title: T2* mapping of subtalar cartilage: Precision and association between anatomical variants and cartilage composition.
abstract: Hindfoot arthritis is an important contributor to foot pain and physical disability. While the subtalar joint (STJ) is most frequently affected, anatomical variants such as facet configuration were suggested to further STJ cartilage deterioration. T2* mapping enables detection of ultra-structural cartilage change, particularly in thin cartilage layers, but its feasibility in the STJ has not yet been evaluated. The purpose of this study was to evaluate segmentation consistency and inter-scan short-term precision error of T2* mapping of talocalcaneal cartilage and to investigate the relationship between facet configuration and STJ T2* values. Using 3Tesla morphological magnetic resonance imaging, STJ configuration was categorized according to the degree of fusion between anterior, medial, or posterior facets. Subsequently, two repeats of multi-echo gradient recalled echo sequences were performed to obtain T2* maps with repositioning. Segmentation consistency of T2* values attained an ICC of 0.90 (95%CI 0.69-0.99). Precision errors comprised a coefficient of variation (CV) ranging 0.01-0.05, corresponding to a root mean square CV of 0.03-0.04. A 2-joint configuration type (i.e., fused anterior-medial facets) was significantly associated with a decrease in posterior facet T2* values (β = -0.6, p = 0.046). STJ T2* mapping is a reliable method requiring at least a 4% difference within people to enable detection of significant change. Anatomical variants in STJ configuration were associated with T2* values with the more stable 3-joint types exhibiting more favorable cartilage outcomes. Longer-term larger-scaled studies focusing on arthritis pathology are needed to further support the use of T2* mapping in hindfoot disease monitoring. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1969-1976, 2016.
authors.affiliation: Faculty of Medicine, Dentistry and Health Sciences, Centre for Health, Exercise and Sports Medicine (CHESM), The University of Melbourne, 161 Barry Street, Carlton VIC 3053, Melbourne, Australia.
authors.forename: Ans
authors.initials: A
authors.lastname: Van Ginckel
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.|Department of Podiatry, Artevelde University College, Ghent, Belgium.|Department of Rheumatology, Ghent University Hospital, Ghent, Belgium.
authors.forename: Sophie
authors.initials: S
authors.lastname: De Mits
authors.affiliation: Faculty of Medicine, Dentistry and Health Sciences, Centre for Health, Exercise and Sports Medicine (CHESM), The University of Melbourne, 161 Barry Street, Carlton VIC 3053, Melbourne, Australia.
authors.forename: Kim L
authors.initials: KL
authors.lastname: Bennell
authors.affiliation: Faculty of Medicine, Dentistry and Health Sciences, Centre for Health, Exercise and Sports Medicine (CHESM), The University of Melbourne, 161 Barry Street, Carlton VIC 3053, Melbourne, Australia.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Bryant
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium.|Department of Physiotherapy, Aspetar, Doha, Qatar.
authors.forename: Erik E
authors.initials: EE
authors.lastname: Witvrouw
mesh_terms: D000328:Adult; D063405:Anatomic Variation; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D013380:Subtalar Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: MRI; T2*; anatomy; reliability; subtalar joint