No abstract

Radial artery patency is sensitive to both target location and proximal target stenosis. Selective use of the radial artery to targets of the left anterior descending and circumflex distributions remains encouraging. Radial artery grafts to targets of the right coronary artery or those with moderate stenosis appear to be at particularly high risk of failure.

Purpose: To evaluate whether dynamic imaging of the coronary arteries can be performed with intracoronary infusion of low-dose gadolinium (Gd)-based contrast agent and assess the effect of long duration and multiple infusions on the image signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Materials and Methods:Dynamic coronary magnetic resonance (MR) imaging (130 msec/image) and contrast agent first pass myocardial perfusion studies were performed with intracoronary infusions of low-dose Gd-based MR contrast agent on dogs (N ϭ 4) using a fast multislice gradient recalled echo (GRE) sequence.Results: Contrast-enhanced coronary arteries were clearly imaged during infusion periods as long as 2.3 minutes. The SNR and CNR of the contrast-enhanced coronary arteries remained essentially unchanged over multiple consecutive angiographic sessions. In addition, we demonstrated that first pass studies performed with intracoronary injection of MR contrast agent can be used as a means of assessing regional myocardial perfusion. Conclusion:These studies demonstrated that, using intracoronary infusion of Gd, coronary magnetic resonance angiography (MRA) can be performed with high temporal resolution, and multiple low-dose slow infusions of Gd-based MR contrast agent can be performed without compromise of the vessel SNR and CNR. VASCULAR INTERVENTIONS require high spatial resolution and fast angiographic imaging. Currently, contrast-enhanced x-ray angiography, with its real-time temporal resolution and sub-millimeter spatial resolution, is the method of choice for monitoring and performing vascular procedures. Several recent studies (1-5) suggest the potential of magnetic resonance (MR) imaging to guide vascular interventions. Compared to x-ray angiography, MR offers several benefits. First, because of its high contrast resolution and intrinsic sensitivity to flow, MR allows the assessment of both morphology and function. Second, unlike x-ray angiography, MR imaging is intrinsically three-dimensional, allowing free selection of volume and scan-planes. These can be selected to better visualize the procedure without manually repositioning the patient or imaging instrument. Third, MR imaging does not use ionizing radiation, and therefore is safer for both the medical staff and patient. In addition, MR gadolinium (Gd)-based contrast agents are less toxic and have fewer side effects than iodinated x-ray contrast agents (6,7).In principle, MR imaging can provide an integrated and comprehensive approach to vascular intervention, permitting diagnosis of a vascular pathological condition, guidance of a suitable intervention, and assessment of the interventional results during the same session and with the same modality. Recent studies have demonstrated MR visualization of vascular catheters and interventional devices with passive (8 -11) and active methods (2,(12)(13)(14), and contrast-enhanced angiography with submillimeter spatial resolution (15). In addition, MR guidance has been used in performing percutaneous translumina...

No abstract

No abstract

No abstract

Magnetic resonance imaging with radiofrequency tissue tagging permitted circumferential strain calculation. This technology quantitatively demonstrated improvements in left ventricular wall motion after coronary artery bypass grafting for both individual regions and the entire ventricle. This noninvasive method may prove useful in preoperative evaluation and postoperative serial assessment of left ventricular wall motion.

No abstract