Accuracy and precision of proton density fat fraction measurement across field strengths and scan intervals: A phantom and human study

Abstract

Background Complex‐based chemical shift imaging‐based magnetic resonance imaging (CSE‐MRI) is emerging as a preferred method for noninvasively quantifying proton density fat fraction (PDFF), a promising quantitative imaging biomarker (QIB) for longitudinal hepatic steatosis measurement. Purpose To determine linearity, bias, repeatability, and reproducibility of the PDFF measurement using CSE‐MRI (CSE‐PDFF) across scan intervals, MR field strengths, and readers in phantom and nonalcoholic fatty liver disease (NAFLD) patients. Study Type Institutional Review Board (IRB)‐approved prospective. Subjects Fat‐water phantom and 20 adult patients. Field Strength/Sequence 1.5 T and 3.0 T MR systems and a commercially available CSE‐MRI sequence (IDEAL‐IQ). Assessment Two independent readers measured CSE‐PDFF of fat‐water phantom and NAFLD patients across two field strengths and scan intervals (same‐day and 2‐week) each and in a combination of both. MR spectroscopy‐based PDFF (MRS‐PDFF) was used as the reference standard for phantom PDFF. Statistical Tests Linearity and bias of measurement were evaluated by linear regression analysis and Bland–Altman plots, respectively. Repeatability and reproducibility were assessed by coefficient of variance and repeatability / reproducibility coefficients (RC). The intraclass correlation coefficient was used to validate intra‐ and interobserver agreements. Results CSE‐PDFF showed high linearity and small bias (–0.6–0.4 PDFF%) with 95% limits of agreement within ±2.9 PDFF% across field strengths, 2‐week interscan period, and readers in the clinical scans. CSE‐PDFF was highly repeatable and reproducible both in phantom and clinical scans, with the largest observed RC across field strengths and 2‐week interscan period being 3 PDFF%. Data Conclusion CSE‐PDFF is a robust QIB with high linearity, small bias, and excellent repeatability/reproducibility. A change of more than 3 PDFF% across field strengths within 2 weeks of scan interval likely reflects a true change, which is well within the clinically acceptable range. Level of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:305–314.

Proton density fat fraction MRI of vertebral bone marrow: Accuracy, repeatability, and reproducibility among readers, field strengths, and imaging platforms

“…Concordant with our findings, a recent phantom study showed high precision of PDFF measurements (mean bias of 0.22 PDFF%) obtained with imagers from multiple different vendors and at both 1.5T and 3.0T across multiple sites. 25 In patients, previous studies on steatosis quantification have shown high linear correlation and small mean bias in MRIdetermined PDFF ranging from 0.9-3.7% across two 26,27 and three 28 different MRI platforms. In our study, the reproducibility of MRI-determined PDFF in lumbar bone marrow was comparable to or even better than that reported for liver fat quantification, possibly owing to the inherent heterogeneity of steatosis across the liver (ie, because of different ROI locations).…”

Noninvasive evaluation of nonalcoholic fatty liver disease: Current evidence and practice

“…Nasr et al[ 6 ] found that 1 H-MRS had a specificity of 100% and sensitivity of 79% with a PDFF cut-off value of 3%, a specificity of 94% and sensitivity of 87% with a PDFF cut-off value of 2%. Although recognized as the most accurate noninvasive tool to assess PDFF quantitatively, MRS is limited to its device- and operator-dependency, complexity, and potentially errors[ 71 ]. Complex-based chemical shift imaging-based MRI (CSE‐MRI) is regarded as a promising method to quantify PDFF, which could quantitatively assess liver fat content with a refined pulse sequence[ 72 - 74 ].…”

“…Complex-based chemical shift imaging-based MRI (CSE‐MRI) is regarded as a promising method to quantify PDFF, which could quantitatively assess liver fat content with a refined pulse sequence[ 72 - 74 ]. It exhibits a high correction with MRS‐PDFF ( r 2 = 0.985 for 1.5 T MR systems, r 2 = 0.991 for 3.0 T MR systems)[ 71 ]. MR diffusion weighted imaging (DWI) measures motion of water protons diffusing and tissue perfusing[ 75 , 76 ] and is regarded another promising tool for assessing liver fat content[ 77 ], while it exerts poor performance for detecting steatosis in comparison with MRS and dual echo in phase and out of phase imaging[ 78 ].…”

A comparison of liver fat fraction measurement on MRI at 3T and 1.5T

“…PDFF measurements have been previously compared between 1.5T and 3T, using different manufacturers [16][17][18][19][20]. The largest comparison cohort across manufacturers was in n = 24 obese individuals which made a comparison of 1.5T Ingenia Philips, 3T Ingenia Philips and 3T 750 W GE.…”

“…The mean bias associated with field strength for this meta-analysis was -1.2%. Other smaller cohorts have compared normal individuals against phantoms, diabetics against non-diabetics and children, with biases varying between -0.4 to +1.2% [17][18][19][20].…”