American Society of Radiologic Technologist (ASRT) Practice Exam

What type of contrast medium dissociates into two molecular particles when dissolved in water?

1. Nonionic agents

2. Hydroxyl groups

3. Amines

4. Ionic agents

The correct answer is: Ionic agents

The correct answer is that ionic agents dissociate into two molecular particles when dissolved in water. Ionic contrast media contain ionic compounds that separate into positively and negatively charged ions in solution. This dissociation is significant because it influences the osmotic properties of the solution, which can affect the patient’s physiological response when the contrast medium is administered during imaging procedures. Understanding the behavior of ionic agents in solution is fundamental for radiologic technologists, as it helps in selecting the appropriate contrast medium based on the clinical scenario. The dissociation leads to higher osmolarity compared to nonionic agents, which remain intact in solution and do not break apart into separate ions. This can result in a higher risk of adverse effects such as allergic reactions or discomfort during the procedure when using ionic agents, which is critical knowledge for patient safety and care. The other choices, such as nonionic agents, hydroxyl groups, and amines, do not fit this description. Nonionic agents are designed to not dissociate into ions, which makes them generally safer with fewer side effects. Hydroxyl groups and amines are chemical groups rather than types of contrast media and do not pertain to the context of the question regarding the behavior of contrast materials in solution.