CME Sonography 108: Achilles Tendon Ultrasound: Sonoanatomy and Pathologies Abstract. The Achilles tendon is the thickest tendon in the human body. Due to its superficial location and the high prevalence of its pathologies, the Achilles tendon is one of the most frequently sonographed tendons. As a cost-effective and quickly available diagnostic tool, sonography has become indispensable as an examination method for "achillodynia", which occurs in both athletes and non-athletes alike. With modern, high-resolution ultrasound devices, the ultrastructure of the Achilles tendon can be shown in such detail that the term "sonohistology" was formed. Using Doppler sonography and elastography, tendon characteristics which no other modality is capable to show can be visualized. Ultrasound has also been established in the guidance of therapeutic interventions for Achilles tendon disorders. In this article, the sonopathology of the most common Achilles tendon disorders - degenerative and traumatic - are addressed.