3D myocardial tissue tracking with slice followed cine DENSE MRI

PURPOSE: To track three-dimensional (3D) myocardial tissue motion using slice followed cine displacement encoded imaging with stimulated echoes (DENSE). MATERIALS AND METHODS: Slice following (SF) has previously been developed for 2D myocardial tagging to compensate for the effect of through-plane motion on 2D tissue tracking. By incorporating SF into a cine DENSE sequence, and applying displacement encoding in three orthogonal directions, we demonstrate the ability to track discrete elements of a slice of myocardium in 3D as the heart moves through the cardiac cycle. The SF cine DENSE tracking algorithm was validated on a moving phantom, and the effects of through-plane motion on 2D cardiac strain were investigated in six healthy subjects. RESULTS: A through-plane tracking accuracy of 0.46 +/- 0.32 mm was measured for a typical range of myocardial motion using a rotating phantom. In vivo 3D measurements of cardiac motion were consistent with prior myocardial tagging results. Through-plane rotation in a mid-ventricularshort-axis view was shown to decrease the magnitude of the 2D end-systolic circumferential strain by 3.91 +/- 0.43% and increase the corresponding radial strain by 6.01 +/- 1.07%. CONCLUSION: Slice followed cine DENSE provides an accurate method for 3D tissue tracking.     

Myocardial 3D strain calculation by combining cine displacement encoding with stimulated echoes (DENSE) and cine strain encoding (SENC) imaging

Three‐dimensional (3D) strain maps of the myocardium provide a coordinate‐system–independent quantification of myocardial deformation and kinematics. We combine two MRI techniques, displacement encoding with stimulated echoes (DENSE) and strain encoding (SENC), to fully formulate a 3D strain map in a single slice of myocardium. The method utilizes 2D DENSE in‐plane displacement measurements in two adjacent slices in conjunction with a single SENC through‐plane strain measure to calculate the 3D strain tensor. Six volunteers were imaged and the technique demonstrated 3D strain measures in all volunteers that are consistent with those reported in the literature from 3D tagging. The mean peak strain (± standard deviation [SD]) for six healthy volunteers for the first, second, and third principal strains are 0.42 ±0.11, –0.10 ±0.03, and –0.21 ±0.02, respectively. These results show that this technique is capable of reliably quantifying 3D cardiac strain. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Myocardial tissue tracking with two-dimensional cine displacement-encoded MR imaging: development and initial evaluation

A breath-hold two-dimensional cine magnetic resonance (MR) pulse sequence based on displacement encoding with stimulated echoes (DENSE) for quantitative myocardial motion tracking was developed and evaluated. In the sequence, complementary spatial modulation of magnetization was used for time-independent artifact suppression, and echo-planar imaging was used for rapid data sampling. Twelve healthy volunteers underwent cine DENSE MR imaging, and six of them also underwent conventional MR imaging myocardial tagging. The circumferential shortening component of strain (E(cc)) was measured on cine DENSE MR images and conventional tagged MR images. With complementary spatial modulation of magnetization, 10% or less of the total cine DENSE MR image energy was attributed to an artifact-generating echo during systolic imaging. Two-dimensional intramyocardial displacement and strain were measured at cine DENSE MR imaging with spatial resolution and temporal resolution of 2.7 x 2.7 mm and 60 msec, respectively. E(cc) measured at cine DENSE MR imaging correlated well with that measured at conventional MR imaging tagging (slope = 0.88, intercept = 0.00, R = 0.87).     

Increasing the signal-to-noise ratio in DENSE MRI by combining displacement-encoded echoes.

A new technique was developed to increase the signal-to-noise ratio (SNR) in displacement encoding with stimulated echoes (DENSE) MRI. This signal-averaged DENSE (sav-DENSE) technique is based on the SNR advantage of extracting a pair of DENSE images with uncorrelated noise from the complex complementary spatial modulation of the magnetization image, and combining them during image reconstruction. Eleven healthy volunteers were imaged at three short-axis locations with the use of sav-DENSE, cine DENSE, and myocardial tagging pulse sequences. In this study, sav-DENSE increased the SNR by 15-34% as compared to cine DENSE. Circumferential strain values measured by sav-DENSE and myocardial tagging were strongly correlated (slope = 0.95, intercept = -0.02, R = 0.92) and within the 95% limits of agreement. The breath-hold sav-DENSE technique yielded relatively accurate and precise quantification of 2D intramyocardial function, with a 40.2-ms temporal resolution and a 3.5 x 3.5 mm2 spatial resolution.     

Numerical and in vivo validation of fast cine displacement‐encoded with stimulated echoes (DENSE) MRI for quantification of regional cardiac function

Quantitative assessment of regional cardiac function can improve the accuracy of detecting wall motion abnormalities due to heart disease. While recently developed fast cine displacement‐encoded with stimulated echoes (DENSE) MRI is a promising modality for the quantification of regional myocardial function, it has not been validated for clinical applications. The purpose of this study, therefore, was to validate the accuracy of fast cine DENSE MRI with numerical simulation and in vivo experiments. A numerical phantom was generated to model physiologically relevant deformation of the heart, and the accuracy of fast cine DENSE was evaluated against the numerical reference. For in vivo validation, 12 controls and 13 heart‐disease patients were imaged using both fast cine DENSE and myocardial tagged MRI. Numerical simulation demonstrated that the echo‐combination DENSE reconstruction method is relatively insensitive to clinically relevant resonance frequency offsets. The strain measurements by fast cine DENSE and the numerical reference were strongly correlated and in excellent agreement (mean difference = 0.00; 95% limits of agreement were 0.01 and ?0.02). The strain measurements by fast cine DENSE and myocardial tagged MRI were strongly correlated (correlation coefficient = 0.92) and in good agreement (mean difference = 0.01; 95% limits of agreement were 0.07 and ?0.04). Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

3D cine displacement‐encoded MRI of pulsatile brain motion

Pulsatile brain motion is considered to be an important mechanical link between blood and cerebrospinal fluid (CSF) dynamics. Like many severe brain diseases, different types of hydrocephalus are associated with impairment of these dynamics. In this work a cine displacement‐encoded imaging method employing stimulated echoes (DENSE) and a three‐dimensional (3D) segmented echo‐planar imaging (EPI) readout for brain motion measurements in all three spatial directions is presented. Displacement‐encoded data sets of 12 healthy volunteers were analyzed with respect to reproducibility, periodicity, and intra‐ as well as intersubject physiological consistency. In addition, displacement values were compared with data derived from phase‐contrast (PC) velocity measurements in a subset of all measured subjects. Using DENSE, displacements as low as 0.01 mm could be detected and observation of the 3D pulse pressure wave propagation was possible. Among other parameters, peak displacements in the central brain regions were measured: feet–head (FH): thalamus (0.13 ± 0.01 mm); right–left (RL): thalamus (0.06 ± 0.01 mm); and anterior–posterior (AP): caudate nucleus (0.05 ± 0.01 mm). Magn Reson Med 61:153–162, 2009. © 2008 Wiley‐Liss, Inc.     

Circumferential strain in the wall of the common carotid artery: Comparing displacement‐encoded and cine MRI in volunteers

The walls of conduit arteries undergo cyclic stretching from the periodic fluctuation of arterial pressure. Atherosclerotic lesions have been shown to localize to regions of excessive stretching of the arterial wall. We employed a displacement encoding with stimulated echoes (DENSE) sequence to image the motion of the common carotid artery wall and map the two‐dimensional (2D) circumferential strain. The sequence utilizes a fully‐balanced steady‐state free‐precession (SSFP) readout with 0.60 mm in‐plane resolution. Preliminary results in volunteers at 1.5T (N = 4) and 3.0T (N = 17) are compared to measurements of the lumen circumference from cine images. The agreement between the two independent measurements at both field strengths (P ≤ 0.001) supports the use of DENSE as a means to map the pulsatile strain in the carotid artery wall. Magn Reson Med 60:8–13, 2008. © 2008 Wiley‐Liss, Inc.     

Selective suppression of artifact‐generating echoes in cine DENSE using through‐plane dephasing

In displacement‐encoded imaging with stimulated echoes (DENSE), tissue displacement is encoded in the phase of the stimulated echo. However, three echoes generally contribute to the acquired signal (the stimulated echo, the complex conjugate of the stimulated echo, and an echo due to T₁ relaxation). It is usually desirable to suppress all except the stimulated echo, since otherwise the additional echoes will cause displacement measurement errors. Ideally, suppression of the artifact‐generating echoes would be independent of time, T₁, and displacement‐encoding frequency, and would not require additional acquisitions. In this study through‐plane gradients were used to selectively dephase artifact‐generating echoes without causing significant signal loss of the stimulated echo. A cine DENSE sequence was modified to include dephasing gradients and perform complementary spatial modulation of magnetization (CSPAMM). For single‐acquisition cine DENSE using dephasing alone, artifact suppression was similar to CSPAMM with two acquisitions. The use of dephasing with CSPAMM required two acquisitions, but demonstrated greater artifact suppression than CSPAMM alone or dephasing alone. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.     

Single‐breath‐hold multiple‐slice DENSE MRI

A method to acquire multiple displacement encoded slices within a single breath hold is presented. Efficiency is improved over conventional DENSE without compromising image quality by readout of multiple slices in the same cardiac cycle, thus utilizing the position‐encoded stimulated echo available in the whole heart. The method was evaluated by comparing strain values obtained using the proposed method to strain values obtained by conventional separate breath‐hold single‐slice DENSE acquisitions. Good agreement (Lagrangian E₂ strain bias = 0.000, 95% limits of agreement ± 0.04, root‐mean‐square‐difference 0.02 [9.4% of mean end‐systolic E₂]) was found between the methods, indicating that the proposed method can replace a multiple breath‐hold acquisition. Eliminating the need for multiple breath holds reduces the risk of changes in breath‐hold positions or heart rate, results in higher patient comfort, and facilitates inclusion of DENSE in a clinical routine protocol. Magn Reson Med 63:1411–1414, 2010. © 2010 Wiley‐Liss, Inc.     

Real‐time single‐heartbeat fast strain‐encoded imaging of right ventricular regional function: Normal versus chronic pulmonary hypertension

Patients with pulmonary hypertension and suspected right ventricular (RV) dysfunction often have dyspnea at rest, making reliable assessment of RV function using traditional breath‐holding methods difficult to perform. Using single‐heartbeat fast strain encoding (Fast‐SENC) imaging, peak systolic RV circumferential and longitudinal strains were measured in 11 healthy volunteers and 11 pulmonary hypertension patients. Fast‐SENC RV longitudinal strain and circumferential strain measurements were compared to conventional SENC and MR tagging, respectively. Fast‐SENC circumferential and longitudinal RV shortening correlated closely with SENC measurements (r = 0.86, r = 0.90, P < 0.001 for all). Circumferential strain, by conventional tagging, showed moderate correlation with Fast‐SENC in pulmonary hypertension patients only (r = 0.5, P = 0.003). A nonuniform pattern of RV circumferential shortening was depicted in both groups. Peak systolic circumferential strain was significantly reduced at the basal RV in pulmonary hypertension patients (?18.06 ± 3.3 versus ?21.9 ± 1.9, P < 0.01) compared to normal individuals, while peak systolic longitudinal strain was significantly reduced at all levels (P < 0.01 for all). Fast‐SENC is a feasible and reliable technique for rapid quantification of RV regional function in a single‐heartbeat acquisition. Information derived from Fast‐SENC allows characterization of RV regional function in normal individuals and in pulmonary hypertension patients. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Balanced multipoint displacement encoding for DENSE MRI

Displacement encoding with stimulated echoes (DENSE) is a quantitative imaging technique that encodes tissue displacement in the phase of the acquired signal. Various DENSE sequences have encoded displacement using methods analogous to the simple multipoint methods of phase contrast (PC) MRI. We developed general n‐dimension balanced multipoint encoding for DENSE. Using these methods, phase noise variance decreased experimentally by 73.7%, 65.6%, and 61.9% compared with simple methods, which closely matched the theoretical decreases of 75%, 66.7%, and 62.5% for one‐dimensional (1D), 2D, and 3D encoding, respectively. Phase noise covariances decreased by 99.2% and 99.3% for balanced 2D and 3D encoding, consistent with the zero‐covariance prediction. The direction bias inherent to the simple methods was decreased to almost zero using balanced methods. Reduced phase noise and improved displacement and strain maps using balanced methods were visually observed in phantom and volunteer images. Balanced multipoint encoding can also be applied to PC MRI. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Single breath‐hold assessment of ventricular volumes using 32‐channel coil technology and an extracellular contrast agent

Purpose:

To evaluate the feasibility of a single breath‐hold 3D cine balanced steady‐state free precession (b‐SSFP) sequence after gadolinium diethylenetriamine penta‐acetic acid (Gd‐DTPA) injection for volumetric cardiac assessment.

Materials and Methods:

Fifteen adult patients routinely referred for cardiac magnetic resonance imaging (MRI) underwent quantitative ventricular volumetry on a clinical 1.5T MR‐scanner using a 32‐channel cardiac coil. A stack of 2D cine b‐SSFP slices covering the ventricles was used as reference, followed by a single breath‐hold 3D cine balanced SSFP protocol acquired before and after administration of Gd‐DTPA. The acquisition was accelerated using SENSE in both phase encoding directions. Volumetric and contrast‐to‐noise data for each technique were assessed and compared.

Results:

The 3D cine protocol was accomplished within one breath‐hold (mean acquisition time 20 sec; spatial resolution 2.1 × 2.1 × 10 mm; temporal resolution 51 msec). The contrast‐to‐noise ratio between blood and myocardium was 234 determined for the multiple 2D cine data, and could be increased for the 3D acquisition from 136 (3D precontrast) to 203 (3D postcontrast) after injecting Gd‐DTPA. In addition the endocardial definition was significantly improved in postcontrast 3D cine b‐SSFP. There was no significant difference for left and right ventricular volumes between standard 2D and 3D postcontrast cine b‐SSFP. However, Bland–Altman plots showed greater bias and scatter when comparing 2D with 3D cine b‐SSFP without contrast.

Conclusion:

3D cine b‐SSFP imaging of the heart using 32 channel coil technology and spatial undersampling allows reliable volumetric assessment within a single breath‐hold after application of Gd‐DTPA. J. Magn. Reson. Imaging 2010;31:838–844. ©2010 Wiley‐Liss, Inc.     

Determination of three‐dimensional ventricular strain distributions in gene‐targeted mice using tagged MRI

A model‐based method for calculating three‐dimensional (3D) cardiac wall strain distributions in the mouse has been developed and tested in a genetically engineered mouse model of dilated cardiomyopathy. Data from MR tagging and harmonic phase (HARP) tracking were used to measure material point displacements, and 3D Lagrangian strains were calculated throughout the entire left ventricle (LV) with a deformable parametric model. A mouse model where cardiomyocytes are specifically made deficient in vinculin (VclKO) were compared to wild‐type (WT) littermates. 3D strain analysis revealed differences in LV wall mechanics between WT and VclKO mice at 8 weeks of age when systolic function had just begun to decline. Most notably, end‐systolic radial strain and torsional shear were reduced in VclKO hearts which contributed to regional mechanical dysfunction. This study demonstrates the feasibility of using MRI tagging methods to detect alterations in 3D myocardial strain distributions in genetically engineered mouse models of cardiovascular disease. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Generalized spatiotemporal myocardial strain analysis for DENSE and SPAMM imaging

Displacement encoding using stimulated echoes (DENSE) and spatial modulation of magnetization (SPAMM) are MRI techniques for quantifying myocardial displacement and strain. However, DENSE has not been compared against SPAMM in phantoms exhibiting nonhomogeneous strain, and interobserver variability has not been compared between DENSE and SPAMM. To perform these comparisons, there is a need for a generalized analysis framework for the evaluation of myocardial strain. A spatiotemporal mathematical model was used to represent myocardial geometry and motion. The model was warped to each frame using tissue displacement maps calculated from either automated phase unwrapping (DENSE) or nonrigid registration (SPAMM). Strain and motion were then calculated from the model using standard methods. DENSE and SPAMM results were compared in a deformable gel phantom exhibiting known nonhomogeneous strain, and interobserver errors were determined in 19 healthy human volunteers. Nonhomogeneous strain in the phantom was accurately quantified using both DENSE and SPAMM. In the healthy volunteers, DENSE produced better interobserver errors than SPAMM for radial strain (-0.009 ± 0.069 vs. 0.029 ± 0.152, respectively, bias ± 95% confidence interval). In conclusion, generalized spatiotemporal modeling enables robust myocardial strain analysis for DENSE or SPAMM.     

Transmural myocardial strain in mouse: Quantification of high‐resolution MR tagging using harmonic phase (HARP) analysis

MR tagging allows noninvasive examination of regional myocardial function with high accuracy and reproducibility. The current tagging method is limited by low tagging resolution for accurate transmural strain quantification. Previously, a spatial modulation of magnetization (SPAMM)‐based method was proposed to increase the tagging resolution by combining two or more tagged images with different tagging grid positions. However, there has been limited application due to the challenge in image processing of multiple data sets. In the current study, we propose a harmonic phase (HARP)‐based method for automated and fast analysis of high tagging resolution images. First‐order harmonic peaks from low tagging resolution images were combined to generate the composite second‐order harmonic peak for strain computation. The combined images reached a tagging resolution of 0.3 mm. The proposed method was applied to the quantification of transmural myocardial wall strain in seven normal C57BL/6 mice. Principal strains, as well as radial and circumferential strains, were quantified using the current method. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Complementary displacement-encoded MRI for contrast-enhanced infarct detection and quantification of myocardial function in mice.

MRI is emerging as an important modality for assessing myocardial function in transgenic and knockout mouse models of cardiovascular disease, including myocardial infarction (MI). Displacement encoding with stimulated echoes (DENSE) measures myocardial motion at high spatial resolution using phase-reconstructed images. The current DENSE technique uses inversion recovery (IR) to suppress T(1)-relaxation artifacts; however, IR is ill-suited for contrast-enhanced infarct imaging in the heart, where multiple T(1) values are observed. We have developed a modified DENSE method employing complementary acquisitions for T(1)-independent artifact suppression. With this technique, displacement and strain are measured in phase-reconstructed images, and contrast-enhanced regions of infarction are depicted in perfectly coregistered magnitude-reconstructed images. The displacement measurements and T(1)-weighted image contrast were validated with the use of a rotating phantom. Modified DENSE was performed in mice (N = 9) before and after MI. Circumferential (E(cc)) and radial (E(rr)) strain were measured, and contrast-enhanced infarcted myocardium was detected by DENSE. At baseline, E(cc) was -0.16 +/- 0.01 and E(rr) was 0.39 +/- 0.07. After MI, E(cc) was 0.04 +/- 0.02 and E(rr) was 0.03 +/- 0.04 in infarcted regions, whereas E(cc) was -0.12 +/- 0.02 and E(rr) was 0.38 +/- 0.09 in noninfarcted regions. In vivo E(cc) as determined by DENSE correlated well with E(cc) obtained by conventional tag analysis (R = 0.90).     

Visualization of multidirectional regional left ventricular dynamics by high‐temporal‐resolution tissue phase mapping

Purpose

To apply high‐temporal‐resolution tissue phase mapping (TPM) to derive a detailed representation of normal regional myocardial motion in a large cohort of 58 normal subjects (three age groups) and one patient with dilated cardiomyopathy.

Materials and Methods

Analysis included transformation of the acquired myocardial velocities into radial, circumferential, and long‐axis motion components representing left ventricular (LV) function with a spatiotemporal resolution of 1.3 × 2.6 × 8 mm³ and 13.8 msec, respectively. To compare multidirectional regional myocardial velocities between groups of subjects, a multisegment and multislice visualization model was employed. Regional myocardial motion was mapped onto the visualization model to display the current status of myocardial motion from base to apex as in‐plane velocity vector fields in conjunction with color‐coded long‐axis plane motion. Moreover, correlation analysis was used to investigate regional differences in myocardial dynamics.

Results

Age‐related changes in LV myocardial velocities resulted in significant differences of peak and time‐to‐peak velocities in the radial and long‐axis directions. Correlation analysis revealed clearly visible regional differences in the temporal evolution of long‐axis and circumferential velocities, particularly between the youngest and oldest age groups. Comparison of pathological LV motion with age‐matched volunteers indicated marked regional alterations in myocardial velocities and dynamics.

Conclusion

High‐temporal‐resolution TPM in combination with a schematic visualization model and correlation analysis permits the identification of local changes in myocardial velocities associated with different age groups and a common LV pathology. J. Magn. Reson. Imaging 2009;29:1043–1052. © 2009 Wiley‐Liss, Inc.     

Strain‐encoded cardiac MR during high‐dose dobutamine stress testing: Comparison to cine imaging and to myocardial tagging

Purpose

To investigate regional strain response during high‐dose dobutamine stress cardiac magnetic resonance imaging (DS‐CMR) using myocardial tagging and Strain‐Encoded MR (SENC).

Materials and Methods

Stress induced ischemia was assessed by wall motion analysis, by tagged CMR and by SENC in 65 patients with suspected or known CAD who underwent DS‐CMR in a clinical 1.5 Tesla scanner. Coronary angiography deemed as the standard reference for the presence or absence of CAD (≥50% diameter stenosis) in all patients.

Results

SENC and conventional tagging detected abnormal strain response in six and five additional patients, respectively, who were missed by cine images and proved to have CAD by angiography (P < 0.05 for SENC versus cine, P = 0.06 for tagging versus cine and p = NS for SENC versus tagging). On a per‐vessel level, wall motion analysis on cine images showed high specificity (95%) but moderate sensitivity (70%) for the detection of CAD. Tagging and SENC yielded significantly higher sensitivity of 81% and 89%, respectively (P < 0.05 for tagging and P < 0.01 for SENC versus wall motion analysis, and p = NS for SENC versus tagging), while specificity was equally high (96% and 94%, respectively, P = NS for all).

Conclusion

Both the direct color‐coded visualization of strain on CMR images and the generation of additional visual markers within the myocardium with tagged CMR represent useful adjuncts for DS‐CMR, which may provide incremental value for the detection of CAD in humans. J. Magn. Reson. Imaging 2009;29:1053–1061. © 2009 Wiley‐Liss, Inc.     

Regional right ventricular function and timing of contraction in healthy volunteers evaluated by strain‐encoded MRI

Purpose

To prospectively determine the feasibility and accuracy of strain‐encoded (SENC) magnetic resonance imaging (MRI) for the characterization of the right ventricular free wall (RVFW) strain and timing of contraction at 3.0 Tesla (3T) MRI.

Materials and Methods

In 12 healthy volunteers the RVFW was divided into three segments (anterior, lateral, and inferior) in each of three short‐axis (SA) slices (apical, mid, and basal) and into three segments (apical, mid, and basal) in a four‐chamber view. The study was repeated on a different day and interobserver and interstudy agreements were evaluated.

Results

Maximal systolic longitudinal strain values were highest at the apex and base, with a pronounced decrease in the medial segments (apex: –19.1% ± 1.4; mid: –17.4% ± 2; base: –19.4% ± 2.4, P < 0.001), and maximal systolic circumferential strain showed the highest values at the apex (apex: –18.1% ± 1.7; mid: –17.6% ± 1.2; base: –16.6% ± 0.9, P < 0.001). Peak systolic longitudinal and circumferential shortening occurred earliest at the apex compared to the mid‐ventricle and base. Excellent interobserver and interstudy correlation and agreement were observed.

Conclusion

The use of SENC MRI for the assessment of normal RV contraction pattern is feasible and accurate in 3T MRI. J. Magn. Reson. Imaging 2008;28:1379–1385. © 2008 Wiley‐Liss, Inc.     

Magnetic resonance imaging quantification of left ventricular dysfunction following coronary microembolization

Microembolization is common after coronary interventions, and therefore this MRI study aimed to quantify the effect of coronary microembolization on left ventricular (LV) function. The left anterior descending artery (LAD) was selectively catheterized in an XMR suite (Philips Medical Systems, Best, The Netherlands) in eight pigs to deliver MR contrast media to measure the LAD territory using first‐pass perfusion and for intracoronary delivery of the embolic agent. Cine, tagged, and delayed contrast‐enhanced MRI (DCE‐MRI) was performed to assess LV volumes, ejection fraction, radial and circumferential strain, and viability at baseline, 1 h, and 1 week after microembolization. Histopathology and histochemical staining were used to characterize and measure the extent of microinfarction. The LAD territory was 35% ± 2% LV mass. Patchy microinfarction on DCE‐MRI at 1 week was 22.0% ± 3.6% LAD territory (7.5% LV mass). Microembolization caused persistent decline in ejection fraction (baseline = 49% ± 1%, 1 h = 29% ± 1%, P = 0.02 and 1 week = 36% ± 1%, P = 0.03) and increased end‐diastolic (79.6 ± 3.9 ml, 85.5 ± 4.5 ml, P = 0.03 and 92.4 ± 6.2 ml, P = 0.06, respectively) and end‐systolic (40.8 ± 2.1 ml, 60.2 ± 3.4 ml, P = 0.02 and 59.3 ± 4.8 ml, P = 0.03, respectively) volumes. The microembolized territory was manifested as dysfunctional regions for 1 week on cine and tagged MRI. Histopathology revealed occlusive microemboli surrounded by necrotic tissue undergoing repair. Microinfarction was visualized after coronary microembolization and caused LV dysfunction disproportionate to the size of myocardial damage. It also changed LV geometry and decreased radial and circumferential strain over the course of 1 week. Magn Reson Med, 2009. © 2008 Wiley‐Liss, Inc.