How to check if a table variable is empty in SQL Server?

This is a section of one of my stored procedure:

@dataInTable dbo.Table_Variable readonly,
....

AND (
    ( @dataInTable IS NULL )
    OR
    ( item IN ( SELECT T FROM @dataInTable ) )
)

@dataInTable IS NULL is wrong in syntax, error is

Must declare the scalar variable "@dataInTable"

So I change it to:

(SELECT T FROM @dataInTable) IS NULL

This works but if @dataInTable has more than 1 item, I get an error:

Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

Understandable, so I change it to:

(SELECT TOP(1) T FROM @ProgramRatings) IS NULL

Works perfectly, what I have is performance concern.

I am wondering, if there has an easier way to check whether a table variable is empty, like

AND (
    ( @dataInTable IS EMPTY )
    OR
    ( item IN ( SELECT T FROM @dataInTable ) )
)