| | Accuracy of 16-detector Multislice Spiral Computed Tomography in the initial evaluation of dilated cardiomyopathyReceived 12 April 2006; received in revised form 3 August 2006; accepted 4 August 2006. Abstract BackgroundMultislice Computed Tomography (MSCT) recently proved its accuracy in the detection of coronary artery disease (CAD). It can also give information about left ventricular function and venous network anatomy. We here sought to validate a MSCT-based strategy in the initial evaluation of patients with dilated cardiomyopathy (DCM). Methods36 patients with DCM underwent cardiac MSCT before conventional coronary angiography with ventriculography. We analysed arterial calcium score (Agatston score equivalent: ASE), coronary stenosis, left ventricular parameters and venous network. ConclusionIn patients undergoing an initial evaluation of DCM, MSCT appears to be an effective alternative to conventional angiography. The following attitude may be proposed: when ASE >1.000, conventional coronary angiography is mandatory due to MSCT's poor interest in such cases; when ASE <1.000, a contrast-enhanced MSCT may, when normal, replace coronary angiography. In Europe, at least 10 million patients suffer from heart failure and probably as many present asymptomatic cardiac dysfunction [1], [2]. The prognosis of heart failure is uniformly poor if the underlying problem cannot be rectified. Coronary artery disease (CAD) is believed to be the only or an associated cause in approximately two thirds of these patients [3] and reperfusion therapy can change the prognosis. Thus, conventional coronary angiography was used to be performed in most patients with dilated cardiomyopathy (DCM) in order to assert CAD status.Contrast-enhanced Multislice Spiral Computed Tomography (MSCT) was introduced a few years ago as a method of non-invasive visualization of coronary artery stenosis [4], [5], [6], [7], [8], [9], [10], [11]. The initial studies did not attempt simultaneous left ventricular (LV) function analysis and cardiac venous system visualization [9], thus not taking full advantage of the acquired data. To evaluate MSCT as an alternative to coronary angiography in the initial evaluation of patients with dilated cardiomyopathies, we prospectively studied its diagnostic accuracy for the detection of significant coronary stenosis (ischemic or non-ischemic cardiomyopathy), for the assessment of the level of left ventricular dysfunction, and for the evaluation of the cardiac venous network and especially left marginal vein anatomy. 1. Materials and methods  1.2. MSCT protocol and image reconstruction Using a 16-slice MSCT (Philips Mx8000 IDT 16, Eindhoven, The Netherlands), a volume data set was acquired (16 mm×0.75mm cross-section; gantry rotation time, 420ms; temporal resolution, 210ms (segmented reconstruction was not applied because of its high sensitivity to heart rate variations); table feed, 2.8mm per rotation), covering the distance from the carina to the diaphragmatic side of the heart. Tube current was 400mAs, with a tube voltage of 120kV. The entire heart was scanned during a single breath-hold; 120ml of contrast agent (Xenetix 350, Guerbet, Aulnay sous Bois, France) was continuously injected at a rate of 4ml/s. Automated detection of peak enhancement in the aortic root was used to initiate the scanning. Cross-sectional images were reconstructed with a slice thickness of 0.8mm at 0.4mm intervals with retrospective gating. Axial images at 0%, 20%, 30%, 40%, 50%, 65%, 75% and 85% of the R-R interval were reconstructed for each patient and analyzed for motion artifacts. A scoring method analogous to the Agatston score [12] was used to quantify coronary calcium. A calcified lesion was defined as an area of ≥3 pixels >130 Hounsfield units, and expressed as Agatston score equivalent (ASE). All data sets were independently analyzed by two physicians experienced in MSCT by multiplanar reformats and three-dimensional reconstructions by the “volume rendering” technique. They were asked to give a consensus as to whether the patients had significant coronary artery disease (no significant coronary artery disease, 1: vessel disease, 2: vessel disease, 3: vessel disease). The observers were asked to state what would have been their recommendations for patient management (coronary angiography indicated (suspected coronary stenosis or bad quality MSCT images) or not). For the assessment of LV volumes and LV ejection fraction (LVEF), reconstructions previously described were used in 0%, 30%, 40%, and 50% of the R-R interval. The resulting multiphase image series were then used to produce multiplanar reformations in the short-axis orientation using the system's standard 3D software (12–16 slices) with a section thickness of 3mm and a gap of 6mm were produced to encompass the entire left ventricle from apex to base just prior to the mitral valve. Automatic endocardial and epicardial border tracking (LV-RV analysis software, Philips, Eindhoven, The Netherlands) was performed separately for each short-axis slice at end-diastole and end-systole. Results were reviewed visually and corrected manually if there was no substantial abnormality; otherwise, the slice was discarded. Papillary muscles were included in the left ventricular cavity. The LV volumes and LVEF were calculated from short-axis views. The volumes were calculated as the sum of the cavity areas multiplied by the section interval (section thickness+section gap), using Simpson's method. All data sets were independently analyzed blind to the angiography data. The venous system was analyzed for 50% and 75% of the R-R interval phase using multiplanar reformatting. The ostium of the cardiac sinus was defined as the site where the cardiac sinus makes an angle with the right atrium. The distance between the ostium of the cardiac sinus and the ostium of the optimal left marginal vein that would be chosen for left ventricular pacing (resynchronization therapy) was determined. The diameter of that vein was also measured. 1.3. Quantitative coronary angiography Invasive coronary angiograms were obtained 1 day after MSCT. Angiograms were evaluated by a blinded independent observer using quantitative coronary angiography (QCA) (Numeric System, DX-DLX, General Electric Medical Systems, Buc, France) and served as gold standard for stenosis detection. Lesions with a diameter reduction of 50% or more were considered to represent significant stenoses. Standard cineventriculography was performed using a 30° right anterior oblique projection, with injection of at least 30ml of contrast medium at a flow rate of 12ml/s, via a 6 French pigtail catheter. Semi-automatic contour-tracking was used to define the end-diastolic image, based on the frame with the largest ventricular silhouette, and the end-systolic image, based on the frame with the smallest ventricular silhouette. Image calibration used a metal ball with a diameter of 4.0cm, with identical X-ray tube positions. End-diastolic and end-systolic LVV (LVEDV and LVESV) were determined using Simpson's method. Cineventriculography was analyzed by two experienced cardiologists. The venous system was analyzed using a 30° right anterior oblique projection and late frames after contrast injection. Left marginal veins were counted for each patient and the angle with the great cardiac vein was also measured. 1.4. Statistics General characteristics of the study sample were assessed by means and standard deviations for continuous variables, and by the proportion of patients for categorical variables. The accuracy of the MSCT in determining LVEDV, LVESV and LVEF was assessed by comparing the values obtained by MSCT and by conventional cineventriculography as the reference test. For linear correlation analysis, Pearson R correlation coefficients between the two values were computed. For LVEDV, LVESV and LVEF, Bland–Altman analyses were performed, plotting the difference between the pair of values according to their mean. Mean difference and limits of agreement were also drawn for each parameter. Concordance between the two techniques for the existence of a more than 50% coronary stenosis was assessed by the determination of the kappa concordance coefficient. Sensibility and specificity of MSCT to detect CAD were computed with 95% confidence interval. Sensitivity and specificity of a strategy that would consist in performing conventional angiography in case of abnormal or inconclusive MSCT were also computed. A ROC (receiver operating characteristic) curve analysis was performed to assess the ability of ASE to detect patients in whom conventional coronary angiography would be required under the above strategy. All analysis were performed using SPSS analysis software, release 12.0 (SPSS Inc., Chicago, IL, USA). 2. Results All patients underwent MSCT without any complication. Mean scan duration was 23.2±4.6s. No intra-venous beta-blocker injection was performed. 2.1. Coronary analysis (Fig. 1) Thirty-six patients underwent both MSCT and conventional coronary angiography. In three cases (8.3%), the coronary network was not assessable by MSCT. Out of the 33 remaining patients, 9 (27.8%) had a significant coronary artery disease as detected on invasive coronary angiography (1: vessel disease, 0 patient; 2: vessel disease, 3 patients; 3: vessel disease, 6 patients). MSCT analysis showed 10 patients with significant coronary artery disease (1: vessel disease, 0 patient; 2: vessel disease, 5 patients; 3: vessel disease, 5 patients). One of the three patients with a inconclusive MSCT presented a significant CAD on conventional angiography. One patient with a significant stenosis on MSCT had a normal conventional angiography. The kappa value was 0.93 (p<0.0001). The sensitivity for detecting significant stenosis was 100% [95% confidence interval: 70–100] and the specificity 96% [95% CI: 80–99]. The positive predictive value was 90% [60–98] and the negative predictive value was 100% [86–100]. 2.2. Calcium scoring Calcification was successfully assessed in all patients. The mean calcium score, expressed as ASE, was 729±1222. The ability of the calcium score to detect patients in whom conventional coronary angiography was indicated (because of an inconclusive MSCT or because of a significant stenosis shown on MSCT) was plotted as a receiver operating characteristic (ROC) curve; the area under the ROC curve was 0.85 (Fig. 2). A cut-off of 1000 was chosen as the best compromise between a as low as possible proportion of non-interpretable or pathological MSCTs and a as high as possible proportion of patients in whom the MSCT alone could rule out CAD. 2.3. Accuracy of the MSCT-based strategy in detecting CAD in patients with dilated cardiomyopathy According to the receiver operating characteristic curve data, the strategy we evaluated is summarized in Fig. 3. For ASE less than 1000 (75% of patients), MSCT detected all non-CAD patients except one (inconclusive MSCT because of motion artifacts), enabling us to avoid conventional coronary angiography in 21 of these 27 patients (77.7%). For ASE greater than 1000, MSCT could have enabled us to avoid conventional coronary angiography in only 2 patients (22.2% of cases), either because significant stenosis were found with a possible indication of revascularization (5 patients, 55.6%), or because the examination could not be interpreted (2 patients, 22.2%). All 10 CAD patients had either evidence of CAD and/or high level of calcifications and/or motion artifacts that precluded interpretation of the MSCT. Thus, the sensitivity of a MSCT-based strategy with coronary angiography in case of abnormal or inconclusive MSCT was 100% [95% confidence interval (CI): 72–100] and the specificity 80% [95% CI: 62–91]. The positive and negative predictive values were respectively 67% and 100%. Finally, this strategy enabled us to avoid conventional coronary angiography in 21 of the 26 patients (80%) that did not present significant stenosis on the gold standard test and though in 21 of the 36 patients (58%) that was scheduled for the initial evaluation of their DCM. 3. Discussion Initial evaluation of patients with dilated cardiomyopathy is important for etiological process and patient management. We tried to evaluate a MSCT-based strategy that would be able to answer these three questions: Is MSCT accurate in detection of coronary stenosis even in a population with dilated ventricles? Does MSCT assessment of left ventricular function correlate well with cineventriculography? When resynchronization therapy is indicated, can MSCT assess the presence of one or more left marginal vein accessible to a stimulation lead? MSCT has been known to be accurate in detecting significant coronary stenosis for a few years, but in many studies sensitivity (63–95%) [7], [10], [13], [14] and specificity (86–98%) [8], [14], [15] were calculated on the interpretable artery segments, while 6.4–20% were not analyzable because of artifacts or calcification [6], [10], [16]. Nevertheless, in some studies all the coronary segments were assessable [7], [11]. We chose to evaluate coronary arteries on a per-vessel instead of a per-segment basis because a stenosis in a single distal segment (number 4, 8, 15 or 16 of the classification of the American Heart Association [17]) cannot explain a dilated cardiomyopathy. The correlation with coronary angiography was quite satisfying. Calcifications obscure the lumen due to beam hardening artifacts and therefore may impair assessment of luminal obstruction. Kuettner [16] showed calcification to be an important factor in analyzing coronary artery MSCT: when the ASE falls below 1000, stenosis detection sensitivity rises from 72% to 98%. That's why we tried to improve the strategy using the calcium scoring data. In patients with ASE greater than 1000, we do not recommend a contrast-enhanced MSCT, which would be of virtually no benefit. Nevertheless, the positive predictive value for significant stenosis of a calcium score of >1000 was no more than 66.6%. Currently, MRI is the non-invasive diagnostic gold standard for the assessment of LV volume, EF and regional myocardial function [18], [19], [20]. Recent studies have reported good correlations between MRI and MSCT results [21], [22], [23] and good correlation between MSCT and cineventriculography when Simpson's method is used [24]. Using automated analysis software, functional analysis by MSCT is no longer limited by time-consuming secondary reformations. Nevertheless, the temporal resolution does not guarantee to catch correctly the end-systolic phase of the cardiac cycle and its temporal resolution does not reach the 20Hz that are request for accurate measurements of EF, end-diastolic-volume and end-systolic volume. In this study, all patients suffered from a dilated cardiomyopathy that does not allow us to add intra-venous beta-blockers during the CT scanner. In spite of these considerations, even when the left ventricle is dilated, volumes and left ventricular ejection fraction can at least be measured with an identical correlation as in smaller ventricles. Cardiac venous system visualization has had little assessment because there was no medical application. With the development of resynchronization therapy for patients with dilated cardiomyopathy and severe heart failure, the venous system became important for permanent pacing [25]. Few studies showed that MSCT could be used to identify patients who do not have additional side branches and therefore may benefit more from epicardial lead placement using a minimally invasive surgical approach and that MSCT could allow virtual navigation in the venous network [26], [27]. The method that used to be performed in most centers was angiography with a late venous time, but the late frames were often forgotten and there was no way to assess the left marginal vein. MSCT seems to be a good new test to help physicians with resynchronization therapy. Advantages of CT to interventional coronary angiography and ventriculography are obvious and have been described many times [5], [10]. MRI, as a non-irradiant tool using no nephrotoxic contrast agent, should be a useful test in this indication, but its temporal resolution is still not high enough to allow coronary artery assessment in large populations and MSCT has better performances in this indication. Furthermore, to our knowledge, an accurate evaluation of the cardiac venous system has never been described using MRI. In patients undergoing an initial evaluation of a dilated cardiomyopathy, MSCT appears to be an effective alternative to conventional angiography. The following attitude may be proposed: in case of a calcium score >1000, conventional coronary angiography is mandatory due to MSCT's poor interest in such cases; in case of calcium score <1000, a contrast-enhanced MSCT may, when normal, replace coronary angiography not only in coronary stenosis assessment but also in left ventricular and venous network evaluation. References [1]. [1]Swedberg K, Cleland J, Dargie H, et al. Guidelines for the diagnosis and treatment of chronic heart failure: executive summary (update 2005): The Task Force for the Diagnosis and Treatment of Chronic Heart Failure of the European Society of Cardiology. Eur Heart J. 2005;26(11):1115–1140.
CrossRef
[2]. [2]Davies M, Hobbs F, Davis R, et al. Prevalence of left-ventricular systolic dysfunction and heart failure in the Echocardiographic Heart of England Screening study: a population based study. Lancet. 2001;358(9280):439–444. Abstract | Full Text |
Full-Text PDF (92 KB)
|
CrossRef
[3]. [3]Hunt SA. ACC/AHA 2005 guideline update for the diagnosis and management of chronic heart failure in the adult: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Update the 2001 Guidelines for the Evaluation and Management of Heart Failure). J Am Coll Cardiol. 2005;46(6):e1–e82.
Full-Text PDF (1563 KB)
|
CrossRef
[4]. [4]Ropers D, Baum U, Pohle K, et al. Detection of coronary artery stenoses with thin-slice multi-detector row spiral computed tomography and multiplanar reconstruction. Circulation. 2003;107(5):664–666.
CrossRef
[5]. [5]Nieman K, Oudkerk M, Rensing BJ, et al. Coronary angiography with multi-slice computed tomography. Lancet. 2001;357(9256):599–603. Abstract | Full Text |
Full-Text PDF (4940 KB)
|
CrossRef
[6]. [6]Mollet NR, Cademartiri F, Nieman K, et al. Multislice spiral computed tomography coronary angiography in patients with stable angina pectoris. J Am Coll Cardiol. 2004;43(12):2265–2270. Abstract | Full Text |
Full-Text PDF (315 KB)
|
CrossRef
[7]. [7]Mollet NR, Cademartiri F, Krestin GP, et al. Improved diagnostic accuracy with 16-row multi-slice computed tomography coronary angiography. J Am Coll Cardiol. 2005;45(1):128–132. Abstract | Full Text |
Full-Text PDF (322 KB)
|
CrossRef
[8]. [8]Martuscelli E, Romagnoli A, D’Eliseo A, et al. Accuracy of thin-slice computed tomography in the detection of coronary stenoses. Eur Heart J. 2004;25(12):1043–1048.
CrossRef
[9]. [9]Leschka S, Alkadhi H, Plass A, et al. Accuracy of MSCT coronary angiography with 64-slice technology: first experience. Eur Heart J. 2005;. [10]. [10]Hoffmann MH, Shi H, Schmitz BL, et al. Noninvasive coronary angiography with multislice computed tomography. JAMA. 2005;293(20):2471–2478.
CrossRef
[11]. [11]Leber AW, Knez A, von Ziegler F, et al. Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography: a comparative study with quantitative coronary angiography and intravascular ultrasound. J Am Coll Cardiol. 2005;46(1):147–154. Abstract | Full Text |
Full-Text PDF (284 KB)
|
CrossRef
[12]. [12]Agatston AS, Janowitz WR, Hildner FJ, Zusmer NR, Viamonte M, Detrano R. Quantification of coronary artery calcium using ultrafast computed tomography. J Am Coll Cardiol. 1990;15(4):827–832. Abstract |
Full-Text PDF (1695 KB)
|
CrossRef
[13]. [13]Dirksen MS, Jukema JW, Bax JJ, et al. Cardiac multidetector-row computed tomography in patients with unstable angina. Am J Cardiol. 2005;95(4):457–461. Abstract | Full Text |
Full-Text PDF (155 KB)
|
CrossRef
[14]. [14]Nieman K, Cademartiri F, Lemos PA, Raaijmakers R, Pattynama PM, de Feyter PJ. Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography. Circulation. 2002;106(16):2051–2054.
CrossRef
[15]. [15]Kuettner A, Beck T, Drosch T, et al. Diagnostic accuracy of noninvasive coronary imaging using 16-detector slice spiral computed tomography with 188ms temporal resolution. J Am Coll Cardiol. 2005;45(1):123–127. Abstract | Full Text |
Full-Text PDF (154 KB)
|
CrossRef
[16]. [16]Kuettner A, Trabold T, Schroeder S, et al. Noninvasive detection of coronary lesions using 16-detector multislice spiral computed tomography technology: initial clinical results. J Am Coll Cardiol. 2004;44(6):1230–1237. Abstract | Full Text |
Full-Text PDF (311 KB)
|
CrossRef
[17]. [17]Austen WG, Edwards JE, Frye RL, et al. A reporting system on patients evaluated for coronary artery disease. Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association. Circulation. 1975;51(4 Suppl):5–40. MEDLINE [18]. [18]Pattynama PM, Lamb HJ, van der Velde EA, van der Wall EE, de Roos A. Left ventricular measurements with cine and spin-echo MR imaging: a study of reproducibility with variance component analysis. Radiology. 1993;187(1):261–268. MEDLINE [19]. [19]Lorenz CH, Walker ES, Morgan VL, Klein SS, Graham TP. Normal human right and left ventricular mass, systolic function, and gender differences by cine magnetic resonance imaging. J Cardiovasc Magn Reson. 1999;1(1):7–21. MEDLINE |
CrossRef
[20]. [20]Setser RM, Fischer SE, Lorenz CH. Quantification of left ventricular function with magnetic resonance images acquired in real time. J Magn Reson Imaging. 2000;12(3):430–438. MEDLINE |
CrossRef
[21]. [21]Mahnken AH, Spuentrup E, Niethammer M, et al. Quantitative and qualitative assessment of left ventricular volume with ECG-gated multislice spiral CT: value of different image reconstruction algorithms in comparison to MRI. Acta Radiol. 2003;44(6):604–611. MEDLINE |
CrossRef
[22]. [22]Juergens KU, Grude M, Maintz D, et al. Multi-detector row CT of left ventricular function with dedicated analysis software versus MR imaging: initial experience. Radiology. 2004;230(2):403–410. MEDLINE |
CrossRef
[23]. [23]Dewey M, Muller M, Teige F, Hamm B. Evaluation of a semiautomatic software tool for left ventricular function analysis with 16-slice computed tomography. Eur Radiol. 2005;. [24]. [24]Juergens KU, Grude M, Fallenberg EM, et al. Using ECG-gated multidetector CT to evaluate global left ventricular myocardial function in patients with coronary artery disease. AJR Am J Roentgenol. 2002;179(6):1545–1550. [25]. [25]Gilard M, Mansourati J, Etienne Y, et al. Angiographic anatomy of the coronary sinus and its tributaries. Pacing Clin Electrophysiol. 1998;21(11 Pt 2):2280–2284. MEDLINE |
CrossRef
[26]. [26]Jongbloed MR, Lamb HJ, Bax JJ, et al. Noninvasive visualization of the cardiac venous system using multislice computed tomography. J Am Coll Cardiol. 2005;45(5):749–753. Abstract | Full Text |
Full-Text PDF (292 KB)
|
CrossRef
[27]. [27]Rioual K, Unanua E, Laguitton S, et al. MSCT labelling for pre-operative planning in cardiac resynchronization therapy. Comput Med Imaging Graph. 2005;29(6):431–439. Abstract | Full Text |
Full-Text PDF (554 KB)
|
CrossRef
a Department of Cardiology, Brest University Hospital, France b Department of Pneumology and Internal Medicine, Brest University Hospital, France c Department of Cardiology, Military Hospital, Brest, France  Corresponding author at: Department of Cardiology, Brest University Hospital, Boulevard Tanguy Prigent, 29609 Brest Cedex, France. Tel.: +33 2 98 34 73 92; fax: +33 2 98 34 73 93.
PII: S0720-048X(06)00330-5 doi:10.1016/j.ejrad.2006.08.010 © 2006 Elsevier Ireland Ltd. All rights reserved. | |
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