La rapidité d’acquisition des nouvelles générations de TDM hélicoïdale en synchronisation rétrospective et l’obtention d’images isotropiques ont donné une avance provisoire à cette technique sur l’IRM. Provisoire, car les nouvelles techniques de balayage de l’espace de Fourier permettent de s’affranchir actuellement des problèmes des mouvements respiratoires et cardiaques grâce à des acquisitions très rapides en apnée, avec une résolution spatiale presque aussi bonne qu’en TDM. Le mythe des acquisitions plus difficiles à programmer en IRM, car dans le plan des coronaires et non dans le plan axial de la TDM, est faux à partir du moment où l’on connaît le trajet des trois artères coronaires principales.

Dans la course à l’imagerie non invasive des artères coronaires, les deux techniques se rapprochent l’une de l’autre, tout en apportant des informations cliniquement pertinentes.

The advent of helical multidetector CT has significantly modified several traditional clinical approaches to cardiovascular diagnosis. The current availability of rapid image acquisition has provided the basis for investigating direct imaging in real time of cardiac structures using CT. Application of thin-section submillimetric image acquisitions to three-dimensional (3D) reconstruction algorithms produces 3D data sets from which images of the coronary arteries may be obtained in any anatomic plane. The advantage of the submillimetric isotropic spatial resolution is partly offset by reduced temporal resolution as well as reduced contrast resolution compared to MRI. This lack in contrast sensitivity prevents accurate perfusion imaging and restricts the clinical use to coronary artery imaging. Moreover, the large amount of iodinated contrast medium injected has potential nephrotoxic effects, which can be deleterious if coronary artery angiography must to be performed. On the other hand, MRI has less spatial resolution, and acquisitions must be performed in the plane of each coronary artery because of reduced volume coverage.

Both techniques play a role in the non-invasive assessment of coronary artery disease, by providing complementary information already useful in a growing number of clinical situations.