What is Molecular Imaging?

Molecular imaging is defined as the measurement and/or imaging of biological processes in living organism at the molecular and cellular level. It is about combining genetic information and new chemistries into new imaging probes, detectable by sophisticated imaging technologies. Advancements arising from this research can enhance our knowledge of disease, lead to earlier disease detection and accelerate drug discovery. The research field has had a significant impact on biomedical research and the clinical practice of imaging.

The nuts and bolts

The key elements to molecular imaging are shown in the figure. The multidisciplinary research involves different fields including target discovery, chemistry, cell biology, modeling of disease, imaging, data processing and clinical research.

While some key molecular targets involved in certain diseases are well established (see faculty research), newer targets, chemical ligands and sensing technologies wait to be developed. Thus, there are four broad areas in which considerable research efforts lie:

  1. defining and developing strategies for identifying suitable “biomarkers”, or “imageable gene products”
  2. development of suitable in vivo ligands,
  3. development of efficient organ and intracellular targeting and amplification strategies, and
  4. development of novel and dedicated small animal imaging systems with high spatial resolution and sensitivity. Much of the research performed at the CMIR addresses these specific needs and opportunities.

Technology development

Biomedical research evolves and advances not only through the assemblage of knowledge, but also through the development of new technologies. Using traditional methods of imaging, clinicians are able to survey the body for anatomic and physiologic abnormalities occurring in disease, albeit at an often late stage. The emergence of new tools enables researchers to address previously intractable problems and to uncover novel potential targets for imaging. Different molecular imaging tools now allow scientists to analyze expression of many gene products in vivo. For example, novel optical imaging technologies and smart sensing reporter probes represent a major methodological advance and illustrate how the advent of new technologies provides powerful tools for researchers.


Molecular imaging has largely become possible by the advances in molecular and cell biology techniques, new methods of combinatorial drug design, high throughput testing and the emergence of novel imaging techniques and probes. Although specific examples of imaging specific targets date back to the early 70’s (e.g. in nuclear medicine), it was not until the mid 90’s that concerted efforts were made to embrace key technologies and broadly develop the field from a biological and molecular perspective. Significant funding for the field became available from NIH and other agencies in the late nineties.

The CMIR at MGH was established in 1994 under the directorship of Ralph Weissleder. Since its inception, the long term goals of the CMIR have been:

  1. the development of novel technologies and methods for in vivo molecular imaging,
  2. extending the technologies to important questions in tumor biology and clinical research and
  3. dissemination to the broadest possible base of researchers.
The Center was originally housed in 3,000 sq. ft. of research space at MGH’s premier CNY research facility. The facility was expanded in 1999 to 5,800 sq. ft. and in 2001 to over 10,000 sq. ft. The Center has been one of the pioneering molecular imaging centers in this country. The Center is currently funded by over 40 grants.