Three-Dimensional Surface-Based Analysis of Cartilage MRI Data in Knee Osteoarthritis: Validation and Initial Clinical Application.
BACKGROUND
Traditional quantitative analysis of cartilage with MRI averages measurements (eg, thickness) across regions-of-interest (ROIs) which may reduce responsiveness.


PURPOSE
To validate and describe clinical application of a semiautomated surface-based method for analyzing cartilage relaxation times ("composition") and morphology on MRI, 3D cartilage surface mapping (3D-CaSM).


STUDY TYPE
Validation study in cadaveric knees and prospective observational (cohort) study in human participants.


POPULATION
Four cadaveric knees and 14 participants aged 40-60 with mild-moderate knee osteoarthritis (OA) and 6 age-matched healthy volunteers, imaged at baseline, 1, and 6 months.


FIELD STRENGTH/SEQUENCE
3D spoiled gradient echo, T1 rho/T2 magnetization-prepared 3D fast spin echo for mapping of T1 rho/T2 relaxation times and delayed gadolinium enhanced MRI of cartilage (dGEMRIC) using variable flip angle T1 relaxation time mapping at 3T.


ASSESSMENT
3D-CaSM was validated against high-resolution peripheral quantitative computed tomography (HRpQCT) in cadaveric knees, with comparison to expert manual segmentation. The clinical study assessed test-retest repeatability and sensitivity to change over 6 months for cartilage thickness and relaxation times.


STATISTICAL TESTS
Bland-Altman analysis was performed for the validation study and evaluation of test-retest repeatability. Six-month changes were assessed via calculation of the percentage of each cartilage surface affected by areas of significant change (%SC), defined using thresholds based on area and smallest detectable difference (SDD).


RESULTS
Bias and precision (0.06 ± 0.25 mm) of 3D-CaSM against reference HRpQCT data were comparable to expert manual segmentation (-0.13 ± 0.26 mm). 3D-CaSM demonstrated significant (>SDD) 6-month changes in cartilage thickness and relaxation times in both OA participants and healthy controls. The parameter demonstrating the greatest 6-month change was T2 relaxation time (OA median %SC [IQR] = 8.8% [5.5 to 12.6]).


DATA CONCLUSION
This study demonstrates the construct validity and potential clinical utility of 3D-CaSM, which may offer advantages to conventional ROI-based methods.


LEVEL OF EVIDENCE
2.


TECHNICAL EFFICACY STAGE
2. J. Magn. Reson. Imaging 2020;52:1139-1151.
['MacKay|James W|JW|0000-0001-7558-3800', 'Kaggie|Joshua D|JD|0000-0001-6706-3442', 'Treece|Graham M|GM|', 'McDonnell|Stephen M|SM|', 'Khan|Wasim|W|', 'Roberts|Alexandra R|AR|', 'Janiczek|Robert L|RL|', 'Graves|Martin J|MJ|', 'Turmezei|Tom D|TD|', 'McCaskie|Andrew W|AW|', 'Gilbert|Fiona J|FJ|']
D000328:Adult D002358:Cartilage, Articular D019786:Gadolinium DTPA D006801:Humans D007223:Infant D007719:Knee Joint D008279:Magnetic Resonance Imaging D008875:Middle Aged D020370:Osteoarthritis, Knee D015203:Reproducibility of Results
knee osteoarthritis 3D cartilage thickness cartilage composition cartilage mapping magnetic resonance imaging