P614 Reduction of bowel wall thickness and doppler signals as early as 36 hours predicts corticosteroid response in a multi-centre prospective cohort of Acute Severe Ulcerative Colitis: USUC Study including the GENIUS cohortYoon‐Kyo An, Roy E. Smith, T Goodsall et al.|Journal of Crohn s and Colitis|2023Cited by 3