Final answer:
13N-Ammonia is used in PET scans to assess myocardial perfusion. Uniform uptake is expected in a healthy heart, while low counts can indicate reduced blood flow. Blood ammonia levels are normally low, as the liver detoxifies ammonia, but elevated levels can result in CNS symptoms and, in extreme cases, coma or death.
Step-by-step explanation:
The question pertains to the use of 13N-Ammonia as a radiotracer in medical imaging—particularly, positron emission tomography (PET) scans of the heart. In a normal patient, low counts of 13N-Ammonia in the myocardium could suggest areas of reduced blood flow or perfusion. However, typically, a healthy heart should exhibit uniform uptake of the tracer, indicating good blood flow throughout the myocardium. It is important to note that ammonia levels in blood must be properly regulated as high levels can lead to ammonia intoxication, affecting the central nervous system (CNS), and could result in symptoms like flapping tremor, slurred speech, blurring of vision, and in severe cases, coma and death. The normal blood level of ammonia is 10-12 µg/dl. Liver functionality plays a crucial role in ammonia regulation as it is the primary site for ammonia detoxification, and any liver abnormality can lead to elevated blood ammonia levels, similar to those observed in hepatic coma.