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Improved venous suppression on renal MR angiography with recessed elliptical centric ordering of K-space
Bernard Ho1, Minh Chao, Hong Lei Zhang
1Department of Radiology, Weill Medical College of Cornell University, New York, NY 10021, USA.
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.
Insights
Recessed elliptical centric ordering improves renal magnetic resonance angiography. This technique enhances signal-to-noise ratio and reduces artifacts for clearer imaging of kidney blood vessels.
Area of Science:
- Radiology
- Medical Imaging
- Cardiovascular Imaging
Background:
- Renal magnetic resonance (MR) angiography is crucial for diagnosing kidney conditions.
- Standard k-space ordering techniques can be limited by artifacts and suboptimal signal-to-noise ratios.
Purpose of the Study:
- To evaluate the effectiveness of recessed elliptical centric ordering of k-space in renal MR angiography.
- To compare image quality metrics between standard and recessed k-space ordering methods.
Main Methods:
- Imaging performed on a 1.5 T MR system using a phased array coil.
- Gadolinium contrast administered, with timing optimized for arterial phase.
- Comparison of standard elliptical centric ordering (8-second delay) versus recessed elliptical centric ordering (4-second delay with k-space center recessed).
Main Results:
- The recessed technique significantly increased aorta signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) (p = 0.02).
- The ratio of renal artery signal to renal vein signal was higher with the recessed technique (4 ± 2 vs. 3 ± 2, p = 0.03).
- Ringing artifact was reduced in both the aorta and renal veins using the recessed method.
Conclusions:
- Recessing the absolute center of k-space improves gadolinium-enhanced renal MR angiography.
- The recessed technique offers enhanced image quality and reduced artifacts for renal vascular imaging.
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