How to return image sizes of an image URL to local variable

Question

I have this function that gets dimensions of a remote image url. The alert pops up with the correct values however i cannot return the value so I can use it to set the size of my local image. How can I get these values into a variable i can use?

function getMeta(url){
        $j("<img/>",{
            load : function(){
                alert(this.width+' '+this.height);
                // return this.width;                   
            },
            src  : url
        });
    }