Left Atrial Function and Mortality in Patients With NSTEMI

OBJECTIVES: Left atrial maximal volume (LAmax) is known to predict mortality in patients with acute myocardial infarction. In a previous pilot study, however, we found that LA function in terms of fractional change and left atrial ejection fraction (LAEF) assessed by multidetector computed tomography (MDCT) is more closely related to clinical heart failure than LAmax.We sought to test the hypothesis that measures of left atrial (LA) function are independent predictors of mortality in patients with acute myocardial infarction.

METHODS: We prospectively included 384 patients presenting with non–ST-segment elevation myocardial infarction (NSTEMI) who underwent retrospectively gated, 64-slice MDCT coronary angiography and subsequent measurements of LA size and function. All patients were treated according to the current guidelines based on invasive coronary angiography. Patients were followed for a minimum of 2 years. The study endpoint was all-cause mortality.

RESULTS: The median follow-up time was 36 months (range 10 to 1,551 days). During follow-up, 35 (9%) patients died. Overall, 1- and 2-year survival in the study cohort was 97% and 94%. LA size and mechanical function was obtained in all patients: mean LAmax was 55 ± 11 ml/m2, LA minimal volume 31 ± 11 ml/m2, fractional change 45 ± 9%, and LAEF 32 ± 9%. Using a Cox proportional hazards model with adjustments for age, number of diseased coronary vessels, left ventricular ejection fraction (LVEF), and Killip class, both fractional change (hazard ratio [HR]: 0.65; 95% confidence interval [CI]: 0.45 to 0.94) and LAEF (HR: 0.63; 95% CI: 0.44 to 0.91) remained independent predictors of mortality. In contrast to this, LAmax was not significantly associated with an increased risk of mortality in this population.

CONCLUSIONS: In a low-risk group of patients with NSTEMI, reduced LA function is an independent predictor of mortality and provides prognostic value incremental to that of LAmax.

PMID:

Comparative Effectiveness and Cost-Effectiveness of Computed Tomography Screening for Coronary Artery Calcium in Asymptomatic Individuals

OBJECTIVES: The aim of this study was to assess the (cost-) effectiveness of screening asymptomatic individuals at intermediate risk of coronary heart disease (CHD) for coronary artery calcium with computed tomography (CT).

METHODS: A Markov model was developed on the basis of the Rotterdam Study. Four strategies were evaluated: 1) current practice; 2) current prevention guidelines for cardiovascular disease; 3) CT screening for coronary calcium; and 4) statin therapy for all individuals. Asymptomatic individuals at intermediate risk of CHD were simulated over their remaining lifetime. Quality-adjusted life years (QALYs), costs, and incremental cost-effectiveness ratios were calculated.

RESULTS: In men, CT screening was more effective and more costly than the other 3 strategies (CT vs. current practice: +0.13 QALY [95% confidence interval (CI): 0.01 to 0.26], +$4,676 [95% CI: $3,126 to $6,339]; CT vs. statin therapy: +0.04 QALY [95% CI: -0.02 to 0.13], +$1,951 [95% CI: $1,170 to $2,754]; and CT vs. current guidelines: +0.02 QALY [95% CI: -0.04 to 0.09], +$44 [95% CI: -$441 to $486]). The incremental cost-effectiveness ratio of CT calcium screening was $48,800/QALY gained. In women, CT screening was more effective and more costly than current practice (+0.13 QALY [95% CI: 0.02 to 0.28], +$4,663 [95% CI: $3,120 to $6,277]) and statin therapy (+0.03 QALY [95% CI: -0.03 to 0.12], +$2,273 [95% CI: $1,475 to $3,109]). However, implementing current guidelines was more effective compared with CT screening (+0.02 QALY [95% CI: -0.03 to 0.07]), only a little more expensive (+$297 [95% CI: -$8 to $633]), and had a lower cost per additional QALY ($33,072/QALY vs. $35,869/QALY). Sensitivity analysis demonstrated robustness of results in women but considerable uncertainty in men.

CONCLUSIONS: Screening for coronary artery calcium with CT in individuals at intermediate risk of CHD is probably cost-effective in men but is unlikely to be cost-effective in women.

PMID: 21982314

Long-Term Prognostic Value of Myocardial Salvage Assessed by Cardiovascular Magnetic Resonance in Acute Reperfused Myocardial Infarction

OBJECTIVES: In acute myocardial infarction, cardiovascular magnetic resonance (CMR) allows for quantifying the extent of salvaged myocardium after reperfusion as a potential strong end point for clinical trials. The aim of this study was to investigate whether the early prognostic significance of myocardial salvage assessed by CMR is sustained at long-term clinical follow-up in patients with ST-elevation myocardial infarction (STEMI) undergoing primary angioplasty.

METHODS: analysed 208 consecutive patients with STEMI undergoing primary angioplasty

RESULTS: The median MSI was 48 (IQR 27 to 73). Long-term follow-up was available in 202 patients (97%) at a median of 18.5 months (IQR 13.8 to 20.8). Major adverse cardiovascular events occurred in 33 patients (16%), with a significantly lower event rate in the MSI ≥ median group (7 vs 26 events, p

CONCLUSIONS: MSI assessed by CMR predicts long-term clinical outcome in acute reperfused STEMI. Therefore, our data support the use of myocardial salvage as an end point for clinical trials investigating novel reperfusion strategies.

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Performance of Angiographic, Electrocardiographic and MRI Methods to Assess the Area at Risk in Acute Myocardial Infarction

OBJECTIVES: Validation of methods to assess the area at risk (AAR) in patients with ST elevation myocardial infarction is limited. A study was undertaken to test different AAR methods using established physiological concepts to provide a reference standard. Main outcome measuredIn 78 reperfused patients with first ST elevation myocardial infarction, AAR was measured by electrocardiographic (Aldrich), angiographic (Bypass Angioplasty Revascularization Investigation (BARI), APPROACH) and cardiovascular magnetic resonance methods (T2-weighted hyperintensity and delayed enhanced endocardial surface area (ESA)). The following established physiological concepts were used to evaluate the AAR

METHODS: (1) AAR size is always ≥ infarct size (IS); (2) in transmural infarcts AAR size=IS; (3) correlation between AAR size and IS increases as infarct transmurality increases; and (4) myocardial salvage ((AAR-IS)/AAR×100) is inversely related to infarct transmurality.

RESULTS: Overall, 65%, 87%, 76%, 87% and 97% of patients using the Aldrich, BARI, APPROACH, T2-weighted hyperintensity and ESA methods obeyed the concept that AAR size is ≥IS. In patients with transmural infarcts (n=22), Bland-Altman analysis showed poor agreement (wide 95% limits of agreement) between AAR size and IS for the BARI, Aldrich and APPROACH methods (95% CI -22.9 to 29.6, 95% CI -28.3 to 21.3 and 95% CI -16.9 to 20.0, respectively) and better agreement for T2-weighted hyperintensity and ESA (95% CI -6.9 to 16.6 and 95% CI -4.3 to 18.0, respectively). Increasing correlation between AAR size and IS with increasing infarct transmurality was observed for the APPROACH, T2-weighted hyperintensity and ESA methods, with ESA having the highest correlation (r=0.93, p

CONCLUSIONS: For measuring AAR, cardiovascular magnetic resonance methods are better than angiographic methods, which are better than electrocardiographic methods. Overall, ESA performed best for measuring AAR in vivo.

PMID: 21930725

Non-Invasive Estimation of Pulmonary Vascular Resistance With Cardiac Magnetic Resonance

OBJECTIVES: To develop a cardiac magnetic resonance (CMR) method for non-invasive estimation of pulmonary vascular resistance (PVR).

METHODS: The study comprised 100 consecutive patients with known or suspected pulmonary hypertension (PH; 53 ± 16 years, 73% women) who underwent same-day right heart catheterization (RHC) and CMR. Increased PVR was defined from RHC as >3 WU (n = 66, 66%). From CMR cine and phase-contrast images, right ventricular (RV) volumes and ejection fraction (RVEF), pulmonary artery (PA) flow velocities and areas, and cardiac output were quantified. The best statistical model to estimate PVR was obtained from a derivation cohort (n = 80) based on physiological plausibility and statistical criteria. Validity of the model was assessed in the remaining 20 patients (validation cohort).

RESULTS: The CMR-derived model was: estimated PVR (in WU) = 19.38 – [4.62 × Ln PA average velocity (in cm/s)] – [0.08 × RVEF (in %)]. In the validation cohort, the correlation between invasively quantified and CMR-estimated PVR was 0.84 (P < 0.001). The mean bias between the RHC-derived and CMR-estimated PVR was -0.54 (agreement interval -6.02 to 4.94 WU). The CMR model correctly classified 18 (90%) of patients as having normal or increased PVR (area under the receiver operator characteristics curve 0.97; 95% confidence interval: 0.89-1.00).

CONCLUSIONS: Non-invasive estimation of PVR using CMR is feasible and may be valuable for PH diagnosis and/or follow-up.

PMID: 21624902

Left Atrial Contractile Function Following a Successful Modified Maze Procedure at Surgery and the Risk for Subsequent Thromboembolic Stroke

OBJECTIVES: The mechanical contraction of the left atrium may be modified after the Maze procedure. Whether this imposes a risk for stroke, even in the presence of sinus rhythm and after removal of the LA appendage, is not known. The aim of this study was to evaluate whether certain post-Maze left atrial (LA) contractile profiles may pose a risk for ischemic stroke.

METHODS: Clinical, surgery-related, and echocardiographic data from 150 patients who underwent radiofrequency and cryoablation Maze procedures without the use of atrial incisions between 2004 and 2009 and were in sustained sinus rhythm were collected and analyzed. The occurrence of stroke was evaluated by reviewing clinical records. All stroke events were adjudicated by a neurologist.

RESULTS: At a mean follow-up time of 24.5 months, 15 patients (10%) had experienced ischemic strokes. Forty-seven patients (31%) had no evidence of LA mechanical contraction at 3 months after surgery (baseline assessment) and on follow-up echocardiography. Multivariate analysis showed that a lack of LA mechanical contraction at baseline was associated with a 5-fold increase in the risk for stroke (p = 0.02) during follow-up. Larger atria imposed a significant risk as well; LA volume index 33 ml/m2 was associated with a 3-fold risk increase (p = 0.03). These effects were maintained regardless of the lack of mechanical valve implantation and anticoagulation treatment.

CONCLUSIONS: Absence of LA contraction and LA volume index 33 ml/m2 result in a significant increase in the risk for thromboembolic stroke after the Maze procedure for patients in sinus rhythm.

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Cardiac PET/CT for the Evaluation of Known or Suspected Coronary Artery Disease

Positron emission tomography (PET) is increasingly being applied in the evaluation of myocardial perfusion. Cardiac PET can be performed with an increasing variety of cyclotron- and generator-produced radiotracers. Compared with single photon emission computed tomography, PET offers lower radiation exposure, fewer artifacts, improved spatial resolution, and, most important, improved diagnostic performance. With its capacity to quantify rest-peak stress left ventricular systolic function as well as coronary flow reserve, PET is superior to other methods for the detection of multivessel coronary artery disease and, potentially, for risk stratification. Coronary artery calcium scoring may be included for further risk stratification in patients with normal perfusion imaging findings. Furthermore, PET allows quantification of absolute myocardial perfusion, which also carries substantial prognostic value. Hybrid PET-computed tomography scanners allow functional evaluation of myocardial perfusion combined with anatomic characterization of the epicardial coronary arteries, thereby offering great potential for both diagnosis and management. Additional studies to further validate the prognostic value and cost effectiveness of PET are warranted.

PMID: 21918042

Scar Size and Characteristics Assessed by CMR Predict Ventricular Arrhythmias in Ischaemic Cardiomyopathy: Comparison of Previously Validated Models

OBJECTIVES: Sudden cardiac death is a major cause of mortality in patients with ischaemic cardiomyopathy. Risk stratification remains challenging. Currently, there is growing interest in scar characteristic assessment as a predictor of sudden cardiac death using cardiac magnetic resonance imaging (CMR). Standard analysis methods are lacking. The present study evaluated previously validated methods of scar assessment by CMR with late gadolinium enhancement (LGE) in their ability to predict ventricular tachyarrhythmias.

METHODS: Patients with ischaemic cardiomyopathy who received an implantable cardioverter defibrillator for primary prevention and in whom a LGE–CMR was performed, were included. Scar core size, peri-infarct zone and total scar size, which is defined as the sum of the core size and peri-infarct zone, were assessed using three previously validated models, and their ability to predict ventricular tachyarrhythmias was evaluated.

RESULTS: Fifty-five patients were included (mean age 64.6±10.8 years, 43 men). During a median follow-up of 2.0 years (IQR 1.0–3.0 years) 26% of patients reached the endpoint of ventricular tachyarrhythmia. All scar characteristics (ie, total scar size, scar core size and peri-infarct zone) of the three methods were predictors of the endpoint (p

CONCLUSIONS: LGE–CMR-derived scar tissue characteristics are of predictive value for the occurrence of ventricular tachyarrhythmias in patients with ischaemic cardiomyopathy. Additional estimation of scar core size and/or peri-infarct zone does not appear to increase the diagnostic accuracy over total scar size alone.

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Right Ventriculo-Arterial Coupling In Pulmonary Hypertension: A Magnetic Resonance Study

OBJECTIVES: To quantify right ventriculo-arterial coupling in pulmonary hypertension by combining standard right heart catheterisation (RHC) and cardiac magnetic resonance (CMR) and to estimate it non-invasively with CMR alone.

METHODS: This was a cross-sectional analysis in a retrospective cohort of consecutive patients from a tertiary care centre. There were 139 adults referred for pulmonary hypertension evaluation. Interventions: CMR and RHC within 2 days (n=151 test pairs). The main outcome measures right ventriculo-arterial coupling was quantified as the ratio of pulmonary artery (PA) effective elastance (Ea, index of arterial load) to right ventricular maximal end-systolic elastance (Emax, index of contractility). Right ventricular end-systolic volume (ESV) and stroke volume (SV) were obtained from CMR and adjusted to body surface area. RHC provided mean PA pressure (mPAP) as a surrogate of right ventricular end-systolic pressure, pulmonary capillary wedge pressure (PCWP) and pulmonary vascular resistance index (PVRI). Ea was calculated as (mPAP − PCWP)/SV and Emax as mPAP/ESV.

RESULTS: Ea increased linearly with advancing severity as defined by PVRI quartiles (0.19, 0.50, 0.93 and 1.63 mmHg/ml/m2, respectively; p

CONCLUSIONS: Right ventriculo-arterial coupling in pulmonary hypertension can be studied with standard RHC and CMR. Arterial load increases with disease severity whereas contractility cannot progress in parallel, leading to severe uncoupling.

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Prognostic Value of Routine Cardiac Magnetic Resonance Assessment of Left Ventricular Ejection Fraction and Myocardial Damage: An International, Multicenter Study

OBJECTIVES: Cardiac Magnetic Resonance (CMR) is considered the reference standard for assessment of left ventricular ejection fraction (LVEF) and myocardial damage. However, few studies have evaluated the relationship between CMR findings and patient outcome, and of these most are small and none are multicenter. We performed an international, multicenter study to assess the prognostic importance of routine CMR in patients with known or suspected heart disease.

METHODS: Consecutive patients from 10 centers in 6 countries undergoing routine CMR assessment of LVEF and myocardial damage by cine and delayed-enhancement imaging (DE-CMR), respectively, were screened for enrollment. Clinical data, CMR protocol information and findings were collected at all sites and submitted to the data-coordinating center for verification of completeness and analysis. The primary endpoint was all-cause mortality.

RESULTS: A total of 1560 patients (59±14 years; 70% male) were enrolled. Mean LVEF was 45±18% and 1049 patients (67%) had hyperenhanced tissue (HE) on DE-CMR indicative of damage. During a median follow-up time of 2.4 years (IQR 1.2, 2.9 years), 176 patients (11.3%) died. Patients who died were more likely to be older (p4 segments) had reduced survival compared to patients with ≤ median HE (p=0.02).

CONCLUSIONS: Both LVEF and amount of myocardial damage as assessed by routine CMR are independent predictors of all-cause mortality. Even in patients with near normal LVEF, significant damage identifies a cohort with high-risk for early mortality.

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Intra-Aortic Balloon Counterpulsation and Infarct Size in Patients With Acute Anterior Myocardial Infarction Without Shock: The CRISP AMI Randomized Trial

OBJECTIVES: Intra-aortic balloon counterpulsation (IABC) is an adjunct to revascularization in patients with cardiogenic shock and reduces infarct size when placed prior to reperfusion in animal models.To determine if routine IABC placement prior to reperfusion in patients with anterior ST-segment elevation myocardial infarction (STEMI) without shock reduces myocardial infarct size.

METHODS: An open, multicenter, randomized controlled trial, the Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction (CRISP AMI) included 337 patients with acute anterior STEMI but without cardiogenic shock at 30 sites in 9 countries from June 2009 through February 2011.Intervention Initiation of IABC before primary percutaneous coronary intervention (PCI) and continuation for at least 12 hours (IABC plus PCI) vs primary PCI alone.Main Outcome Measures Infarct size expressed as a percentage of left ventricular (LV) mass and measured by cardiac magnetic resonance imaging performed 3 to 5 days after PCI. Secondary end points included all-cause death at 6 months and vascular complications and major bleeding at 30 days. Multiple imputations were performed for missing infarct size data.

RESULTS: The median time from first contact to first coronary device was 77 minutes (interquartile range, 53 to 114 minutes) for the IABC plus PCI group vs 68 minutes (interquartile range, 40 to 100 minutes) for the PCI alone group (P = .04). The mean infarct size was not significantly different between the patients in the IABC plus PCI group and in the PCI alone group (42.1% [95% CI, 38.7% to 45.6%] vs 37.5% [95% CI, 34.3% to 40.8%], respectively; difference of 4.6% [95% CI, -0.2% to 9.4%], P = .06; imputed difference of 4.5% [95% CI, -0.3% to 9.3%], P = .07) and in patients with proximal left anterior descending Thrombolysis in Myocardial Infarction flow scores of 0 or 1 (46.7% [95% CI, 42.8% to 50.6%] vs 42.3% [95% CI, 38.6% to 45.9%], respectively; difference of 4.4% [95% CI, -1.0% to 9.7%], P = .11; imputed difference of 4.8% [95% CI, -0.6% to 10.1%], P = .08). At 30 days, there were no significant differences between the IABC plus PCI group and the PCI alone group for major vascular complications (n = 7 [4.3%; 95% CI, 1.8% to 8.8%] vs n = 2 [1.1%; 95% CI, 0.1% to 4.0%], respectively; P = .09) and major bleeding or transfusions (n = 5 [3.1%; 95% CI, 1.0% to 7.1%] vs n = 3 [1.7%; 95% CI, 0.4% to 4.9%]; P = .49). By 6 months, 3 patients (1.9%; 95% CI, 0.6% to 5.7%) in the IABC plus PCI group and 9 patients (5.2%; 95% CI, 2.7% to 9.7%) in the PCI alone group had died (P = .12).

CONCLUSIONS: Among patients with acute anterior STEMI without shock, IABC plus primary PCI compared with PCI alone did not result in reduced infarct size.

PMID: 21878431

Safety of Serial MRI in Patients With Implantable Cardioverter Defibrillators

OBJECTIVES: While patients with cardiac implantable electronic devices could benefit from magnetic resonance (MR) imaging, the presence of such devices has been designated as an absolute contraindication to MR. Although scanning algorithms are proposed for cardiac implantable electronic devices, their safety remains uncertain. To address this issue, the safety of serial cardiac MR scans was evaluated in patients with implantable cardioverter defibrillators (ICDs).

METHODS: Three serial cardiac MR scans were prospectively performed at 1.5 T on 10 patients (9 men) of median age 56 years (range 51–68) with ICDs. ICD interrogation was performed before and after the MR scan and at a follow-up of median 370 days (range 274–723). Image quality was also assessed.

RESULTS: In all patients MR scanning occurred without complications. There were no differences between pre- and post-MR pacing capture threshold, pacing lead or high voltage lead impedance, or battery voltage values. During follow-up there were no occurrences of ICD dysfunction. Although most patients had image artifacts, the studies were generally diagnostic regarding left ventricular function and wall motion. Delayed enhancement imaging was of good quality for inferior wall and inferolateral infarcts, but ICD artifacts often affected the imaging of anterior wall infarcts.

CONCLUSIONS: Serial MR scans at 1.5 T in patients with ICDs, when carefully performed in a monitored setting, have no adverse effects on either patient or device. When required, single or multiple MR scans at 1.5 T may therefore be considered for clinical diagnostic purposes in these patients.

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Characterization of Cardiac Tumors in Children by Cardiovascular Magnetic Resonance Imaging: A Multicenter Experience

OBJECTIVES: Individual centers have relatively little experience with diagnostic imaging of cardiac tumors in children, because of their low prevalence. The accuracy of cardiac MRI diagnosis on the basis of a pre-defined set of criteria has not been tested.The aim of this study was to report the results of an international multicenter experience of cardiac magnetic resonance imaging (MRI) evaluation of cardiac tumors in children, each with histology correlation or a diagnosis of tuberous sclerosis, and to determine which characteristics are predictive of tumor type.

METHODS: An international group of pediatric cardiac imaging centers was solicited for case contribution. Inclusion criteria comprised: 1) age at diagnosis 18 years; 2) cardiac MRI evaluation of cardiac tumor; and 3) histologic diagnosis or diagnosis of tuberous sclerosis. Data from the cardiac MRI images were analyzed for mass characteristics. On the basis of pre-defined cardiac MRI criteria derived from published data, 3 blinded investigators determined tumor type, and their consensus diagnoses were compared with histologic diagnoses.

RESULTS: Cases (n = 78) submitted from 15 centers in 4 countries had the following diagnoses: fibroma (n = 30), rhabdomyoma (n = 14), malignant tumor (n = 12), hemangioma (n = 9), thrombus (n = 4), myxoma (n = 3), teratoma (n = 2), and paraganglioma, pericardial cyst, Purkinje cell tumor, and papillary fibroelastoma (n = 1, each). Reviewers who were blinded to the histologic diagnoses correctly diagnosed 97% of the cases but included a differential diagnosis in 42%. Better image quality grade and more complete examination were associated with higher diagnostic accuracy.

CONCLUSIONS: Cardiac MRI can predict the likely tumor type in the majority of children with a cardiac mass. A comprehensive imaging protocol is essential for accurate diagnosis. However, histologic diagnosis remains the gold standard, and in some cases malignancy cannot be definitively excluded on the basis of cardiac MRI images alone.

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Pharmacology in Nuclear Cardiology

Although exercise remains the preferred method of cardiac stress testing, pharmacological stress plays an important role in nuclear cardiology. The globally ageing population will see an expansion of the application of pharmacological stress testing, and with this, comes the need to understand the pharmacological basis, mechanisms of action, potential interactions and adverse effects to inform usage in less-than-ideal circumstances. This study aims to enhance the decision-making process in day-to-day clinical nuclear cardiology practice through a better understanding of nuances relevant to the pharmacological agents used for cardiac stress testing.

PMID: 21471849

Myocardial Tagging by Cardiovascular Magnetic Resonance: Evolution of Techniques–Pulse Sequences, Analysis Algorithms, and Applications

Cardiovascular magnetic resonance (CMR) tagging has been established as an essential technique for measuring regional myocardial function. It allows quantification of local intramyocardial motion measures, e.g. strain and strain rate. The invention of CMR tagging came in the late eighties, where the technique allowed for the first time for visualizing transmural myocardial movement without having to implant physical markers. This new idea opened the door for a series of developments and improvements that continue up to the current day. Different tagging techniques are currently available that are more extensive, improved, and sophisticated than they were twenty three years ago. Each of these techniques has different versions for improved resolution, signal-to-noise ratio (SNR), scan time, anatomical coverage, three-dimensional capability, and image quality. The tagging techniques covered in this article can be broadly divided into two main categories: 1) Basic techniques, which include magnetization saturation, spatial modulation of magnetization (SPAMM), delay alternating with nutations for tailored excitation (DANTE), and complementary SPAMM (CSPAMM); and 2) Advanced techniques, which include harmonic phase (HARP), displacement encoding with stimulated echoes (DENSE), and strain encoding (SENC). Although most of these techniques were developed by separate research groups and evolved from different backgrounds, they are in fact closely related to each other, and can be interpreted from more than one perspective. Some of these techniques even followed parallel paths of developments, as illustrated in the article. As each technique has its own advantages, some efforts have been made to combine different techniques for improved image quality or composite information acquisition. In this review, different developments in pulse sequences and related image processing techniques are described along with the necessities that led to their invention, which makes this article straightforward to read and the covered techniques easy to follow. Most major studies that applied CMR tagging for studying myocardial mechanics are also summarized. Finally, the current article includes a plethora of ideas and techniques with over 300 references that motivate the reader to think about the future of CMR tagging.

PMID: 21798021