Ultrasound imaging in the classic sense offers imaging at the anatomic level, where investigations and interventions are carried out on two- or three-dimensional pictures with a certain resolution. Although numerous efforts at image enhancement, many mentioned above, can improve resolution, ultrasound has finite capability on the order of millimeters. Ultrasound imaging at the molecular or cellular level, however, does not mean that we are magically expanding resolution down to the micron level. Rather, molecular imaging is a method of detecting or highlighting certain molecules, even if the individual molecules are not uniquely defined. The concept is not unique to ultrasound, being employed with nuclear radiology techniques, MRI, and others. Molecular imaging is a complement, not a replacement, to anatomic imaging.