Final answer:
The statement is true; in a TOF angiography using a GRE sequence, the Entry Slice Phenomenon or Flow Related Enhancement causes blood to appear bright on images, which is useful in visualizing vessels in MR angiography without contrast agents.
Step-by-step explanation:
Using a Gradient Echo (GRE) sequence, Time-of-Flight (TOF) angiography will indeed show bright blood. This effect is known as Entry Slice Phenomenon or Flow Related Enhancement (FRE), which utilizes the difference in magnetization between static tissue and inflowing blood to increase contrast. Thus, the statement provided is A. True. Blood that has not been exposed to previous RF pulses enters the imaging slice with a higher magnetization state than the saturated spins of the stationary tissue. As a result, this fresh blood appears bright on TOF images. This technique is particularly useful in MR angiography to visualize vessels and blood flow without the need for contrast agents.