If you receive a request to come back for a mammogram as the result of your first mammogram, it is called a diagnostic mammogram. This means the doctor would like to inspect more closely something that appeared on the original mammogram. Unlike in a screening mammogram, a radiologist is available to advise the technologist on imaging, so there are sufficient images to reach a conclusion. With the new 3D technology, a diagnostic follow up may only be a breast ultrasound, which is painless and does not involve radiation. An ultrasound can help determine if a suspicious area is a solid growth or a fluid-filled cyst. You also may have an MRI.