PMC3504629_01
Human knee cadaver with visually intact femoral condyles. Forceps tip pointing to a 5x5mm soft region (ROI) that was examined in sagittal sections histologically, biochemically and with MR.
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F1
This soft 'lesion' is referred to as the region of interest ('ROI'; Fig. 1).
A) Original T2 -w image. Without color mapping the ROI (white arrow) in the human posterior femoral condyle (PFC) presents only subtle structural signal inhomogeneity. *(Cutting artifacts). B) SPGR image with fitted T1rho color map. ROI in the PFC (sagittal image orientation through the knee) displays T1rho values up to 120ms (red=abnormal, blue=normal cartilage) as an indicator for extended relaxation times due to an increase in cartilage bound water and a reduction in PG related to catabolic cartilage processes. C) Magnification of the ROI after repeated scanning of the separated PFC. D) Safranin-O stained histo section of a representative sagittal slice through the ROI shows focal PG (red) reduction and a bow-like intrasubstance fissure. The cartilage surface shows only mild irregularities. *(Cutting artifacts)
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F2
Values in the ROI were ~4x higher (-120ms +- 11.8 ms) (Fig. 2b) than in the surrounding unaffected cartilage (30-50ms +- 8 ms ).