Figure 23c. Fatty infiltration of muscles, and vascular malformations. (a, b) Axial nonenhanced CT images of the thorax (a) and abdomen (b) in a patient aged 14 years show thoracic deformity, including a large asymmetric area with the attenuation of fat along the posterior chest wall and infiltrating the paraspinal muscles bilaterally (arrows), more noticeable in the left side than in the right, which causes elevation of the left scapula away from the posterior chest wall (arrowhead in a); less prominent fatty infiltration along the left lateral chest wall and in the muscles of the anterior chest wall, as well as the posterior, lateral, and anterior abdominal wall and the left anterior rectus abdominis muscle; and enlargement of the right psoas muscle with fatty infiltration that surrounds multiple serpentine blood vessels. (c) Axial MR image obtained with a short inversion time inversion recovery, or STIR, sequence at a level similar to that in b, shows vascular malformations within the fatty tissue in the retroperitoneum, right psoas muscle, and abdominal wall.