The slice overlap artifact is another name for crosstalk artifact. If slices of multisliceacquisitions are overlapping, the spinning nuclei belonging to more than one slice getting multiple times saturated, which leads to signal loss in this areas.
The not measured distance between the slices. For some sequences there is a slightest space of e.g. 10-20% necessary. A lower spacing can introduce more noise into adjoining slices.
The entry slice phenomenon arise in MRI when blood with unsaturated spins flows in the observed slice(s). These spins will emit a strong signal, because of their unsaturated status (flow related enhancement). The number of slices affected depends on the flowvelocity and the slice thickness; the direction of flow determines which slices are affected.
Time of FlightMRA is based on this entry slice phenomenon.