AI Article Synopsis

  • Intrinsic activation MR elastography (iMRE) uses heartbeats to evaluate tissue stiffness in focal liver lesions, aiming to better distinguish between malignant and benign types compared to extrinsic MR elastography (eMRE).
  • In a study with 55 participants, both iMRE and eMRE were performed, revealing that malignant lesions had significantly higher shear stiffness and damping ratio than benign ones, especially observed in measurements at various frequencies.
  • The effectiveness of iMRE and eMRE in differentiating lesions was quantified, with areas under the receiver operating characteristic curves (AUC) indicating strong overall diagnostic performance for both techniques, particularly with iMRE and eMRE's shear stiffness values.

Article Abstract

Background: Intrinsic activation MR elastography (iMRE) uses cardiovascular pulsations to assess tissue viscoelastic properties. Applying it to focal liver lesions extends its capabilities.

Purpose: To assess the viscoelastic parameters of focal liver lesions measured by iMRE and compare its diagnostic performance with extrinsic MRE (eMRE) for differentiating malignant and benign lesions.

Study Type: Prospective.

Population: A total of 55 participants underwent MRI with research MRE sequences; 32 participants with 17 malignant and 15 benign lesions underwent both iMRE and eMRE. FIELD STRENGTH/SEQUENCE: iMRE at ~1 Hz heart rate used a 3 T scanner with a modified four-dimensional (4D)-quantitative flow gradient-echo phase contrast and low-velocity encoding cardiac-triggered technique. eMRE employed a gradient-echo sequence at 30, 40, and 60 Hz.

Assessment: Liver displacements were measured using 4D-phase contrast and reconstructed via a nonlinear inversion algorithm to determine shear stiffness (SS) and damping ratio (DR). iMRE parameters were normalized to the corresponding values from the spleen. Lesions were manually segmented, and image quality was reviewed.

Statistical Tests: Kruskal-Wallis, Mann-Whitney, Dunn's test, and areas under receiver operating characteristic curves (AUC) were assessed.

Results: SS was significantly higher in malignant than benign lesions with iMRE at 1 Hz (3.69 ± 1.31 vs. 1.63 ± 0.45) and eMRE at 30 Hz (3.76 ± 1.12 vs. 2.60 ± 1.26 kPa), 40 Hz (3.76 ± 1.12 vs. 2.60 ± 1.26 kPa), and 60 Hz (7.32 ± 2.87 vs. 2.48 ± 1.12 kPa). DR was also significantly higher in malignant than benign lesions at 40 Hz (0.36 ± 0.11 vs. 0.21 ± 0.01) and 60 Hz (0.89 ± 0.86 vs. 0.22 ± 0.09). The AUC were 0.86 for iMRE SS, 0.87-0.98 for eMRE SS, 0.47 for iMRE DR, and 0.62-0.86 for eMRE DR.

Data Conclusion: Cardiac-activated iMRE can characterize liver lesions and differentiate malignant from benign lesions through normalized SS maps.

Level Of Evidence: 2 TECHNICAL EFFICACY: Stage 2.

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Source
http://dx.doi.org/10.1002/jmri.29633DOI Listing

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