Design of a birdcage array for lower extremity angiography.
OBJECTIVE
To investigate the application of a coil array consisting of multiple birdcages for bolus chase magnetic resonance angiography (MRA) of the lower extremities.


METHODS
The prototype consisted of four birdcage coils; two adjacent birdcages for thigh imaging, and two for calf imaging. Decoupling between adjacent coils was achieved using shared capacitors. Bench measurements and MR images were used to evaluate the decoupling scheme. Image signal-to-noise ratios (SNR) were compared between the birdcage array and four commercially available coils. Contrast-enhanced imaging experiments were performed on 10 volunteers and parallel imaging was simulated. This study was approved by the local institutional review board and written informed consent was obtained from each volunteer.


RESULTS
Capacitive decoupling resulted in a reduction in signal leakage. The calf birdcages provided an 84% SNR improvement over a four element array, while the thigh birdcages provided a 53% improvement. Angiographic images illustrated the utility of the coil for peripheral MRA. Parallel imaging was demonstrated with a two-fold reduction factor.


CONCLUSIONS
Birdcage coils were demonstrated to be valuable for lower extremity imaging due to their homogenous sensitivity, good SNR, and cylindrical geometry. Coupling was controlled using shared capacitors that allowed a single birdcage to encompass each leg individually, providing a novel approach to signal reception for peripheral imaging.
Department of Radiology, Weill Medical College of Cornell University, New York, New York, USA.
Ryan
R
Brown
Martin R
MR
Prince
Hale
H
Ersoy
Michael
M
Dooley
Bernard Y
BY
Ho
Azma
A
Mareyam
Kiyarash
K
Mohajer
Yi
Y
Wang
D000465:Algorithms; D000792:Angiography / Q000295:instrumentation* / Q000379:methods*; D016477:Artifacts; D003287:Contrast Media / Q000494:pharmacology; D004867:Equipment Design; D019786:Gadolinium DTPA / Q000494:pharmacology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007866:Leg / Q000098:blood supply; D035002:Lower Extremity / Q000098:blood supply; D018810:Magnetic Resonance Angiography / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D016491:Peripheral Vascular Diseases / Q000175:diagnosis* / Q000473:pathology; D019047:Phantoms, Imaging
D003287:Contrast Media; D019786:Gadolinium DTPA