Abstract: A method of developing a diagnosis and prognosis for an aneurysm in order to determine a procedure for treating the aneurysm. The method includes determining a first diameter of a blood vessel at a first location proximal to an aneurysm, and determining a second diameter of the blood vessel at a second location. The second location incorporates at least a portion of the aneurysm. Next, the ratio of the second diameter to the first diameter is calculated. And, a prognosis of the aneurysm, and a determination of the treatment for the aneurysm, may then be determined based on the ratio.