"以半径度量的面积" can be translated into English as "area measured in terms of the radius" or more commonly and precisely in mathematical contexts, "area expressed in terms of the radius squared" (since area of a circle, for example, is calculated as πr², where r is the radius).
If you specifically refer to the concept where area is directly related to or based on the radius in a general sense (not necessarily limited to circles), the first translation ("area measured in terms of the radius") would suffice. However, if discussing specific geometric shapes like circles, the second translation ("area expressed in terms of the radius squared") is more accurate.