Magnetic resonance imaging can also be used for imaging Chagas' myocardiopathy to show the heart changes in this disease, although having the drawback of being expensive and time consuming when compared with ultrasound. It is useful in differentating between Chagasic cardiac insufficiency (caused by segmental cardiomyopathy) and idiopathic cardiac dilatation, and is useful also in detection of areas more severely affected with myocarditis, especially when heart biopsy is being considered for diagnosis. Areas of myocarditis may enhance with paramagnetic contrast agents such as gadolinium on T2-weighted images. (Fig. 4.36); ongoing work in this area is being done at the Heart Institute (INCOR) of Sao Paulo, Brazil. MRI can also demonstrate quite well the presence of a mural thrombus (Fig. 4.37) or an apical ventricular aneurysm (Fig. 4.38).

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Fig. 4.36 MRI study of the heart showing gadolinium enhancement of areas of myocarditis caused by Chagas' disease. (A) Precontrast (B) Postcontrast. (Courtesy of Dr. Giovani Guido Cerri, INCOR, Sao Paulo).

Fig. 4.37 Magnetic resonance imaging of the heart. Axial section through the short axis of the apex of the left ventricle showing a high signal filling defect corresponding to a mural thrombus within the chamber.

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Fig. 4.38 Magnetic resonance study of the heart of a patient with Chagas' myocardiopathy. T1-weighted images (A and B) obtained in a sagittal-oblique plane through the long axis of the left ventricle showing an apical aneurysm (arrowheads).