The hourglass sign

Abstract

The Hourglass sign is a useful imaging clue for diagnosing diaphragmatic ruptures with viscera herniation on multidetector CT, with a sensitivity ranging from 16% to 63% and a specificity around 98%-100%. This sign is also commonly found in the literature under the name "Collar sign," first described in 1995 by Worthy et al. It refers to the waistlike constriction of the herniated structure at the site of the diaphragmatic rupture.

Hourglass Sign in Liver Hydatid Disease: Significance and Therapeutic Implications

“…The hourglass sign is an imaging sign referring to a waist-like constriction of a herniated structure through a defect. 1 In liver hydatid disease, trans-diaphragmatic migration of hydatid cysts located in the hepatic dome could display this sign. 2 This migration is facilitated by the pressure difference between the thorax and the abdomen.…”