A nurse is caring for a client who has a subarachnoid hemorrhage and asks why they are having a CT angiography. Which of the following should the nurse understand about CT angiography?

Choice A rationale A CT angiogram is primarily a vascular imaging technique. While hydrocephalus can occur secondary to a subarachnoid hemorrhage, a CT angiogram does not directly assess CSF production or overproduction. Specialized CSF flow studies or direct ventricular measurements would be more appropriate for evaluating CSF dynamics. Choice B rationale A CT angiogram visualizes the cerebral vasculature, allowing for the detection of narrowing or spasms in blood vessels, which are common complications following subarachnoid hemorrhage. Vasospasm significantly reduces cerebral blood flow, leading to secondary ischemia and potentially further neurological deficits. Early detection is crucial for intervention. Choice C rationale While a standard CT scan can reveal gross structural changes, a CT angiogram's primary purpose is to visualize blood vessels. For detailed, minimal changes in brain parenchyma, such as early ischemic changes or subtle tissue abnormalities, an MRI is generally superior due to its higher soft tissue contrast resolution. Choice D rationale A CT angiogram's main focus is the vascular system. While severe brain edema can be indirectly inferred from mass effect on vessels, a standard non-contrast CT scan is more effective for directly visualizing and quantifying brain edema by assessing tissue density changes and ventricular compression.