NFE values acquired over 7 years for present in vivo study. Dashed lines indicate cutoff points of 4 pathological classifications identified in earlier work (see Fig. 1).1 Ultimately, 6 of 9 high-risk sites improved to NFE value below 0.03 (mild/none). Two sites, B12 and H14, continued to exhibit NFE>0.04, indicating continuing nonlinear deterioration. Site B14 exhibited positive/negative volatility. NFE, normal fit error; QPD, quantitative percussion diagnostics.