Investigation of choice for lumbar prolapsed disc -

REF : essential ohopedics, Maheshwari , 9th edition , pg.no.256 MRI is the investigation of choice . it shows the prolapsed disc theca, nerve roots very clearly .others are 1. x- ray , 2.myelography - shows* complete or incomplete block to the flow of dye at the level of a disc * an indentation of dye column * root cut off sign : normally dye fills up the nerve roots sheath . In cases where a lateral disc prolapse is pressing on the nerve root, the sheath may not be filled .It appears on x- ray , as abrupt blunting of dye column filling the root sheath. 3.CT scan 4.electomyography