Chemical exchange saturation transfer (CEST) is an advanced MR contrast, which is sensitive to metabolic parameters as pH or protein content. The present study shows the ammonia-sensitivity of amide proton CEST imaging at a fixed pH value. The in vivo applicability is tested in a population of patients suffering from hepatic encephalopathy (HE), which is linked to ammonia accumulation within the brain. In HE, the CEST signal is especially reduced within occipital and cerebral regions. This reduction may be related to increased ammonia levels in HE patients.