The choice between a nasal endoscopy and a CT scan depends on the patient and the condition being evaluated. CT scans are useful for evaluating nasal and sinus anatomy and identifying structural abnormalities, but nasal endoscopy provides a more direct view of the interior of the nasal passages and sinuses. Nasal endoscopy is often used to diagnose conditions like sinusitis and nasal polyps. The best option may depend on the patient's specific needs and the doctor's recommendation, and in some cases, a combination of both may be necessary to make a diagnosis.