美元符号关联数组索引

I am using Google Analytics API in PHP. I am fetching JSON data which I am converting into Associative Array by using Json_decode however when try to access attribute dxp$dimension, it gives error since it evals $dimension as a separate variable.

How do I evaluate whole thing as an Index for fetching data?

$array['dxp$dimension']

Use a single tick instead of double:

$array['variable$name'];