Which imaging characteristic indicates a low flow lesion on MRI post-gadolinium?

A bright T1 image following gadolinium administration typically indicates the presence of a low-flow lesion. This is because low flow lesions, such as certain types of vascular malformations or tumors, tend to retain the contrast agent for a longer duration, leading to an increased signal intensity on T1-weighted images. This characteristic is often seen in lesions that lack significant vascularity or rapid blood flow, which allows for greater contrast uptake.

In contrast, flow voids are seen in areas where there is high flow, as the rapid movement of blood can lead to an absence of signal in those regions. Pulsatile flow is also indicative of higher flow states and would not align with the characteristics of a low flow lesion. Indistinct margins can be present in various types of lesions but do not specifically denote low flow characteristics and could apply to malignant or inflammatory processes instead.