E. Kent Yucel

Two-dimensional assessment of right ventricular function: an echocardiographic-MRI correlative study.

Background: While echocardiography is used most frequently to assess right ventricular (RV) function in clinical practice, echocardiography is limited in its ability to provide an accurate measure of RV ejection fraction (RVEF). Hence, quantitative estimation of RV function has proven difficult in clinical practice. Objective: We sought to determine which commonly used echocardiographic measures of RV function were most accurate in comparison with an MRI‐derived estimate of RVEF. Methods: We analyzed RV function in 36 patients who had cardiac MRI studies and echocardiograms within a 24 hour period. 2D parameters of RV function—right ventricular fractional area change (RVFAC), tricuspid annular motion (TAM), and transverse fractional shortening (TFS) were obtained from the four‐chamber view. RV volumes and EFs were derived from volumetric reconstruction based on endocardial tracing of the RV chamber from the short axis images. Echocardiographic assessment of RV function was correlated with MRI findings. Results: RVFAC measured by echocardiography correlated best with MRI‐derived RVEF (r = 0.80, P < 0.001). Neither TAM (r = 0.17; P = 0.30) nor TFC (r = 0.12; p< 0.38) were significantly correlated with RVEF. Conclusions: RVFAC is the best of commonly utilized echocardiographic 2D measure of RV function and correlated best with MRI‐derived RV ejection fraction. Condensed Abstract: While echocardiography is used most frequently to assess RV function in clinical practice, echocardiography is limited in its ability to provide an accurate measure of RV ejection fraction (RVEF). Using cardiac MRI, RV fractional area change (RVFAC), determined either by MRI or echocardiography, was found to correlate best with MRI‐derived RVEF.

Clinical indications for cardiovascular magnetic resonance (CMR): Consensus Panel report

Cardiovascular magnetic resonance (CMR) is established in clinical practice for the diagnosis and management of diseases of the cardiovascular system. However, current guidelines for when this technique should be employed in clinical practice have not been revised since a Task Force report of 1998. Considerable technical and practice advances have been made in the intervening years and the level of interest from clinicians in this field is at an unprecedented level. Therefore the aim of this report from a Consensus Panel of established experts in the field of CMR is to update these guidelines. As CMR is a multi-disciplinary technique with international interest, the Consensus Panel was composed of European and American cardiologists and radiologists with major input from members with additional established expertise in paediatric cardiology, nuclear cardiology, magnetic resonance physics and spectroscopy, as well as health economics. The Consensus Panel was originated, approved and funded in its activities by the Working Group on CMR of the European Society of Cardiology and the Society for Cardiovascular Magnetic Resonance. The Consensus Panel recommendations are based on evidence compiled from the literature and expert experience. If there is insufficient evidence in the literature, this is indicated in the report but usually no recommen-

Contrast agent‐enhanced, free‐breathing, three‐dimensional coronary magnetic resonance angiography

For free‐breathing, high‐resolution, three‐dimensional coronary magnetic resonance angiography (MRA), the use of intravascular contrast agents may be helpful for contrast enhancement between coronary blood and myocardium. In six patients, 0.1 mmol/kg of the intravascular contrast agent MS‐325/AngioMARK™ was given intravenously followed by double‐oblique, free‐breathing, three‐dimensional inversion‐recovery coronary MRA with real‐time navigator gating and motion correction. Contrast‐enhanced, three‐dimensional coronary MRA images were compared with images obtained with a T2 prepulse (T2Prep) without exogenous contrast. The contrast‐enhanced images demonstrated a 69% improvement in the contrast‐to‐noise ratio (6.6 ± 1.1 vs. 11.1 ± 2.5; P < 0.01) compared with the T2Prep approach. By using the intravascular agent, extensive portions (> 80 mm) of the native left and right coronary system could be displayed consistently with sub‐millimeter in‐plane resolution. The intravascular contrast agent, MS‐325/AngioMARK™, leads to a considerable enhancement of the blood/muscle contrast for coronary MRA compared with T2Prep techniques. The clinical value of the agent remains to be defined in a larger patient series. J. Magn. Reson. Imaging 1999;10:790–799.

Magnetic Resonance Angiography Update on Applications for Extracranial Arteries

179. Hofman MB, Paschal CB, Li D, Haacke EM, van Rossum AC, Sprenger M. MRI of coronary arteries: 2D breath hold vs 3D respiratory-gated acquisition.J Comput Assist Tomogr. 1995;19:56–62. 180. Manning WJ, Li W, Boyle NG, Edelman RR. Fat-suppressed breath-hold magnetic resonance coronary angiography. Circulation.Magnetic resonance angiography (MRA) has excited the interest of many physicians working in cardiovascular disease because of its ability to noninvasively visualize vascular disease. Its potential to replace conventional x-ray angiography (CA) that uses iodinated contrast has been recognized for many years, and this interest has been stimulated by the current emphasis on cost containment, outpatient evaluation, and minimally invasive diagnosis and therapy. In addition, recent advances in magnetic resonance (MR) technology resulting from fast gradients and use of contrast agents have allowed MRA to make substantial advances in many arterial beds of clinical interest. The goal of this scientific statement is to present the current state of MRA of the extracranial arteries and to suggest current as well as possible future clinical applications for MRA. For the purposes of this statement, MRA is defined as MR techniques that provide cross-sectional or projectional images of normal and diseased arterial anatomy. It does not deal with the equally important area of quantitative flow measurement with MR. The first section deals with the technical basis of MRA. Subsequent sections deal with individual vascular beds in which MRA has shown clinical promise. The “gold standard” for many manifestations of vascular disease, especially arterial occlusive disease, is CA, an invasive, costly, and potentially hazardous procedure. MRA could represent an alternative, noninvasive approach. Rather than a single technique, MRA actually represents a family of different techniques. As outlined below, contrast between blood and soft tissues is derived from completely different MR mechanisms in the various MR techniques. We will consider the basic principles underlying the MR imaging (MRI) appearance of flowing blood and the techniques used to image blood flow and render angiogram-like MRI scans. Depending on the imaging technique used, blood may appear bright or dark. On traditional spin-echo MR images, blood vessels usually …

Characterization of Human Atherosclerotic Plaques by Intravascular Magnetic Resonance Imaging

Background— Development and validation of novel imaging modalities to assess the composition of human atherosclerotic plaques will improve the understanding of atheroma evolution and could facilitate evaluation of therapeutic strategies for plaque modification. Surface MRI can characterize tissue content of carotid but not deeper arteries. This study evaluated the usefulness of intravascular MRI (IVMRI) to discern the composition of human iliac arteries in vivo. Methods and Results— Initial studies validated IVMRI against histopathology of human atherosclerotic arteries ex vivo. A 0.030-inch-diameter IVMRI detector coil was advanced into isolated human aortoiliac arteries and coupled to a 1.5-T scanner. Information from combined T1-, moderate T2-, and proton-density–weighted images differentiated lipid, fibrous, and calcified components with favorable sensitivity and specificity and allowed accurate quantification of plaque size. The validated approach was then applied to image iliac arteries of 25 human subjects in vivo, and results were compared with those of intravascular ultrasound (IVUS). IVMRI readily visualized inner and outer plaque boundaries in all arteries, even those with extensive calcification that precluded IVUS interpretation. It also revealed the expected heterogeneity of atherosclerotic plaque content that was noted during ex vivo validation. Again, IVUS did not disclose this heterogeneity. The level of interobserver and intraobserver agreement in the interpretation of plaque composition was high for IVMRI but poor for IVUS. Conclusions— IVMRI can reliably identify plaque composition and size in arteries deep within the body. Identification of plaque components by IVMRI in vivo has important implications for the understanding and modification of human atherosclerosis.

Soluble CD40 ligand levels indicate lipid accumulation in carotid atheroma: An in vivo study with high-resolution MRI

Objective—The CD40/CD40 ligand pathway mediates inflammatory processes important in atherogenesis and the formation of the intraplaque lipid pool. We tested the hypothesis that plasma levels of soluble CD40 ligand are elevated in patients with evidence of a lipid pool on high-resolution magnetic resonance imaging (MRI) of carotid stenoses. Methods and Results—We recruited 49 patients with evidence of carotid atherosclerosis on ultrasonography; 3 patients could not undergo carotid MRI because of claustrophobia. The remaining 46 patients underwent high-resolution MRI of the carotid arteries. Two radiologists blinded to all other data determined the presence or absence of an intraplaque lipid pool based on the loss of signal between the 20-ms echo time (TE20) and the fat-suppressed TE55 fast spin-echo images. Plasma levels of soluble CD40 ligand were determined by ELISA. Baseline levels of soluble CD40 ligand were higher among patients with evidence of intraplaque lipid (n=14) than among those without it (n=32; median, 2.54 ng/mL; interquartile range [IQR], 1.85 to 3.52 vs median, 1.58 ng/mL; IQR, 1.21 to 2.39;P =0.02). In contrast, soluble CD40 ligand levels were not correlated with percent diameter stenosis (r =−0.19;P =0.21). The relative risk for intraplaque lipid associated with soluble CD40 ligand levels above the median was 6.0 (95% confidence interval, 1.15 to 31.23;P =0.03). The magnitude of this predictive effect did not substantially change after adjustment for traditional cardiovascular risk factors (relative risk, 5.12; 95% confidence interval, 0.78 to 33.73;P =0.09). Conclusions—Plasma levels of soluble CD40 ligand may predict patients with features of high-risk atherosclerotic lesions. These data provide novel insight into the mechanism through which elevated levels of soluble CD40 ligand may reflect cardiovascular risk in humans and illustrate the potential value of interfacing high-resolution MRI with studies of vascular inflammation.

A summary of safety of gadofosveset (MS-325) at 0.03 mmol/kg body weight dose: Phase II and Phase III clinical trials data.

Objective:We sought to summarize the Phase II and Phase III clinical trials safety data for gadofosveset (Vasovist, MS-325), a new magnetic resonance angiography contrast agent. Materials and Methods:Subjects with known or suspected vascular disease were administered 0.03 mmol/kg gadofosveset (767 subjects) or placebo (49 subjects) in phase II and phase III studies. Overall safety data were pooled from 8 studies and included adverse event monitoring, clinical laboratory assays, vital signs, oxygen saturation, physical examination, and electrocardiography. The safety was monitored for 72 to 96 hours postinjection (PI), and safety comparison with x-ray angiography using iodinated contrast media also was performed in 318 subjects. In the phase II trial, 5 doses of gadofosveset and placebo were evaluated. In this study, 38 patients were administered placebo and 39 patients received 0.03 mmol/kg gadofosveset. Results:In pooled data, treatment related adverse events were reported by 176 (22.9%) patients receiving gadofosveset and by 16 (32.7%) patients receiving placebo. In phase II trial, treatment-related adverse events were reported by 13 of the 39 (33.3%) patients receiving gadofosveset and 9 of the 38 (23.7%) patients receiving placebo. No severe or serious adverse events were reported in either gadofosveset or placebo groups in this phase II trial. Pooled data revealed no clinically significant trends in adverse events, laboratory assays, vital signs, or oxygen saturation. A QTc prolongation of 2.8 milliseconds was observed at 45 minutes after MS-325 injection; however, this trend was similar to that of the placebo group at the same time point (3.2 milliseconds). Conclusion:Gadofosveset has exhibited a good safety profile and can be safely administered as an intravenous bolus injection. The overall rate and experience of adverse events was similar to that of placebo. The safety profile of gadofosveset is comparable with that of other gadolinium contrast agents as reported in the literature.

Percutaneous Treatment of High-Output Chylothorax with Embolization or Needle Disruption Technique

Surgical ligation of the thoracic duct is associated with a high degree of morbidity; therefore, a minimally invasive approach is desirable. Herein, eight percutaneously treated patients are described. In four patients, the thoracic duct was embolized with use of coils and glue. In the other four patients, lymphatic ducts were disrupted by multiple needle punctures. The median chest tube drainage substantially decreased in both patient groups from more than 1,300 mL the day before the procedure to less than 300 mL 2 days after the procedure. The median times to chest tube removal were 7 days in the embolization group and 3.5 days in the needle disruption group.

Time of flight renal MR angiography: Utility in patients with renal insufficiency

We studied the renal arteries prospectively in 16 patients with renal insufficiency using a combination of two-dimensional and three-dimensional time of flight magnetic resonance angiography (MRA). Results were compared with conventional angiography. All renal arteries were identified by MRA. Accuracy for classifying renal arteries into patent, moderately (30-70%) stenotic, severely (> 70%) stenotic, or occluded was 91%. With regard to the presence or absence of severe occlusive disease (> 70% stenosis or occlusion) the sensitivity was 100%, with a specificity of 93%.

2013 appropriate utilization of cardiovascular imaging: A methodology for the development of joint criteria for the appropriate utilization of cardiovascular imaging by the American college of cardiology foundation and American college of radiology

The American College of Radiology (ACR) and the American College of Cardiology Foundation (ACCF) have jointly developed a method to define appropriate utilization of cardiovascular imaging. The primary role of this method is to create a series of documents to define the utility of cardiovascular imaging procedures in relation to specific clinical questions, with the aim of defining what, if any, imaging tests are indicated to help to determine diagnosis, treatment, or outcome. The methodology accomplishes this aim through the application of systematic evidence reviews integrated with expert opinion by means of a rigorous Delphi process. By obtaining broad input during the development process from radiologists, cardiologists, primary care physicians, and other stakeholders, these documents are intended to provide practical evidence-based guidance to ordering providers, imaging laboratories, interpreting physicians, patients, and policymakers as to optimal cardiovascular imaging utilization. This document details the history, rationale, and methodology for developing these joint documents for appropriate utilization of cardiovascular imaging.