Creatine peak
Creatine is one of the compounds examined in MR spectroscopy. It resonates at 3.0 ppm chemical shift and is found in metabolically active tissues (brain, muscle, heart) where it is important in storage and transfer of energy. It tends to be maintained at a relatively constant level, and is predominantly used as a convenient internal standard (allow for ratio calculations), although it reduces in high grade gliomas. Of note it is not prominent in cerebral metastases and a absence of a creatine peak in an enhancing cerebral mass suggests metastasis over glioblastoma .