When imaging a geriatric patient, which imaging parameter is typically adjusted in a PCA MRA sequence?

In the context of a PCA (Posterior Cerebral Artery) MRA (Magnetic Resonance Angiography) sequence for geriatric patients, the parameter that is typically adjusted is the VENC, or velocity-encoded value.

Geriatric patients often present with vascular changes and conditions that can affect blood flow dynamics. The VENC parameter is critical because it relates to the maximum velocity of blood flow that can be measured in the region of interest. This value must be set appropriately for the patient’s specific vascular flow characteristics—particularly because older patients may have altered hemodynamics compared to younger individuals. An incorrectly set VENC can lead to aliasing artifacts in the images or missed pathological findings due to misinterpretation of the flow dynamics.

By adjusting the VENC, the MRI technologist ensures that the imaging parameters are optimized for the specific physiologic conditions of the patient. This ensures that the MRA sequence is able to accurately capture the relevant vascular structures and flow information, leading to better diagnosis and management of conditions affecting the brain's vascular supply.