Respiratory-triggered spin-echo echo-planar imaging-based mr elastography for evaluating liver stiffness.

BACKGROUND

Magnetic resonance elastography (MRE) has proven to be useful for assessing chronic liver disease. However, MRE images are acquired with breath-holding (BH) to limit respiratory motion artifacts, which may be difficult in some patients.

PURPOSE

To implement a respiratory-triggered (RT) spin-echo echo-planar imaging (SE-EPI) MRE technique and to validate its performance through comparison to a BH SE-EPI MRE technique.

STUDY TYPE

Prospective feasibility study.

SUBJECTS

Twenty-three adult volunteers (18 without and 5 with liver disease).

FIELD STRENGTH/SEQUENCES: 1.5 T Philips Ingenia MR scanner; RT and BH SE-EPI MRE sequences.

ASSESSMENT

Four axial images were obtained through the middle of the liver with each technique. Liver stiffness measurements (in kPa) were made from elastograms, with 95% confidence maps overlaid, for both MRE sequences.

STATISTICAL TESTS

Liver stiffness measurements were compared using the paired t-test (two-sided). Absolute agreement between the two techniques was evaluated using Lin's concordance coefficient (r ). Bland-Altman analysis was used to assess the mean bias between the techniques and 95% limits of agreement, using BH MRE as the reference standard.

RESULTS

There was excellent agreement (r = 0.98; 95% confidence interval: 0.96-0.99) between RT and BH SE-EPI MRE. Mean (±SD) stiffness values from BH and RT SE-EPI MRE techniques were 2.40 ± 1.15 kPa and 2.37 ± 1.06 kPa, respectively, with no significant difference (P = 0.54) and no significant bias (mean bias of +0.03 kPa; 95% limits of agreement: -0.39 to 0.45 kPa). Measurable regions of interest in the liver were slightly smaller with the RT technique (mean difference of 1.91 cm ; P = 0.04).

DATA CONCLUSION

RT SE-EPI MRE is feasible and yields comparable results to BH SE-EPI MRE.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:391-396.