Lomas, David J.

BackgroundTo evaluate the reliability of MRE using a spin‐echo echo‐planar imaging (SE‐EPI) renal MRE technique in healthy volunteers.MethodsInstitutional review board approved prospective study in which all participants provided written informed consent. Sixteen healthy volunteers comprising seven males and nine females with a median age of 35 years (age range: 23 to 59 years) were included. Coronal 90 Hz and 60 Hz MRE acquisitions were performed twice within a 30‐min interval between examinations. Renal MRE reliability was assessed by (i) test–retest repeatability, and (ii) inter‐rater agreement between two independent readers. The MRE‐measured averaged renal stiffness values were evaluated using: intraclass correlation coefficient (ICC), Bland‐Altman and the within‐subject coefficient of variation (COV).ResultsFor test–retest repeatability, Bland‐Altman showed a mean stiffness difference between examinations of 0.07 kPa (95% limits of agreement: −1.41, 1.54) at 90 Hz and 0.01 kPa (95% limits of agreement: −0.51, 0.53) at 60 Hz. Coefficient of repeatability was 1.47 kPa and 0.52 kPa at 90 Hz and 60 Hz, respectively. The within‐subject COV was 13.6% and 7.7% at 90 Hz and 60 Hz, respectively. ICC values were 0.922 and 0.907 for test–retest repeatability and 0.998 and 0.989 for inter‐rater agreement, respectively (P < 0.001).ConclusionSE‐EPI renal MRE is a reliable technique. J. Magn. Reson. Imaging 2015;42:844–850.

A nuclear magnetic resonance imaging (MRI) method is presented for quantitatively mapping the physical response of a material to harmonic mechanical excitation. The resulting images allow calculation of regional mechanical properties. Measurements of shear modulus obtained with the MRI technique in gel materials correlate with independent measurements of static shear modulus. The results indicate that displacement patterns corresponding to cyclic displacements smaller than 200 nanometers can be measured. The findings suggest the feasibility of a medical imaging technique for delineating elasticity and other mechanical properties of tissue.