Performance of C‐SENSE Accelerated Rapid Liver Shear Stiffness Measurement Using Displacement Wave Polarity‐Inversion Motion Encoding: An Evaluation Study

Abstract

BackgroundLiver shear stiffness measurement using magnetic resonance elastography (MRE) aids in the noninvasive diagnosis and staging of liver fibrosis. Inadequate breath‐holds can lead to inaccurate stiffness estimation and/or failed MRE exams.PurposeTo prospectively evaluate the performance of compressed sensitivity encoding (C‐SENSE) accelerated rapid MRE measurement of liver shear stiffness using displacement wave polarity‐inversion motion encoding.Study TypeRetrospective.SubjectsEleven with liver disease and 10 asymptomatic subjects.Field Strength/Sequence1.5 T; gradient‐recalled‐echo (GRE) MRE.AssessmentAll participants underwent: 1) two‐dimensional (2D) GRE MRE with inflow saturation using SENSE acceleration factor (R) of 2 (standard of care [SC]); 2) 2D rapid MRE with (RwS); and 3) without (RnS) inflow saturation using C‐SENSE R = 3; and 4) spatial three‐dimensional (3D) rapid MRE with inflow saturation (R3D) using C‐SENSE R = 4; with nominally identical spatial resolution and coverage. Image analyst (D.G., 2 years of experience) drew identical and maximal regions of interest (ROIs) in right hepatic lobe.Statistical TestsLinear regression, intra‐class correlation coefficients (ICC), Bland–Altman analyses, and the Wilcoxon signed‐rank test were used to assess consistency and agreement of liver stiffness measurements for manually drawn identical and maximal ROIs.ResultsIn 21 participants (37 ± 14 years) with liver stiffness (2.3 ± 0.7 kPa), body mass index (BMI 27 ± 7 kg/m2), proton density fat fraction (PDFF 9 ± 9%), and T2* (27 ± 4 msec); rapid MRE sequences showed excellent agreement (ICC > 0.95) with SC MRE and no correlation (r2 < 0.1) of the differences (mean difference <0.2 kPa, <6%; limits of agreement <0.4 kPa, <16%) with BMI, PDFF, and T2*. Breath‐hold times were: 14 seconds (SC), 5 seconds (RnS), 7 seconds (RwS) per slice, and 16 seconds for the R3D acquisition.Data ConclusionsC‐SENSE accelerated GRE MRE sequences, using displacement wave polarity‐inversion motion encoding, produce equivalent measurements of liver stiffness and have potential clinical benefit in patients with limited breath‐holding capacity.Level of Evidence1Technical EfficacyStage 1

Phase‐regularized and displacement‐regularized compressed sensing for fast magnetic resonance elastography

“…34 However, the in-plane resolution of the standard of care SE-EPI MRE is usually reduced by a factor of 3 compared with the standard of care GRE MRE sequence. 5,6 This reduces reconstruction accuracy, since most reconstruction methods depend strongly on the wavelength to voxel ratio 35,36 and require at least 9-10 voxels per wavelength. 37 Furthermore, as GRE-MRE has the unique advantage of providing higher spatial resolution in the readout direction, GRE-MRE with compressed sensing can reduce the scanning time while maintaining a sufficient spatial resolution.…”

“…37 Furthermore, as GRE-MRE has the unique advantage of providing higher spatial resolution in the readout direction, GRE-MRE with compressed sensing can reduce the scanning time while maintaining a sufficient spatial resolution. 5 Therefore, comparing the diagnostic performance of GRE-MRE with compressed sensing and SE-EPI could be interesting for future work.…”

“…4 However, the in-plane resolution of SE-EPI-MRE is three times lower than that of the GRE-MRE sequence. [4][5][6] The long breath-hold time and low resolution are two significant bottlenecks in extending MRE for applications such as pediatric liver diagnosis. 3 Also, multiple breath-hold acquisitions cause interslice misalignment in the displacement image, a significant roadblock for applying three-dimensional (3D) elasticity inversion.…”

Editorial for “Performance of C‐SENSE Accelerated Rapid Liver Shear Stiffness Measurement Using Displacement Wave Polarity‐Inversion Motion Encoding: An Evaluation Study”

“…The work by Pednekar et al uses a breath‐hold two‐dimensional GRE acquisition for hepatic MRE in a single breath‐hold per slice and aims to reduce the total breath‐hold duration by combining displacement wave polarity‐inversion for motion encoding and sparse data sampling 7 . The authors compare three methods: Their standard of care method, labeled as SC, is a standard two‐dimensional GRE acquisition employing conventional parallel imaging with sensitivity encoding (SENSE) with a reduction factor R = 2 and motion encoding every three mechanical cycles without polarity‐inverted motion encoding (original repetition time‐TR, breath‐hold duration = 14 seconds per slice).…”

“…The work by Pednekar et al uses a breath-hold twodimensional GRE acquisition for hepatic MRE in a single breath-hold per slice and aims to reduce the total breath-hold duration by combining displacement wave polarity-inversion for motion encoding and sparse data sampling. 7 The authors compare three methods: Their standard of care method, labeled as SC, is a standard two-dimensional GRE acquisition employing conventional parallel imaging with sensitivity encoding (SENSE) with a reduction factor R = 2 and motion encoding every three mechanical cycles without polarity-inverted motion encoding (original repetition time-TR, breath-hold duration = 14 seconds per slice). Their second variant, labeled as RnS, is a rapid twodimensional GRE acquisition employing a combination of compressed sensing and SENSE with a total reduction factor R = 3, motion encoding every 1.5 mechanical cycles with polarityinverted motion encoding and no inflow saturation (half TR, breath-hold duration = 5 seconds per slice).…”