Step 1 :The problem provides the vertices of a parallelogram $Q R S T$ as $Q(-4,2), R(-2,4), S(0,1)$, and $T(-2,1)$.
Step 2 :We are asked to find the new coordinates of the vertices after a counterclockwise rotation of $270^{\circ}$ about the origin.
Step 3 :The transformation rule for a counterclockwise rotation of $270^{\circ}$ about the origin is $(x, y) \rightarrow (y, -x)$. This means that the x-coordinate of each point becomes the y-coordinate of the new point, and the y-coordinate of each point becomes the negative of the x-coordinate of the new point.
Step 4 :Applying this rule to the given vertices, we get the new vertices as $(2, 4), (4, 2), (1, 0), (1, 2)$.
Step 5 :Thus, the new coordinates of the vertices of the parallelogram after a counterclockwise rotation of $270^{\circ}$ about the origin are \(\boxed{(2, 4), (4, 2), (1, 0), (1, 2)}\).