Showing papers by "Steffen E. Petersen published in 2006"

Detailed analysis of myocardial motion in volunteers and patients using high-temporal-resolution MR tissue phase mapping.

Abstract: Purpose To detect and investigate details in left ventricular (LV) motion patterns with a temporal resolution comparable to that of echocardiography. Material and Methods To assess global and regional myocardial motion in high temporal detail, respiratory-gated MR phase-contrast measurements with three-directional velocity encoding (venc) were performed in 12 healthy volunteers and two patients with LV hypertrophy in basal, midventricular, and apical locations of the LV with a temporal resolution of 13.8 msec. Results The volunteer data revealed details in LV motion patterns that were known only from echocardiography. For all volunteers, characteristic myocardial motion patterns, such as triphasic global diastolic expansion, could be detected with high accuracy. One volunteer underwent an additional echocardiographic measurement in order to corroborate the complex motion features as measured by MRI. Patient examinations revealed substantial changes in diastolic function compared to motion patterns in healthy volunteers. Conclusion The proposed high-temporal-resolution velocity-mapping technique provides previously undetectable information on LV performance, and is highly promising for the detection of local and global motion abnormalities in patients with disturbed LV performance, such as diastolic dysfunction. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.

Myocardial tissue phase mapping with cine phase-contrast mr imaging: regional wall motion analysis in healthy volunteers.

Abstract: Purpose: To establish prospectively a database of normal three-dimensional systolic and diastolic endocardial and epicardial velocity values for all myocardial segments in healthy volunteers by using cine phase-contrast velocity magnetic resonance imaging, also called tissue phase mapping (TPM). Materials and Methods: The study was approved by the institutional ethics committee and was conducted according to principles of the Declaration of Helsinki; each subject provided informed written consent. Ninety-six healthy volunteers (57 [59%] men, 39 [41%] women; mean age, 38 years ± 12 [standard deviation]) underwent cardiac phase-contrast imaging with a black blood segmented k-space gradient-echo sequence for the analysis of three-dimensional myocardial velocity with high spatial resolution at 1.5 T on basal, midventricular, and apical short-axis views. Eighteen consecutive volunteers were imaged twice to determine interstudy reproducibility, and intra- and interobserver variability values were analyzed. Syst...

Determination of cardiac volumes and mass with FLASH and SSFP cine sequences at 1.5 vs. 3 Tesla: a validation study.

Abstract: Purpose To compare cardiac cine MR imaging using steady state free precession (SSFP) and fast low angle shot (FLASH) techniques at 1.5 and 3 T, and to establish their variabilities and reproducibilities for cardiac volume and mass determination in volunteers. To assess the feasibility of SSFP imaging in patients at 3 T and to determine comparability to volume data acquired at 1.5 T. Materials and Methods Ten healthy volunteers underwent cardiac magnetic resonance imaging using SSFP and segmented gradient-echo FLASH, using both a 1.5 and a 3 T MR system on the same day. Ten patients with impaired left ventricular (LV) function were also studied at both field strengths with SSFP. Results For both SSFP and FLASH, field strength had no effect on the quantification of LV and right ventricular (RV) volumes, mass, or function (P ≥ 0.05 for field strength for all parameters). At both 1.5 and 3 T, SSFP yielded smaller LV mass (e.g., at 3 T 109 ± 30 g vs. 142 ± 37 g; P = 0.011) and larger LV volume (e.g., at 3 T end-diastolic volume 149 ± 37 mL vs. 133 ± 31 mL at 5 T; P = 0.041) measurements than FLASH. In patients with reduced LV function, all volume and mass measurements were again similar for SSFP sequences at 1.5 vs. 3 T. In volunteers and patients, measurement variabilities for LV parameters were small for both field strength and sequences, ranging between 3.7% and 10.7% for mass. Conclusion Compared to 1.5 T, cardiac cine MR imaging at 3 T, using either FLASH or SSFP sequences, is feasible and highly reproducible. Field strength does not have an influence on quantification of cardiac volume or mass, but the systematic overestimation of LV mass and underestimation of LV volume by FLASH compared to SSFP is present at both 1.5 and 3 T. Normal values for cardiac volumes and mass established at 1.5 T can be applied to scans obtained at 3 T. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.

Thrombus detection in the left atrial appendage using contrast-enhanced MRI: a pilot study.

Abstract: OBJECTIVE. Left atrial thrombi are an important cause for embolism-related morbidity and mortality. Transesophageal echocardiography (TEE), the clinical reference, is semiinvasive; thus, we aimed to assess the value of contrast-enhanced cardiovascular MRI for the detection of thrombus in the left atrial appendage.CONCLUSION. The image quality was good for both 2D perfusion (grade 4 ± 1) and 3D turbo fast low-angle shot (FLASH) (grade 4 ± 1, n.s.). Compared with TEE, 2D perfusion, 3D turboFLASH, and the combination of both techniques yielded sensitivities of 47/35/44%, specificities of 50/67/67%, positive predictive values of 73/75/80%, and negative predictive values of 25/27/29%, respectively. The size of the thrombus was overestimated by 2D perfusion (66%) and by 3D turboFLASH (25%) and agreement for location and shape of thrombus was 50% and 75% for 2D perfusion and 75% and 50% for 3D turboFLASH, respectively. The TEE thrombus size was significantly larger in patients with true-positive diagnoses by 2D ...

Sex‐specific characteristics of cardiac function, geometry, and mass in young adult elite athletes

Abstract: Purpose:To study young adult elite athletes with age- and sex-matched sedentary controls to assess sex-specific differences for left ventricular (LV) and right ventricular (RV) volumes and mass as well as for LV contraction and relaxation.Materials and Methods:A total of 23 male athletes (mean age 2

Cardiac cine MR-imaging at 3T: FLASH vs SSFP.

Abstract: The implications of an increase in field strength, from 1.5 T to 3 T, for routine functional cardiac examinations have been systematically investigated. Flip angle optimization was carried out for identical SSFP and FLASH cine imaging sequences at 1.5 T and 3 T, which supported the use of 20 degrees (FLASH 1.5 T and 3 T) and >60 degrees (SSFP 1.5 T and 3 T). The optimized sequences were applied in a study of cardiac function in a group of ten normal volunteers. Both SSFP and FLASH sequences showed significant SNR increases in the myocardium and blood at 3 T compared with 1.5 T, increases of 48% and 30% (myocardium and blood, respectively) for the SSFP sequence and 19% and 13% for the FLASH sequence. The SSFP sequence also showed a significant increase in CNR (22%). Image quality assessment revealed that the SSFP acquisitions were superior to FLASH at both field strengths. Although SSFP contained more artifacts at 3 T, they would not prevent its clinical use. We conclude that cardiac functional examinations at 3 T should use SSFP sequences.

Time-Resolved Contrast-Enhanced MR Angiography of the Thorax in Adults with Congenital Heart Disease

Abstract: OBJECTIVE. The aim of this study was to evaluate the diagnostic value of time-resolved contrast-enhanced MR angiography in adults with congenital heart disease.SUBJECTS AND METHODS. Twenty patients with congenital heart disease (mean age, 38 ± 14 years; range, 16-73 years) underwent contrast-enhanced turbo fast low-angle shot MR angiography. Thirty consecutive coronal 3D slabs with a frame rate of 1-second duration were acquired. The mask defined as the first data set was subtracted from subsequent images. Image quality was evaluated using a 5-point scale (from 1, not assessable, to 5, excellent image quality). Twelve diagnostic parameters yielded 1 point each in case of correct diagnosis (binary analysis into normal or abnormal) and were summarized into three categories: anatomy of the main thoracic vessels (maximum, 5 points), sequential cardiac anatomy (maximum, 5 points), and shunt detection (maximum, 2 points). The results were compared with a combined clinical reference comprising medical or surgica...

Hypertrophic cardiomyopathy in Noonan Syndrome closely mimics familial hypertrophic cardiomyopathy due to sarcomeric mutations

Abstract: A 27 year old female with Noonan syndrome and hypertrophic cardiomyopathy underwent cardiovascular magnetic resonance imaging. These images showed asymmetrical septal hypertrophy with maximal left ventricular end-diastolic wall thickness of 25 mm. Following administration of gadolinium, areas of hyperenhancement were seen in the anterior, anteroseptal and lateral walls. This is the first report of focal gadolinium hyperenhancement in hypertrophic cardiomyopathy due to Noonan syndrome and suggests that myocardial fibrosis can be imaged by MR hyperenhancement as seen previously in sarcomeric hypertrophic cardiomyopathy.

Percutaneous Left Atrial Appendage Transcatheter Occlusion (PLAATO): Planning and Follow-Up Using Contrast-Enhanced MRI

Abstract: 3University of Oxford, OCMR, John Radcliffe Hospital, Oxford, United Kingdom. eft atrial thrombus is a frequent cause of cerebral stroke or peripheral embolism in patients with atrial fibrillation. Anticoagulation is required to prevent further cerebral events [1]. The main location for left atrial thrombus formation is the left atrial appendage, possibly because of the phenomenon of atrial stunning [2]. Therefore, in patients with contraindications to warfarin treatment, occlusion of the left atrial appendage could be a potential alternative strategy for prophylaxis of embolism. In comparison with surgical amputation, the percutaneous left atrial appendage transcatheter occlusion (PLAATO) is a minimally invasive technique [3]. Currently, after the PLAATO procedure, chest radiography is performed to confirm the correct placement of the occluder and transesophageal echocardiography is performed to evaluate possible thrombotic appositions on the device. To date, it has been impossible to assess the degree of residual left atrial appendage perfusion, which would indicate the degree of noncoverage of the atrial-facing surface of the device with neoendothelial-like cells [4]. In our report, we present the potential of contrast-enhanced MRI, before and after PLAATO, to assess left atrial appendage perfusion in a patient. L

Sex-specific characteristics of cardiac function, geometry, and mass in young adult elite athletes

Abstract: PURPOSE: To study young adult elite athletes with age- and sex-matched sedentary controls to assess sex-specific differences for left ventricular (LV) and right ventricular (RV) volumes and mass as well as for LV contraction and relaxation. MATERIALS AND METHODS: A total of 23 male athletes (mean age 25±4 years, training 22±7 h/week in rowing, swimming, or triathlon) and 20 female athletes (mean age 24±4 years, training 19±5 h/week in rowing, swimming, or triathlon) and age- and sex-matched sedentary controls (21 males/17 females) underwent cardiovascular magnetic resonance (CMR) imaging (1.5 T). Cardiac phase contrast imaging using a black-blood k-space segmented gradient echo sequence was used for analysis of cardiac contraction and relaxation and steady-state free-precession cine images were acquired for determination of cardiac volumes and mass. RESULTS: Male and female athletes showed similar increases in LV and RV volume and mass indices when compared with controls (ranging between 15% and 42%). No sex-specific differences in training effect on LV and RV volumes, mass indices, and ejection fractions, as well as LV to RV ratios of these volume and mass indices (parameters of balanced LV and RV dilatation and hypertrophy) were observed (all P for interaction >0.05). Similarly, no sex-specific differences in training effect on cardiac contraction and relaxation were found (all P for interaction >0.05). CONCLUSION: Young adult elite athletes do not show sex-specific adaptive structural and functional changes to exercise training in accordance with the benign nature of the hypertrophy associated with athlete's heart.