Free-breathing, T2prep, 3D coronary MRA with a shorter acquisition window resulted in improved CNR and better coronary artery definition, allowing the assessment of coronary disease. This approach offers the potential for free-breathing, noninvasive assessment of the major coronary arteries.

No abstract

Double-oblique submillimeter free-breathing coronary MRA allows depiction of extensive parts of the native coronary arteries. The results obtained in patients suggest that the method has the potential to be applied in broader prospective multicenter studies where coronary MRA is compared with X-ray angiography.

Among patients referred for their first x-ray coronary angiogram, three-dimensional coronary magnetic resonance angiography allows for the accurate detection of coronary artery disease of the proximal and middle segments. This noninvasive approach reliably identifies (or rules out) left main coronary artery or three-vessel disease.

Recent studies suggest that coronary magnetic resonance angiography (MRA) is emerging as a valuable tool for the assessment of proximal to mid coronary artery integrity (1). However, MR scanner hardware, software, and methodology are under constant development. As a consequence, a growing number of coronary MRA imaging methods, including steady-state free precession (SSFP) (2), echo-planar imaging (EPI) (3-5), fast spin echo (6), spiral (7,8), and more conventional segmented k-space gradientecho sequences with (9 -11) and without (12) the application of exogenous contrast agents, have been and continue to be explored. Furthermore, imaging at different field strengths, parallel imaging (13,14), and motion-compensation strategies such as breath-holding (5,15), prospective (16) or retrospective (17) In order to compare data obtained with different approaches, adequate visualization and presentation of the coronary MRA data need to be ensured (21). Furthermore, an objective quantitative comparison between images acquired with different methods is desirable (12). To address this need, we developed a quantitative software tool ("Soap-Bubble") that facilitates multiplanar reformatting (MPR) of 3D volume-targeted coronary MRA data sets, while also providing frequently explored quantitative measures such as signal-to-noise (SNR) and contrast-tonoise (CNR) ratios, vessel length and diameter, and local vessel sharpness. The first results obtained with this software implementation are presented. METHODS ImplementationThe Soap-Bubble tool for coronary reformatting and quantitative coronary analysis was implemented under IDL 5.2 (Interactive Data Language; Research Systems Inc., Boulder, CO), on a commercial Microsoft Windows2000 (Microsoft Corp., Redmond, WA) 1.4 MHz Pentium©4 platform (OptiPlex GX400, Dell Computers, Austin, TX) equipped with a three-button mouse (Logitech, Fremont, CA). ReformattingContemporary coronary MRA techniques include thin-slab 3D volume-targeted acquisitions along the major segments of the left and right coronary arterial systems (5,22). These relatively thin slabs encompass contiguous sections of the major proximal to mid coronary arteries. However, the geometry of the coronary arterial tree together with the tortuous nature of the individual coronary segments generally prevent visualization of the entire coronary anatomy in one single image (Fig. 1). Therefore, multiplanar reformatting (MPR) and maximum intensity projections (MIPs) have been used for improved visualization and quantitative coronary analysis.In the present report, we propose an alternative technique for visualization and subsequent quantitative analysis of 3D coronary MRA data sets. The technique includes a user-assisted preselection of a curved subvolume included in the 3D coronary MRA data set. Ideally, this curved subvolume includes all the coronary segments and branches enclosed in the acquired volume. All the voxels that are not included in this user-prescribed subvolume are discarded and are not used for subsequent visuali...

Torsional behavior as observed in pressure- and volume-overloaded hearts is consistent with current theoretical findings. A delayed diastolic untwisting in the pressure-overloaded hearts of the patients may contribute to a tendency toward diastolic dysfunction.

In vivo free-breathing coronary vessel wall and plaque imaging with MR has been successfully implemented in humans. Coronary wall thickness and wall area were significantly greater in patients with angiographic CAD. The presented technique may have potential applications in patients with known or suspected atherosclerotic CAD or for serial evaluation after pharmacological intervention.

Background-Stem cell labeling with iron oxide (ferumoxide) particles allows labeled cells to be detected by magnetic resonance imaging (MRI) and is commonly used to track stem cell engraftment. However, the validity of MRI for distinguishing surviving ferumoxide-labeled cells from other sources of MRI signal, for example, macrophages containing ferumoxides released from nonsurviving cells, has not been thoroughly investigated. We sought to determine the relationship between the persistence of iron-dependent MRI signals and cell survival 3 weeks after injection of syngeneic or xenogeneic ferumoxides-labeled stem cells (cardiac-derived stem cells) in rats. Methods and Results-We studied nonimmunoprivileged human and rat cardiac-derived stem cells and human mesenchymal stem cells doubly labeled with ferumoxides and ␤-galactosidase and injected intramyocardially into immunocompetent Wistar-Kyoto rats. Animals were imaged at 2 days and 3 weeks after stem cell injection in a clinical 3-T MRI scanner. At 2 days, injection sites of xenogeneic and syngeneic cells (cardiac-derived stem cells and mesenchymal stem cells) were identified by MRI as large intramyocardial signal voids that persisted at 3 weeks (50% to 90% of initial signal). Histology (at 3 weeks) revealed the presence of iron-containing macrophages at the injection site, identified by CD68 staining, but very few or no ␤-galactosidase-positive stem cells in the animals transplanted with syngeneic or xenogeneic cells, respectively. Conclusions-The persistence of significant iron-dependent MRI signal derived from ferumoxide-containing macrophages despite few or no viable stem cells 3 weeks after transplantation indicates that MRI of ferumoxide-labeled cells does not reliably report long-term stem cell engraftment in the heart. (Circulation. 2008;117:1555-1562.)