Fig 1. Near-occlusion ICA stenosis with distal ICA collapse, threadlike "string sign." CTA axial source image (A) near the skull base and coronal MPR (B) showing collapse of the right distal ICA (thin arrow) in comparison to normal caliber left distal ICA (arrowhead). These arteries are continuous from the proximal carotid bulb and are headed toward the carotid canal. Both features should be identified on MPRs with reference to the axial source images to distinguish collapsed ICAs from other vessels, especially the ascending pharyngeal artery. C, 3D-rendered (left) and oblique sagittal MPR (right) of the right carotid arteries showing the severe carotid bulb stenosis, appearing amputated on reformatted images. There is collapse of the right distal ICA (thin arrow), similar in size to the ascending pharyngeal artery on the oblique sagittal MPR (thick solid arrow). The identification of both these vessels was confirmed on the axial source images and other MPRs by identifying their origins and anatomic continuations.