J. Nelissen, Amsterdam, NL

Magnetic Resonance Elastography (MRE) non-invasively measures tissue viscoelastic properties. Assessing liver stiffness with MRE requires several breath-holds. Compressed Sensing (CS) acceleration combines data sparsity and incoherent data sampling patterns allowing high acceleration factors with minimal loss in data quality. This study aimed to demonstrate the feasibility of CS accelerated liver MRE in healthy volunteers and compare it to the standard acquisition (with SENSitivity Encoding [SENSE] acceleration factor 2).

Material and methods

MRE data were acquired in an IRB-approved setting in 7 healthy volunteers at 4 wave phase-offsets during 50 Hz external vibration and with three motion encoding directions. CS acceleration factors of 4, 6 and 8 were compared to SENSE factor 2. CS factor 8 allowed a single breath-hold scan of 24 s as opposed to the standard SENSE sequence (4 × 19 s). Reproducibility of SENSE and agreement between CS and SENSE were assessed using Bland-Altman and repeatability index analysis.

Results

Mean stiffness values (kPa) for SENSE factor 2, CS factor 4-6-8 were 2.18, 2.19, 2.09 and 2.12 kPa, respectively. Repeatability index for SENSE factor 2 was 9.5, comparable to literature values. Mean difference for the repeated SENSE factor 2 scan was 0.04 kPa while for CS factor 4-6-8 compared to SENSE factor 2 these were 0.02, -0.11, -0.01 and 0.11 kPa, respectively.

Conclusion

Accelerating liver MRE with Compressed Sensing up to 8 times yields similar stiffness values compared to the standard acquisition with SENSE. Furthermore, acceleration factors above 8 make single breath-hold acquisition possible.

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