There are no reliable laboratory tests for ATC. Ultrasound imaging of ATC lesions reveals a hypoechoic mass (appears dark on ultrasound) with invasion of the local structures and may help to better characterize the presence or absence of neck lymph node metastases. If surgery is planned, however, then a contrast-enhanced computed tomography (CT) scan of the neck must be performed. A PET scan is preferred for staging ATC but a CT scan of the neck, chest, abdomen, and pelvis can be substituted if the former is unavailable. Magnetic resonance imaging (MRI) of the brain is also recommended to assess for distant metastases.