In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Initial brain magnetic resonance imaging ( MRI ) were obtained after the hospitalization , including DWI ( 8 / 8 ) , apparent diffusion coefficient ( ADC ) map ( 4 / 8 ) , FLAIR ( 7 / 8 ) , and T2 - weighted image ( 8 / 8 ) .
### Output Text:
Initial brain magnetic resonance imaging ( MRI ) were obtained after the hospitalization , including DWI ( 8 / 8 ) , apparent diffusion coefficient ( ADC ) map ( 4 / 8 ) , FLAIR ( 7 / 8 ) , and T2 - weighted image ( 8 / 8 ) . 