Some tests are done routinely, and others are done depending on whether the results would impact treatment decisions: PET or integrated PET-CT CT from neck to pelvis and bone scan (done if PET-CT is not available) MRI of chest (for tumors near apex or diaphragm to evaluate vascular supply) Biopsy of questionable nodes (if PET is indeterminate) Head CT or brain MRI PET scanning is a reasonably accurate, noninvasive test used to identify malignant mediastinal lymph nodes and other distant metastases (metabolic staging).