An apparatus for diagnosing a patient includes a catheter having a tip. The apparatus includes a bioptome disposed in proximity to the tip to obtain a tissue sample of the patient. The apparatus includes a radiodetector disposed in proximity to the tip to detect radiation in the patient. A method for diagnosing a patient includes the steps of moving a tip of a catheter to a desired location in a blood vessel of the patient determined by radiation detected by a radiodetector disposed in proximity to the tip. There is the step of obtaining a tissue sample of the patient with a bioptome disposed in proximity to the tip.