Ultrashort–Echo Time MR Imaging of the Patella with Bicomponent Analysis: Correlation with Histopathologic and Polarized Light Microscopic Findings

Abstract

To correlate short and long T2* water fractions, derived from ultrashort-echo time (TE) magnetic resonance (MR) imaging, with semiquantitative histopathologic and polarized light microscopic (PLM) assessment of human cadaveric patellae cartilage. Twenty human cadaveric patellae were evaluated by using ultrashort-TE imaging, spin-echo imaging, histopathologic analysis, and PLM, with institutional review board approval. Short and long T2* water components were evaluated for each patella by using bicomponent fitting of ultrashort-TE signal decay. Four to six regions of interest (ROIs) within each patella were chosen for correlation between ultrashort-TE bicomponent analysis, histopathologic grading (Mankin score), and PLM grading (Vaudey score). Ultrashort-TE imaging with bicomponent analysis showed two distinct water components with a short T2* and a longer T2* in all patellae. ROI analysis showed that the short T2* fraction was correlated significantly with the Mankin (ρ = 0.66, P < .001) and Vaudey (ρ = 0.68, P < .001) scores. The Mankin scores were weakly positively correlated with T2 (ρ = 0.28, P = .13) and short T2* (ρ = 0.24, P = .14) but were negatively correlated with long T2* (ρ = -0.55, P < .01). The Vaudey scores were weakly positively correlated with T2 (ρ = 0.18, P = .16) and short T2* (ρ = 0.22, P = .14) but were negatively correlated with long T2* (ρ = -0.55, P < .01). Short T2* water fraction derived from ultrashort-TE imaging with bicomponent analysis correlates significantly with both the Mankin and Vaudey scores and may serve as a biomarker of cartilage degeneration.