Vincent B. Ho

ACCF/ACR/AHA/NASCI/SCMR 2010 Expert Consensus Document on Cardiovascular Magnetic Resonance A Report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents

Robert A. Harrington, MD, FACC, FAHA, Chair Jeffrey L. Anderson, MD, FACC, FAHA[††][1] Eric R. Bates, MD, FACC Charles R. Bridges, MD, MPH, FACC, FAHA Mark J. Eisenberg, MD, MPH, FACC, FAHA Victor A. Ferrari, MD, FACC, FAHA Cindy L. Grines, MD, FACC[††][1] Mark A. Hlatky, MD, FACC,

Expert Consensus DocumentACCF/ACR/AHA/NASCI/SCMR 2010 Expert Consensus Document on Cardiovascular Magnetic Resonance: A Report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents

American College of Cardiology Foundation Representative; †North merican Society for Cardiovascular Imaging Representative; ‡Society or Cardiovascular Magnetic Resonance Representative; §American cademy of Pediatrics; American College of Radiology Representaive; ¶ACCF Task Force Liaison; #American Heart Association epresentative. **The findings and conclusions in this expert consensus ocument reflect ACCF policy and do not necessarily represent the iews of the Uniformed Services University of the Health Sciences, the .S. Department of Defense, or the U.S. Government, by whom Dr.

Aortic Dilatation and Dissection in Turner Syndrome

Background— The risk for aortic dissection is increased among relatively young women with Turner syndrome (TS). It is unknown whether aortic dilatation precedes acute aortic dissection in TS and, if so, what specific diameter predicts impending deterioration. Methods and Results— Study subjects included 166 adult volunteers with TS (average age, 36.2 years) who were not selected for cardiovascular disease and 26 healthy female control subjects. Ascending and descending aortic diameters were measured by magnetic resonance imaging at the right pulmonary artery. TS women were on average 20 cm shorter, yet average aortic diameters were identical in the 2 groups. Ascending aortic diameters normalized to body surface area (aortic size index) were significantly greater in TS, and ≈32% of TS women had values greater than the 95th percentile of 2.0 cm/m2. Ascending diameter/descending diameter ratios also were significantly greater in the TS group. During ≈3 years of follow-up, aortic dissections occurred in 3 women with TS, for an annualized rate of 618 cases/100 000 woman-years. These 3 subjects had ascending aortic diameters of 3.7 to 4.8 cm and aortic size indices >2.5 cm/m2. Conclusions— The risk for aortic dissection is greatly increased in young women with TS. Because of their small stature, ascending aortic diameters of <5 cm may represent significant dilatation; thus, the use of aortic size index is preferred. Individuals with a dilated ascending aorta defined as aortic size index >2.0 cm/m2 require close cardiovascular surveillance. Those with aortic size index ≥2.5 cm/m2 are at highest risk for aortic dissection.

Medical 3D Printing for the Radiologist

While use of advanced visualization in radiology is instrumental in diagnosis and communication with referring clinicians, there is an unmet need to render Digital Imaging and Communications in Medicine (DICOM) images as three-dimensional (3D) printed models capable of providing both tactile feedback and tangible depth information about anatomic and pathologic states. Three-dimensional printed models, already entrenched in the nonmedical sciences, are rapidly being embraced in medicine as well as in the lay community. Incorporating 3D printing from images generated and interpreted by radiologists presents particular challenges, including training, materials and equipment, and guidelines. The overall costs of a 3D printing laboratory must be balanced by the clinical benefits. It is expected that the number of 3D-printed models generated from DICOM images for planning interventions and fabricating implants will grow exponentially. Radiologists should at a minimum be familiar with 3D printing as it relates to their field, including types of 3D printing technologies and materials used to create 3D-printed anatomic models, published applications of models to date, and clinical benefits in radiology. Online supplemental material is available for this article.

Aortic valve disease in Turner syndrome.

OBJECTIVES Our goal was to determine the prevalence and characteristics of aortic valve disease in girls and women with monosomy for the X chromosome, or Turner syndrome (TS). BACKGROUND Complications from congenital aortic valve disease are a major source of premature mortality in TS, but accurate data on the prevalence of aortic valve abnormalities and their association with aortic root dilation are not available. METHODS This prospective study characterized the aortic valve and proximal aorta in 253 individuals with TS age 7 to 67 years using transthoracic echocardiography as our primary screening tool, supplemented with magnetic resonance imaging. RESULTS Transthoracic echocardiography revealed a normal tricuspid aortic valve (TAV) in 172 and a bicuspid aortic valve (BAV) in 66 subjects. Transthoracic echocardiography could not visualize the aortic valve in 15 of 253 or 6%. Magnetic resonance imaging diagnosed 12 of 15 of these cases (8 BAV and 4 TAV), so that only 3 of 253 (1.2%) could not be visualized by either modality. The aortic valve was bicuspid in 74 of 250 (30%) adequately imaged subjects. The prevalence was equal in pediatric (<18 years, n = 89) and adult populations. Over 95% of abnormal aortic valves in TS resulted from fusion of the right and left coronary leaflets. Ascending aortic diameters were significantly greater at the annulus, sinuses, sinotubular junction, and ascending aorta in the BAV group, with aortic root dilation in 25% of subjects with BAV versus 5% of those with TAV. CONCLUSIONS Girls and women with TS need focused screening of the aortic valve and root to identify the many asymptomatic individuals with abnormal valvular structure and/or aortic root dilation.

Cardiac MRI: Recent progress and continued challenges

Cardiac MRI continues to develop and advance. MRI accurately depicts cardiac structure, function, perfusion, and myocardial viability with an overall capacity unmatched by any other single imaging modality. MRI is an accepted and widely utilized tool for cardiovascular research. Its clinical use has been limited, but is increasing because of its proven clinical efficacy, the proliferation of cardiac‐capable MRI systems, and the development of improved pulse sequences. The following article reviews the landmark developments in this field, with an emphasis on recent progress in the evaluation of ischemic or acquired heart disease. J. Magn. Reson. Imaging 2002;16:111–127. Published 2002 Wiley‐Liss, Inc.

Gadolinium‐enhanced 3D magnetic resonance angiography of the thoracic vessels

MAGNETIC RESONANCE IMAGING has long been recognized as a useful tool for the non-invasive evaluation of the thoracic vasculature. Unlike computed tomography and conventional angiography, MRI is not associated with the concerns related to ionizing radiation exposure or to contrast-related nephrotoxicity. MRI is also capable of oblique image acquisition and multiplanar reformation, which aids the illustration of the thoracic vessels, inherently intertwined and complex in their arrangements. In addition, MRI using cine technique affords cardiac referenced data that enables dynamic assessment of blood flow, yielding information comparable to an echocardiogram. Gadolinium (Gd)-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) is a newer technique that provides high-resolution (ie, 3D) data very quickly and is well suited for the depiction of intrathoracic vessels. Improvements in gradient technology now allow a Gd-enhanced 3D MRA to be performed during a 20–40 second breath-hold. Because it relies on T1-shortening effects of circulating Gd-chelate contrast media and not inherent flow characteristics, Gdenhanced 3D MRA can often depict pathologic vascular segments that are not adequately visualized using unenhanced flow-based MRI techniques. In addition, Gdenhanced 3D MRA provides volumetric data that can be processed for multiplanar reformation (MPR) and maximum intensity projection (MIP) viewing. In this article, the technical considerations and potential applications for Gd-enhanced 3D MRA of the systemic and pulmonary vessels within the chest will be discussed and illustrated. Traditionally, T1-weighted spin-echo and gradientecho pulse sequences have been employed for delineation of vascular pathology within the chest (1–10). The combination of T1-weighted spin-echo and gradientecho images can often provide the information necessary for the assessment of simple clinical queries such as patency of a vessel (Fig. 1) or delineation of a vascular ring (Fig. 2). These techniques, however, rely on flowing blood (ie, the movement of blood during the acquisition period) for their illustration of vascular structures. This flow dependency makes these techniques prone to flowrelated image artifacts, thereby frequently limiting their clinical utility. On spin-echo pulse sequences, vessels are characterized by their dark lumina. The black appearance of blood, also known as flow void, on spin-echo imaging occurs secondary to the wash-out of blood prior to the refocusing pulse and sampling of the echo. The washout may be incomplete if the echo time is too short, the vessel courses primarily within the imaging plane, or the blood flow is too slow. Incomplete wash-out results in the persistence of signal within the vessel lumen, which may result in the masking of underlying luminal pathology such as an intimal tear or the erroneous simulation of a vascular occlusion or thrombosis. A superior black blood effect is achieved by using preparatory pulses such as a double inversion pulse to null blood signal for more effective suppression even when the blood flow is slow. Unlike spin-echo imaging, time-of-flight (TOF) and phase contrast (PC)-MRA depict flowing blood with bright signal intensity. TOF imaging relies on the wash-in or in-flow effect of unsaturated protons; PC imaging relies, on the phase shift experienced by moving protons traveling along the gradient field (7–13). Both TOF and PC imaging provide higher intra-vascular signal-tonoise ratios than spin-echo pulse sequences. These ‘‘bright blood’’ pulse sequences (ie, TOF and PC imaging) often show intraluminal abnormalities (Fig. 1b) not clearly identified on black blood spin-echo images. However, should blood flow be slow, turbulent, or complex, vascular signal on gradient-echo images becomes unreliable. Disturbances in blood flow can often result in signal loss, which can result in the underestimation of vessel patency, overestimation of a stenosis, or even simulation of a vascular occlusion. 1Department of Radiology, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0030. 2MR Research Division, Department of Radiology, Uniformed Services University, Bethesda, Maryland 20814. 3Cornell University, New York, NY 10021 Contract Grant Sponsor: Whitaker Foundation, GE. *Address reprint requests to: M.R.P., Cornell University, MRI Division, 416 East 55th Street, New York, NY 10021. Received June 29, 1999; Accepted July 13, 1999. JOURNAL OF MAGNETIC RESONANCE IMAGING 10:758–770 (1999)

Coronary artery anomalies and variants: technical feasibility of assessment with coronary MR angiography at 3 T.

The purpose of this study was to prospectively use a whole-heart three-dimensional (3D) coronary magnetic resonance (MR) angiography technique specifically adapted for use at 3 T and a parallel imaging technique (sensitivity encoding) to evaluate coronary arterial anomalies and variants (CAAV). This HIPAA-compliant study was approved by the local institutional review board, and informed consent was obtained from all participants. Twenty-two participants (11 men, 11 women; age range, 18-62 years) were included. Ten participants were healthy volunteers, whereas 12 participants were patients suspected of having CAAV. Coronary MR angiography was performed with a 3-T MR imager. A 3D free-breathing navigator-gated and vector electrocardiographically-gated segmented k-space gradient-echo sequence with adiabatic T2 preparation pulse and parallel imaging (sensitivity encoding) was used. Whole-heart acquisitions (repetition time msec/echo time msec, 4/1.35; 20 degrees flip angle; 1 x 1 x 2-mm acquired voxel size) lasted 10-12 minutes. Mean examination time was 41 minutes +/- 14 (standard deviation). Findings included aneurysms, ectasia, arteriovenous fistulas, and anomalous origins. The 3D whole-heart acquisitions developed for use with 3 T are feasible for use in the assessment of CAAV.

Optimization of Gadolinium-Enhanced Magnetic Resonance Angiography Using an Automated Bolus-Detection Algorithm (MR SmartPrep)y

Gadolinium (Gd)-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) is a quick method for performing noninvasive diagnostic angiography. A major technical obstacle to the successful implementation of this technique, however, is the proper coordination of the data acquisition with th

MR angiography using steady-state free precession.

Contrast‐enhanced MR angiography (CE‐MRA) using steady‐state free precession (SSFP) pulse sequences is described. Using SSFP, vascular structures can be visualized with high signal‐to‐noise ratio (SNR) at a substantial (delay) time after the initial arterial pass of contrast media. The peak blood SSFP signal was diminished by <20% 30 min after the initial administration of 0.2 mmol/kg of Gd‐chelate. The proposed method allows a second opportunity to study arterial or venous structures with high image SNR and high spatial resolution. A mask subtraction scheme using spin echo SSFP‐S(−) acquisition is also described to reduce stationary background signal from the delayed SSFP angiography images. Magn Reson Med 48:699–706, 2002.