Part 1: Recommend a type of diagnostic image, with or without contrast, for the following patients: 1) A patient with persistent lower back pain resistant to conservative interventions. 2) A 74-year-old male with dyspnea, productive green phlegm, fever and chills, and malaise. 3) A 48-year-old female who is 48-hours postoperative complaining of right-calf pain.

Part 2: 1) When are computed tomography (CT) scans indicated? 2) When are magnetic resonance imaging (MRIs) indicated? 3) What helps the FNP decided whether to use contrast or not when ordering a CT scan or MRI?