The term "double track sign" refers to a medical imaging finding that can be observed in various conditions, primarily involving the pylorus in infants (pyloric stenosis) or dural sinuses in adults (venous sinus thrombosis). In the context of pyloric stenosis, it signifies a narrowed pyloric channel, appearing as two parallel lines on imaging, often visualized on ultrasound or barium studies. In venous sinus thrombosis, it indicates a thrombosed sinus with contrast flowing around the clot, forming two distinct hyperintense lines.