Novel technique for MR elastography of the prostate using a modified standard endorectal coil as actuator.
OBJECTIVE
To present a novel method for MR elastography (MRE) of the prostate at 3 Tesla using a modified endorectal imaging coil.


METHODS
A commercial endorectal coil was modified to dynamically generate mechanical stress (contraction and dilation) in a prostate phantom with embedded phantom "lesions" (6 mm diameter) and in a porcine model. Resulting tissue displacements were measured with a motion-sensitive EPI sequence at actuation frequencies of 50-200 Hz. Maps of shear modulus G were calculated from the measured phase-difference shear-wave patterns.


RESULTS
In the G maps of the phantom, "lesions" were easily discernible against the background. The average G values of regions of interest placed in the "lesion" (8.2 ± 1.9 kPa) were much higher than those in the background (3.6 ± 1.4 kPa) but systematically lower than values reported by the vendor (13.0 ± 1.0 and 6.7 ± 0.7 kPa, respectively). In the porcine model, shear waves could be generated and measured shear moduli were substantially different for muscle (7.1 ± 2.0 kPa), prostate (3.0 ± 1.4 kPa), and bulbourethral gland (5.6 ± 1.9 kPa).


CONCLUSIONS
An endorectal MRE concept is technically feasible. The presented technique will allow for simultaneous MRE and MRI acquisitions using a commercial base device with minor, MR-conditional modifications. The diagnostic value needs to be determined in further trials.
Department of Diagnostic and Interventional Radiology, Leipzig University Hospital, Leipzig, Germany.
Gregor
G
Thörmer
Martin
M
Reiss-Zimmermann
Josephin
J
Otto
Karl-Titus
KT
Hoffmann
Michael
M
Moche
Nikita
N
Garnov
Thomas
T
Kahn
Harald
H
Busse
D055119:Elastic Modulus / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000295:instrumentation*; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008280:Magnetics / Q000295:instrumentation*; D008297:Male; D019047:Phantoms, Imaging; D011467:Prostate / Q000473:pathology* / Q000502:physiology*; D012007:Rectum / Q000473:pathology / Q000502:physiology; D013314:Stress, Mechanical; D014159:Transducers