Ultrasound imaging distinguishes between normal and weak muscle1 Gloria Chi-Fishman, PhD, Jeanne E. Hicks, MD, Holly M. Cintas, PhD, Barbara C. Sonies, PhD, Lynn H. Gerber, MD  Archives of Physical Medicine and Rehabilitation  Volume 85, Issue 6, Pages 980-986 (June 2004) DOI: 10.1016/j.apmr.2003.07.008

Fig 1 Anatomy of the thigh: (A) anterior view of the rectus femoris muscle, illustrating the measured distance from a point just below the ASIS to the midsuperior border of the patella; the marked horizontal skin line at two thirds of this measured distance from the ASIS-guided ultrasound transducer placement and scanning. (B) Cross-sectional view of the rectus femoris muscle at midthigh level, illustrating the traced muscle boundary and the measured X and Y diameters. Adapted from Netter FH. Atlas of human anatomy. Summit (NJ): Ciba-Geigy Corp; 1989. Reprinted with permission.20 Archives of Physical Medicine and Rehabilitation 2004 85, 980-986DOI: (10.1016/j.apmr.2003.07.008)

Fig 2 Comparison of relaxed-contracted configurational changes in X (horizontal) and Y (vertical) diameters of the rectus femoris cross-section at 90° knee flexion in a 50-year-old woman with polymyositis (MMT score, 7) and her age- and gender-matched healthy control (MMT score, 10). Both the untraced and traced frames of the same images are presented, to illustrate contour tracing and diameter measurements. On the right side of each panel, unfilled arrowheads depict focal zones for regional beam concentration, and numbers with tick marks indicate scan depth in centimeters. Note that the X and Y lines cross at the center of mass (traced area). The images displayed are smaller than the original 640×480 size because of cropping to remove subject demographics, time codes, and other irrelevant information. Archives of Physical Medicine and Rehabilitation 2004 85, 980-986DOI: (10.1016/j.apmr.2003.07.008)

Fig 3 Mean normalized contracted-relaxed difference scores (Δnormalized) and standard deviations (SDs) for X and Y diameters of the rectus femoris muscle in patients with polymyositis and their controls by subject group at (A) the 60° and (B) the 90° knee-flexion positions. Note the consistent trend of smaller changes in patients than in controls at 60°. Significant patient-control contrasts are marked with their respective P values in both panels. Archives of Physical Medicine and Rehabilitation 2004 85, 980-986DOI: (10.1016/j.apmr.2003.07.008)

Fig 4 Comparison of mean MVIC muscle force (+SD) in patients with polymyositis and their controls by subject group at the 60° and 90° knee-flexion positions. Significant contrasts are marked with their respective P values. Archives of Physical Medicine and Rehabilitation 2004 85, 980-986DOI: (10.1016/j.apmr.2003.07.008)

Fig 5 Scatterplots of mean subject data with regression lines and 95% confidence interval of regression lines, illustrating the relationship between muscle force and rectus femoris muscle diameters in X (○) and Y (■) dimensions during MVIC at the 60° (top panels) and the 90° (bottom panels) knee-flexion angles. As shown, correlations are moderately strong for 60°Y and 90°Y but weak for 60°X and 90°X. Archives of Physical Medicine and Rehabilitation 2004 85, 980-986DOI: (10.1016/j.apmr.2003.07.008)