Anatomy of the thoracic aorta: magnetic resonance imaging and interpretation of flow phenomena

Anatomic and radiologic bases of surgery of the thoracic aorta

Lesions of the thoracic aorta create problems related to their site and relations with the main aortic branches. The aim of surgery must be to treat the lesion while ensuring perfusion of the tissues excluded by clamping during the operation. Anatomic study of the aortic lesions is based on imaging. Angiography is still often the basic examination though it shows only the lumen and course of the aorta. However, CT and MRI visualise the aortic wall and especially the relations of the aorta to the mediastinal structures. A comparison of anatomic and imaging studies was made on 10 fresh subjects coming from the anatomy department of the Saints-Pères and from the school of surgery of Fer à Moulin. Sections were made every 3 to 5 mm in 3 planes (sagittal, coronal and axial) after CT localisation of the plane of section. This anatomic study was correlated with CT and MR images made on healthy volunteers. The choice of surgical management of a lesion of the thoracic aorta is based on preoperative anatomic assessment by imaging applied not only to the aorta but also to its branches and the territory supplied.

Magnetic resonance imaging of the heart compared with anatomic and ultrasonographic data

The authors present a correlation study between the anatomy of the heart and its appearance with magnetic resonance imaging (MRI) and ultrasonography (US). Six hearts were studied by MR, then sliced along the same planes. The results are presented and compared with the data obtained in volunteers by MRI and ultrasonography. The correlation between the MRI of isolated hearts and their anatomic slices is excellent, the thinnest anatomic details are reproduced. The use of double oblique slices provides incidences similar to those of ultrasonography. The same incidences can be obtained in vivo. The morphologic study of the heart by these imaging techniques is thus very precise, as well as the study of cardiac volumes.