODS

DSCT coronary angiography was performed in 60 patients. Thirteen datasets were reconstructed in 5% increments from 20-80%. Two readers independently assessed image quality of each segment in each percentage-interval, using scores ranging from 1 (no motion artifacts) to 4 (nonevaluable).

RESULTS

Mean heart rate (HR) was 69.0 +/- 18.9 beats per minute (bpm) (range, 35-117 bpm). Diagnostic image quality (scores 1-3) was found in 97.8% of all segments (763 of 780). The 70% RR-interval provided best image quality in all patients and all HRs. The narrowest reconstruction window providing diagnostic image quality was 60-70% for HR <60 bpm, 60-80% for 60-70 bpm, 55-80% for 70-80 bpm, and 30-80% for HR >80 bpm.

CONCLUSIONS

DSCT coronary angiography provides best image quality for various HRs at 70%. The ECG-pulsing window can be adapted according to the HR while maintaining diagnostic image quality.

Reliable High-Speed Coronary Computed Tomography in Symptomatic Patients

OBJECTIVES

Our objective was to prospectively evaluate the diagnostic performance of the high-speed dual-source computed tomography scanner (DSCT), with an increased temporal resolution (83 ms), for the detection of significant coronary lesions (> or =50% lumen diameter reduction) in a clinically wide range of patients.

BACKGROUND

Cardiac motion artifacts may decrease coronary image quality with use of earlier computed tomography scanners that have a limited temporal resolution.

METHODS

We prospectively studied 100 symptomatic patients (79 men, 21 women, mean age 61 +/- 11 years) with atypical (18%) or typical (55%) angina pectoris, or unstable coronary artery disease (27%) scheduled for conventional coronary angiography. Mean scan time was 8.58 +/- 1.52 s. Mean heart rate was 68 +/- 11 beats/min. Quantitative coronary angiography was used as the standard of reference. Irrespective of image quality or vessel size, all segments were included for analysis.

RESULTS

Invasive coronary angiography demonstrated no significant disease in 23%, single-vessel disease in 31%, and multivessel disease in 46% of patients; 1,489 coronary segments, containing 220 significant (14.8%) stenoses, were available for analysis. Sensitivity, specificity, and positive and negative predictive values of DSCT coronary angiography for the detection of significant lesions on a segment-by-segment analysis were 95% (95% confidence interval [CI] 90 to 97), 95% (95% CI 93 to 96), 75% (95% CI 69 to 80), 99% (95% CI 98 to 99), respectively, and on a patient-based analysis 99% (95% CI 92 to 100), 87% (95% CI 65 to 97), 96% (95% CI 89 to 99), and 95% (95% CI 74 to 100), respectively.

CONCLUSIONS

Noninvasive DSCT coronary angiography is highly sensitive to detect and to reliably rule out the presence of a significant coronary stenosis in patients presenting with atypical or typical angina pectoris, or unstable coronary artery disease.

Can Late Supraclavicular Echo Doppler Reliably Predict Angiographical String Sign of Lima to Lad Area Grafts?

OBJECTIVE

To investigate whether supraclavicular ultrasonography of left internal mammary artery (LIMA) to left anterior descending (LAD) area grafts can reliably predict (distal) string sign grafts on arteriography.

METHODS

Fifty-five patients (42 M, 61 +/- 7 years) with the LIMA to LAD area grafting were prospectively studied. Control arteriography was performed at 1.4 +/- 0.8 years postoperatively. Angiography demonstrated in 46 patients (group I) functional grafts, in 4 patients (group II) sequential distal string sign grafts and in 5 patients (group III) total string sign grafts. Ultrasonography was performed at 1.8 +/- 0.8 year postoperatively and compared with control angiography. Data were tested by unpaired t- and ANOVA tests. The diagnostic accuracy was assessed by the area under the curve of the Receiver Operator Characteristic. A formula was developed to predict the probability of (distal) string sign phenomena of sequential as well as single LIMA grafts.

RESULTS

Between the groups all duplex parameters showed a highly significant linear relation (p < or = 0.004) and all parameters between group I and III are significantly different with high Area Under Curve values. The model for the probability of (distal) string sign grafts fitted best with diastolic and systolic peak velocities as the most discriminative factors for (distal) string sign grafts.

CONCLUSIONS

Postoperative supraclavicular duplex as a method to assess the patency of LIMA to LAD area grafts allows discriminating functional grafts from (distal) string sign grafts.

Diagnostic Performance of Multidetector CT Angiography for Assessment of Coronary Artery Disease: Meta-analysis

PURPOSE

To review the literature on the diagnostic performance of multidetector computed tomographic (CT) angiography for assessment of symptomatic coronary artery disease, with conventional coronary angiography as the reference standard.

MATERIALS AND METHODS

A PubMed and manual search of the literature published between January 1998 and May 2006 on use of multidetector CT angiography compared with coronary angiography in patients with symptomatic coronary artery disease was performed. Summary estimates of diagnostic odds ratio, sensitivity, and specificity were calculated. Random-effects models were used to compare the diagnostic performance of four-, 16-, and 64-detector CT angiographic units, and the proportion of nonassessable coronary arterial segments was evaluated.

RESULTS

Fifty-four studies were included in the meta-analysis: 22 studies with four-detector CT angiography, 26 with 16-detector CT angiography, and six with 64-detector CT angiography. The pooled sensitivity and specificity for detecting a greater than 50% stenosis per segment were 0.93 (95% confidence interval [CI]: 0.88, 0.97) and 0.96 (95% CI: 0.96, 0.97) for 64-detector CT angiography, 0.83 (95% CI: 0.76, 0.90) and 0.96 (95% CI: 0.95, 0.97) for 16-detector CT angiography, and 0.84 (95% CI: 0.81, 0.88) and 0.93 (95% CI: 0.91, 0.95) for four-detector CT angiography, respectively. Results of regression analysis indicated that the diagnostic performance significantly improved with the newer generations of multidetector CT scanners (64- and 16-detector vs four-detector units), adjusted for exclusion of nonassessable segments, and contrast agent concentration used (P < .05). Simultaneously, the nonassessable proportion of segments significantly decreased with the newer generations of multidetector CT scanners, adjusted for heart rate, prevalence of significant disease, and mean age.

CONCLUSION

With the newer generations of multidetector CT scanners, the diagnostic performance for the assessment of coronary artery disease has significantly improved, and the proportion of nonassessable segments has decreased.

Practicality, safety and accuracy of computed tomography coronary angiography in the evaluation of low TIMI-risk score chest pain patients: a pilot study

OBJECTIVES

The present pilot study aimed to assess the practicality, safety and accuracy of performing CT coronary angiography (CT-CA) in the evaluation of acute chest pain of patients with low thrombolysis in myocardial infarction (TIMI) risk scores.

METHODS

The present prospective observational study was undertaken in a university teaching hospital between November 2004 and December 2005. Participants were a convenience sample of patients admitted to hospital for investigation of chest pain with TIMI risk scores <3. Consenting patients underwent CT-CA within 48 h of presentation. Outcomes of interest were practicality (proportion of diagnostic quality scans obtained and preparation time for CT-CA), rate of serious adverse events, and accuracy at the patient level using selective coronary angiography as the reference standard.

RESULTS

Thirty-four patients were recruited. Diagnostic quality scans were obtained in 26/34 or 76% of patients (four failed CT-CA and four non-diagnostic scans). The median CT preparation time was 1.9 h (range 0.17-4.0). No serious adverse events were found. Fourteen of those 26 patients with diagnostic CT-CA subsequently had selective coronary angiography, of which nine were positive. The sensitivity and specificity of CT-CA in identifying patients with significant coronary artery disease were 9/9 (100%; 95% confidence interval 72-100%) and 4/5 (80%; 95% confidence interval 28-100%), respectively.

CONCLUSIONS

The majority of acute chest pain patients with low TIMI risk scores were successfully scanned with a 16-slice CT to produce CT-CA studies with good diagnostic quality and accuracy. No major adverse events were found. The place of CT-CA in diagnostic workup for chest pain remains to be defined.

Non-invasive visualization of coronary atherosclerosis: state-of-art

Coronary artery disease remains the leading cause of death in the Western world. Non-invasive coronary artery imaging challenges any diagnostic modality because the coronary arteries are small and tortuous, whereas cardiac contraction and respiration cause motion artifacts. Therefore, non-invasive coronary imaging requires high spatial and temporal resolution. This review discusses the feasible applications in coronary imaging of magnetic resonance imaging and multi-slice computed tomography (MSCT), which are currently the only non-invasive diagnostic modalities for direct coronary atherosclerosis imaging. Particular attention and focus is devoted to the potential indications and clinical impact of MSCT due to its fast development and the robust results recently reported. MSCT of the coronary arteries is a promising imaging modality for the assessment of the coronary lumen and wall.

Diagnostic value of the 16-detector row multislice spiral computed tomography for the detection of coronary artery stenosis in comparison to invasive coronary angiography

OBJECTIVES

The aim of this study was to determine the diagnostic accuracy of 16-slice multislice spiral computed tomography (MSCT) of the coronaries and to provide data in a real clinical setting. Previous 16-slice MSCT studies presented data excluding patients with calcification, vessels of < 1.5 or 2 mm, and segments with impaired image quality. By including these data for 16-slice MSCT, a direct comparison with new data from 64-slice MSCT is possible.

METHODS AND RESULTS

Sixty two patients with suspected or known coronary artery disease (CAD) were prospectively enrolled and underwent computed tomography angiography (CTA) and invasive coronary angiography (ICA). All vessels were evaluated for the presence of a significant coronary artery stenosis (>50%) using the American Heart Association (AHA) 15-segment model. From the evaluation of 917 segments, sensitivity, specificity, and positive and negative predictive value (NPV) (positive predictive value [PPV] and NPV) for the presence of relevant coronary stenosis were 73, 98, and 71 and 98% per segment and 94, 90, and 91 and 93% per patient, respectively. The influence of age, gender, body surface area (BSA), heart rate (HR), stents, and Ca(2+)-score value was analyzed. High Ca(2+)-score values were the only statistically significant predictor for impaired diagnostic accuracy.

CONCLUSIONS

In summary, CTA with evaluation of all vessel segments in a broad spectrum of patients allowed accurate and fast noninvasive coronary artery evaluation, including evaluation of stented segments. These data are very similar to those published recently for 64-slice scanners.

Influence of heart rate on diagnostic accuracy and image quality of 16-slice CT coronary angiography: comparison of multisegment and halfscan reconstruction approaches

The lower the heart rate the better image quality in multislice computed tomography (MSCT) coronary angiography. We prospectively assessed the influence of heart rate on per-patient diagnostic accuracy and image quality of MSCT coronary angiography and compared adaptive multisegment and standard halfscan reconstruction. A consecutive cohort of 126 patients scheduled to undergo conventional coronary angiography was examined with 16-slice CT. For all heart rate groups, per-patient diagnostic accuracy was significantly higher for multisegment than halfscan reconstruction with values of 95 vs. 79% (p < 0.05, <65 bpm, 38 patients), 85 vs. 66% (p < 0.05, 65-74 bpm, 47 patients), and 78% vs. 41% (p < 0.001, >74 bpm, 41 patients). Differences in diagnostic accuracy between adjacent heart rate groups were only significant for halfscan reconstruction for the comparison between the 65-74 and >74 bpm group (p < 0.05). The vessel lengths free of motion artifacts were significantly longer with multisegment reconstruction in all heart rate groups and for all coronary arteries (p < 0.005). For noninvasive MSCT coronary angiography, both per-patient diagnostic accuracy and image quality decline with increasing heart rate, and multisegment reconstruction at high heart rates yields similar results as standard halfscan reconstruction at low heart rates.

Newer concepts for imaging anomalous aortic origin of the coronary arteries in adults

Of the different kinds of coronary anomalies observed in adults, anomalous origin of a coronary artery from the opposite sinus of Valsalva with an "interarterial" course (ACAOS) entails a high risk of clinical consequences related to the intramural course of the ectopic coronary artery. We review current imaging modalities for differentiating this condition from generally benign coronary anomalies and for quantifying the severity of individual cases. For identifying ACAOS, noninvasive modalities (echocardiography, computed tomographic angiography, and coronary magnetic resonance angiography) are preferred: the favored modalities are transthoracic echocardiography in children and multidetector computed tomography in adults. For evaluating the pathophysiologic mechanisms of ischemia in ACAOS and subclassifying the severity of individual forms, coronary intravascular ultrasonography provides enhanced temporal and spatial resolution. The critical quantifiable features of the coronary anatomy in ACAOS seem to be hypoplasia, lateral compression at the level of the intramural course, and possibly exercise-related further narrowing of the proximal ectopic segment. Definitive guidelines are being developed for the optimal workup and treatment of ACAOS.

Detection and characterization of coronary bifurcation lesions with 64-slice computed tomography coronary angiography

AIMS

To compare the performance of 64-slice computed tomography coronary angiography (CTCA) and invasive coronary angiography (ICA) in the detection and classification (according to the Medina system) of bifurcation lesions (BLs).

METHODS AND RESULTS

We studied 323 consecutive patients undergoing 64-slice CTCA prior to ICA. All coronary segments >or=2 mm in diameter were evaluated for the presence of a significant (>or=50% diameter reduction on quantitative coronary angiography) BL. Evaluation of BL by CTCA included the assessment of significant lumen obstruction in both main and side branch vessels. Forty-one out of 43 patients (46/48 lesions) with significant BL were identified by CTCA. Excluding coronary segments with non-diagnostic image quality (5%), the sensitivity, specificity, and positive and negative predictive values of CTCA for detecting significant BL were 96, 99, and 85 and 99%, respectively. In 39 of these 41 patients, CTCA assessment was concordant with the Medina lesion classification on ICA.

CONCLUSION

Sixty-four-slice CTCA allows accurate assessment of complex BL.

Multislice computed tomographic characteristics of coronary lesions in acute coronary syndromes

OBJECTIVES

To evaluate the feasibility of noninvasive assessment of the characteristics of disrupted atherosclerotic plaques, the authors interrogated the culprit lesions in acute coronary syndromes (ACS) by multislice computed tomography (CT).

BACKGROUND

Disrupted atherosclerotic plaques responsible for ACS histopathologically demonstrate large lipid cores and positive vascular remodeling. It is expected that plaques vulnerable to rupture should bear similar imaging signatures by CT.

METHODS

Either 0.5-mm x 16-slice or 64-slice CT was performed in 38 patients with ACS and compared with 33 patients with stable angina pectoris (SAP) before percutaneous coronary intervention. The coronary plaques in ACS and SAP were evaluated for the CT plaque characteristics, including vessel remodeling, consistency of noncalcified plaque (NCP <30 HU or 30 HU <NCP <150 HU), and spotty or large calcification.

RESULTS

In the CT profile of culprit ACS and SAP lesions, the frequency of 30 HU <NCP <150 HU (100% vs. 100%, p = NS) was not different, and large calcification (22% vs. 55%, p = 0.004) was significantly more frequent in the stable lesions. Positive remodeling (87% vs. 12%, p < 0.0001), NCP <30 HU (79% vs. 9%, p < 0.0001), and spotty calcification (63% vs. 21%, p = 0.0005) were significantly more frequent in the ACS lesions. Presence of all 3 (i.e., positive remodeling, NCP <30 HU, and spotty calcification) showed a high positive predictive value, and absence of all 3 showed a high negative predictive value for the culprit plaques associated with ACS.

CONCLUSIONS

The CT characteristics of plaques associated with ACS include positive vascular remodeling, low plaque density, and spotty calcification. It is logical to presume that plaques vulnerable to rupture harbor similar characteristics.

Feasibility of gadolinium-diethylene triamine pentaacetic acid enhanced multidetector computed tomography for the evaluation of coronary artery disease

BACKGROUND

Multidetector computed tomography (MDCT) has been proposed as a noninvasive method for the diagnosis of obstructive coronary artery disease (CAD). In patients with high risk of iodinated contrast adverse effects such as acute allergic-type reactions, the use of gadolinium could be an alternative.

OBJECTIVE

We sought to evaluate the feasibility of gadolinium-enhanced MDCT for the diagnosis of obstructive CAD.

METHODS

Twenty patients (mean age, 61 years; range, 50-73 years) referred for X-ray coronary angiography were studied by both gadolinium and iodine-enhanced 16-row MDCT coronary angiography. The degree of enhancement and the accuracy for detection of obstructive CAD (>50% diameter reduction) were evaluated with X-ray coronary angiography as the standard. Renal nephrotoxicity was strictly monitored.

RESULTS

Gadolinium- and iodine-enhanced MDCT showed adequate visualization of the coronary arteries in 310 of the 312 coronary artery segments that were available by X-ray angiography, respectively. The average density of the coronary arteries in both iodine and gadolinium CT scans was 253.65 Hounsfield unit (HU) and 135.20 HU, respectively. In a per-coronary segment analysis, gadolinium- and iodine-enhanced MDCT showed sensitivities of 89% vs 84%, specificities of 96% vs 95%, and negative predictive values of 97% vs 96%, respectively. In a per-patient analysis, both gadolinium- and iodine-enhanced MDCT showed sensitivities of 92.85% vs specificities of 83.33%. Intermethod agreement between gadolinium- and iodine-enhanced MDCT (kappa) was 0.95 (P < 0.0001).

CONCLUSION

Our preliminary results indicate lower attenuation with gadolinium but similar diagnostic accuracy for the detection of obstructive CAD when compared with iodine-enhanced MDCT. Therefore, gadolinium is a feasible alternative contrast agent for patients with iodine contrast allergy referred for MDCT coronary angiography.

Significant Coronary Artery Stenosis: Comparison on Per-Patient and Per-Vessel or Per-Segment Basis at 64-Section CT Angiography

PURPOSE

To prospectively evaluate the accuracy of 64-section computed tomographic (CT) coronary angiography for assessing significant stenosis on a global and segmental level, by using conventional coronary artery angiography as the reference standard.

MATERIALS AND METHODS

This study was HIPAA compliant and had local institutional review board approval. Patients gave informed consent. Patients suspected of having coronary artery disease (CAD) underwent both conventional coronary catheter angiography and contrast material-enhanced retrospectively electrocardiographically gated 64-section multi-detector row CT of the coronary arteries. Two experienced observers analyzed all CT scans for signs of CAD (stenosis of 0%, <or=49%, 50%-69%, 70%-99%, or 100%). Diagnostic accuracy of CT coronary angiography compared with that of conventional angiography was determined on a per-segment, per-vessel, and per-patient basis. No patients, vessels, or segments were excluded from analysis. Spearman correlation, cross tables, and a chi(2) test were used for statistical analysis.

RESULTS

On a per-segment basis, 92.4% (762 of 825) of all segments could be clearly evaluated. In 7.6% of segments, image quality was compromised either by misregistration (16%), motion artifacts (30%), or small vessel size (54%). Correlation coefficients for detection and grading of stenosis were r=0.65 on a per-segment, r=0.83 on a per-vessel, and r=0.88 on a per-patient basis. Stenoses of 50% or greater were detected with accuracy, sensitivity, and specificity, respectively, of 96.1% (793 of 825), 82% (50 of 61), and 97.1% (743 of 765) on a per-segment basis, 90.9% (150 of 165), 89% (32 of 36), and 91.5% (118 of 129) on a per-vessel basis, and 89% (49 of 55), 100% (19 of 19), and 83% (30 of 36) on a per-patient basis.

CONCLUSION

On a per-patient basis, 64-section multi-detector row CT coronary angiography enables the diagnosis of significant (>or=50%) stenosis in CAD with an accuracy of 89%. On a per-segment and per-vessel basis, diagnostic accuracy is still impaired, primarily by limited spatial resolution.

Sixty-Four Slice CT Evaluation of Aortic Stenosis Using Planimetry of the Aortic Valve Area

OBJECTIVE

The purpose of our study was to evaluate planimetry of the aortic valve area with 64-slice CT in comparison with transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in patients with aortic stenosis.

MATERIALS AND METHODS

Thirty-six patients with aortic valve disease referred for coronary 64-slice CT angiography were examined. Planimetry of the aortic valve area with 64-slice CT was compared with TTE using the Doppler continuity equation for calculation of the aortic valve area and with planimetric measurement of the aortic valve area using TEE.

RESULTS

Planimetry of the aortic valve area with CT (1.11 +/- 0.42 cm2) showed a good correlation with TTE (1.05 +/- 0.42 cm2) (r = 0.88, p < 0.001) in 32 patients and a good correlation with TEE (1.41 +/- 1.61 cm2) (r = 0.99, p < 0.0001) in 10 patients. The mean and maximum transvalvular pressure gradients were correlated with the aortic valve area as measured with CT (r = -0.68, p = 0.0001; and r = -0.67, p = 0.0001, respectively). Beta-blockers were not given (mean heart rate, 62.5 +/- 10.7 beats per minute).

CONCLUSION

MDCT allows accurate planimetry of the aortic valve area in patients with aortic stenosis. In patients referred for 64-slice CT coronary angiography, concomitant aortic stenosis can be identified and evaluated.

Coronary CT Angiography

Owing to ongoing technical refinements and intense scientific and clinical evaluations, computed tomography (CT) of the heart has left the research realm and matured into a clinical application that is about to fulfill its promise to replace invasive cardiac catheterization in selected patient populations. CT coronary angiography is technically more challenging than other CT applications owing to the nature of its target, the continuously moving heart. Rapid technical developments in this field require constant adaptation of acquisition protocols. These challenges, however, are in no way insurmountable for users with knowledge of the general CT technique. The intent of this communication is to provide those interested in and involved with coronary CT angiography with a step-by-step "manual" describing the authors' approach to performing coronary CT angiography. Included are considerations regarding appropriate patient selection, patient medication, radiation protection, contrast enhancement, acquisition and reconstruction parameters, image display and analysis techniques, and the radiology report. The recommendations are based on the authors' experience, which spans the evolution of multi-detector row CT for cardiac applications, from its beginning to the advent of the most current generations of 64-section and dual-source CT technologies, which they believe herald the entrance of this examination into routine clinical practice.

64-Slice Multidetector Computed Tomography (MDCT) for Detection of Aortic Regurgitation and Quantification of Severity

BACKGROUND

Recent advances in 64-slice multidetector computed tomography (MDCT) provide an opportunity to assess coronary artery disease, left ventricular function and, potentially, valvular heart disease.

OBJECTIVE

To determine the ability of 64-MDCT to both detect and to quantify the severity of aortic regurgitation (AR), as compared with transthoracic echocardiography (TTE).

METHODS

We evaluated a total of 64 patients (43 males, mean age 63+/-11 years), 30 with varying severities of AR as assessed by TTE and 34 matched controls. The severity of AR by TTE was determined using the vena contracta, the ratio of jet to left ventricular outflow tract (LVOT) height, and the ratio of the jet to LVOT cross-sectional area. AR by MDCT was defined as a lack of coaptation of the aortic valve leaflets in diastole and, if detected, the maximum anatomic aortic regurgitant orifice was determined.

RESULTS

All 34 control patients without AR were correctly identified by MDCT. There were 14 patients with mild AR, 10 with moderate AR, and 6 with severe AR by TTE. Of these patients, MDCT correctly identified 21 patients with AR (sensitivity 70%, specificity 100%, positive predictive value [PPV] 100%, and negative predictive value [NPV] 79%). Anatomic regurgitant orifice area measured by MDCT correlated well with the TTE-derived vena contracta (r=0.79, P<0.001), ratio of jet to LVOT height (r=0.79, P<0.001), and ratio of jet to LVOT cross-sectional area (r=0.75, P<0.001).

CONCLUSIONS

Direct planimetric measurement of the aortic valve anatomic regurgitant orifice area on 64-MDCT provides an accurate, noninvasive technique for detecting and quantifying AR.

Evaluation of Coronary Stents and Stenoses at Different Heart Rates With Dual Source Spiral CT (DSCT)

OBJECTIVES

Evaluation of coronary arteries at higher heart rates and in the presence of coronary stents remains problematic. The utilization of dual source computed tomography (DSCT) might improve the visualization of the coronary arteries under these conditions by imaging at a temporal resolution of 83 milliseconds, independent of heart rate.

MATERIALS AND METHODS

Vessel phantoms (diameter 2-4 mm) were attached to a robotic device to simulate cardiac motion and scanned with a DSCT system. The phantoms had either inserts leading to 50% stenosis or carried stents. Images were evaluated for motion artifacts and measurements of the normal, stenotic, and in-stent lumen at different heart rates (50-120 bpm) were performed. Quantile regression analysis was performed to investigate heart rate dependence of the measurement errors.

RESULTS

Visualization of the stenoses and stents was possible without motion artifacts at heart rates of up to 120 bpm. Image quality was similar for the static (0 bpm) and the dynamic (50-120 bpm) scans. Errors for diameter measurements of the vessel lumen and the stenotic lumen were low (3-mm vessel: 1-2%), but considerable for in-stent diameter measurements (3-mm stent: 27-32%). A window/level setting of 1500/300 Hounsfield units was more favorable for stent evaluation. No heart rate dependence was found.

CONCLUSIONS

Depiction of coronary stents with DSCT is possible across a large range of simulated heart rates without motion artifacts and with image quality superior to that of previous generations of CT scanners.

Accessory appendages of the left atrium as seen during 64-slice coronary CT angiography

PURPOSE

To document the frequency and variations in number and anatomical shape of accessory appendages of the left atrium as seen on 64-slice cardiac CT.

METHODS AND MATERIALS

Retrospective review of the anatomy of the left atrium as depicted by cardiac CT using the acquisition protocol designed for coronary CT Angiography and performed in 166 patients over a 6-month period with a 64-slice ECG-gated CT scanner (Siemens Medical Solutions). The local IRB provided a waiver of informed consent for this retrospective study. Structures less than 5 mm in shape were excluded, as well as large accessory pulmonary veins.

RESULTS

Seventeen (17) of 166 patients (10%) had 18 accessory left atrial appendages (only one patient had two). Fifteen (15) accessory appendages were located along the right upper atrial wall and measured 0.9 x 0.6 x 0.5 cm(3) +/- 0.2 x 0.2 x 0.1 (Type 1). Three (3) were located along the left lower atrial wall, and were larger (0.9-2.5 cm cross-section) (Type 2). The right upper accessory appendages were mostly shaped like small diverticuli and the left lower ones were shaped like flat cauliflower expansions.

CONCLUSIONS

Accessory left atrial appendages were visualized in 10% of 166 patients during 64-slice coronary CT angiography.

Diagnostic performance of 64-channel multislice computed tomography in assessment of significant coronary artery disease in symptomatic subjects

The recent development of 64-channel multislice computed tomography (MSCT) has resulted in noninvasive coronary artery imaging improvement. This study was conducted to determine the accuracy of 64-slice MSCT in a relatively unselected group of 143 patients with presentations suggestive of coronary artery disease, including those with unstable angina pectoris, who underwent both coronary computed tomographic angiography and invasive coronary angiography. No arrhythmia was considered an exclusion criterion except for atrial fibrillation or frequent extrasystoles. In patients with fast heart rates, a beta blocker was administered orally. Data were obtained using electrocardiography gated 64-slice MSCT. Computed tomographic angiography and invasive coronary angiography findings of each coronary segment were compared to determine the sensitivity, specificity, positive predictive value, and negative predictive value of MSCT in the detection of their normalcy or insignificant (<50% diameter decrease) stenosis versus significant (>or=50% diameter decrease) stenosis or total occlusion. In per-patient assessment, the calculated sensitivity, specificity, positive predictive value, and negative predictive value of MSCT were 96%, 67%, 91%, and 83%, respectively. These values in per-artery evaluation were 94%, 94%, 87%, and 97%, and corresponding values in per-segment analysis were 92%, 97%, 77%, and 99%, respectively. In conclusion, computed tomographic angiography has high diagnostic performance in the assessment of significant coronary artery disease in most patients in a daily routine practice, including those presenting with unstable angina pectoris symptoms.

Utility of multislice computed tomography as a strategic tool for complex percutaneous coronary intervention

OBJECTIVES

Multislice computed tomography (MSCT) has been currently utilized as a non-invasive diagnostic modality to detect coronary artery disease. We sought to investigate whether preprocedural lesion assessment by MSCT could offer strategic guidance in the setting of elective complex percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Twenty-six complex coronary artery lesions in 23 patients were evaluated using 16-row MSCT scanner and an off-line image analysis workstation prior to the PCI. Procedural strategies of PCI were planned based on the morphologic and geometric analysis of the target lesion and vessel. MSCT provided valuable strategic information, which was useful for subsequent PCI procedure. The three-dimensional computed tomography (CT) images allowed us to determine optimal working view angle that best demonstrated the target lesion with least foreshortening. Furthermore, the thin-slab maximum intensity projected CT images of the target lesion served as a preprocedural road map depicting the bends of complex luminal path, vessel geometry and occluded segment of the vessel. As results, procedural success was achieved in all cases with complex lesions including chronic total occlusion.

CONCLUSIONS

Our preliminary results showed that preprocedural lesion and vessel assessment by MSCT provided important additive strategic information that led to successful complex PCI procedures.

Normal and variant coronary arterial and venous anatomy on high-resolution CT angiography

OBJECTIVE

This article displays the normal and variant anatomy of the coronary arteries and subjacent cardiac veins using a high-resolution 64-MDCT scanner.

CONCLUSION

Knowledge of the anatomy of the coronary arteries and subjacent cardiac veins as displayed with maximum intensity and volume-rendered projections is important for correct image interpretation of coronary CT angiography examinations.

Diagnostic accuracy of 64-slice CT in the assessment of coronary stents

PURPOSE

The purpose of this study was to assess the diagnostic accuracy of 64-slice computed tomography (64-CT) coronary angiography in the detection of coronary in-stent restenosis.

MATERIALS AND METHODS

Ninety-five patients (72 men and 23 women, mean age 58+/-8 years) with previous percutaneous coronary intervention with stenting and suspected restenosis underwent 64-CT (Sensation 64, Siemens). The mean time between stent deployment and 64-CT was 6.1+/-4.2 months. The scan parameters were: slices 32 x 2, individual detector width 0.6 mm, rotation time 0.33 s, feed 3.84 mm/rotation, 120 kV, 900 mAs. After the intravenous administration of iodinated contrast material (Iomeprol 400 mgI/ml, Iomeron, Bracco) and a bolus chaser (40 ml of saline), the scan was completed in <12 s. All coronary segments with a stent were assessed on 64-CT by two observers in consensus and judged as: patent, with intimal hyperplasia (lumen reduction of <50%), with in-stent restenosis (> or =50%), or with in-stent occlusion (100%). The consensus reading was compared with conventional coronary angiography.

RESULTS

Four patients were excluded because of insufficient image quality. In the remaining 91, we assessed 102 stents (31 RCA; 10 LM; 54 LAD; 7 CX). In 14 (13.7%) stents, in-stent restenosis (n=8) or in-stent occlusion (n=6) was found. Intimal hyperplasia was detected in 11 (10.8%) stents. The sensitivity and negative predictive value of 64-CT for in-stent occlusion were 100% and 100%, respectively, whereas for all stenoses, >50% they were 92.9% and 98.7%, respectively.

CONCLUSIONS

We found that 64-CT has a high diagnostic accuracy for the detection of in-stent restenosis in a selected patient population.

Pre- and postoperative evaluation of congenital heart disease in children and adults with 64-section CT

Although echocardiography is the imaging method of choice for diagnostic, preoperative, and postoperative evaluation of congenital heart disease, computed tomography (CT) is a helpful complementary imaging modality, particularly for postoperative evaluation. A thorough understanding of the normal anatomy and the morphologic features of congenital heart diseases is a prerequisite for choosing the optimal CT technique and achieving an accurate diagnosis. Furthermore, a close collaboration with a cardiologist with special training and expertise in congenital heart diseases is required. A sequential segmental approach should be used in evaluating morphologic features, especially during the review of CT images obtained in patients with rare congenital cardiac defects and in postoperative adult patients. To accurately document and interpret the altered flow conditions in patients with congenital heart disease, knowledge of the wide spectrum of surgical procedures and familiarity with the dedicated protocols for performing 64-section CT are needed.

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.

Comparison of multidetector 64-slice computed tomographic angiography to coronary angiography to assess the patency of coronary artery bypass grafts

This study prospectively evaluated the diagnostic accuracy of 64-slice computed tomographic angiography (CTA) in assessing the patency of coronary artery bypass grafts compared with invasive coronary angiography. In total 147 bypass grafts (100 venous grafts and 47 mammary artery grafts) were evaluated in 50 consecutive patients. Contrast-enhanced 64-slice CTA was performed and compared with invasive angiography. The computed tomographic angiographic scan protocol used 64- x 0.5-mm slice collimation and 0.33-second gantry rotation time during simultaneous electrocardiographic gating. Patients with a heart rate >65 beats/min received beta blockers. Overall 145 of 147 bypass grafts (98.6%) were detected by CTA; 2 nonvisualized grafts were occluded at the time of invasive angiography. Of the grafts visualized, 28 were totally occluded, 103 were patent, and 14 had significant stenoses that were confirmed by invasive angiography. Ninety-five percent (111 of 117) of patent grafts demonstrated good run-off distal to anastomoses but without an ability to accurately evaluate the presence of retrograde flow; 83% (97 of 117) of distal anastomoses were adequately evaluated, whereas the remaining 17% (20 of 117) were not well visualized due to vascular clips and/or calcification artifacts. Two grafts were not demonstrated by invasive angiography but were detected by CTA and found to be widely patent. In conclusion, multidetector 64-slice CTA is a valuable tool for direct visualization of coronary bypass grafts and assessment of their patency. Dysfunctional bypass grafts can be detected with high diagnostic accuracy.

Multislice Computed Tomography for Preoperative and Postoperative Assessment in Totally Endoscopic Coronary Artery Bypass Grafting

This article reviews the clinical value of noninvasive multi-slice computed tomography (MSCT) angiography before and after totally endoscopic coronary artery bypass surgery. The use of coronary and aorto-iliaco-femoral MSCT angiography in the preoperative assessment is addressed and the use of bypass MSCT angiography for postoperative control of bypass graft patency is discussed.

Diagnostic Accuracy of Image Postprocessing Methods for the Detection of Coronary Artery Stenoses by Using Multidetector CT1

PURPOSE

To retrospectively evaluate the diagnostic accuracy of multidetector computed tomography (CT) coronary angiography for detection of hemodynamically significant (>or=50%) stenoses by using various image postprocessing methods, with conventional coronary angiography as the reference standard.

MATERIALS AND METHODS

The analysis used data from previous studies, use of which had been approved by the Institutional Review Board. Sixteen-section multidetector CT data sets for 40 patients (30 men, 10 women; mean age 56 years +/- 8; mean heart rate, 61 beats per minute +/- 6) were evaluated. Six independent investigators evaluated the data sets for the presence of stenoses with diameter reduction of 50% or more, by using either exclusively transverse images, free oblique multiplanar reconstructions (MPRs), free oblique maximum intensity projections (MIPs, 5 mm thick), prerendered curved MPRs, prerendered curved MIPs, or prerendered three-dimensional volume rendered reconstructions (VRTs). Evaluation results were compared with conventional coronary angiography for each artery in a blinded fashion (chi(2) test).

RESULTS

Overall, 35 coronary artery stenoses were present. Percentage of evaluable arteries and accuracy for detecting stenosis (percentages of accurately classified arteries were, respectively, 99% and 88% for transverse, 99% and 91% for oblique MPR, 94% and 86% for oblique MIP, 94% and 83% for curved MIP, 93% and 81% for curved MPR, and 91% and 73% for VRT). Accuracy was significantly higher for oblique MPR than for curved MPR (P=.01), curved MIP (P=.03), and VRT (P<.001).

CONCLUSION

The evaluation of multidetector CT coronary angiography with interactive image display methods, especially interactive oblique MPRs, permits higher diagnostic accuracy than evaluation of prerendered images (curved MPR, curved MIP, or VRT images).

Unique application of multislice computed tomography in adults with congenital heart disease

PURPOSE

Adults with congenital heart disease (CHD) form a growing population of patients requiring coronary artery assessment. In light of their increased incidence of coronary anomalies and need for reoperations, it is important to define their coronary anatomy. The purpose of this study was to define the spectrum of coronary artery anatomies and feasibility of coronary artery delineation in adults with CHD using 16- and 64-slice computed tomography angiography.

MATERIALS AND METHODS

Coronary multislice computed tomography (MSCT) examinations performed in adults with CHD between 2004 and 2005 were reviewed with institutional review board approval. Informed consent was not required. In addition to image quality, the following coronary parameters were evaluated by analysis of axial, multiplanar reformatted, and volume-rendered images: (1) relationship to great arteries, (2) ostia number and location, (3) proximal course, (4) length of vessel seen, and (5) dominance.

RESULTS

Eighty-five examinations in adults with CHD adults were identified. The relationship of the great vessels, number and location of the coronary ostia, and proximal course of the coronaries could be identified in all studies. Coronary anomalies were detected in 16 (19%) subjects. The entire coronary tree was visible in 77 (91%) of subjects.

CONCLUSIONS

MSCT provides detailed, noninvasive assessment of complex coronary artery anatomy in adults with CHD. MSCT should be considered a useful modality in the assessment of these patients, as it does not require arterial access and provides detailed 3-dimensional anatomic information that has important implications for long-term management.

Detection of significant coronary artery stenosis with 64-section MDCT angiography

PURPOSE

To prospectively evaluate the diagnostic performance of 64-section multidetector computed tomography (MDCT) to detect significant coronary artery stenosis using conventional coronary angiography (CCA) as the reference standard.

MATERIALS AND METHODS

Institutional Review Board approval and informed consent were obtained. In this prospective study, 80 patients (61 male, 19 female, mean age 56) were examined. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. McNemar test was used to search for the significant difference between 64-section MDCT angiography and CCA to detect stenosis. Also, kappa index (kappa) for the agreement between MDCT angiography and CCA was calculated.

RESULTS

The sensitivity, specificity, positive (PPV) and negative predictive values (NPV) for detecting significant stenosis were 96%, 98%, 91%, 99%, respectively. The sensitivity, specificity, PPV and NPV for classification of patients with or without CAD were 100% for all. McNemar test demonstrated no significant difference between 64-section MDCT angiography and CCA. Also, kappa index (kappa) indicated excellent agreement.

CONCLUSION

Sixty-four section MDCT angiography is an effective diagnostic tool for the detection of significant coronary artery stenosis. Especially, the potential to differentiate patients with and without CAD may provide MDCT an important role in the prevention of unnecessary invasive diagnostic procedures.

Dose Performance of a 64-Channel Dual-Source CT Scanner1

PURPOSE

To prospectively compare the dose performance of a 64-channel multi-detector row computed tomographic (CT) scanner and a 64-channel dual-source CT scanner from the same manufacturer.

MATERIALS AND METHODS

To minimize dose in the cardiac (dual-source) mode, the evaluated dual-source CT system uses a cardiac beam-shaping filter, three-dimensional adaptive noise reduction, heart rate-dependent pitch, and electrocardiographically based modulation of the tube current. Weighted CT dose index per 100 mAs was measured for the head, body, and cardiac beam-shaping filters. Kerma-length product was measured in the spiral cardiac mode at four pitch values and three electrocardiographic modulation temporal windows. Noise was measured in an anthropomorphic phantom. Data were compared with data from a 64-channel multi-detector row CT scanner.

RESULTS

For the multi-detector row and dual-source CT systems, respectively, weighted CT dose index per 100 mAs was 14.2 and 12.2 mGy (head CT), 6.8 and 6.4 mGy (body CT), and 6.8 and 5.3 mGy (cardiac CT). In the spiral cardiac mode (no electrocardiographically based tube current modulation, 0.2 pitch), equivalent noise occurred at volume CT dose index values of 23.7 and 35.0 mGy (coronary artery calcium CT) and 58.9 and 61.2 mGy (coronary CT angiography) for multi-detector row CT and dual-source CT, respectively. The use of heart rate-dependent pitch values reduced volume CT dose index to 46.2 mGy (0.265 pitch), 34.0 mGy (0.36 pitch), and 26.6 mGy (0.46 pitch) compared with 61.2 mGy for 0.2 pitch. The use of electrocardiographically based tube current-modulation and temporal windows of 110, 210, and 310 msec further reduced volume CT dose index to 9.1-25.1 mGy, dependent on the heart rate.

CONCLUSION

For electrocardiographically gated coronary CT angiography, image noise equivalent to that of multi-detector row CT can be achieved with dual-source CT at doses comparable to or up to a factor of two lower than the doses at multi-detector row CT, depending on heart rate of the patient.

Usefulness of 64-slice multislice computed tomography coronary angiography to assess in-stent restenosis

OBJECTIVES

This study sought to evaluate the diagnostic accuracy of 64-slice multislice computed tomography (MSCT) coronary angiography in the follow-up of patients with previous coronary stent implantation.

BACKGROUND

Recent investigations have shown increased image quality and diagnostic accuracy for noninvasive coronary angiography with 64-slice MSCT as compared with previous-generation MSCT scanners, but data on the evaluation of coronary stents are scarce.

METHODS

In 182 patients (152 [84%] male, ages 58 +/- 11 years) with previous stent (> or =2.5 mm diameter) implantation (n = 192), 64-slice MSCT angiography using either a Sensation 64 (Siemens, Forchheim, Germany) or Aquilion 64 (Toshiba, Otawara, Japan) was performed. At each center, coronary stents were evaluated by 2 experienced observers and evaluated for the presence of significant (> or =50%) in-stent restenosis. Quantitative coronary angiography served as the standard of reference.

RESULTS

A total of 14 (7.3%) stented segments were excluded because of poor image quality. In the interpretable stents, 20 of the 178 (11.2%) evaluated stents were significantly diseased, of which 19 were correctly detected by 64-slice MSCT. Accordingly, sensitivity, specificity, and positive and negative predictive value to identify in-stent restenosis in interpretable stents were 95.0% (95% confidence interval [CI] 85% to 100%), 93.0% (95% CI 90% to 97%), 63.3% (95% CI 46% to 81%), and 99.3% (95% CI 98% to 100%), respectively.

CONCLUSIONS

In-stent restenosis can be evaluated with 64-slice MSCT with good diagnostic accuracy. In particular, a high negative predictive value of 99% was observed, indicating that 64-slice MSCT may be most valuable as a noninvasive method of excluding in-stent restenosis.

The case in favor of screening for coronary artery disease with coronary CT angiography

Coronary computed tomographic angiography is leading a technologic revolution in the field of cardiac imaging. For the first time, it is possible to image the wall of the coronary artery noninvasively to assess plaque burden, characterize plaque, and assess the degree of stenosis. This paper explores the possibility of using coronary computed tomographic angiography as a screening tool. Key screening examination elements, the pros and cons of screening, the limitations of current technology, and potential pitfalls are discussed.

Usefulness of multislice spiral computed tomography coronary angiography in patients with acute chest pain in the emergency department

BACKGROUND

Despite reports that multislice spiral computed tomography (MSCT) has high sensitivity and specificity in preselected patient populations, the routine clinical feasibility and utility of MSCT coronary angiography in patients with acute chest pain in the emergency department remains uncertain.

OBJECTIVES

We sought to determine whether 16-slice MSCT coronary angiography can provide diagnostically useful images in patients with acute chest pain in the emergency department.

METHODS

Ninety-eight patients in the emergency department (41 men, 57 women; mean age +/- SD, 48.1 +/- 11.9 y) with acute chest pain underwent MSCT coronary angiography. Coronary calcium (Agatston) scoring was performed, followed by contrast-enhanced MSCT. Images were evaluated for mean image quality (MIQ) and for degree of stenosis. These data were correlated with body mass index (BMI; in kg/m(2)), heart rate, beat-to-beat variation, and calcium score to assess their influence on image quality.

RESULTS

The 28 patients (29%) with nondiagnostic MIQs had significantly higher BMIs (mean +/- SD, 32.9 +/- 9.1 vs 28.9 +/- 6.7; P < 0.05) and heart rates (mean +/- SD, 71.0 +/- 11.9 beats/min vs 65.6 +/- 9.9 beats/min; P < 0.05) than patients with diagnostic MIQs. Forty-five patients (46%) had at least 1 nondiagnostic coronary segment. These patients had significantly higher heart rates (mean +/- SD, 70.5 +/- 10.3 vs 64.1 +/- 13.7; P < 0.05) than patients with only diagnostic-quality scans. Image quality correlated inversely and strongly with BMI and heart rate.

CONCLUSIONS

Sixteen-slice MSCT coronary angiography cannot routinely provide diagnostically useful images in patients with acute chest pain in the emergency department.

The role of coronary CT angiography (CTA) for patients presenting with acute chest pain. Defining problem-specific, evidence-based indications of a novel imaging modality

In the current issue, Stillman et al. (Int J Cardiovasc Imaging, 2007) discuss the role of coronary CTA in patients presenting with acute chest pain. The authors conclude, that CTA will provide novel information on the presence and significance of CAD in patients presenting with acute chest pain. Based on the lack of evidence-based data, specific recommendations for its appropriate use are incomplete. Most experts agree, that there is the need for large clinical trials to determine the accuracy and precision of MDCT for triage of patients with acute chest pain.

Imaging techniques in cardiac resynchronization therapy

Cardiac resynchronization therapy is a high cost therapeutic option with proven efficacy on improving symptoms of ventricular failure and for reducing both hospitalization and mortality. However, a significant number of patients do not respond to cardiac resynchronization therapy that is due to various reasons. Identification of the optimal pacing site is crucial to obtain the best therapeutic result that necessitates careful patient selection. Currently, using echocardiography for mechanical dyssynchrony assessment performs patient selection. Multi-Detector-Row Computed Tomography (MDCT) and Magnetic Resonance Imaging (MRI) are new imaging techniques that may assist the cardiologist in patient selection. These new imaging techniques have the potential to improve the success rate of cardiac resynchronization therapy, due to pre-interventional evaluation of the venous coronary anatomy, to evaluation of the presence of scar tissue, and to improved evaluation of mechanical dyssynchrony. In conclusion, clinical issues associated with heart failure in potential candidates for cardiac resynchronization therapy, and the information regarding this therapy that can be provided by the imaging techniques echocardiography, MDCT, and MRI, are reviewed.

Analysis of Cardiac Dimensions, Mass and Function in Heart Transplant Recipients Using 64-slice Multi-detector Computed Tomography

BACKGROUND

Heart transplant recipients present a challenge to cardiac multi-detector computed tomography (MDCT) imaging due to high resting heart rates and body mass indices. Previous studies demonstrated the feasibility of coronary allograft vasculopathy detection by MDCT in heart transplant recipients. However, its performance in assessing cardiac structure and function in these patients has not been evaluated. The aim of this study was to compare 64-slice MDCT analysis of cardiac structure and function to 2-dimensional echocardiography in heart transplant recipients.

METHODS

Two independent observers used both semi-automated and automated software to measure chamber dimensions and left ventricular ejection fraction and mass in 20 heart transplant recipients by 64-slice MDCT. Inter-observer variability was determined. The results were compared with echocardiographic measurements provided by another blinded observer.

RESULTS

There was moderate agreement between MDCT and echocardiography for chamber dimension measurements, except for left atrial diameter. Ejection fraction by MDCT was slightly lower (mean difference: -2 +/- 9%, p = 0.29) than that obtained by echocardiography and the correlation was moderate (R = 0.49 to 0.54). Left ventricular mass measurements were significantly lower by MDCT (mean difference: -87 +/- 44 g, p < 0.001). Inter-observer agreement for MDCT analysis of left ventricular function (R = 0.90) and mass (R = 0.83) were excellent.

CONCLUSIONS

These findings demonstrate moderate agreement between 64-slice MDCT and echocardiography in the assessment of chamber dimensions as well as left ventricular mass and function in heart transplant recipients with low inter-observer variability. Also, the addition of cardiac structural and functional analysis to MDCT coronary angiography requires no additional scan time, contrast administration or radiation exposure.

Sixty-four–slice multidetector computed tomography: the future of ED cardiac care

Multidetector computed tomography (MDCT) imaging, a technological advance over traditional CT, is a promising possible alternative to cardiac catheterization for evaluating patients with chest pain in the emergency department (ED). In comparison with traditional CT, MDCT offers increased spatial and temporal resolution that allows reliable visualization of the coronary arteries. In addition, a "triple scan," which includes evaluation for pulmonary embolism and thoracic aortic dissection, can be incorporated into a single study. This test will enable emergency physicians to rapidly evaluate patients for life-threatening illnesses and may allow safer and earlier discharges of many patients with chest pain in comparison with a traditional rule-out protocol. In this article, we will highlight the technological advances of MDCT imaging, review the literature on coronary angiography via MDCT, and discuss the future of this technology as it relates to the ED.

Aortic root catheter-directed coronary CT angiography in swine: coronary enhancement with minimum volume of iodinated contrast material

OBJECTIVE

The purpose of this study was to evaluate the minimum amount of contrast material for coronary imaging with aortic root catheter-directed enhancement and 64-MDCT angiography (MDCTA).

MATERIALS AND METHODS

A 64-MDCT scanner was used after animal institutional review board approval to study four swine (40-60 kg). Heart rate reduction to 65 beats per minute was achieved with atenolol by mouth and i.v. Cardizem. Common femoral artery access was obtained with a 5-French micropuncture kit and sonographic guidance. A diffusiontip (640 side holes), 5-French pigtail catheter was positioned in the aortic root on the CT table with a retrofitted C-arm fluoroscopy unit and connected to an arterial power injector. Aortic root MDCTA (retrospective ECG gating; collimation, 0.6 mm; tube rotation time, 0.33 second; scanning time, 10-12 seconds; tube voltage, 120 kVp; effective mAs, 850 mAs; pitch, 0.2; field of view, 109-123 mm; slice thickness and increment, 0.6 and 0.3 mm) was begun 1 second after the injection of 100 mL of various Visipaque (iodixanol) concentrations (10%, 20%, 30%, 40%) at 10 mL/s. Coronary mean and peak densities, 3D maximum intensity projections, and 4D projections were obtained.

RESULTS

The mean pooled coronary attenuation values (H +/- SD) for the right (RCA), left anterior descending (LAD), and left circumflex (LCx) coronary arteries at various concentrations (10%, 20%, 30%, 40%) were as follows: 10% (RCA [232.6 +/- 64.0], LAD [180.4 +/- 45.1], and LCx [176.6 +/- 56.2]); 20% (RCA [383.0 +/- 98.7], LAD [324.3 +/- 60.1], and LCx [331.8 +/- 105.5]); 30% (RCA [441.8 +/- 137.6], LAD [401.3 +/- 125.8], and LCx [418.5 +/- 173.0]); and 40% (RCA [717.3 +/- 377.7], LAD [573.3 +/- 233.3], and LCx [584.8 +/- 189.0]). Coronary imaging with aortic root MDCTA was feasible at all concentrations, and the attenuation values were statistically significantly greater than 250 H at 20%, 30%, and 40% (p < 0.05). The attenuation values with aortic root MDCTA using one fifth of the volume of contrast material are comparable to those currently achieved both clinically and experimentally with peripheral i.v. MDCTA.

CONCLUSION

Aortic root MDCTA can depict the coronary arteries with as little as 20 mL of contrast material. This may provide an alternative means of coronary evaluation in patients with renal insufficiency.

Presence and severity of noncalcified coronary plaque on 64-slice computed tomographic coronary angiography in patients with zero and low coronary artery calcium

How well absence of coronary artery calcium (CAC) predicts the absence of noncalcified coronary artery plaque (NCAP) has not been elucidated. We conducted a cross-sectional study of 554 outpatients to quantify NCAP prevalence as a function of CAC score. All patients underwent CAC scoring followed by 64-slice computed tomographic coronary angiography. Patients were categorized as having 0 CAC (416 patients) or low CAC (138 patients; men with CAC scores from 1 to 50 and women with scores from 1 to 10). Prevalence of detectable NCAP was 6.5% in patients with 0 CAC and 65.2% in those with low CAC. Compared with patients with 0 CAC, those with low CAC had markedly increased rates of NCAP occluding <50% of the arterial lumen (56.5% vs 6.0%, p <0.001) and > or =50% of the arterial lumen (8.7% vs 0.5%, p <0.001). In conclusion, in outpatients with a low to intermediate risk presentation and no known coronary artery disease, absence of CAC predicts low prevalence of any NCAP and very low prevalence of significantly occlusive NCAP. Low but detectable CAC scores are significantly less reliable in predicting plaque burden due to their association with high overall NCAP prevalence and nearly a 10% rate of significantly occlusive NCAP.