Defining response to radiotherapy in rectal cancer using magnetic resonance imaging and histopathological scales

Table 8 Summary of magnetic resonance imaging regression scale available in the literature

mrTRG scale	mrTRG
	(Low no. - More regression)[47]
1	Radiological complete response: no evidence of ever treated tumour
2	Good response (dense fibrosis; no obvious residual tumour, signifying minimal residual disease or no tumour)
3	Moderate response (50% fibrosis or mucin, and visible intermediate signal)
4	Slight response (little areas of fibrosis or mucin but mostly tumour)
5	No response (intermediate signal intensity, same appearances as original tumour)