Diaphragmatic muscular bundles (slips): ultrasound evaluation of incidence and appearance

Diaphragmatic muscular bundles (slips) connect the central tendon of the diaphragm to the inner aspect of the lower thoracic cage. They cause hepatic invaginations which may be visualized at ultrasound (US) or computed tomography. Two hundred patients underwent prospective US of the diaphragm and liver to determine the incidence and characteristics of slips. The incidence was 15%, rising to 30% in those aged 80 years and over. Slips average 1.2 cm in depth (range 0.1-3.6 cm) and their occurrence has no racial or sexual bias. Multiple slips were seen in 4% of patients, all females. Slips are echogenic and have a variety of appearances, typically nodular on transverse section and strand-like longitudinally. Knowledge of these structures will avoid confusion with liver and peridiaphragmatic pathology.