Myocardial Extracellular Volume Estimation by CMR Predicts Functional Recovery Following Acute MI

Figures

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  Figure 1. Estimation of Infarct ECV In the per-segment analysis (left), ECV is taken in segments throughout the myocardium (16 segments in 3 short-axis slices, and these regions of interest are motion corrected in the MOLLI sequence before T1 estimation. Pre- and post-contrast T1 images are used to derive ECV. In the per-patient analysis (right), the infarct zone is determined by signal intensity analysis on LGE images, which is then transposed to MOLLI images. Areas of MO are excluded, as are pixels at a tissue interface that may be susceptible to partial volume effects to highlight the infarct zone (yellow contour). This contour is motion corrected for all images in the MOLLI sequence. ECV = extracellular volume; LGE = late gadolinium enhancement; MO = microvascular obstruction; MOLLI = modified Look-Locker inversion.

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  Figure 2. Comparison of LGE Transmural Extent and ECV With Regional Function and Strain (Top) A patient with high acute infarct transmural extent (78%, arrows) on LGE (A) as quantified by threshold analysis (B). There is relatively low infarct ECV (0.44), as illustrated here by the modest gradation from normal myocardial ECV (yellow/green, arrows) on an ECV map (C). Recovery of function is good at 3 months, as seen on cine imaging (systolic image, D, arrows) and normal peak systolic strain (blue myocardium, E). (Bottom) A patient with modest transmural extent of infarction acutely (F and G) has high acute ECV within the infarct zone (0.70, H, arrows). A septal regional wall motion abnormality persists at 3 months (systolic cine image, I, arrows) with decreased strain septally (yellow myocardium, J). Abbreviations as in Figure 1.

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  Figure 3. Comparison of Per-Segment Convalescent Regional Wall Motion Score With LGE Transmural Extent and Infarct ECV (A) LGE transmural extent; (B) infarct ECV. Note relatively wide ranges for transmural extent. Box denotes median and 25th and 75th percentiles; mean is indicated by a plus sign, and whiskers are at 9th and 91st percentiles.

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  Figure 4. Acute Transmural Extent of LGE and Acute Infarct ECV Compared With Improvement in Wall Motion Score Over 3 Months (A) Acute transmural extent of LGE; (B) acute infarct ECV. Data for dysfunctional segments (n = 163) are shown. Abbreviations as in Figure 1.

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  Figure 5. ROC Curve Comparing Infarct ECV and Transmural Extent of Infarction in Dysfunctional Segments (n = 163) With Improvement in Wall Motion Score at 90 Days Remote segments not shown. A variety of thresholds for LGE transmural extent are shown. C-statistic (AUC) and 95% confidence interval is shown in the legend for each method. AUC = area under the curve; FWHM = full-width half-maximum; ROC = receiver-operating characteristic; other abbreviations as in Figure 1.

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  Figure 6. Segmental Analysis Comparing Each Quartile of Acute LGE Transmural Extent With Mean Convalescent Wall Motion Score Groups are split by a cutoff value of 0.5 for acute ECV. A higher score indicates more severe segmental dysfunction. The left bar in each quartile represents patients with ECV <0.5; the right bar represents ECV >0.5. Abbreviations as in Figure 1.

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  Figure 7. Comparison of Convalescent Infarct Zone Strain With Acute Transmural Extent of LGE and Acute Infarct ECV (A) Acute transmural extent of LGE; (B) acute infarct ECV. Per-patient data (n = 35) shown. Abbreviations as in Figure 1.