Effective therapies for the treatment of PKD will need to be delivered as early as possible, before a measurable decline in kidney function, to preserve functional tissue. Currently, it is difficult to make an accurate prognosis of the progression of early-stage PKD since the growth of microscopic cysts is difficult to detect by standard imaging modalities and changes in total kidney volume measured within a reasonable time period are too small to be informative. Even though early cysts may not cause detectable changes in total kidney volume, their progressive enlargement damages the surrounding tissue and is a prelude to chronic kidney disease.