Extensive pneumatized air cells causing susceptibility artifacts in the petrosus part of the ICA

Abstract

3D-Time-of-flight magnetic-resonance-angiography (TOF MRA) is an established method in vessel analysis. However, many artifacts that occur may lead to a false diagnosis. This retrospective study evaluates the coherence of MR artifacts to extensive pneumatized air cells surrounding the internal carotid artery (ICA) in the petrosus part of the temporal bone. Patients who received 3D-TOF MRA and multidetector helical computed tomography (CT) angiography were registered from April 2012 to April 2013. Of these patients, both ICAs in the petrosus part were analyzed. Vertical maximum intensity projection (MIP) artifacts were graduated as normal, mild to moderate, and severe artifacts. The distinction of the vertical part of the pneumatized air cells was also categorized in three groups, regarding the circumference of the ICA in pneumatization ≤ 90°, between 90° and 180°, and ≥ 180°. A total of 203 vessels were collected for analysis. The more extensive the pneumatized air cells were present, the more band-like artifacts and pseudostenosis at the vertical portion of the petrosus part of the ICA were registered. Careful examination of the source images and evaluation of the size of the pneumatized air cells with CT scan are essential to avoid false positive diagnosis in the distal petrosus part of the ICA.