Repeatability of Quantitative Knee Cartilage T₁, T₂, and T_1ρ Mapping With 3D‐MRI Fingerprinting

Abstract

BackgroundThree‐dimensional MR fingerprinting (3D‐MRF) techniques have been recently described for simultaneous multiparametric mapping of knee cartilage. However, investigation of repeatability remains limited.PurposeTo assess the intra‐day and inter‐day repeatabilities of knee cartilage T1, T2, and T1ρ maps using a 3D‐MRF sequence for simultaneous measurement.Study TypeProspective.SubjectsFourteen healthy subjects (35.4 ± 9.3 years, eight males), scanned on Day 1 and Day 7.Field Strength/Sequence3 T/3D‐MRF, T1, T2, and T1ρ maps.AssessmentThe acquisition of 3D‐MRF cartilage (simultaneous acquisition of T1, T2, and T1ρ maps) were acquired using a dictionary pattern‐matching approach. Conventional cartilage T1, T2, and T1ρ maps were acquired using variable flip angles and a modified 3D‐Turbo‐Flash sequence with different echo and spin‐lock times, respectively, and were fitted using mono‐exponential models. Each sequence was acquired on Day 1 and Day 7 with two scans on each day.Statistical TestsThe mean and SD for cartilage T1, T2, and T1ρ were calculated in five manually segmented regions of interest (ROIs), including lateral femur, lateral tibia, medial femur, medial tibia, and patella cartilages. Intra‐subject and inter‐subject repeatabilities were assessed using coefficient of variation (CV) and intra‐class correlation coefficient (ICC), respectively, on the same day and among different days. Regression and Bland–Altman analysis were performed to compare maps between the conventional and 3D‐MRF sequences.ResultsThe CV in all ROIs was lower than 7.4%, 8.4%, and 7.5% and the ICC was higher than 0.56, 0.51, and 0.52 for cartilage T1, T2, and T1ρ, respectively. The MRF results had a good agreement with the conventional methods with a linear regression slope >0.61 and R2 > 0.59.ConclusionThe 3D‐MRF sequence had high intra‐subject and inter‐subject repeatabilities for simultaneously measuring knee cartilage T1, T2, and T1ρ with good agreement with conventional sequences.Evidence Level1Technical EfficacyStage 1

Editorial for “Repeatability of Quantitative Knee Cartilage T1, T2, and T1ρ Mapping with 3D‐MRI Fingerprinting”

“…MRF can be used to obtain multiple fully registered parameter maps with rapid acquisition. In the article by Zhang et al, 10 the repeatability of T 1 , T 2 , and mapping using 3D MRF in knee cartilage was assessed on a cohort of 14 healthy volunteers. The acquisition of T 1 , T 2 , and maps took 9 minutes, with a voxel size of 0.7 × 0.7 × 3.0 mm 3 and a total of 18 slices.…”