Figure 12a. Axial steady-state diffusion-weighted images of the patellofemoral cartilage in a healthy volunteer, obtained with effective b values (beff) of 115 (a), 350 (b), and 630 (c) sec/mm2. Imaging is performed with three levels of diffusion weighting (effective b value), and navigation is performed to minimize the effects of motion. Note the decreasing signal for cartilage as free water is suppressed at higher b values. Diffusion-weighted imaging may allow early demonstration of breakdown of the collagen matrix. (Courtesy of Karla Miller, Stanford University, Stanford, Calif.)