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.

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.

High-spatial-resolution delayed enhancement MR imaging allows noninvasive identification of scar induced by RF ablation following isolation therapy of the PV.

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.

The efficient delivery of nanomaterials to specific targets for in vivo biomedical imaging is hindered by rapid sequestration by the reticuloendothelial system (RES) and consequent short circulation times. To overcome these two problems, we have prepared a new stealth PEG polymer conjugate containing a terminal 1,1-bisphosphonate (BP) group for strong and stable binding to the surface of ultrasmall-superparamagnetic oxide nanomaterials (USPIOs). This polymer, PEG(5)-BP, can be used to exchange the hydrophobic surfactants commonly used in the synthesis of USPIOs very efficiently and at room temperature using a simple method in 1 h. The resulting nanoparticles, PEG(5)-BP-USPIOs are stable in water or saline for at least 7 months and display a near-zero ζ-potential at neutral pH. The longitudinal (r1) and transverse (r2) relaxivities were measured at a clinically relevant magnetic field (3 T), revealing a high r1 of 9.5 mM–1 s–1 and low r2/r1 ratio of 2.97, making these USPIOs attractive as T1-weighted MRI contrast agents at high magnetic fields. The strong T1-effect was demonstrated in vivo, revealing that PEG(5)-BP-USPIOs remain in the bloodstream and enhance its signal 6-fold, allowing the visualization of blood vessels and vascular organs with high spatial definition. Furthermore, the optimal relaxivity properties allow us to inject a dose 4 times lower than with other USPIOs. PEG(5)-BP-USPIOs can also be labeled using a radiolabeled-BP for visualization with single photon emission computed tomography (SPECT), and thus affording dual-modality contrast. The SPECT studies confirmed low RES uptake and long blood circulation times (t1/2 = 2.97 h). These results demonstrate the potential of PEG(5)-BP-USPIOs for the development of targeted multimodal imaging agents for molecular imaging.

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...

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.

Three-dimensional free-breathing coronary magnetic resonance angiography was performed in eight healthy volunteers with use of real-time navigator technology. Images acquired with the navigator localized at the right hemidiaphragm and at the left ventricle were objectively compared. The diaphragmatic navigator was found to be superior for vessel delineation of middle to distal portions of the coronary arteries.