1.4.3 Radiographic evaluation
Axial scans of the neck obtained
using contrast-enhanced MRI were reviewed by a radiologist. The
circumference of tumor attachment to the artery and the disappearance of
fat gaps were utilized to estimate the extent of carotid artery invasion
[6], which was classified into three subtypes according to the
involvement grade (IG) (Fig. 1-A-C) as follows before therapy:
(1) Low-involvement: the tumor invaded and/or contacted less than 180º
of the carotid artery.
(2) Mid-involvement: the tumor invaded and/or contacted more than 180º
but less than 270º of the carotid artery.
(3) High-involvement: the tumor invaded and/or contacted more than 270º
of the carotid artery.
(Fig. 1-A-C)
The MRI maps before (Fig.1-D) and after (Fig.1-d) induction chemotherapy