Sarcophagus fragment of Emperor Constantine the Great (?)

Sarcophagus fragment presumed to be that of Emperor Constantine the Great (?). The iconic red Egyptian porphyry material is the same used for for Sarcophagi of Helena and Constantina (now in the Vatican Museums), depicting victorious Roman Cavalry riding above captured barbarians. It is unclear if such imagery was intended for the sarcophagus of a highly religious Christian man, or whether the coffin was repurposed for his burial.