Simon C Koestner

University Hospital of Lausanne, Lausanne, Vaud, Switzerland

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Publications (6)31.96 Total impact

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    ABSTRACT: For free-breathing cardiovascular magnetic resonance (CMR), the self-navigation technique recently emerged, which is expected to deliver high-quality data with a high success rate. The purpose of this study was to test the hypothesis that self-navigated 3D-CMR enables the reliable assessment of cardiovascular anatomy in patients with congenital heart disease (CHD) and to define factors that affect image quality. CHD patients ≥2 years-old and referred for CMR for initial assessment or for a follow-up study were included to undergo a free-breathing self-navigated 3D CMR at 1.5T. Performance criteria were: correct description of cardiac segmental anatomy, overall image quality, coronary artery visibility, and reproducibility of great vessels diameter measurements. Factors associated with insufficient image quality were identified using multivariate logistic regression. Self-navigated CMR was performed in 105 patients (55 % male, 23 ± 12y). Correct segmental description was achieved in 93 % and 96 % for observer 1 and 2, respectively. Diagnostic quality was obtained in 90 % of examinations, and it increased to 94 % if contrast-enhanced. Left anterior descending, circumflex, and right coronary arteries were visualized in 93 %, 87 % and 98 %, respectively. Younger age, higher heart rate, lower ejection fraction, and lack of contrast medium were independently associated with reduced image quality. However, a similar rate of diagnostic image quality was obtained in children and adults. In patients with CHD, self-navigated free-breathing CMR provides high-resolution 3D visualization of the heart and great vessels with excellent robustness.
    Full-text · Article · Jul 2015 · Journal of Cardiovascular Magnetic Resonance
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    ABSTRACT: Purpose: To assess the diagnostic performance of respiratory self-navigation for whole-heart coronary magnetic resonance (MR) angiography in a patient cohort referred for diagnostic cardiac MR imaging. Materials and methods: Written informed consent was obtained from all participants for this institutional review board-approved study. Self-navigated coronary MR angiography was performed after administration of a contrast agent in 78 patients (mean age, 48.5 years ± 20.7 [standard deviation]; 53 male patients) referred for cardiac MR imaging because of coronary artery disease (n = 40), cardiomyopathy (n = 14), congenital anomaly (n = 17), or "other" (n = 7). Examination duration was recorded, and the image quality for each coronary segment was assessed with consensus reading. Vessel sharpness, length, and diameter were measured. Quantitative values in proximal, middle, and distal segments were compared by using analysis of variance and t tests. A double-blinded comparison with the results of x-ray angiography was performed when such results were available. Results: When patients with different indications for cardiac MR imaging were examined with self-navigated postcontrast coronary MR angiography, whole-heart data sets with 1.15-mm isotropic spatial resolution were acquired in an average of 7.38 minutes ± 1.85. The main and proximal coronary segments could be visualized in 92.3% of cases, while the middle and distal segments could be visualized in 84.0% and 55.8% of cases, respectively. Subjective scores and vessel sharpness were significantly higher in the proximal segments than in the middle and distal segments (P < .05). Anomalies of the coronary arteries could be confirmed or excluded in all cases. Per-vessel sensitivity and specificity for stenosis detection were 64.7% and 85.0%, respectively, in the 31 patients for whom reference standard x-ray coronary angiography results were available. Conclusion: The self-navigated coronary MR angiography sequence shows promise for coronary imaging. However, technical improvements are needed to improve image quality, especially in the more distal coronary segments.
    No preview · Article · Feb 2014 · Radiology
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    ABSTRACT: Introduction: Cardiac anatomy of patients with congenital heart disease (CHD) is often complex and accurate evaluation mandates MR image acquisition in several non-standardized planes requiring considerable operator involvement and multiple breath-holds. The utility of self-navigated isotropic 3D-free-breathing whole-heart MRI (SN-3D) was assessed for the visualization of the heart, coronary arteries (CA) and great vessels (GV) in CHD patients. Methods: Data acquisition was performed during free breathing on a 1.5T-MRI scanner with a 3D-radial trajectory modified for respiratory self-navigation after gadobutrol injection; it was ECG-triggered, with a T2-preparation pulse and fat-saturated SSFP readout. The isotropic image data were reformatted offline. Image quality was graded and GV diameters were measured at several levels in all patients. 3D MR-angiography (MRA) was performed in a subset of patients and the GV diameters were also measured for comparison. Results: 38 patients (66% male, age 23±10y) were included. Heart rate was 71±13 bpm, scan duration 9.1±4.2 min, isotropic resolution 1.1×1.1×1.1 mm3. Image quality was good in 23, moderate in 10, mediocre in 2, and poor in 3. 3D datasets allowed the assessment of the arrangement of heart chambers and great vessels, the venous return anatomy after atrial switch for transposition of the great arteries (TGA), the morphology of cavo-pulmonary connections after Fontan operation, the morphology of the pulmonary arteries in tetralogy of Fallot or morphology of the great vessels after arterial switch for TGA. GV diameters with SN-3D were accurate using conventional MRA as the gold standard (n=25, r2=0.91, bias 0.1±2.2 mm), with a low intra- and inter-observer variability (3.7% and 5.4%). Moreover, the proximal 3 cm of the CA could be well visualized and its 3D course followed in most of the patients with moderate or good image quality (n=33: LAD 97%, LCx 73%, RCA 91%), making SN-3D useful to detect anomalous CA. Conclusion: The SN-3D methodology enables time-efficient whole-heart coverage during free breathing. The high isotropic resolution supports multi-planar offline reformatting in any plane orientation, which is particularly useful in CHD patients with complex anatomy. Self-navigation and the absence of fold-over artifacts enhance the ease of use and favor a fast acquisition planning. Reformatted images allow accurate measurement of the GV, and even small anatomical structures could be precisely identified illustrating the potential of this methodology to assess the anatomy of the proximal course of CA.
    Full-text · Article · Sep 2013 · Journal of Cardiovascular Magnetic Resonance
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    ABSTRACT: To compare coronary computed tomographic (CT) angiography with first-pass magnetic resonance (MR) myocardial perfusion imaging in patients with chest pain and low to intermediate probability of coronary artery disease (CAD). Local ethics committee approval and patient written informed consent were obtained. Patients with chest pain and low to intermediate pretest probability of CAD underwent both coronary CT angiography and MR myocardial perfusion imaging. Coronary CT angiographic and MR myocardial perfusion images were analyzed qualitatively by blinded observers. Obstructive CAD was defined as more than 50% diameter stenosis at coronary CT angiography. Data were expressed with 95% confidence intervals (CIs) calculated from binomial expression. In 145 (94.2%) of 154 eligible patients, both coronary CT angiography and MR myocardial perfusion imaging were performed successfully. Mean age was 57 years +/- 10 (standard deviation), and 45.5% of patients were male. Mean interval between coronary CT angiography and MR myocardial perfusion imaging was 4.6 days +/- 3.0; median was 5.0 days. CT coronary angiography revealed obstructive CAD in 52 (35.9%) patients and 78 (17.9%) coronary arteries. At MR myocardial perfusion imaging, myocardial ischemia was demonstrated in 33 (22.8%) patients and 59 (13.6%) vessel territories. Of patients without CAD at coronary CT angiography, 90.5% (57 of 63; 95% CI: 82.6%, 95.0%) had normal myocardial perfusion at MR myocardial perfusion imaging. Of patients with nonobstructive CAD, 83.3% (25 of 30; 95% CI: 69.5%, 91.6%) had normal myocardial perfusion at MR myocardial perfusion imaging. Myocardial ischemia was detected at MR myocardial perfusion imaging in 42.3% (22 of 52; 95% CI: 29.5%, 56%) of patients with obstructive CAD at coronary CT angiography. MR myocardial perfusion imaging and coronary CT angiography have complementary roles in evaluation of patients who are suspected of having CAD. Coronary CT angiography can be used to reliably rule out CAD, but its capability to demonstrate hemodynamically significant CAD is limited. The combination of both techniques enables the clinician to evaluate morphology and functional relevance of CAD comprehensively and noninvasively.
    No preview · Article · Feb 2010 · Radiology
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    Full-text · Article · Jan 2009 · Journal of Cardiovascular Magnetic Resonance
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    Preview · Article · Jan 2009 · Journal of Cardiovascular Magnetic Resonance

Publication Stats

24 Citations
31.96 Total Impact Points


  • 2013-2015
    • University Hospital of Lausanne
      • Service de cardiologie
      Lausanne, Vaud, Switzerland
  • 2010
    • VU University Amsterdam
      Amsterdamo, North Holland, Netherlands
  • 2009
    • VU University Medical Center
      • Department of Cardiology
      Amsterdamo, North Holland, Netherlands