Anne Shu-Lei Chin MD, Presenter: Nothing to Disclose

Robert John Herfkens MD, Abstract Co-Author: Consultant, Bracco Group, Milan, Italy

To solve some limitations of conventional CE-MRA, we evaluated a 3D balanced SSFP ECG-gated, respiratory-navigated free-breathing MR angiography sequence for imaging the thoracic aorta without contrast medium.

Twenty consenting patients referred for evaluation of the thoracic aorta were imaged under an IRB-approved protocol using a 3D balanced SSFP ECG-gated, respiratory-navigated free-breathing MR angiography (MRA)sequence on a 1.5T MR system (Twin Speed, GE Medical Systems, Waukesha, WI). Non-contrast MRA was performed using the following parameters: TR=3.9 ms, TE=2.4 ms, FA=90 degrees, matrix 256x256, FOV 30-35 cm, BW=125 kHz, slice thickness 2.4 mm with 1.2 mm slice spacing. Two overlapping slabs were acquired using 20 localizations per slab, and a cardiac trigger delay set in mid-diastole individualized for each patient. A respiratory navigator was used to image at end-expiration yielding a scan efficiency between 30-40%. Conventional CE-MRA was also performed in half the patients using 0.1 mmol/kg gadolinium administered @ 2cc/sec using the following parameters: TR/TE = 3.9/0.9 ms, slice thickness 2.4 mm with 1.2 mm slice spacing, FOV= 30-35 cm, matrix 512x192, scan time less than 30 secs. Signal-to-noise ratio (SNR) was measured at pre-determined regions of the thoracic aorta. A subjective visual score for image quality and vessel sharpness on a scale from 1 to 4 was assessed for each region. Any artifactual degradation of image quality was also noted.

Superior SNR, less motion artifact, and improved visibility of the thoracic aorta with more sharply defined borders was obtained using 3D balanced SSFP ECG-gated, respiratory-navigated free-breathing MRA. This allows for more accurate measurements of the aortic root and ascending aorta compared with CE-MRA.

3D balanced SSFP ECG-gated, respiratory-navigated free-breathing MR angiography provides high-resolution, motion-free evaluation of the thoracic aorta without need for contrast media.

Pre-surgical measurements for root or ascending aortic pathology needs to be precise for surgical planning and follow-up. To date, conventional CE-MRA and non-gated CT angiography remain inadequate.

Chin, A, Herfkens, R, Three-dimensional (3D) Balanced Steady State Free Precession (SSFP) ECG-Gated, Respiratory-Navigated, Free-Breathing MR Angiography: A Non-contrast Solution for Root and Ascending Aortic Imaging.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5005079.html