Multimodal thinking on breast cancer
Sunday 09.00 PT: The US National Cancer Institute’s Network for Translational Research in Optical Imaging is a multicentre programme tasked with realizing practical optical modalities for early cancer detection, cancer diagnosis and measurement of response to therapy. Yesterday evening I went along to a dedicated BiOS session to hear about the network’s efforts in applying diffuse optical imaging for enhanced detection of breast cancer.
Brian Pogue, associate professor of engineering at Dartmouth College (Hanover, NH), kicked off the session by reviewing the integration of near-infrared spectroscopy (NIRS) into standard MRI and CT instrumentation. While this type of hybrid imaging is still in its infancy, he reckons that using it to guide therapy or to properly individualize the choice of therapy is “the next logical step”.
With this in mind, Dartmouth researchers, in collaboration with Philips Medical Systems, have developed a prototype small-animal imaging system that integrates NIRS into a 3 T MR breast biopsy coil.
“We use MR for imaging, NIR for spectroscopy,” said Pogue, adding that such an approach allows quantification of molecular tracers and biophysical imaging of tissue using contrast mechanisms that are not otherwise available.
Right now, however, the optical-fibre interface (for light delivery) is too cumbersome for the clinical setting, while the cost of integration takes optical spectroscopy out of the “inexpensive category”.
Soren Konecky of the University of Pennsylvania (Philadelphia, PA) provided an alternative take on the multimodal theme. His presentation reported on a small pilot study (17 patients) to evaluate the coregistration of diffuse optical tomography (DOT) and PET images of the human breast.
The purpose here is not primary detection of breast cancer, rather the evaluation of a patient’s response to therapy and early identification of resistance factors during treatment - information which can be used by doctors to adapt the treatment plan accordingly.
Unlike CT, MRI and ultrasound, DOT and PET primarily measure the physiological characteristics of tissue, rather than its anatomical structure. So why use optical and PET modalities in tandem?
“The combined analysis of optically measured parameters, such as haemoglobin concentration/oxygenation and blood flow, with PET parameters, such as fluoro-deoxyglucose uptake as a measure of glucose metabolism, may provide new and important information,” notes Konecky’s conference abstract.
He adds that “coregistration of DOT and PET parameters affords a method for increased tumour sensitivity and specificity compared to the stand-alone modalities.”