Figure 4.

depicts color T₂ maps (beneath which is the reference gray scale image generated from the shortest echo image of the T₂ mapping sequence) obtained in vivo in a 3T MR scanner in the coronal plane 11 weeks after vascular interruption surgery in goat 4 (Panels A and B). Panel A demonstrates normal epiphyseal cartilage of the medial femoral condyle in the left unoperated (control) limb. Red oval marks an area of increased relaxation time, consistent with ischemic cartilage necrosis, and delay of the progression of the ossification front in the operated right medial femoral condyle (Panel B). In the proton density image of the same goat, obtained in vivo at 3T, a faint linear hyperintensity (red arrowheads) is suggestive for a fissure extending through the articular-epiphyseal cartilage complex (Panel C). Increased relaxation time and delayed progression of the ossification front in the area of ischemic cartilage necrosis are apparent in the T2 map obtained at 9.4T ex vivo (Panel D). A fissure extending through the articular-epiphyseal cartilage complex is apparent in the safranin O stained histological section of the operated right medial femoral condyle (Panel E) along with an adjacent area of pallor consistent with cartilage necrosis. Hematoxylin and eosin stained section at 40 × (inset) showing the interface of necrotic (above dotted line) and viable (below dotted line) epiphyseal cartilage from the area identified with the black rectangle in panel E. Black arrows indicate the surgical scars (Panels B–E).