Medicare payment policy spurs new indications

Historians may look back on May 8, 2006, as a turning point in the history of molecular imaging. Before then, FDG-PET was chronically tangled in political problems that slowed its entry into the clinical mainstream. But in May, as the result of an unusual collaboration, Medicare payment took effect for most applications of FDG-PET and PET/CT in oncology.

At the same time the payment plan launched, a national PET registry was implemented to monitor the effect of the new indications on clinical decision making and patient management.

The payment policy includes 114 new indications spanning diagnosis, staging, and restaging. For the first time, Medicare will also provide payment for treatment monitoring of nearly every type of cancer.

But payment is contingent upon mandatory participation in a two-year survey managed by the American College of Radiology Imaging Network. Referring physicians must complete pre- and postimaging surveys in order to qualify a procedure for reimbursement. As of the middle of May 2006, the registry included 701 participants.

Results of large clinical trials in the first half of 2006 suggest that several molecular-based MR applications are also poised to enter the mainstream. The multicenter Magnetic Resonance Imaging for Breast Cancer Screening Trial confirmed the value of dynamic contrast-enhanced MRI as a screening tool for middle-aged women with genetic susceptibility to breast cancer. At the International Society for Magnetic Resonance in Medicine meeting in May, researchers at Catharina Hospital in Eindhoven, the Netherlands, demonstrated that the lymphotrophic nanoparticle ferumoxtran-10 reliably identifies prostatic lymph node metastases.

The MR tests, performed on 120 presurgical patients and 17 controls in a nonacademic setting, were 89% sensitive and 99% specific for metastastic nodes.

Nanotechnologies are also contributing important basic discoveries among more than 1000 scientific papers on molecular imaging published in the past six months. A basic scientific session on novel contrast media at the ISMRM meeting attracted an audience of more than 1200. Big things are expected from recent innovations with these ultrasmall agents.

In one instance, an interdisciplinary research team at the University of California, Los Angeles has demonstrated that miniature, microfluidic integrated circuits can manufacture FDG for PET imaging (Science 2005;310(5766):1793-1786). Large arrays of these "labs-on-a-chip" promise to revolutionize production methods for FDG and other radiopharmaceutical agents, said Dr. Sam Gambhir, director of the molecular imaging program at Stanford University.

At Stanford, researchers are exploring the capability of self-illuminating quantum dots. These are the first nanoparticles that may be used in optical imaging without an external illumination source, thereby greatly increasing sensitivity, according to Gambhir.

The microdot produces light from its R-Luc8 protein through a process called bioluminescence resonance energy transfer. The nanoparticle can potentially report several molecular events simultaneously by emitting light at several frequencies (Nat Biotech 2006; 24(3):339-343).

Concerns about the potential toxicity of carbon nanotubes may diminish because of work conducted at the University of London's Center for Drug Delivery Research. Investigators found that nanoparticles do not dwell in the liver and kidneys as long as suspected, and their circulation profile is ideal for molecular imaging, according to Dr. King Li, associate director of radiology at the National Institutes of Health. The findings will lead to more research exploiting the huge surface receptor and contrast media capacity of this material (PNAS 2006; 103(9):3357-3362).