Current controversy, confusion, and imprecision in the use and interpretation of rectal MRI.

There has been a rapid increase in the utilization of MRI in rectal cancer staging in the USA essentially replacing endorectal ultrasound and mimicking the trend in Europe seen in the 1990s and 2000s. Accompanying this trend, there is a demand, and recognized need, for greater precision and clarification of confusing, misunderstood and poorly understood concepts, facts, statements and nomenclature regarding rectal cancer and the use of pelvic MRI for diagnosis. As such, this Review, part evidence-based and part expert opinion, will attempt to elucidate and clarify several concepts the authors have encountered in 25 years of imaging rectal cancer, focusing on MRI.