Figure 2a:

Sagittal intermediate-weighted fat-saturated two-dimensional fast spin-echo MR images of the right knees in four different subjects with signal abnormalities. (a) Hypointense lesion in the medial femur (arrow). (b) Inhomogeneous lesion in the lateral trochlea consisting of both hypointense (white arrows) and hyperintense (black arrow) components next to each other. (c) Hyperintense lesion in the medial femur condyle (arrows). (d) Hyperintense lesion with swelling in the trochlea (white arrow) accompanied by bone marrow edema pattern signal in the underlying bone consisting of a small subchondral component and a more remote larger part (black arrows).