Value of MR and CT Imaging for Assessment of Internal Carotid Artery Encasement in Head and Neck Squamous Cell Carcinoma

Objective. This study was conducted to assess the value of CT and MR imaging in the preoperative evaluation of ICA encasement. Methods. Based upon three patient groups this study was performed. Retrospective analysis of 260 neck dissection reports from 2001 to 2010 was performed to determine unexpected peroperative-diagnosed encasement. Two experienced head and neck radiologists reviewed 12 scans for encasement. Results. In four out of 260 (1.5%) patients undergoing neck dissection, preoperative imaging was false negative as there was peroperative encasement of the ICA. Of 380 patients undergoing preoperative imaging, the radiologist reported encasement of the ICA in 25 cases. In 342 cases no encasement was described, 125 of these underwent neck dissection, and 2 had encasement peroperatively. The interobserver variation kappa varied from 0.273 to 1 for the different characteristics studied. Conclusion. These retrospectively studied cohorts demonstrate that preoperative assessment of encasement of the ICA using MRI and/or CT was of value in evaluation of ICA encasement and therefore contributively in selecting operable patients (without ICA encasement), since in only 1.5% encasement was missed. However, observer variation affects the reliability of this feature. 1. Introduction Preoperative diagnosis of internal carotid artery (ICA) involvement changes the primary treatment of head and neck tumors. Literature data on carotid encasement in head and neck cancer are scarce. One series reported on a 5% to 10% incidence of cervical lymph node metastases invading the ICA not diagnosed on preoperative imaging using 5 different imaging signs [1]. Encasement of the ICA is both a poor prognostic indicator and often a contraindication to surgical treatment [2]. Removal of lymph node metastases from the ICA may lead to stroke and carotid rupture in 3.3% and 5.5%, respectively [3]. The risk for cerebral damage after removal of the ICA is 3.3% to 30% [1]. Although grafting of the carotid artery, as generally performed in vascular disease and glomus tumors, is possible, it is generally not advocated because the outcome in oncologic patients is dismal [4]. Many attempts have been undertaken to classify carotid invasion on preoperative imaging including ultrasound, followed by magnetic resonance imaging (MRI) and computed tomography (CT) scan [1, 2, 5–13]. In 1995 Yousem et al. [2] demonstrated in a series of 49 patients undergoing neck dissection for head and neck tumors clinically suspicious for encasement that more than 270 degrees of circumferential involvement of