Guiding Cancer Treatment with Molecular Imaging

The following article was written by Miguel Pampaloni, M.D., Ph.D., Chief of Nuclear Medicine.

A recent article in Molecular Imaging discusses the promise of combining positron emission tomography (PET) with computed tomography (CT) in oncology.

At UCSF, we are using advanced nuclear imaging modalities that are able to unfold molecular mechanisms in the diseased cell. These advanced modalities are key to an accurate diagnosis and treatment of the oncologic patient. At the forefront lies PET technology, which we are using to image radioligands (molecules labeled to small amounts of radioactivity) that are created to target specific functional body processes.

Not only does molecular imaging reveal the functional characteristics of disease, but PET enables in vivo imaging with high (< 1 cm) resolution and high (nanomolar) sensitivity.  The addition of CT to PET instruments yields both functional/molecular information and structural images. That may be why PET/CT has become the most rapidly developing medical imaging modality.

The Molecular Imaging article refers to “a major avenue of research centered on correlating imaging probes such as FDG [fluorodeoxyglucose] with cancer phenotypes.” Most solid cancers typically have high rates of glucose utilization and therefore are very well suited to be imaged by PET.

It is becoming increasingly evident that molecular imaging will bring a new perspective to our understanding of cancer biology and its relevance in the planning of multidisciplinary treatments for cancer. FDG PET/CT is already an integral part of the initial work-up in patients scheduled to undergo surgery, radiation and chemotherapy treatments at UCSF. Metabolic imaging with FDG PET has an even greater value in assessing the early response to chemoradiation treatments. With FDG PET the response can be assessed well before conventional morphologic imaging, which allows clinicians to alter patient management appropriately.

UCSF is also one of the few locations in the country where researchers are participating in clinical trials of radiopharmaceuticals designed to examine hypoxia, cell proliferation and other molecular processes in tumors. Such research is expected to lead to a better characterization of tumor features, which is pivotal for tailoring cancer treatment to the individual patient.

The Molecular Imaging article discusses the use of nuclear medicine to gauge the response to cancer treatment, but indicates a lack of research regarding its use to predict survival rates. We at UCSF are finding increasing evidence that FDG/PET studies can predict not only response, but also survival for patients with diseases such as gastrointestinal tumors and breast cancer.