Accelerating MR elastography: a multiecho phase-contrast gradient-echo sequence.
OBJECTIVE
To demonstrate the feasibility of using a multiecho phase-contrast (PC) gradient-echo sequence with motion-sensitizing gradient (MSG) to accelerate MR elastography (MRE) acquisitions in comparison to single-echo PC sequences.


METHODS
The sequence was implemented and compared with a conventional single-echo sequence as the standard of reference in both agarose phantoms and in vivo in the biceps of three healthy volunteers. For reconstruction of the elasticity modulus, a local frequency estimation (LFE) algorithm was used. ETL factors of 1-16 were evaluated.


RESULTS
Phantom experiments demonstrated excellent consistency between single-echo and multiecho measurements in terms of wave equivalency, SNR, and reconstructed shear modulus. Additionally, the in vivo MRE examinations showed an excellent correspondence to the single-echo results. Minor loss of wave amplitude was observed at higher ETL factors.


CONCLUSIONS
The results demonstrate that a multiecho sequence is suitable for accelerating MRE in nearly homogeneous tissue, such as muscle. It provides equivalent elasticity values in a significantly reduced scan time compared to a single-echo sequence. The maximum achievable ETL factor must be individually determined for the target tissue.
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany. stefan.maderwald@uni-essen.de
Stefan
S
Maderwald
Kai
K
Uffmann
Craig J
CJ
Galbán
Armin
A
de Greiff
Mark E
ME
Ladd
D000054:Acceleration; D000328:Adult; D000362:Agar; D000465:Algorithms; D004548:Elasticity; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology; D019047:Phantoms, Imaging; D033081:Shear Strength; D013314:Stress, Mechanical; D014732:Vibration
D000362:Agar