Claudia Maria Hillenbrand PhD, Presenter: Nothing to Disclose

Eddy Wong MS, Abstract Co-Author: Nothing to Disclose

Mark A Griswold PhD, Abstract Co-Author: Nothing to Disclose

Daniel Robert Elgort MS, Abstract Co-Author: Nothing to Disclose

Jonathan Stuart Lewin MD, Abstract Co-Author: Nothing to Disclose

Jeffrey Lewis Duerk PhD, Abstract Co-Author: Nothing to Disclose

Shaoxiong Zhang MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To assess intravascular (IV) parallel acquisition techniques (PAT) for quick screening of long vessel wall segments (i.e. aorta, vena cava) using catheter-based opposed solenoid array coils.

Catheter-based array coils were constructed by mounting 2 or 3 solenoids equidistantly on the tip of a 5F catheter. Elements were connected to individual receivers of a 1.5T MR scanner. Coils were used independently for tracking or combined for IV imaging. To screen suspicious wall pathology within a vascular tree, a rapid acquisition (AQ) of extended longitudinal segments is needed to minimize artifacts from blood flow and motion. Reduction of AQ times can be efficiently accomplished with PAT. Thus, IVPAT using the dedicated micro-arrays was investigated in phantom and porcine imaging trials (n=7). Several IV imaging protocols incl. GE-, SE- and SSFP-sequences were employed. In each case, a full and a reduced k-space image (acceleration factor AF= 2,3) was acquired and compared to each other.

Localized sensitivities for each solenoid which are required for PAT were obtained in phantom trials. Comparison of full k-space and PAT images (e.g. TRUFI, TE/TR 6/12ms, FOV/SL 55/3mm, 128²) from vessel phantoms revealed equivalent overall image quality. No PAT reconstruction artifacts appeared. Decreased signal to noise ratio (SNR) was observed in PAT images outside the region of interest where the coil sensitivity was lowest. Signal losses did not affect the overall image quality in the area of interest. In PAT pig experiments, especially TSE (TE/TR 12/521ms, ETL 11) showed good performance at about 30-50% of the AQ time required by standard imaging.

The feasibility of IVPAT for vessel wall imaging, at significantly reduced AQ times, was shown. SNR differences were less than √1/(1-AF), predicted by the decreased AQ time and use of PAT. This suggests a successful trade-off in AQ time and motion artifact immunity. By using PAT and extending the number of micro coils, a larger segment can be covered and higher AF may be realized. This may facilitate time efficient IV survey imaging and has the positive side effect of providing enhanced tracking capabilities from multiple markers.

J.S.L.,J.L.D.: Research grant by Siemens Medical Solutions.

Hillenbrand, C, Wong, E, Griswold, M, Elgort, D, Lewin, J, Duerk, J, Zhang, S, et al, , Assessment of Intravascular Parallel MR Imaging.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4414595.html