Wall Motion Imaging Research Articles

Imaging of Wall Motion Coupled With Blood Flow Velocity in the Heart and Vessels in Vivo: A Feasibility Study

The mechanical property and geometry changes as a result of cardiovascular disease affect both the wall motion and blood flow in the heart and vessels, whereas the latter two are also coupled and therefore continuously influence one another. Simultaneous and registered imaging of both cardiovascular wall motion and blood velocity may thus contribute to more complete computational models of cardiovascular mechanical and fluid dynamics as well as provide additional diagnostic information. The objective of this paper was to determine the feasibility of imaging cardiovascular wall motion coupled with blood flow in vivo. Normal ( n = 6) and infarcted ( n = 5) murine left ventricles, and normal ( n = 5) and aneurysmal ( n = 4) murine abdominal aortas, were imaged in longitudinal views with a 30-MHz ultrasound probe. Using electrocardiogram (ECG) gating, 2-D radio-frequency (RF) data were acquired at a frame rate of 8 kHz. The axial wall velocity and blood velocity were estimated using a speckle-tracking technique. Spatially and temporally registered imaging of both cardiovascular wall motion and blood flow was shown to be feasible. Reduced wall motion was detected in the infarcted region, whereas vortex flow patterns were imaged in diastolic phases of both normal and infarcted left ventricles. The myocardial wall motion and blood flow were found to be more synchronous in the normal heart, where the blood moves toward the anteroseptal wall after the mitral valve opens ( i.e., rapid filling phase), and the anteroseptal wall simultaneously undergoes outward motion. In the infarcted heart, however, in the rapid filling phase, the basal anteroseptal wall starts moving about 20 ms before the mitral valve opens and the blood enters the left ventricle. In the normal aorta, the wall motion and blood velocity were uniform and synchronous. In the aneurysmal aorta, reduced and spatially varied wall motion and vortex flow patterns in the aneurysmal sac were found. The wall motion and blood velocity were thus less synchronous in the aneurysmal aorta. Cardiovascular wall motion and blood flow were both imaged in mice in vivo. This dual information may provide important insights for the diagnosis of cardiovascular disease as well as essential parameters for its biomechanical modeling.

A new approach to autocalibrated dynamic parallel imaging based on the Karhunen‐Loeve transform: KL‐TSENSE and KL‐TGRAPPA

TSENSE and TGRAPPA are autocalibrated parallel imaging techniques that can improve the temporal resolution and/or spatial resolution in dynamic magnetic resonance imaging applications. In its original form, TSENSE uses temporal low-pass filtering of the undersampled frames to create the sensitivity map. TGRAPPA uses a sliding-window moving average when finding the autocalibrating signals. Both filtering methods are suboptimal in the least-squares sense and may give rise to mismatches between the undersampled k-space raw data and the corresponding coil sensitivities. Such mismatches may result in aliasing artifacts when imaging patients with heavy breathing, as in real-time imaging of wall motion by MRI following a treadmill exercise stress test. In this study, we demonstrate the use of an optimal linear filter, i.e., the Karhunen-Loeve transform filter, to estimate the channel sensitivity for TSENSE and acquire the autocalibration signals for TGRAPPA. Phantom experiments show that the new reconstruction method has comparable signal-to-noise ratio performance to traditional TSENSE/TGRAPPA reconstruction. In vivo real-time cardiac cine experiments performed in five healthy volunteers post-exercise during rapid respiration show that the new method significantly reduces the chest wall aliasing artifacts caused by respiratory motion (P < 0.001).

Influence of Left Ventricular Hypertrophy and Geometry on Diagnostic Accuracy of Wall Motion and Perfusion Magnetic Resonance During Dobutamine Stress

The purpose of this study was to determine the influence of left ventricular (LV) hypertrophy and geometry on the diagnostic accuracy of wall motion and additional perfusion imaging during high-dose dobutamine/atropine stress magnetic resonance for the detection of coronary artery disease. Combined dobutamine stress magnetic resonance (DSMR)-wall motion and DSMR-perfusion imaging was performed in a single session in 187 patients scheduled for invasive coronary angiography. Patients were classified into 4 categories on the basis of LV mass (normal, ≤ 81 g/m(2) in men and ≤ 62 g/m(2) in women) and relative wall thickness (RWT) (normal, <0.45) as follows: normal geometry (normal mass, normal RWT), concentric remodeling (normal mass, increased RWT), concentric hypertrophy (increased mass, increased RWT), and eccentric hypertrophy (increased mass, normal RWT). Wall motion and perfusion images were interpreted sequentially, with observers blinded to other data. Significant coronary artery disease was defined as ≥ 70% stenosis. In patients with increased LV concentricity (defined by an RWT ≥ 0.45), sensitivity and accuracy of DSMR-wall motion were significantly reduced (63% and 73%, respectively; P<0.05) compared with patients without increased LV concentricity (90% and 88%, respectively; P<0.05). Although accuracy of DSMR-perfusion was higher than that of DSMR-wall motion in patients with concentric hypertrophy (82% versus 71%; P < 0.05), accuracy of DSMR-wall motion was superior to DSMR-perfusion (90% versus 85%; P < 0.05) in patients with eccentric hypertrophy. The accuracy of DSMR-wall motion is influenced by LV geometry. In patients with concentric remodeling and concentric hypertrophy, additional first-pass perfusion imaging during high-dose dobutamine stress improves the diagnostic accuracy for the detection of coronary artery disease.

Diagnostic and prognostic value of myocardial perfusion gated SPECT in orthotopic heart transplant recipients

BackgroundCardiac allograft vasculopathy (CAV) limits long-term survival after heart transplantation. Diagnostic and prognostic value of gated single photon emission computed tomography (gated SPECT) has not been documented in this setting. Methods and ResultsWe identified 110 consecutive heart transplant recipients (with transplantation >18 months) who underwent stress–rest gated SPECT and coronary angiography within 1 month, and were clinically monitored in a single heart transplantation center. Visual scoring of perfusion and wall motion images used a 16-segment model. Left ventricular function was automatically calculated. Coronary angiography was normal in 64 patients (58%) and abnormal in 46 (any CAV, 42%), of whom 19 had severe stenoses. Sensitivity and negative predictive (NPV) value were .63 and .75 for identification of any CAV, and .84 and .96 for severe CAV. Cox regression analysis showed that independent predictors of cardiac death and retransplantation were the presence of any angiographic CAV lesions (RR = 8.816, P = .043) and a stress perfusion defect >3 segments (RR = 5.607, P = .0053). A stress perfusion defect >3 segments predicted the need for late coronary revascularization >2 months (RR = 6.11, P = .0002). ConclusionsWe conclude that perfusion gated SPECT is a useful noninvasive screening test and may be proposed to help identify heart transplant recipients with a high risk of poor clinical outcome. A normal gated SPECT was associated with a low risk of cardiac hard event and might alleviate the need for coronary angiography.

470: Discordance between Morphological and Functional Alterations during Cardiac Allograft Rejection: Diagnostic Value of Myocardial Wall Motion and Deformation Imaging

Although the ISHLT scoring system is the basis of therapeutic decisions for heart transplant acute rejection (AR) it does not always reflect the severity of functional alterations during AR. Myocardial wall motion and deformation analysis, easy to perform by Tissue Doppler (TD) and 2D strain imaging, reveal myocardial dysfunction undetectable by simple echocardiography. We compared the lesions detectable in endomyocardial biopsies (EMBs) with functional data provided by TD and 2D strain imaging.

Influence of left ventricular hypertrophy and geometry on diagnostic accuracy of wall motion and perfusion analysis during dobutamine stress magnetic resonance

Methods Combined wall motion (DSMR) and perfusion imaging (DSMRP) was performed in a single session in 156 patients scheduled for invasive coronary angiography. Patients were classified into four categories based on LV mass (normal ≤81 g/m2 in men, ≤62 g/m2 in women) and relative wall thickness (RWT, normal <0.45): normal geometry, concentric remodeling, concentric hypertrophy and eccentric hypertrophy. Wall motion and perfusion images were interpreted sequentially, blinded to other data. Significant coronary artery disease (CAD) was defined as ≥70% stenosis. from 13th Annual SCMR Scientific Sessions Phoenix, AZ, USA. 21-24 January 2010

Multicontrast late gadolinium enhancement imaging enables viability and wall motion assessment in a single acquisition with reduced scan times

To determine the accuracy of multicontrast late enhancement imaging (MCLE) in the assessment of myocardial viability and wall motion compared to the conventional wall motion and viability cardiac magnetic resonance imaging (MRI) pulse sequences. Forty-one patients with suspected myocardial infarction were studied. Patients underwent assessment of cardiac function with cine steady-state free-precession (SSFP), followed by late gadolinium enhancement (LGE) imaging using inversion recovery gradient echo scanning (IR-GRE) sequence and MCLE. MCLE was compared to cine SSFP in the assessment of wall motion, ejection fraction (EF), left ventricular (LV) mass, LV end-diastolic volume (EDV), and to IR-GRE for measuring infarct size. MCLE, IR-GRE, and SSFP imaging demonstrated excellent agreement in the assessment of EF, LV infarct size, and LV mass (r > 0.95, P < 0.001 for all measures), as well as in the assessment of wall motion (kappa statistic 0.75). MCLE provided coregistered images for the assessment of viability and wall motion without loss of accuracy in the assessment of quantitative cardiac parameters. MCLE provides accurate quantitative cardiac assessment with reduced scan times compared to the conventional sequences and thus may be used as an alternative to conventional cine SSFP and IR-GRE imaging.

Assessing the Prognostic Value of Cardiovascular Imaging

Cardiovascular imaging has become the focus of attention from both physicians and payers. The former see the potential of newer modalities to permit new and exciting insights into the diagnosis and management of coronary artery disease (CAD), that, in turn, may result in enhanced patient care strategies and new efficient clinical algorithms. On the other hand, payers have understandable concerns about the excessive use and enormous costs associated with cardiovascular imaging. These concerns have been exacerbated by the rapid expansion of the imaging devices used for the assessment of patients with known or suspected CAD. Cardiovascular stress imaging has long been the domain of stress single photon emission computed tomography myocardial perfusion imaging (SPECT MPI) and stress echocardiography wall motion studies. At present, stress positron emission tomography (PET) MPI, cardiac computed tomography coronary angiography (CTA) (and, possibly, stress CT MPI), as well as cardiac magnetic resonance imaging (CMR) MPI and wall motion studies are utilized in daily practice. Whether all of these modalities will be reimbursed in the future is uncertain, but little doubt remains that their rigorous validation will be compulsory. Article see p 1390 Cardiac magnetic resonance imaging is an evolving technique with growing indications within the clinical cardiology setting. Whereas late gadolinium enhancement (LGE) has gained acceptance as an accurate approach for viability assessment, CMR stress imaging use is increasing as well. Nonetheless, stress CMR techniques are in their relative infancy, and evidence is only now beginning to accumulate justifying their use. Whereas several studies have examined the diagnostic accuracy of stress CMR, only recently have sufficient numbers of patients been collected to assess the prognostic value of this approach1–5 (Table).6 The validation of stress CMR is more complex than that of previous modalities, inasmuch as a routine study would include rest function and …

Intracardiac Echocardiography‐Guided Cardiac Resynchronization Therapy: Technique and Clinical Application

We undertook a pilot investigation to evaluate the feasibility of a novel technique using intracardiac echocardiography (ICE) for intraoperative assessment of cardiac resynchronization therapy (CRT). We evaluated ICE intraoperative imaging of left ventricular (LV) function and aortic valvular flow as well as safety of implementation. ICE was used to guide CRT system lead placement, assess impact of pacing modes, and optimization of device programming. Twenty-three patients underwent ICE imaging. ICE showed global hypokinesis in six patients, regional wall motion abnormality only in 10 patients, and both in seven patients. Optimized CRT modes included mean atrioventricular (AV) interval of 170 ms and interventricular timing using simultaneous right ventricular (RV)-LV pacing (five patients), LV pacing only (one patient), and sequential LV to RV stimulation (15 patients) or RV to LV stimulation (two patients). ICE-guided CRT acutely improved mean left ventricular ejection fraction (LVEF) from 24 +/- 9% to 41 +/- 1% (P < 0.00001). During follow-up of 3-24 (mean 11) months, New York Heart Association class improved in all patients from a mean of 3.2 +/- 0.4 at implant to 1.6 +/- 0.7 (P < 0.0001), with improvement of LVEF from 19 +/- 7% to 34 +/- 12% (P = 0.0001). Actuarial survival was 83% at 12 months. (1) ICE imaging is reliable and safe for continuous intraoperative imaging of LV wall motion, and assesses baseline status and impact of CRT interventions.(2) Intraoperative ICE-guided CRT optimization resulted in an increase in LVEF acutely and consistent improvement in heart failure.(3) Sequential biventricular pacing and longer AV interval programming were more often used in ICE-guided CRT.

Prognostic correlates of combined coronary flow reserve assessment on left anterior descending and right coronary artery in patients with negative stress echocardiography by wall motion criteria

Aims:To assess the prognostic correlates of Doppler echocardiographically derived coronary flow reserve (CFR) on two coronaries in patients with negative stress echo. Vasodilator stress echocardiography allows dual imaging of regional...

Diagnostic Value of Parametric Imaging of Left Ventricular Wall Motion From Contrast-Enhanced Echocardiograms in Patients With Poor Acoustic Windows

Analysis of left ventricular (LV) regional wall motion (RWM) is subjective and may be challenging in patients with suboptimal images, even with contrast enhancement. It was hypothesized that the amplitude and timing of RWM obtained from contrast-enhanced echocardiograms can be accurately represented in still-frame parametric images. This study was designed to (1) test this hypothesis, (2) establish the diagnostic value of these images as an aid for inexperienced readers, and (3) test the feasibility of automated quantitative analysis of RWM. Contrast-enhanced apical 4-chamber, 2-chamber, and 3-chamber LV views were acquired in 45 patients with poor acoustic windows. The interpretation of dynamic images by an experienced reader who classified RWM as normal or abnormal was used as a reference for comparisons against (1) visual interpretation of parametric images, (2) interpretation of dynamic images by two inexperienced readers (American Society of Echocardiography level I) without and subsequently with parametric images, and (3) automated quantification of RWM. Expert readers detected abnormal RWM in 30 patients (437 of 945 segments). Visual interpretation of parametric images showed good agreement with the reference (sensitivity, 85%; specificity, 82%; accuracy, 84%). The interpretations by inexperienced readers improved with the addition of parametric images, with increases in specificity (from 58% to 79%) and accuracy (from 74% to 84%), despite a slight decrease in sensitivity (from 92% to 91%). Automated classification was feasible and accurate (sensitivity, 82%; specificity, 78%; accuracy, 80%). Parametric images derived from contrast-enhanced echocardiograms of patients with poor acoustic windows accurately depicted RWM, improved the diagnostic accuracy of inexperienced readers, and allowed the objective detection of RWM abnormalities.

Abstract 4185: Does Combined Stress, Delayed Enhancement, and Functional Cardiac Magnetic Resonance Imaging Yield Incremental Prognostic Value and Risk Stratification?

Background. Evaluation of the intermediate risk patient (Pt) using combined cardiac magnetic resonance imaging (CMR) assessment of adenosine stress perfusion (STRESS), myocardial delayed enhancement viability (MDE), and ventricular wall motion imaging (WM) is a promising clinical approach. Whether this technique yields risk stratification and incremental prognostic value over pre-CMR data is uncertain. Methods. We identified 1,002 consecutive patients [Age 64±14, 58% male, 50% prior coronary artery disease (CAD)] undergoing combined CMR for suspicion of CAD or ischemia. STRESS first-pass gadolinium gradient echo pulse sequence, MDE, and steady state free precession WM were interpreted using 17-segment, 5 point scoring. Summed scores (SS) were calculated for each. The primary endpoint was all-cause death (ACD), the secondary endpoint cardiac death (CD). Incremental prognostic value was defined as an increased Cox proportional hazards model (CPH) global chi-square with the addition of CMR data after adjustment for clinical and historical data. Results: Follow-up (FU) at 2.6±1.2 years after CMR (2.4% lost to FU) identified 78 ACD (8.0%) and 38 CD (3.9%). Compared to pts with normal stress CMR (STRESS, MDE, and WM all normal), pts with abnormal results had greater ACD rates over FU (5.9% vs 11%, p=0.006). After adjusting for the most predictive pre-CMR data (dyspnea, rest heart rate, age, and known renal disease; global chi-square 55, p&lt;0.001), the addition of SS from STRESS, MDE, or WM added incremental value for prediction of ACD (chi-squares: 66, 64, 67; all p&lt;0.001, respectively). After adjusting for pre-CMR data and WM SS, only MDE SS added further (chi-square 71, p&lt;0.001); STRESS SS did not add to WM SS (p=0.17). CPH predicting CD identified both STRESS and SWMS as incremental predictors (chi-square 55, p&lt;0.001) Conclusion : STRESS, MDE and WM all add incremental value for prediction of ACD and CD over pre-CMR data and can be combined to further enhance prognostication.

Abstract 2830: Additional Value of Myocardial Perfusion Imaging during Dobutamine Stress Magnetic Resonance for the Assessment of Coronary Artery Disease

Background: Dobutamine stress magnetic resonance (DSMR) imaging has emerged as a valuable tool for the detection of inducible wall motion abnormalities (WMA). The role of perfusion imaging during DSMR is not well defined. We examined whether the addition of myocardial perfusion imaging during DSMR provides incremental benefit for the evaluation of coronary artery disease (CAD). Methods and Results: DSMR was combined with perfusion imaging (DSMRP) in 455 consecutive patients who were scheduled for clinically indicated invasive coronary angiography. Perfusion images were acquired in three standard short axis views at rest and during maximum dobutamine-atropine stress. Wall motion and perfusion images were interpreted sequentially, blinded to other data. Significant (≥70%) stenoses were present in 285 patients in invasive coronary angiography. For the overall population the addition of perfusion imaging improved sensitivity for the detection of CAD (91% versus 85%, P=0.001) with a significant reduction in specificity (70% vs. 82%, P=0.001) and no difference in diagnostic accuracy (84% vs. 84%, P n.s.). DSMRP enabled the correct diagnosis of CAD in an additional 13% of patients. DSMRP enhanced diagnostic accuracy in patients with left ventricular hypertrophy (LVH) (87% vs. 80%, P&lt;0.001), resting WMAs (84% vs. 80%, P&lt;0.001), prior CAD (85% vs. 82%, P&lt;0.001) and it improved sensitivity in patients with single vessel disease (91% vs. 84%, P&lt;0.001). Conclusion: The addition of perfusion imaging during DSMR is a useful technique for the diagnosis of CAD and adds additional diagnostic value in patients with LVH, resting WMAs, prior CAD and single-vessel disease.

Abstract 4234: Prognostic Implication of the Continuous Prognostic Spectrum of Coronary Flow Reserve in Patients with and without Angiographically Obstructive Coronary Artery Disease

Dual imaging of wall motion and coronary flow reserve (CFR) on left anterior descending (LAD) artery is now the state-of-the art technique for vasodilator stress echo. The additive prognostic value of CFR over regional wall motion has been established, but there is more than a binary (normal-abnormal ) response in CFR, which can be continuously titrated. Objectives. To assess the prognostic value of Doppler echocardiographic derived CFR in patients with and without angiographically obstructive coronary artery disease (CAD). 1244 patients (785 men, age 64±11 yy) with known or suspected CAD underwent dipyridamole (up to 0.84 mg/kg over 6′) stress echo with CFR evaluation of left anterior descending artery by Doppler and coronary angiography. Patients were followed-up for a median of 17 months. Mean CFR in the entire population was 2.25±0.64. During follow-up, there were 227 events (26 deaths, 55 STEMI, and 146 NSTEMI). Patients (n=384) undergoing revascularization were censored. Using the Kaplan-Meier method, the lowest quartile of CFR (&lt;1.80) was associated with a significantly (p&lt;0.0001) worst event rate than other quartiles (Figure ), both considering the group with (83 vs 53%, p&lt;0.0001) and without (53 vs 12%, p&lt;0.0001) obstructive CAD at angiography. CFR is a strong and independent prognostic predictor in patients with known or suspected CAD, but the spectrum of prognostic stratification is expanded if the response is titrated according to a continuous scale rather than artificially dichotomized.

Additional Value of Myocardial Perfusion Imaging During Dobutamine Stress Magnetic Resonance for the Assessment of Coronary Artery Disease

Dobutamine stress magnetic resonance (DSMR) imaging has emerged as a valuable tool for the detection of inducible wall motion abnormalities. The role of perfusion imaging during DSMR is not well defined. We examined whether the addition of myocardial perfusion imaging during DSMR provides incremental benefit for the evaluation of coronary artery disease. DSMR was combined with perfusion imaging in 455 consecutive patients who were scheduled for clinically indicated invasive coronary angiography. Perfusion images were acquired in 3 standard short-views at rest and during maximum dobutamine-atropine stress. Wall motion and perfusion images were interpreted sequentially, blinded to other data. Significant (> or =70%) stenoses were present in 285 patients on invasive coronary angiography. The use of DSMR combined with perfusion imaging versus DSMR increased sensitivity (91% versus 85%, P=0.001), but not specificity (70% versus 82%, P=0.001), resulting in identical overall diagnostic accuracy (84% versus 84%, P=NS; Youden index 0.61 versus 0.67). DSMR combined with perfusion imaging enabled the correct diagnosis of coronary artery disease in an additional 13% of DSMR-negative patients at the cost of 11% more false-positive cases. The addition of perfusion imaging during DSMR improves sensitivity for the diagnosis of coronary artery disease but does not enhance overall diagnostic accuracy because of a concomitant decrease in specificity.

Direct imaging of current-induced domain wall motion in CoFeB structures

By direct x-ray photoemission electron microscopy imaging, we probe current-induced domain wall motion in 20nm thick CoFeB wires. We observe transverse walls for all wire widths up to 1500nm as a consequence of the small saturation magnetization of the material. High critical current densities above 1×1012A∕m2 for wall displacement due to the spin transfer torque effect are found. The critical current densities jc increase further with decreasing wire width indicating that jc is governed by extrinsic pinning due to edge defects. In addition to wall displacements, we observe wall transformations to energetically favorable wall types due to heating. Owing to the high Curie temperature though, the sample temperature stays below the Curie temperature even for the highest current densities where structural damage sets in.

Inversion‐recovery‐prepared SSFP for cardiac‐phase‐resolved delayed‐enhancement MRI

Delayed-enhancement magnetic resonance imaging (DE-MRI) can be used to visualize myocardial infarction (MI). DE-MRI is conventionally acquired with an inversion-recovery gradient-echo (IR-GRE) pulse sequence that yields a single bright-blood image. IR-GRE imaging requires an accurate estimate of the inversion time (TI) to null the signal from the myocardium, and a separate cine acquisition is required to visualize myocardial wall motion. Simulations were performed to examine the effects of a steady-state free precession (SSFP) readout after an inversion pulse in the setting of DE-MRI. Using these simulations, a segmented IR-SSFP sequence was optimized for infarct visualization. This sequence yields both viability and wall motion images over the cardiac cycle in a single breath-hold. Viability images at multiple effective TIs are produced, providing a range of image contrasts. In a study of 11 patients, IR-SSFP yielded infarct sizes and left ventricular ejection fractions (LVEFs) similar to those obtained by IR-GRE and standard SSFP, respectively. IR-SSFP images yielded improved visualization of the infarct-blood border because of the simultaneous nulling of healthy myocardium and blood. T(1) (*) recovery curves were extracted from IR-SSFP images and showed excellent qualitative agreement with theoretical simulations.

Contrast dobutamine stress myocardial perfusion echocardiography: current methodology and clinical applications

Accurate evaluation of regional systolic wall thickening by echocardiography is largely dependent on adequate endocardial border resolution. Despite the recent introduction of tissue harmonic imaging, 15-20% of patients have poor endocardial border definition. Even with the use of ultrasonic contrast agents and resulting improvement in the endocardial delineation, conventional dobutamine stress echocardiography, though it has a high sensitivity for the diagnosis of coronary artery disease in patients with multivessel disease on coronary angiography, has limited ability to diagnose multivessel disease on the basis of inducible wall motion abnormalities in multivessel distributions. As in the ischemic cascade during demand stress myocardial perfusion abnormalities precede wall motion abnormalities, techniques which image myocardial perfusion as compared to wall motion are able to detect functionally significant coronary artery disease at an earlier stage and potentially at a submaximal stress. With real time myocardial perfusion imaging it is possible to simultaneously assess myocardial perfusion and function not only at rest but also during stress, which makes it a sensitive technique to detect and risk- stratify flow limiting coronary artery disease as compared to conventional wall motion imaging during stress. Furthermore, it has now become feasible to assess the changes in myocardial blood flow that occur during stress testing with the availability of softwares which makes it possible to quantitatively analyse these images, potentially improving the sensitivity and specificity of contrast echocardiography even further. © 2006 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.

Accelerated 4D Dobutamine Stress MR Imaging with k-t BLAST: Feasibility and Diagnostic Performance

To prospectively determine feasibility and diagnostic performance (with angiography as reference standard) of k-space and time (k-t) broad-use linear acquisition speed-up technique (k-t BLAST) cine imaging during dobutamine stress for identification of inducible cardiac wall motion abnormalities. The study was conducted according to standards of the Charité and Virchow-Klinikum Ethics Committee. Patients gave written consent. Dobutamine stress magnetic resonance (MR) imaging was conducted in 65 patients (mean age, 63 years +/- 9 [standard deviation]; 49 men) with conventional cine steady-state free precession (SSFP). Accelerated four-dimensional (4D) k-t BLAST single-breath-hold imaging with complete left ventricular (LV) coverage was also performed at rest and during stress. For the cine SSFP and accelerated cine techniques, duration of imaging at rest and LV end-diastolic volume and ejection fraction were assessed. Segmental agreement for resting and inducible wall motion abnormalities was determined. In a subgroup (n = 40), direct comparison between SSFP and accelerated cine was performed for coronary stenosis detection. A paired Student t test was used to assess significance of continuous variables. Pearson correlation was used to test correlation between the techniques. Sensitivity, specificity, and diagnostic accuracy were calculated (standard definitions). For quantitative measurement of agreement, Cohen kappa was applied. For accelerated cine, imaging duration at rest was shortened by 40%. Correlations between cine SSFP and accelerated cine for LV parameters were 135 mL +/- 37 versus 129 mL +/- 31 (r = 0.89) for end-diastolic volume and 59% +/- 8 versus 58% +/- 7 (r = 0.95) for ejection fraction. kappa Values for segmental wall motion at rest and stress ranged from 0.77 to 0.91. Sensitivity, specificity, and diagnostic accuracy for coronary stenosis (>or=50%) detection based on arterial territory were 82%, 87%, and 86%, respectively, for cine SSFP and 82%, 86%, and 85%, respectively, for accelerated cine imaging. Accelerated 4D k-t BLAST wall motion imaging at rest and at dobutamine stress is rapid and feasible; LV measurements were nearly identical between the imaging approaches. Segmental wall motion analysis at rest and at stress show excellent agreement and reliable depiction of myocardial territories supplied by coronary arteries with 50% or more luminal narrowing.

Myocardial Wall Motion Imaging with Cardiac Magnetic Resonance Imaging

SummaryWall motion imaging with cardiac magnetic resonance imaging (CMR) provides important functional information about global and regional myocardial function. This review will give an overview of the current state of myocardial wall motion imaging, especially focusing on the clinical role of dobutamine stress CMR in ischaemic heart disease. Dobutamine stress CMR provides functional information on the myocardium under conditions of pharmacologically induced stress. High‐dose dobutamine is used for wall motion analysis of the left ventricle. Wall motion abnormalities are indicative of myocardial ischaemia and occur in the ischaemic cascade before the onset of chest pain and ECG abnormalities. As a result of technological advances, dobutamine stress CMR has evolved towards a very accurate cardiac stress test. The current state of dobutamine stress CMR allows us to obtain cine MR images with high spatial and temporal resolution in rest and during stress. The use of myocardial tagging has improved the diagnostic accuracy even further. The addition of first‐pass perfusion imaging at peak dose dobutamine might enhance accuracy even more. Besides being able to detect myocardial ischaemia, low‐dose dobutamine can be used to assess myocardial viability. With these capabilities, viability, wall motion and myocardial perfusion can be assessed in a single examination. The safety and feasibility of dobutamine stress CMR has been proven. The technique and clinical implications are discussed.