The echocardiography measurements of the internal dimension of the proximal coronary segments are expressed as Z scores, which are normalized on the basis of body surface area.
Z scores given in ECHO are interpreted as follows:

The ECHO can be normal when done at 1st contact with the patient. Therefore, even if the initial ECHO is normal, it should be repeated at 1-2 weeks and again at 4-6 weeks. IVIG administration should not be withheld even if an ECHO is normal initially. With a diseased coronary the further follow up depends upon the size of the aneursyms, when they stabilize and how is the response to therapy.