Magnetic resonance acquisition to determine the lumen length of a tortuous phantom aorta.

PURPOSE: Endovascular abdominal aortic aneurysm repair is a technique that requires an accurate measurement of the aneurysm's lumen length prior to the procedure. This study examines the accuracy of luminal length measurement in an aortic phantom using magnetic resonance angiography (MRA) axial source images. METHODS AND RESULTS: Tortuous phantom aortas were constructed using water-filled plastic tubing (7 mm in diameter with lengths of 80 to 160 mm). The tubes were molded into three-dimensional "S" or "C" shapes that simulated the luminal course of a tortuous aorta. Phantoms were imaged at angles of 0 degrees, 15 degrees, 30 degrees, and 45 degrees to the image slice direction on a 1.5T Signa MR scanner using a transaxial two-dimensional time-of-flight (TOF) and a T1-weighted spin-echo acquisition. The luminal length of the phantom was calculated after establishing the lumen center coordinates in axial source images and then measuring the distance between two sequential slices using the Pythagorean theorem. The accuracy of this measurement in the phantom was 89% to 99.6%, proportional to the length of the tubing. Accuracy was not affected by angulation of < 45 degrees. CONCLUSION: Two-dimensional TOF MRA source images can provide an accurate measurement of the phantom aorta's lumen length.