I am not sure what nodes they want to take out. Can they say that there are cancerous nodes from CT or MRIs scans?

The tumour is on a left side tongue


25/09/12 - diagnosis: lateral left side tongue moderate SCC (10-15mm)
15/10/12 - operation: partial glossectomy + neck dissection
17/11/12 - operation: excision of the tongue scar (or extensive biopsy)
26 y.o., non-smoker, social drinker