Rapid Radial T1 and T2 Mapping of the Hip Articular Cartilage With Magnetic Resonance Fingerprinting

Background

Quantitative MRI can detect early changes in cartilage biochemical components, but its routine clinical implementation is challenging.

Purpose

To introduce a novel technique to measure T₁ and T₂ along radial sections of the hip for accurate and reproducible multiparametric quantitative cartilage assessment in a clinically feasible scan time.

Study Type

Reproducibility, technical validation.

Subjects/Phantom

A seven‐compartment phantom and three healthy volunteers.

Field Strength/Sequence

A novel MR pulse sequence that simultaneously measures proton density (PD), T₁, and T₂ at 3 T was developed. Automatic positioning and semiautomatic cartilage segmentation were implemented to improve consistency and simplify workflow.

Assessment

Intra‐ and interscanner variability of our technique was assessed over multiple scans on three different MR scanners.

Statistical Tests

For each scan, the median of cartilage T₁ and T₂ over six radial slices was calculated. Restricted maximum likelihood estimation of variance components was used to estimate intrasubject variances reflecting variation between results from the two scans using the same scanner (intrascanner variance) and variation among results from the three scanners (interscanner variance).

Results

The estimation error for T₁ and T₂ with respect to reference standard measurements was less than 3% on average for the phantom. The average interscanner coefficient of variation was 1.5% (1.2–1.9%) and 0.9% (0.0–3.7%) for T₁ and T₂, respectively, in the seven compartments of the phantom. Total scan time in vivo was 7:13 minutes to obtain PD, T₁, and T₂ maps along six radial hip sections at 0.6 × 0.6 × 4.0 mm³ voxel resolution. Interscanner variability for the in vivo study was 1.99% and 5.46% for T₁ and T₂, respectively. in vivo intrascanner variability was 1.15% for T₁ and 3.24% for T₂.

Data Conclusion

Our method, which includes slice positioning, model‐based parameter estimation, and cartilage segmentation, is highly reproducible. It could enable employing quantitative hip cartilage evaluation for longitudinal and multicenter studies.

Level of Evidence: 1

Technical Efficacy: Stage 1

J. Magn. Reson. Imaging 2018.

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