How to use unicode text in Case Statement in SQL Server

Hi! How I can use N idicate for operation WHEN in sql?

For example:  I input in IMT cell 17

SELECT 
CASE SUBSTRING(IMT) 
           WHEN 10 THEN 'кӯдакони то 18 сола'
           WHEN 11 THEN 'ҶБВ'
           WHEN 12 THEN 'ИҶБВ'
           WHEN 13 THEN 'Афғонистон'
           WHEN 14 THEN 'Чернобил'
           WHEN 15 THEN 'бемории умумӣ'
           WHEN 16 THEN 'бемории касбӣ'
           WHEN 17 THEN 'бемории рӯҳи'
           END  AS IMT
FROM PROBTABLE

In result output show:

IMT

бемории рӯҳи.

How I can use Unicode text in when operator?