Optimising an Update statemement with a very large Where clause
Instead of one massive update statement, use multiple update statements one for each where clause.

UPDATE [DatabeseOne].[dbo].[TableOne]
SET    [KeyWord] = 'X Ray'
WHERE  [ReviewNote] COLLATE Latin1_General_CS_AS LIKE('%- X-Ray -%')

UPDATE [DatabeseOne].[dbo].[TableOne]
SET    [KeyWord] = 'BMD'
WHERE  [ReviewNote] COLLATE Latin1_General_CS_AS LIKE('%- bone densitometry -%')