Transaxial MRI of a 69 year old female control subject (A) and a 69 year old female with acute low back pain before (B) and immediately following osteopathic manipulation treatment (C). These images from the L3-L4 region illustrates the spatial orientation of the psoas, quadratus lumborum (QL), iliocostalis lumborum/longissimus thoracis, and multifidus muscles. Ten-millimeter thick transaxial images were obtained from the lumbar region with a 2000 msec repetition time, 30 and 65 msec echo times, and a 10-mm slice-to-slice interval. These derived images were used to calculate the transverse relaxation time (T2), and allows for a noninvasive measurement of the metabolic and hemodynamic responses of skeletal muscle in association with muscle activity. Note the similar signal intensity in the left and right lumbar muscles of the control subject (A), the asymmetry in the psoas and quadratus lumborum muscles before treatment (B), and the attenuation of this asymmetry immediately following treatment (C).