Figure 27a. Soft-tissue abscess in a patient with a history of drug use and shoulder pain. Lateral (a) and posterior (b) volume-rendered spiral CT images obtained after administration of intravenous contrast material show a large abscess that involves the right shoulder. The full extent of the abscess is seen, including involvement of the supraspinous (arrowheads), infraspinous (solid arrow), and teres minor (open arrow) muscles. Blood cultures were positive for S aureus.