Fast cardiac magnetic resonance (CMR) protocol for biventricular functional assessment and tissue characterisation.

Major advances in the field of pediatric cardiology and cardiac surgery over the last several decades have led to a dramatic improvement in survival rates for most forms of congenital heart disease (CHD). For example, hypoplastic left heart syndrome, a previously lethal defect, now has early survival rates up to 90% at major centers.1 These improved outcomes have produced a growing population of survivors with complex CHD who are now reaching adulthood (Figure 1). During this period, improvements in surgical and medical treatments have been accompanied by developments in diagnostic modalities. Echocardiography has replaced catheterization as the primary diagnostic modality, and it is now uncommon for newborn infants to undergo catheterization for purely diagnostic purposes. Although echocardiography remains the bedrock of noninvasive cardiac imaging, the array of diagnostic modalities and techniques available continue to grow and this has spawned the specialty of “noninvasive cardiac imaging” and the need for the “cardiac imager” to be adept in all the different modalities. Figure 1. Percentage of patients under the age of 1 year (grey bars) and over the age of 18 years (black bars) undergoing echocardiography at Children’s Hospital Boston from 1983 through 2006. Note the reverse trends of these age groups reflecting the steady increase in the proportion of adult patients with congenital heart disease. Although the absolute number of infants undergoing echocardiography during this time period has increased, their proportion has steadily declined. Echocardiography, cardiac magnetic resonance (CMR), and cardiac computed tomography (CCT) are the primary modalities used for noninvasive cardiac imaging in patients with CHD. Nuclear scintigraphy is used in selected circumstances. The Table summarizes the strengths and weaknesses of each modality. Figure 2 shows temporal trends in utilization for the various noninvasive cardiac imaging techniques at our center. It is clear that echocardiography is the most frequently …

An asymptomatic athletic 42-year-old man has an abnormal 12-lead ECG obtained during his initial employment examination at a new job (Figure 1). He had no family history of hypertrophic cardiomyopathy (HCM) or unexplained sudden deaths. Echocardiogram demonstrated a 13-mm ventricular septal thickness without systolic anterior motion of the mitral valve. The patient exercised on a standard Bruce protocol stress (exercise) echocardiogram for 12 minutes, without symptoms or arrhythmias, and with appropriate blood pressure augmentation. In the immediate recovery period, systolic anterior motion was absent and outflow tract velocities were normal. A 24-hour ambulatory (Holter) ECG demonstrated normal sinus rhythm without ventricular ectopy. This clinical evaluation left a number of unanswered questions for the patient regarding the diagnosis of HCM, prognosis, and whether a genetic heart disease was present in his family. Figure 1. Abnormal 12-lead ECG in a 42-year-old man demonstrating normal sinus rhythm with left anterior fascicular block, RSR′ in leads V1 and V2, and left ventricular hypertrophy. Since the early 1970s, cardiovascular imaging has played a critical role in describing the structure and function of the heart in HCM.1–5 Indeed, HCM is a disorder uniquely suited to noninvasive imaging, given HCM’s characteristic heterogeneous morphology and hemodynamics, including dynamic left ventricular (LV) outflow obstruction.2,3 For much of 40 years, echocardiography has been the dominant imaging technique, first with rudimentary M-mode and then ultimately 2-dimentional imaging and Doppler,2 now widely available and accessible. The past decade has witnessed the introduction of cardiac magnetic resonance (CMR) into clinical HCM practice.1,3–10 This contemporary technique provides images with high spatial and temporal resolution and sharp contrast between the myocardial border and blood pool, allowing precise measurements of LV wall thickness and complete tomographic reconstruction of the entire cardiac chamber (without …

Assessment of Left Ventricular Mass in Hypertrophic Cardiomyopathy by Real-Time Three-Dimensional Echocardiography Using Single-Beat Capture Image

A 48-year-old man, with only a history of mild systemic hypertension, was initially evaluated after presenting with symptoms of exertional dyspnea occurring predominantly with inclines. At that time, an abnormal 12-lead ECG was obtained demonstrating left ventricular hypertrophy by conventional voltage criteria, prompting additional testing with a 2-dimensional echocardiogram that showed normal systolic function (ejection fraction=65%), with 14-mm ventricular septal thickness and 12 mm in the posterolateral wall, and mild systolic anterior motion (SAM) of the mitral valve (bend of anterior leaflet into outflow tract without septal contact). A stress nuclear stress test showed no myocardial ischemia at rest or at peak exercise with a normal blood pressure response and no arrhythmias or ST-T changes during exercise or in recovery. The patient was prescribed a β-blocker for treatment of systemic hypertension. During the next 2 years, the patient developed more limiting exertional symptoms with routine activities. β-Blocker dosage was increased, and a repeat echocardiogram demonstrated similar findings to the initial study, borderline left ventricular (LV) wall thickness despite well-controlled blood pressure. The abnormal ECG, and mild SAM at rest, raised consideration for a diagnosis of hypertrophic cardiomyopathy (HCM) and management for limiting heart failure symptoms. HCM is often suspected in a patient based on the presence of cardiovascular symptoms, detection of abnormal ECG, systolic ejection murmur on routine examination, or as part of pedigree screening.1,2 Abnormalities on ECG are present in >90% of patients with HCM, although no specific ECG pattern is pathognomonic.1 Clinical diagnosis of HCM can reliably be made in the majority of patients with 2-dimensional transthoracic echocardiography by imaging increased LV wall thickness (≥15 mm) with a nondilated cavity in the absence of any disease known to cause LV hypertrophy of that magnitude (ie, systemic hypertension or aortic stenosis).1–5 In …

Background In hypertrophic cardiomyopathy (HCM) patients, quantification of left ventricular (LV) mass carries important prognostic implications. Two-dimensional echocardiography (2DE) has limited accuracy for LV mass calculation, due to plane position errors, geometric assumptions and asymmetric distribution of LV hypertrophy in HCM. Purpose We aimed to explore: (1) the accuracy of three-dimensional echocardiography (3DE) vs 2DE to quantify LV mass in HCM compared to cardiac magnetic resonance (CMR); (2) the relationship of 3DE LV mass with non-sustained ventricular tachycardia (NSVT) and late gadolinium enhancement (LGE)≥15% by CMR. Methods In consecutive HCM patients referred to our Cardiomyopathy Clinic between 2020 and 2023, 2DE and 3DE were used to assess LV mass. LV systolic function was assessed by 3DE ejection fraction (LVEF) and peak global 2D longitudinal strain (2DGLS). Clinical, 24h ECG Holter and CMR data were collected. Results A total of 180 HCM patients (pts, age 58±18 years, 55% men) were enrolled. Apical HCM was present in 56 pts (31%) and obstructive HCM in 69 pts (38%). Maximal LV wall thickness (MWT) by 2DE was 19.5±4.6 mm. LV mass was 150±51 g/m2 by 2DE, 80±25 g/m2 by 3DE, and 79±26 g/m2 by CMR. Fifty-seven pts (32%) had evidence of NSVT at ECG Holter monitoring. LGE≥15% was present in 32% pts. Aim #1: In a subset of 63 pts who underwent CMR, 3DE LV mass was strongly correlated with CMR LV mass (r=0.85, p<0.001), while 2DE LV mass was not (p=0.38). LV mass by 3DE showed a better agreement with LV mass (bias 3.8 g/m2, LOA -25 to 32 g/m2) by CMR than 2DE (bias 68 g/m2, LOA -35 to 172 g/m2). Aim #2: In the entire cohort, 3DE LV mass had a stronger association compared to 2DE LV mass with the presence of LGE≥15% (AUC 0.68 for 3DE versus 0.56 for 2DE, p=0.08) and NSVT (AUC 0.65 for 3DE versus 0.54 for 2DE, p=0.06). By multivariable analysis, LV mass by 3DE was an independent predictor of LGE≥15% (HR 1.03) and of NSVT (HR 1.03), outperforming 2DGLS and MWT in the latter regression. Using the Youden Index from ROC curve, the optimal cutoff for predicting LGE≥15% using 3DE mass was 87 g/m² (sensitivity 47%, specificity 91%). The addition of 3DE LV mass to a model including 2DE MWT, 2DE LV mass and 2DGLS had a significant incremental value for the prediction of LGE≥15% (Figure 1). Conclusions In HCM patients, LV mass by 3DE was strongly correlated to LV mass by CMR and was an independent predictor of significant LV myocardial fibrosis and ventricular arrhythmias. In centers with low access to CMR, implementation of 3DE to measure LV mass in HCM patients may improve arrhythmic risk stratification compared to 2DE.

Assessment of cardiac function continues to be an important issue in patients with assumed left ventricular (LV) dysfunction [1–10]. In particular in patients with enlarged left ventricles, such as occurs in ischemic and idiopathic dilated cardiomyopathy, accurate assessment of LV function remains pivotal [11–14]. To assess myocardial function, different diagnostic methods are currently performed such as echocardiography, single photon emission computed tomography (SPECT), and cardiac magnetic resonance imaging (CMR) [15–23]. In the clinical arena, detection of myocardial function is predominantly based on echocardiographic studies. In addition, nuclear techniques, showing preserved tracer uptake and metabolism in viable myocardium, may also assess left ventricular function and wall motion. Volumetric analysis by gated SPECT imaging offers considerable additional value to SPECT myocardial perfusion imaging in characterizing functional abnormalities thereby potentially improving test specificity [24–37]. Subsequent to echocardiography and gated SPECT imaging, CMR has now long been recognized as an accurate and reliable means of evaluating LV function. Considerable progress has been made in the field of CMR, providing accurate evaluation of LV function parameters in coronary artery disease, heart failure, hypertrophic cardiomyopathy, and many other cardiac diseases [38–49]. CMR may be more accurate than echocardiography and gated SPECT in establishing LV volumetric parameters because of its more objective analysis and superb spatial resolution, respectively [50–58]. In the current issue of the International Journal of Cardiovascular Imaging, Holloway et al. [59] nicely determined the accuracy of visual analysis of LV function in comparison with the accepted quantitative reference standard CMR. Cine CMR imaging was performed at 1.5 T on 44 patients with a range of LV ejection fractions (EF) between 5 and 80%. Eighteen clinicians were asked to visually assess LVEF after sequentially being shown cine images of a four-chamber (horizontal long axis), two-chamber (vertical long axis) and a short axis stack. The authors found strong correlations between visual and quantitative assessment. However, LVEF was underestimated in all categories (by 8.4% for horizontal long axis, 8.4% for horizontal long axis + vertical long axis and 7.9% for horizontal long axis + vertical long axis + short axis stack). LVEF was particularly underestimated in patients with mild LV dysfunction (17.4%, P < 0.01), less for moderate (4.9%) and not for severe impairment (1%). It was concluded that assessing more than one view of the heart improved visual assessment of LVEF. However, the 18 clinicians underestimated LVEF by 8.4% on average, with particular inaccuracy for those patients with mild LV dysfunction. Given the important clinical information provided by LV assessment, in particular in deformed left ventricles, the authors recommended quantitative analysis for accurate assessment of LV function. Several studies have compared visual and quantitative assessment of LVEF, both in normal subjects and patients with impaired LV function [60–68]. Nearly all studies showed that LVEF is underestimated by visual estimation compared with the quantitative assessment. Holman et al. [65], using a dedicated analytical software package (MASS version 1.0) including a modified centerline method and a new 3D-analysis approach, showed in 25 patients after acute myocardial infarction that the use of three-dimensional quantitative analysis of cine CMR images accurately quantifies the extent of regional LV dysfunction in the infarcted heart. Van der Geest et al. [66] evaluated a computer algorithm for the automated detection of LV endocardial and epicardial boundaries in time series of short-axis CMR images based on an Active Appearance Motion Mode. In 20 short-axis CMR examinations, manual contours were defined in multiple temporal frames (from end-diastole to end-systole) in multiple slices from base to apex. Global LV function results derived from automatically detected contours were compared with results obtained from manually traced boundaries. Automated contour detection resulted in small, but statistically non-significant, underestimations of LV volumes and mass: and an excellent agreement was observed in the LVEF. The fully automated contour detection method provided assessment of quantitative global LV function that is comparable to manual analysis, but offered the advantage of being more consistent, more reproducible, and less operator-dependent. Sievers et al. [67] investigated 100 subjects (40 normal subjects, 40 patients with ischemic cardiomyopathy, and 20 patients with nonischemic cardiomyopathy) using a 1.5-T CMR imager. LVEF was significantly underestimated by the visual reader in all 3 groups. The difference was larger in normal subjects than in patients with cardiomyopathy. The interobserver variability was smaller for the quantitative assessment than for the visual estimation. Attili et al. [69] reported that recent quantitation-oriented advances in CMR hardware and software have resulted in significant improvements in image quality and a reduction in imaging time. To conclude, the study by Holloway et al. [59] confirms that the visual CMR approach for LVEF assessment may be used for rapid assessment of LV function in clinical practice where accuracy is of less concern. For an accurate analysis of LV function, the quantitative standard short axis approach is required.

Background The sharp increase in demand for Cardiac Magnetic Resonance (CMR) imaging, driven by its greater inclusion in guidelines, necessitates measures to enhance accessibility. A significant challenge, even in high-resource facilities, is the long scanning times. Rapid and ultrarapid scanning protocols (under 20 minutes) can effectively support diagnosis and management while fully complying with guidelines for specific indications. Until now, these rapid and ultrarapid protocols have primarily been implemented in low to medium-resource settings. We aimed to evaluate the feasibility and effectiveness of a rapid scanning pilot program within a high-volume, tertiary referral CMR center. Methods In a single high-volume CMR centre (~800 scans/year), a 20-minute scan slot was created. Scanning protocol included bSFFP cines (4-, 2-, 3-, short-axis stack, LV outflow tract, aortic valve), T1 mapping (3 short axis) and late-enhancement (LV long axis, short-axis stack), as in the figure. Eligible patients, i.e. those referred for hypertrophic cardiomyopathy (HCM) screening in genetic positive / phenotype negative probands’ relatives, viability assessment in chronic ischemic heart disease, left ventricular hypertrabeculation, and hypertensive heart disease, were identified by medical record review at the time of CMR scan scheduling, by an experienced CMR doctor. Results and discussion: 15 patients (7 HCM relatives, 4 viability, 2 hypertrabeculation, 2 hypertensive heart disease; F: 6 [40%], average age 40±23y, age range 18-80y) underwent the rapid scanning protocol over 4 months (1 slot/week). The average scanning time was 20±4 min (range 16-29 min), meaning that two rapid CMR scans can be performed in a standard 45-minute slot, and the shortened scan duration may also improve patients’ experience. No patients needed re-protocolling during the scan nor scan repetition (i.e. no extra sequences were needed), meaning that the patient’s selection was appropriate. Conclusion Rapid scanning cardiac magnetic resonance (CMR) is feasible in high-volume centers and could enhance resource optimization and accessibility. Further research is needed to assess its economic impact, as this method is suitable for only a specific subgroup of patients. Additionally, exploring its use in situations like claustrophobia would be beneficial.

Aims Long scanning times impede cardiac magnetic resonance (CMR) clinical uptake. A ‘one-size-fits-all’ shortened, focused protocol [e.g. only function and late-gadolinium enhancement (LGE)] reduces scanning time and costs, but provide less information. We developed two question-driven CMR and stress-CMR protocols, including tailored advanced tissue characterization, and tested their effectiveness in reducing scanning time while retaining the diagnostic performances of standard protocols. Methods and results Eighty-three consecutive patients with cardiomyopathy or ischaemic heart disease underwent the tailored CMR. Each scan consisted of standard cines, LGE imaging, native T1-mapping, and extracellular volume. Fat/oedema modules, right ventricle cine, and in-line quantitative perfusion mapping were performed as clinically required. Workflow was optimized to avoid gaps. See Figure 1 for protocol details. Time target was &amp;lt;30 min for a CMR and &amp;lt;35 min for a stress-CMR. CMR was considered impactful when its results drove changes in diagnosis or management. Advanced tissue characterization was considered impactful when it changed the confidence level in the diagnosis. Images’ quality was assessed. A ‘control group’ of 137 patients was identified among scans performed before February 2020. Compared to standard protocols, the average scan duration dropped by &amp;gt; 30% (CMR: from 42 ± 8 to 28 ± 6min; stress-CMR: from 50 ± 10 to 34 ± 6min, both P &amp;lt; 0.0001). Independent on the protocol, CMR was impactful in ∼60% cases, and advanced tissue characterization was impactful in &amp;gt; 45% of cases. Quality grading was similar between the two protocols. Tailored protocols did not require additional staff. Conclusions Tailored CMR and stress-CMR protocols including advanced tissue characterization are accurate and time-effective for cardiomyopathies and ischaemic heart disease.

Is MRI the Preferred Method for Evaluating Right Ventricular Size and Function in Patients With Congenital Heart Disease?

PERIOPERATIVE myocardial complications after noncardiac surgery affect more than 1 million operations each year and are leading causes of morbidity and mortality, especially among patients undergoing vascular surgery. Myocardial complications such as perioperative myocardial infarction (MI) are common and are the most likely cause for perioperative death in all surgical populations.1In general surgery, the risk for perioperative MI is 0.8% in men older than 50 yr2and varies with the cardiovascular status, comorbidities, and the extent of the procedure, reaching more than 20% among patients undergoing vascular surgery.3As patients become older and sicker and procedures become more aggressive and extensive, physicians must find novel approaches to evaluate and prepare cardiac patients for noncardiac procedures and reduce perioperative myocardial events.The American Heart Association–American College of Cardiology guidelines for cardiac risk evaluation use the patient's history, physical examination, and functional capacity, and taking into account the expected surgery, one may recommend further assessment with noninvasive testing or coronary angiography.4The purpose of this review is to provide an overview of available imaging tools that could potentially be used for perioperative evaluation of cardiac patients before noncardiac surgery, in accord with recent guidelines and with focus on the recent progress made with cardiac computed tomography (CT).Traditionally, preoperative evaluation has relied on the patient's history, physical examination, and functional capacity. After preoperative evaluation, the physician should determine the clinical predictors as major, intermediate, or minor4and evaluate the functional capacity of the patient. New York Heart Association class II heart failure, which equals 4 metabolic equivalents,4has also been found to be an important predictor of perioperative cardiac complications after major noncardiac surgery. The cutoff value of 4 or more metabolic equivalents determines an adequate cardiac functional capacity and reserve and predicts perioperative cardiac events in patients treated with high-risk noncardiac surgery.5Finally, the extent and risk associated with the procedure should be categorized as major, intermediate, or minor. The cardiac risk is the combined incidence of cardiac death and nonfatal MI and is greater than 5% for high-risk procedures, whereas intermediate-risk procedures have less than 5% cardiac risk (1–5%), and low-risk procedures have less than 1% cardiac risk.4Indeed, based on these criteria, the flowchart of Eagle et al. 4suggests when a noninvasive test or coronary angiography may be appropriate to evaluate cardiac function, reserve, or ability to withstand surgical stress. Pertinent to the utility of evaluating cardiac structure and function, new imaging techniques for evaluation of the heart have emerged in the past couple of decades. These techniques may provide more comprehensive information regarding the structure and function of the heart and coronary arteries, and evaluate adequately patients who have mechanical restrictions to perform exercise-induced stress. Such developments in cardiac imaging may eventually provide an opportunity to revise and refine the steps involving the evaluation of cardiac patients.6,7This approach should be evaluated cautiously and should take into consideration recent recommendations and guidelines. For example, the current American Heart Association–American College of Cardiology guidelines recommend the use of perioperative β-blocker therapy as an alternative approach to decrease cardiovascular risk.8β-Blockers initiated at least 1 week before major vascular surgery and continued for 30 days postoperatively reduced significantly the perioperative incidence of nonfatal MI and death from cardiac causes in high-risk patients.9In addition to beta blockers, statins may reduce perioperative mortality in patients undergoing major vascular surgery and may have an additive effect to β-blockers.10,11The strategy of preoperative coronary artery revascularization before elective major vascular surgery to reduce perioperative cardiac morbidity and mortality was investigated in the Coronary Artery Revascularization Prophylaxis trial, a multicenter study involving patients with vascular disease and significant coronary artery disease (CAD), but no unstable angina. Cardiac revascularization did not result in increased survival, either perioperatively or in long-term follow-up, in patients who needed elective vascular surgery.12However, although the Coronary Artery Revascularization Prophylaxis study is a cornerstone trial in the perioperative care of cardiac patients for noncardiac surgery, it had some limitations. In particular, only 9% of the patients scheduled to undergo vascular operations were eligible for the study. The main reasons for exclusion were insufficient cardiac risk, an urgent vascular surgery, previous revascularization without ischemia, severe coexisting illnesses, left main coronary artery stenosis of at least 50%, left ventricular ejection fraction less than 20%, and severe aortic stenosis. The outcome of these patients has not been adequately evaluated.Indeed, taking into consideration the patient's perioperative cardiac risk according to clinical predictors, functional capacity, and the extent of the future surgery, the anesthesiologist must decide whether further cardiac assessment or perioperative medical management are indicated. Patients whose functional capacity is difficult to establish, who underwent previous coronary revascularization, who have unstable or changed cardiac status, or who have severe comorbidities may need further evaluation. Several imaging techniques are available for evaluation of cardiac patients, including cardiac CT, coronary angiography, stress echocardiography, cardiac magnetic resonance imaging (CMRI), and myocardial nuclear studies.Computed tomography is widely available in large medical centers and is routinely used in clinical practice. The basic principle of CT is that a fan-shaped, thin x-ray beam passes through the body at many angles to allow for cross-sectional images. After collimation of the beam (i.e. , achieving a definitive slice thickness using a collimator) to reduce scatter, the photons are recorded on a corresponding detector array, and the transmission data are digitized. A “filtered back projection” reconstruction algorithm, which takes into account the attenuation of the x-ray beam along its path, allows for reconstruction of the grayscale values of each picture element (pixel) with reference to the value for water and air, to depict cross-sectional images. Reconstruction algorithms and multirow detectors applied in current scanners enable three-dimensional volumetric imaging and multiple high-quality reconstructions of various volumes of interest.13Current clinical scanners used for cardiovascular imaging employ either a rotating x-ray source with a circular, stationary detector array (e.g. , helical CT) or electromagnetic deflection of an electron beam to replace mechanical motion (electron beam computed tomography [EBCT]).14Multidetector computed tomography (MDCT) is a helical CT with a large array of detectors, which allow it to acquire a large number of slices simultaneously (4–256) and greatly increase its resolution. However, to obtain quantitative measurements of tissue opacity within a specific cardiac phase (e.g. , for measurement of perfusion), the scanning time should generally be less than 100 ms.15Sufficiently high temporal resolution (the time required to acquire the data for one image) is currently offered only by the EBCT (50 ms/image) and the novel Dual-Source CT (SOMATOM® Defi-nition; Siemens Medical Systems, Forchheim, Germany) (83 ms/image), a recently released model of MDCT that has two x-ray tubes (rather than one) positioned at 90° to each other, thereby doubling temporal resolution.16However, this technique remains to be validated for such measurements.Electron beam computed tomography was developed in the 1980s and hailed as an ultimate cardiac scanner. It allows almost simultaneous data acquisition from up to eight parallel slices (7–8 mm thick) by rapid sweeping of an electron beam along target rings in as little as 50 ms per scan. Because it does not involve moving parts (and therefore decreases the need for cooling), the speed of acquisition (temporal resolution) with EBCT is faster than with MDCT (table 1) and usually does not require slowing the heart rate pharmacologically. The high speed of EBCT is offset by moderate image quality and relatively restricted power for acquisition of a large number of images, which decreased its popularity for comprehensive cardiac studies. Consequently, its availability is limited, resulting in declining use of this technology.Multidetector computed tomography is a relatively ubiquitous and newer scanner that has temporal resolution of 330–400 ms/image, which enables many studies of cardiac anatomy and global function (e.g. , ejection fraction and cardiac output). Spatial resolution can be achieved with 64-slice scanners using isotropic voxels (consistent three-dimensional image quality in any reconstruction plane) of 0.4 × 0.4 × 0.4 mm. The technique involves continuous rotation of the x-ray tube and detectors and simultaneous translation of the patient through the gantry opening, and can acquire multiple simultaneous sections of variable widths using prospective electrocardiographic triggering.17Alternatively, retrospective electrocardiographic gating enables reconstruction of images at any desired time in the cardiac cycle. Data can be used from multiple slices to reconstruct other imaging planes. The images are of best quality when the resting heart rate (HR) is less than 70 beats/min. At faster heart rates, motion artifacts may become more prominent, and therefore HR may need to be pharmacologically decreased before scanning. The temporal resolution of MDCT determines the overall scan time. As gantry rotation speeds increase, the minimum slice thickness decreases, with submillimeter sections throughout the heart acquired during a single breath hold. The overall CT scan time is approximately 12 s, and the mean total time for the examination is less than 13 min with 64-slice technology.The improvement in MDCT technology enabled the assessment of significant luminal stenosis and identification of nonstenotic atherosclerotic plaques. Virtual noninvasive angiography, with three-dimensional reconstruction of coronary anatomy from cardiac CT images, can provide information about coronary luminal obstruction, calcium scoring, and composition of the plaque.18Furthermore, it has the added benefit of offering fine details of the examined vessels (fig. 1).Excellent sensitivity and specificity were found for evaluation of proximal, middle and distal left anterior descending, first diagonal, proximal and distal circumflex, obtuse marginal and proximal mid and distal right coronary artery.19A meta-analysis of diagnostic performance of MDCT compared with invasive coronary angiography showed a sensitivity of 85% and a specificity of 95% for identification of CAD. On average, 87% of segments had diagnostic image quality, with a significant increase from 78% with 4-slice systems to 96% with the more recent 16-slice systems.6Multidetector computed tomography could provide a clinically useful tool in the workup of symptomatic patients before angiography.20A patient with chronic chest pain indicative of CAD could undergo CT angiography, and if low calcium score and no circumferential calcifications (or other test results indicative of ischemia) are found, invasive angiography may not be indicated, because MDCT has excellent negative predictive value to rule out CAD. By this approach, patients with primarily microvessel disease (which may cause angina and abnormal stress test results) may be identified and not required to go through unnecessary fluoroscopic angiography, and aggressive medical therapy would be indicated before surgery.20MDCT also has high diagnostic accuracy in detecting bypass graft stenosis and occlusions in symptomatic patients after coronary artery bypass grafting, which might potentially reduce dramatically the number of unnecessary invasive angiographies performed in these patients.21However, although the MDCT technique has been extensively evaluated for its accuracy for detection of CAD compared with standard coronary angiography,6,19,20,22it has not been applied for the routine evaluation of cardiac patients for noncardiac surgery and, to date, is not a recommended technique for perioperative risk stratification.The main technical limitations of cardiac CT for evaluation of the coronary arteries include the difficulty in handling cardiac motion, arrhythmia, severe calcifications, vessel size less than 1.5 mm, breathing, the presence of stents, and poor enhancement.22Lesions with extensive calcified components and implanted coronary stents compromise the accuracy of MDCT coronary angiography by causing artifacts.23Stent type and diameter influence evaluability of in-stent restenosis by MDCT, but in evaluable stents, sensitivity is still 86% and specificity is 98%.24When HR is reduced below 70 beats/min, image quality is improved, especially in terms of the visualization of the right coronary and left circumflex arteries, which are both significantly prone to motion artifacts (particularly at higher HR) because of their close proximity to the atrium, which is reactivated during the early diastolic phase.25For evaluation of coronary artery calcium volume with MDCT, thin-slice retrospective spiral electrocardiographic–gated scanning is desirable.26Most studies on coronary calcification have been performed using EBCT, which is still considered the “gold standard” (table 1). To image the coronary arteries with EBCT, 30–40 axial images are obtained with 3-mm slice thickness, using single-slice prospective electrocardiographic triggering in the craniocaudal direction along the full length of the heart. Rapid image acquisition at 100 ms allows accurate measurement of calcium deposits in the coronary arteries.27Quantification of coronary artery calcifications was found to be independently associated with cardiac events in a 3-yr follow-up of thousands of initially asymptomatic patients.28Noninvasive characterization and quantification of atherosclerotic plaque burden may also have important implications for the prevention of CAD progression and its complications.18For the past several years, CMRI has been considered the reference standard for assessment of left ventricular (LV) functions. However, cardiac CT is playing an increasingly important role in this evaluation. Both CT and CMRI surpass two-dimensional imaging techniques, such as standard two-dimensional echocardiography, for cardiac quantification because of their ability to generate contiguous short axis cine images, allowing for three-dimensional measurements without the use of geometric assumptions.29Postprocessing tools allow fast and semiautomatic determination of LV function parameters from MDCT data in analogy to known CMRI evaluation approaches.30Studies have demonstrated excellent correlation between cardiac CT and CMRI for LV ejection fraction, end-diastolic volume, end-systolic volume, stroke volume, and myocardial mass.30Furthermore, global and regional LV functions agree well with echocardiography, with correlation coefficients ranging from 0.91 to 0.97 for MDCT and from 0.93 to 0.98 for CMRI.7,30,31Although MDCT is not considered to be the first-line modality for assessment of LV function, it can provide a combined assessment of cardiac morphology and function without the need for additional radiation exposure in patients undergoing MDCT coronary angiography. The acquisition of images is performed according to the R–R interval. For MDCT, the image data are gated with the electrocardiogram to allow reconstruction at various times throughout the cardiac cycle. CT allows quantitative analysis of regional and global systolic function in normal and pathologic conditions by using short axis slices from the base to the apex of the heart. End-diastole and end-systole are defined as maximal and minimal LV volume, and LV ejection fraction is the difference between them.30Diastolic function can also be assessed from the rate of change of the LV volume during diastole.13Also, because temporal resolution for electrocardiographic-gated cardiac CT scans (down to 165 ms) is poorer in comparison to cine CMRI (30–40 ms), CT imaging may miss peak ejection rate or peak filling rate. However, advances in MDCT imaging that will improve temporal resolution may correct this problem.16Regional wall motion abnormalities, myocardial thinning, ventricular aneurysm, and mural thrombi in the infarcted area can all be detected by cardiac CT. Dual-phase contrast CT can detect acute MI characterized by an initial filling defect and late enhancement at the site of the damaged myocardium. Late enhancement may have the potential to distinguish viable from nonviable myocardium, and has significant prognostic value for the recovery of the myocardial wall motion and thickness after ischemia and in response to therapeutic revascularization.32In patients with previous MI, MDCT permits accurate, noninvasive assessment of coronary artery stenosis, LV function, and perfusion, assessed from a single data set.33If the myocardium supplied by the stenotic or occluded vessel is still viable, medical treatment or revascularization can be considered to reduce the risk of perioperative ischemia in the affected myocardium.Experimental studies in animals and humans demonstrated that cardiac CT could be used to assess microvascular function, although this technique is not used clinically, partially because of high radiation exposure. Evaluation of myocardial perfusion at rest and after infusion of vasodilators imposing cardiac challenge can reveal the presence of otherwise undetectable limited myocardial flow reserve, which might have a significant value for detection of borderline or very early alterations in cardiac microvascular function, as well as detecting increases in microvascular permeability that may reflect endothelial dysfunction or ischemic changes.34The use of CT scanning is limited by the need for contrast media and radiation exposure (table 2). The risks associated with contrast media administration include extravasation at the contrast injection site, allergic contrast reaction, and a decline in function, as well as and vascular In patients with administration of contrast media is media has been reduced and is than that used during angiography potential of alternative contrast such as might further decrease the various radiation are with MDCT, and scanning may allow a decrease in radiation of cardiac function and volumes may from to potentially any based on gated that data several cardiac limitations include the need to image quality in patients and the need for and physicians for acquisition and of cardiac CT data of the limitations of MDCT is the need to decrease heart rate at time of which may be in some It further the need for CT technology to acquisition time a greater volume of developed scanners such as the Dual-Source MDCT may this to temporal the number of that can be from axial CT images is limited only by gantry rotation speed and patient heart decreased ejection fraction in is associated with decreased overall postoperatively and with increased incidence of heart failure, but no has been found with main associated with cardiac events is the presence of wall motion has a low predictive is appropriate in patients who American Heart Association–American College of Cardiology clinical guidelines and who would require if no surgery were as well as in with aortic sensitivity of can be by the heart either or pharmacologically. stress test with administration of can provide information about cardiac function, ventricular and function, and a is in to 85% of maximal HR or or as wall motion abnormalities, whereas a in ejection fraction in response to administration is a of more severe CAD. has excellent negative predictive values and sensitivity but moderate specificity and is significantly and long-term cardiac risk using initial cardiac risk assessment and noninvasive testing with may the perioperative and long-term treatment of patients undergoing major vascular comparison with other noninvasive a diagnostic new of may improve cardiac risk compared with standard in patients undergoing noncardiac surgery whose functional capacity be evaluated by stress stress has a relatively low and can assess cardiac structure and function, wall thickness, aortic and the presence of However, has sensitivity for detection of single vessel disease and is to distinguish between microvascular and CAD (table because wall motion can be found in progress has been made during the past in which is used to evaluate a of heart and including CAD. CMRI is based on the of which and to an magnetic CMRI a causes deflection of the from the direction of the main magnetic The is during the of the back their in the magnetic are and data are used for image many image are for assessment of global ventricular and function, ejection fraction, stroke volume, and detection of and acute and chronic LV can be and using analysis of may find use in the clinical magnetic resonance imaging has higher temporal resolution but resolution (the ability to distinguish between two on the image) than cardiac resolution of 1.5 × 1.5 may have an CMRI for detection of because its overall accuracy in the detection of coronary artery stenosis is higher (table 2). The axial image of MDCT allows more vascular as compared with CMRI that may artifacts to sensitivity and specificity of CMRI for detection of coronary artery stenosis are and whereas of coronary segments are is noninvasive and high-quality images of the heart (table 2). However, CMRI examination be applied in patients who have a or and the presence of and stents can CMRI images and to is the of the test than an during which the patient must be CMRI is an important noninvasive tool and does not the use of potential contrast are needed to evaluate its use as a perioperative tool and its correlation with perioperative cardiac use of myocardial computed tomography and tomography has in the past two because of their in useful information about myocardial perfusion and function based on administration of an unstable with has been used for many for preoperative cardiac evaluation. the coronary response associated with testing not the HR and has been used in patients scheduled to undergo vascular surgery. However, has low and negative predictive and was not significantly associated with the incidence of perioperative MI, ischemia, or other the other the of this test was when used in patients undergoing aortic surgery whose risk could not have been on the of clinical value of imaging for preoperative cardiac assessment in high-risk has been demonstrated in patients before and vascular of myocardial with is important in patients with LV function to and the potential of revascularization can be These studies showed excellent correlation of with cardiac both perioperatively within 30 days and at long-term has high sensitivity in coronary disease but limited sensitivity for detecting significant disease and CAD (table 2). It also little functional data other than myocardial perfusion and has relatively low resolution that the quality of scanners have a maximal of approximately is required for before the performance of myocardial perfusion because the coronary effect of or is by with can be used to functional recovery of viable myocardium after coronary artery a is from a a in and with an results in of both the and the with to in the of electromagnetic radiation of two which in from each and are detected by a of radiation detectors at The difference in time the photons each radiation detector is used to detect the source of the of radiation detectors are in the gantry with million of per the imaging is useful in noninvasive quantification of myocardial flow and coronary flow reserve, and is also of detecting early disease in high-risk asymptomatic and the progression or of is to especially in patients and in undergoing remains a significant its high and limited availability currently its use as a technology of coronary angiography is well and involves injection of contrast media into the coronary artery by imaging in multiple planes. is by comparison of diameter at a stenotic site with that of a normal reference can evaluate coronary stenosis, LV function, and (table coronary angiography is an invasive technique and has a major rate of including mortality in of it may involve for the patient and is associated with other such as vascular complications for diagnostic and for complications and complications the risk of coronary angiography with that of MDCT, some risks are common to both procedures, such as an allergic contrast reaction, and exposure to whereas are to contrast media injection causes severe allergic in of risks of a of for MDCT angiography and for coronary angiography. However, the and risks and a overall risk of mortality from coronary that for MDCT angiography use of a power in a vascular with cardiac CT an additional risk of which in of the relatively significant number of negative invasive angiographies performed each the risks to this procedure by using noninvasive can greatly to the morbidity and mortality of coronary angiography. the number of negative angiographies might to significant because the of cardiac may be as as times that of cardiac evaluation of patients with or known cardiac disease for noncardiac surgery has been in the of of and The preoperative evaluation on assessment of clinical predictors, functional capacity, and the extent of the surgical The first-line to reduce perioperative morbidity and mortality include medical therapy with with HR and However, the strategy may also include of noninvasive imaging techniques that provide comprehensive and assessment of cardiac structure and In particular, in patients with restricted physical in assessment of the functional capacity is obtained using imaging with evaluation of the heart may potentially to treatment Cardiac CT is can provide coronary angiography for plaque assessment and scoring, and can assess LV function, and myocardial in a fast and relatively CT can in out significant CAD and determination of the need for invasive angiography. cardiac CT might potentially be the tool for overall evaluation of cardiac patients for noncardiac surgery. at this is no that preoperative cardiac CT scanning is to reduce perioperative studies are needed to assess the role of cardiac CT in the evaluation of patients at risk for cardiovascular disease before noncardiac surgery.

A new compressed sensing cine cardiac MRI sequence with free-breathing real-time acquisition and fully automated motion-correction: A comprehensive evaluation

Background Myocardial microvascular disease is primarily characterized by arteriolar obliteration and capillary rarefaction, and may occur during the disease course of different disorders. With the present study, we introduce a novel and easy-to-perform cardiovascular magnetic resonance (CMR) parameter named “myocardial transit time” (MTT). Methods N=20 patients with known hypertrophic cardiomyopathy (HCM) and N=20 control patients without relevant cardiac disease underwent dedicated CMR studies on a 1.5-T MR scanner (Ingenia, Philips, Best, The Netherlands). The CMR protocol comprised cine and late-gadolinium-enhancement (LGE) imaging and first-pass perfusion acquisitions at rest for MTT measurement: an imaging plane covering both the aortic bulbus and the coronary sinus was planned in order to track the flooding of gadolinium. MTT was defined as the time interval between first appearance of gadolinium in the aortic bulbus and the subsequent appearance of gadolinium in the coronary sinus reflecting the transit time of gadolinium in the myocardial microvasculature (in the absence of epicardial coronary artery disease). Results There was no significant difference in left ventricular ejection fraction (LV-EF) between both groups: 61% (55–68%) in HCM patients vs. 60% (58–67%) in controls (p=ns) whereas LV mass was significantly higher in HCM patients (79g/m2 (63–98g/m2) vs. 50g/m2 (45–56g/m2) in controls, p&lt;0.001). The extent of LGE was 17% (6–22%) in HCM patients while there was no LGE at all in the control group (p&lt;0.001). MTT at rest was substantially longer in HCM patients: 11.0sec (9.1–14.5sec) vs. 6.5sec (4.8–8.4sec) in controls (p&lt;0.001). Correlation analyses revealed a significant relationship between LV mass and MTT (r = +0.64, p&lt;0.001) as well as between LGE extent and MTT (r=0.75, p&lt;0.001). ROC analysis resulted in an area-under-curve (AUC) of 0.90 for MTT and showed an optimal sensitivity/specificity cut-off of 7.85sec to differentiate HCM from controls. Patient characteristics HNCM patients (N=20) Control group (N=20) p-value Absolute MTT, sec 11.0 (9.1–14.5) 6.5 (4.8–8.4) &lt;0.001 MTT indexed to heart rate 0.159 (0.100–0.198) 0.081 (0.063–0.106) &lt;0.001 No. of patients with MTT &lt;7.85 sec, n (%) 2 (10) 15 (75) &lt;0.001 MTT = Myocardial Transit Time, HNCM = Hypertrophic Non obstructive Cardiomyopathy. Multiple images illustrating MTT method Conclusion “Myocardial transit time” (MTT) is a novel and easy-to-perform CMR parameter that allows a quick assessment of the extent of myocardial microvascular disease. This novel CMR parameter may open new vistas in the assessment of microvascular disease - not only in HCM patients. Future studies will show the usefulness and clinical relevance of this novel CMR parameter.

Background: Left ventricular (LV) mass is an important prognostic factor in hypertrophic cardiomyopathy (HCM). LV mass can be easily accessed by M-mode or 2D echocardiography; however it includes assumption and might be incorrect in LV with asymmetricity. Real time three dimensional echocardiography (RT3DE) has been introduced as an accurate method to assess the LV mass and recently, RT3DE by single beat capture with online analysis program has been introduced. We validated LV mass using new RT3DE technique compared to cardiac magnetic resonance (CMR). Method: Thirty six HCM patients were consecutively enrolled and 3 patients were excluded due to poor RT3DE images. All the patients underwent CMR and RT3DE within the same day. LV mass was derived from the following methods; the ASE formula (M-mode mass), truncated ellipsoid method by 2D echocardiography (2D mass) and RT3DE (RT3DE mass). RT3DE image was acquired using the SC2000 System. The LV mass data were compared with the LV mass analyzed by CMR. Results: Mean frame rate of RT3DE was 13.1±2.3 frame/second. Pearson's interclass coefficient (ICC) showed close correlation of RT3DE mass and CMR mass (r=0.92 and p&lt; 0.0001). However, M-mode mass and 2D mass had smaller ICC when compared with CMR (r=0.50, p=0.01 and r=0.78, p&lt;0.001) Bland-Altman analysis showed reasonable limits of agreement with small positive bias (15.1). Bias was greater in M-mode LV mass and 2D LV mass (-39.1 and 21.2) Conclusions: LV mass measured by single-beat captured RT3DE is a feasible and accurate method in HCM patients. Because LV shape is asymmetrical in many subjects with HCM, LV mass derived from 2D or M-mode is much more inaccurate than symmetrical LVs. Correct assessment of LV mass using single-beat captured RT3DE will be useful in HCM patients in real clinical practice.

Background Cardiovascular mortality is higher in developing countries. Part of that is suboptimal testing. Cardiac magnetic resonance (CMR) is the gold standard for measuring structure, function of the heart and adds incremental value by imaging scarring and to assess iron level. Despite the existence of MRI units, CMR is identified as a complex test, with poor training and availability in developing countries. Purpose To assess the potential impact of a faster CMR protocol at a multicentre level in developing countries; implementing it with an education program, for the assessment cardiomyopathies. Methods An international partnership. A rapid CMR protocol for the evaluation of cardiac volumes, function and tissue characterization (Cardiac Iron T2* and LGE for scar) Figure 1a. We deployed the protocol as a multicentre study: Argentina, Peru, India and South Africa accompanied by a program of education. Pre-scan clinical information, scanning data: complications, image quality and post-scan follow-up of participants for the assessment on impact, between 3 to 24 months. Results 510 scans (4 countries, 6 cities, 12 centres) were performed with the rapid CMR protocol. Contrast studies in 378 (74%). There were no scan-related complications. Quality of the studies was maintained in a high level as an average of 89%. 97% of studies responded referral's question. All patients with contrast CMR scan have had at least one 2D echocardiogram before CMR. Average scan duration was 21±6 mins for contrast studies and 12±3 for non-contrast T2* protocol. The most common underlying diagnoses were non-ischaemic cardiomyopathy in 73% of participants (including cardiac iron level assessment in 26%, HCM in 17%, DCM in 15%), 27% for ischaemic cardiomyopathy and 15% for other pathologies. 4 of the 12 participant centres started to incorporate CMR for the first time. Findings impacted management in 60% of patients, including new diagnosis in 21% of participants. See table 1, figure 1b. For just cardiac iron assessment: 1/3 of participants had iron deposited in the heart with 14% of patients in severe levels. Conclusions CMR can be delivered faster and easier. When this abbreviated protocol is enabled with education, it can be implemented in developing countries with existing technology. This protocol shows high quality exam, with an important impact on patient's management. Characteristics and impact on management Contrast studies Non-contrast studies All patients (%) 378 (74) 132 (36) Age, mean (range) years 54 (16–93) 24 (13–41) Male (%) 151 (39) 64 (48) Pre-echocardiography exam (%) 370 (98) 42 (32) Scanning duration mean (SD) 21 (6) 12 (3) Good quality exam (%) 329 (87) 120 (91) Impact on management Total All patients (%) 510 (100) Completely new diagnosis (%) 105 (21) Change/Addition of Medication (%) 128 (25) Intervention/ Surgery (%) 31 (6) Invasive angiography/biopsy (%) 25 (5) Hospital discharge/admission (%) 15 (3) TOTAL 306 (60%) SD: Standard Deviation. Acknowledgement/Funding Global Engagement UCL, UK Foreign &amp; Commonwealth Office and The Peruvian Scientific, Technological Development and Technological Innovation (FONDECYT)

Dynamic right ventricular evaluation in pulmonary arterial hypertension using novel ultra-fast cardiac magnetic resonance imaging acquisition