MRI Technologistover 8 years ago

Time-of-flight (TOF) effects refer to signal variations resulting from the motion of protons flowing into or out of an imaging volume during a given pulse sequence. In both spin-echo and gradient-echo imaging, inflow of spins results in increased signal; this phenomenon is known as flow-related enhancement (FRE). Conversely, outflow of spins may result in decreased signal intensity, a phenomenon known as flow related (or high-velocity) signal loss, also called "washout".