Tumor markers and multimodal magnetic resonance imaging in predicting rectal cancer stage and differentiation

Table 1 Magnetic resonance imaging staging criteria

MRI staging criteria	Description
T1 stage	The tumor is limited to the mucosal layer, presenting as a polypoid structure within the lumen or as a local mass
T2 stage	The thickness of the wall exceeds 0.5 cm, but the tumor has not yet extended to the surrounding fat tissue, with a clear distinction from surrounding fat
T3 stage	The tumor extends to the surrounding fat tissue but has not reached the fascia. This stage is defined as tumor penetration through the wall layer and invasion into surrounding fat
T4 stage	The tumor further invades the pelvic region and may be accompanied by distant metastasis

MRI: Magnetic resonance imaging.