Contrast-enhanced MRI lights up prostate nodes

Fexumoxtran-10-enhanced MRI is as accurate for detecting the lymphatic spread of prostate cancer when performed in a community hospital as it is in academic settings.

A prospective trial involving 120 patients at Catherina Hospital in Eindhoven, the Netherlands, found that MRI enhanced with the iron oxide nanoparticle was 89% sensitive and 99% specific for differentiating between metastatic and nonmetastatic prostate lymph nodes.

Its negative and positive predictive values were 94% and 98%, respectively.

Ferumoxtran-10-enhanced MRI comfortably outperformed multislice CT. It was 44% sensitive and 96% specific to metastatic nodes. Its positive and negative predictive values were 67% and 91%, respectively.

The results are not surprising to radiologists familiar with the long research history of ferumoxtran-10. In 2003, researchers at Massachusetts General Hospital established that the agent was 100% sensitive on a patient basis and 90% sensitive on a nodal basis for this application. (NEJM 2003; 348(25): 2491-2499).

The more recent Catherina Hospital trial demonstrates that this performance can be duplicated by nonexpert physicians.

"The trial shows the value of this protocol in a community hospital among physicians who previously did not have experience with it. Only a small learning curve is involved," said Dr. Harrie van den Bosch, director of cardiovascular MRI at Catharina.

The Catherina Hospital study is part of a multicenter Dutch trial involving more than 400 patients. Staff radiologist Dr. Alette Wilhelmina Daniels-Gooszen presented the team's results at the 2006 International Society for Magnetic Resonance in Medicine meeting held in Seattle in May.

Ferumoxtran-10 consists of dextran-coated iron oxide particles averaging 10 nm in diameter. Macrophages take up the agent following intravenous administration and then transport it to lymph nodes involved to aid in diagnosing metastatic activity.

Developed by Advanced Magnetics in Cambridge, MA, the MRI contrast agent was licensed for distribution by Cytogen in the U.S. under the trade name Combidex and to Guerbet in Europe under the name Sinerem.

The FDA issued an approvable letter, subject to certain conditions, for Combidex in March 2005. Advanced Magnetics is seeking a broad indication for the differentiation of metastatic from nonmetastatic lymph nodes in all cancers. The company plans to respond to an FDA request for more clinical performance data before year's end.

Sinerem is moving toward European Commission approval and may achieve it by 2008, according to Daniels-Gooszen.