In vivo imaging in clinical practice

Over the past decade, the use of non-invasive, in vivo optical imaging has dramatically improved animal models in preclinical research.

The technique encompasses chemiluminescence, bioluminescence and fluorescence imaging from the visible to the near infrared spectrum, as well as Cerenkov light emission from PET/SPECT probes.

Alongside this, multimodality co-registration of 3D optical molecular imaging data with micro CT offers enhanced resolution and improved anatomical context.

One application that has experienced the benefits of the technology is the development of anti-cancer agents.

There is currently an acute need to augment the predictability of our preclinical models to enable translation to successful clinical trials. The co-registration of fluorescence probes with bioluminescence is an extremely powerful in vivo screening technique.

The capability to multiplex the information obtained from an animal model by generating multiple relevant biomarker readouts can significantly improve the predictability of the model.

For instance, readouts of fluorescence imaging biomarkers of apoptosis, drug resistance, hypoxia, angiogenesis, invasiveness, and differentiation in combination with firefly luciferase, a commonly used bioluminescent marker in biomedical research with good sensitivity for optical detection of tumor growth and metastasis, can help predict the long-term therapeutic response of a cancer.

The hurdle at this point is that the probes and instrumentation have to go through regulatory approval

Using this technique, researchers could further identify early diagnostics, potential molecular targets and novel therapeutics.

The imaging technique is always dictated by the root biological question. Currently, there is no single imaging modality that universally addresses all proper analyses.

Therefore, the answer is multi-modality, multi-reporter imaging in combination with careful experimental design. This is something researchers are working to advance, while moving the technique towards clinical use. For instance,

PerkinElmer is developing an open air fluorescence imaging system that will allow for its large portfolio of fluorescent imaging agents to be translated into clinical applications.

The system could help distinguish healthy tissue from cancer, which is currently the Holy Grail in tumor resection. Historically, cancer surgeons have always faced the issue of not knowing exactly which areas are cancerous and which is normal.

Traditionally the surgeon has to rely on their experience and gut instinct- it is a bit like making a blind assessment.

The intent with our system is that we can inject fluorescent probes that are specifically activated by cancer cells. By illuminating the surgical field with a fluorescent light source, the surgeon can then more readily identify cancer tissue.

You can imagine when doing brain surgery this is extremely helpful as we do not want to resect healthy neurons and further impair function.

The hurdle at this point is that the probes and instrumentation have to go through regulatory approval and that is time-consuming. It is probably the biggest bottle neck in getting the technology into the clinics. Once we do however, its significance could be huge.