Molecular Imaging

Li Liu, MD
Last Modified: November 1, 2001

What is molecular imaging?
Thanks.

Li Liu, MD, OncoLink editorial assistant, responds:

Dear M:
Thank you for your interest and question.

Important developments in molecular sciences in the past decade have provided unprecedented opportunities in genome research, an understanding of the molecular mechanisms of disease, and the development of innovative therapies at the genetic level. These developments have been made possible, in part, because of automated and accelerated sequencing and progress in drug development. Associated with the developments in basic molecular biology are the remarkable advances in x-ray imaging technology and methodology.

Most traditional cross-sectional imaging techniques such as magnetic resonance (MR) imaging, computed tomography (CT), and ultrasonography (US) are reliant on physical and physiologic properties as the main source of contrast for the purposes of disease detection and characterization. Molecular imaging reaches beyond these and other imaging techniques by exploiting specific molecules as the source of image contrast. The development of specific imaging probes has allowed elucidation of metabolic pathways and specific cell cycle functions. Newer techniques such as optical imaging hold promise for the detection and further study of disease and pathogenesis at the microscopic level.

Molecular imaging with magnetic resonance spectroscopy and positron emission tomography (PET) is currently possible in clinical practice. These modalities permit functional, biochemical, and physiologic assessment of important aspects of malignancy. PET, in particular, measures the amount of sugar used by cells. Areas of increased sugar utilization represent tumor activity.

Research is ongoing to fuse standard radiology images with functional images to better identify tumors. Hopefully, this will allow doctors to better define the extent of disease and apply the current treatment modalities in an even more effective manner. When these types of molecular assessments are made, a more physiologic approach to therapy is possible. Molecular imaging evolving technologies will be invaluable in the diagnosis, staging, monitoring of therapeutic effectiveness, and understanding of cancer.