Page 115 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

• Delayed Contrast Enhancement (DCE) can be used to visualize and quantify the deposition of collagen in the RV myocardium. DCE imaging is performed about ten minutes after injection of a MRI contrast agent. In healthy myocardium, the contrast agent then has been washed out, but in non-viable, damaged and fibrotic myocardium the contrast agent is still present. Thus, ‘’bright is dead’’ with this technique. In two studies it was shown that abnormal DCE is present in the RV and confined to the insertion points of the RV and interventricular septum [29-31]. Interestingly, these findings may suggest that mechanical factors contribute to the occurrence of fibrosis. In both studies, the extent of contrast enhancement correlated positively with mean PAP, and pulmonary vascular resistance and was inversely related to RV ejection fraction. Figure 3 shows a typical example of DCE in PAH. T1 mapping might serve as a good alternative for DCE imaging [32].
• A method to study regional myocardial contraction patterns is myocardial tagging, allowing for the measurement of segmental myocardial strain. This method labels the myocardial tissue with parallel lines or a grid (typical distance 7 mm) of magnetic pre-saturation at the beginning of the cardiac cycle (R-wave of ECG). These lines remain visible as ‘dark’ lines in MRI cine images, and thereby display the regional myocardial strains over the cardiac cycle by changes in the line- or grid-pattern. In PH, the RV myocardial wall is thick enough to explore RV contraction patterns by this technique, but in the non-hypertrophied RV wall spatial resolution of the technique
Chapter 7
Figure 3: Delayed contrast enhancement in a scleroderma patient with pulmonary hypertension. This figure shows extensive delayed contrast enhancement at the insertion points.
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