MRA innovation mimics cardiac catheterization

August 1, 2004

Duke University researchers introduced a new MR approach at the SCMR meeting that produces cine angiograms analogous to cardiac catheterization without radiation or a contrast agent.

Duke University researchers introduced a new MR approach at the SCMR meeting that produces cine angiograms analogous to cardiac catheterization without radiation or a contrast agent.

The technique developed by Wolfgang G. Rehwald, Ph.D., a senior scientist with Siemens Medical Solutions, captures blood flow information that escapes detection with conventional MR angiography. In a representative 2D blood flow study of a pulmonary artery in canine subjects, blood was shown filling the pulmonary tree for 11 cm. Branch vessels as small as 1.5 mm in diameter were depicted. Rehwald also displayed in vivo examples of the near-real-time sequence in cine images of the human aorta and internal carotid and renal arteries.

The T1-weighted MR pulse sequence exploits a condition called global coherent free precession to create the real-time images, Rehwald said. While in a GCFP state, protons produce a continuous radio-frequency signal even in the absence of RF excitation. The condition creates a steady stream of coherently excited blood that freely precesses as it flows through anatomy that is not affected by the ongoing excitation.