I have metastatic breast cancer to the spine. is a ct scan w/contrast or pet scan better for diagnoses?

Specific tests: It sounds like you have a formulated diagnosis. Above tests are used based on the type of question asked. Typically done for surveillance for cancers, PET scan is typically full body and has a functional (metabolic) component, while CT scans are best to compare with previous similar studies and provide structural detail ( preferred for chest and abdomen).