Nanoparticle imaging research focuses on diagnostic and therapeutic possibilities
The utilization of nanometer-size compounds in medicine offers the potential for a new era of diagnostic imaging, as well as the promise of new capabilities for delivering therapies tailored and targeted for a specific disease, namely cancer and cardiac disease, according to Michael J. Welch, PhD, who delivered the Eugene P. Pendergrass New Horizons Lecture. He is a professor of radiology, chemistry and molecular biology and pharmacology at the Mallinckrodt Institute of Radiology at Washington University in St. Louis.
“Long-circulating nanoparticles functionalized with ligands for receptors over-expressed by tumor cells have promising applications for active and passive tumor targeting,” he said. These findings have allowed scientists to attach nanoparticles to radionuclides for MR, SPECT, PET and near-infrared optical imaging that function as probes for specific disease or inflammation. The pharmacokinetics of the nanoparticle can be altered to suit the requirements of the imaging technology being used, Welch said.
Welch forecasted that initial breakthroughs in clinical utilization of nanoparticle-based agents will be in agents “targeting cardiovascular function or with dual-use agents with imaging and drug delivery properties.”
Virtual colonoscopy: Perfect storm or chariot of fire?
During the Annual Oration in Diagnostic Radiology, keynote lecturer Elizabeth McFarland, MD, challenged attendees to “run the enduring race” in the effort to increase CT colonography (CTC) utilization in the restrictive reimbursement climate.
The 2008 joint colorectal cancer screening guidelines of the American Cancer Society, US GI Multi-society Task Force and ACR were a benchmark of multidisciplinary efforts. Yet, the economics of CTC will be greatly impacted as third-party payors and CMS now face reimbursement decisions based on new levels of validation and public policy recommendations. “The key challenge to CTC in today’s climate is to bring policy and practice into the line with knowledge,” she said.
Other issues include defining target lesion size for polyp detection and of radiation dose imparted by CT. Training is another issue to be conquered, both for radiologists and gastroenterologists. She proposed a focus on quality, creating standards for extracolonic findings and more responsibility for radiologists as ways to try to overcome the challenges that CTC faces in the current restrictive reimbursement environment. The choice, she said, lays in the hands of the radiologist—to weather the “perfect storm” or to be like famous “Chariots of Fire” runner Eric Liddell and “run the enduring race,” to bring practice and policy in line with knowledge for virtual colonoscopy.
Personalized medicine needs multispecialty collaboration
With the increasing convergence of imaging and radiotherapy delivery technologies, there is a great need for medical specialists in radiation oncology, diagnostic radiology and molecular biology to work together to improve the collaborative care of patients, according to Minesh P. Mehta, MD, who presented the Annual Oration in Radiation Oncology, “Alchemy, Early Detection, Precision Guidance, and Radiotherapy.”
“There is an absolute necessity for reintegrating diagnostic imaging and radiotherapy as vital partners in the battle against cancer,” said the professor in the department of human oncology & n eurosurgery at the University of Wisconsin School of Medicine and Public Health in Madison.
Mehta proposed that overcoming radiation resistance could be made easier by “flipping a single genetic switch,” allowing drug modulation to change drug tumor sensitivity to radiation. Imaging—such as PET and MR—could help by identifying resistance mechanisms and predicting the need for heavier doses of radiation in certain areas such as those with low oxygen levels.
Theragnostic radiotherapy opens up truly individualized treatment of specific tumors and voxels based on biologic capacity—like “dose painting with numbers,” Mehta said.