Affiliations: Department of Radiology, Weill Medical College of
Cornell University, New York, NY 10021, USA
Note: [] Corresponding author: Martin R. Prince, MD, PhD, 416 East 55th
Street, New York, NY 10022, USA. Tel.: +1 212 746 6801; Fax: +1 212 752 8908;
E-mail: [email protected]
Abstract: Purpose: To evaluate recessed elliptical centric ordering of k-space
in renal magnetic resonance (MR) angiography. Methods: All imaging was performed on the same 1.5 T MR imaging
system (GE Signa CVi) using the body coil for signal transmission and a phased
array coil for reception. Gd, 30 ml, was injected manually at 2 ml/sec timed
with automatic triggering (SmartPrep). In thirty patients using standard
elliptical centric ordering, the scanner paused 8 seconds between detection of
the leading edge of the Gd bolus and initiation of scanning beginning with the
center of k-space. For the recessed-elliptical centric ordering in 20
consecutive patients, this delay was reduced to 4 seconds but the absolute
center of k-space recessed in by 4 seconds such that in all patients the
absolute center of k-space was acquired 8 seconds after detecting the leading
edge of the bolus. On the arterial phase images signal-to-noise ratio (SNR) was
measured in the aorta, each renal artery and vein and contrast-to-noise ratio
(CNR) was measured relative to subcutaneous fat. The standard deviation of
signal outside the patient was considered to be "noise" for calculation of SNR
and CNR. Incidence of ringing artifact in the aorta and renal veins was
noted. Results: Aorta SNR and CNR was significantly higher with the
recessed technique (p = 0.02) and the ratio of renal artery signal to renal
vein signal was higher with the recessed technique, 4 ± 2, compared to
standard elliptical centric, 3 ± 2 (p = 0.03). Ringing artifact was also
reduced with the recessed technique in both the aorta and renal veins. Conclusion: Gadolinium-enhanced renal MR angiography is improved by
recessing the absolute center of k-space.
Keywords: magnetic resonance angiography, renal artery stenosis, gadolinium, Fourier
