How does molecular imaging differ from structural imaging?
Molecular imaging allows for the noninvasive functional and molecular characterization of normal tissues and disease processes of interest, even when morphologic changes in tissues have not yet occurred. Structural imaging (such as with radiography, computed tomography [CT], magnetic resonance imaging [MRI], and ultrasonography [US]) allows for the noninvasive anatomic assessment of normal tissues and disease conditions based on morphologic and gross functional alterations that occur. Molecular imaging techniques typically have higher contrast resolution (i.e., the ability to distinguish between differences in image intensity) and lower spatial resolution (i.e., the ability to distinguish two adjacent structures as being separate) compared to structural imaging techniques. As such, molecular imaging and structural imaging techniques are complementary.