All quiet at the contrast agent front?

By Prof. Peter Rinck

Visiting professor, University of Mons, Belgium

The most striking feature for me at ECR this year is the expansion of company-sponsored satellite meetings. Usually limited to lunch sessions, they now run in parallel to the proffered papers, competing with the scientific session marathon.

The contributions on new developments in contrast agent research drown in the overwhelming numbers of clinical papers. At first sight, when reading through the program, one gets the feeling that we are back to the times when contrast agent research was carried out by a few groups at universities, though with a certain lack of economic reality and commercial concerns.

The companies traditionally involved in contrast agents seem to have learned from their big mistakes of the last 10 years, and the results are fairly cruel: cuts in their research laboratories. Some of the big players closed down their research sites or have completely disappeared from the scene. Some traditional hardware manufacturers are trying to move into molecular imaging on their own, and results of their involvement remain to be seen. Limited research is left in Berlin and Paris. Otherwise, it's status quo ante, at least at ECR.

A partly old, partly fresh guard has been mobilized to restore vanishing fortunes. At places, it looked like a tale of desperation against changing times. Some of the presentations and satellite symposia did not improve the reputation of the industry. They are rather a media hype to push products developed more than a decade ago. They are good products, no doubt, but not worth scientifically veiled symposia.

For contrast agent manufacturers, this megacongress is first of all a sales fair. Sales-relevant papers dominate the lectures and posters, whereas cutting-edge developments for specialists remain in the background, to be presented elsewhere; for example, at the small EMRF meeting on contrast agent research in June.

The novelty and big marketing scoop of the congress is the introduction of Schering's Vasovist as the first blood pool contrast agent designed for use with MR angiography. Vasovist was developed as MS-325 by Epix Pharmaceuticals, and Schering is its worldwide marketing partner. The contrast agent reversibly binds to albumin and provides prolonged intravascular enhancement, a possible advantage over the existing extracellular MR contrast agents.

Guerbet keeps its competing compound Vistarem under wraps in Vienna. The new approach requires a collaboration with the hardware manufacturers. Because of the extended period for the development of these compounds, they have backed MR angiography with the traditional extracellular gadolinium agents.

Limited novelties in contrast agent research

A fresh breeze in contrast agent research is blowing from some of the university-based research groups. Interestingly, those radiological university and research centers in Europe that have received heavy state or industrial grants still have problems in competing with U.S.-based sites. Although many European names feature in the authors' lists, the place of work lies somewhere between San Francisco and New York.

Matrix metalloproteinases (MMPs) play an important role in atherosclerotic plaque progression, rupture, and thrombosis. A gadolinium-labeled short peptide ligand for MMPs (P947) allows molecular imaging of such atherosclerosis-associated matrix metalloproteinases, thus turning it into a specific MR contrast agent (S. Amirbekian et al.; presentation number: B-537). H.E. Daldrup-Link presented similar developments (presentation number: A-042). She pointed out that ultrasmall superparamagnetic iron oxides (USPIO) are currently investigated for the diagnosis of various phagocytosis associated processes, such as inflammation, encephalomyelitis and atherosclerosis. Their activity may correlate with the phagocytic activity of the investigated process, counting them under the novel receptor-targeted contrast agents and "smart" contrast agents. As an example, she showed the tyrosine kinase HER-2/neu receptor, which has a significant role in staging and treating breast cancer.

The capacity of USPIO-enhanced MR imaging to detect and follow monocyte/macrophage activity in various inflammatory disorders reaches beyond the vascular compartment. D. Weishaupt (presentation number: A-094) stressed that using USPIO macrophage activity, several inflammatory diseases of the central nervous system, as well as musculoskeletal infections, nephritis, and arthropathies may be targeted, promising a breakthrough in noninvasive imaging of cellular progression of disease.

More straightforward topics were introduced in a collaborative Dutch/Danish effort. Their pilot study showed oral manganese to be a simple and inexpensive contrast agent to improve visualization of liver metastases by selectively increasing liver signal intensity (H.M. Dekker; presentation number: B-456).

Last but not least, the problems with high field strengths for contrast and contrast agents were once more underlined by a study at 7T: Ultrahigh-field contrast is overall lower and contrast patterns are significantly altered compared to conventional MRI. Acquisition parameters thus have to be carefully optimized (P. Schmalbrock; presentation number: C-715).

This article is based on the personal views of the author and not those of Diagnostic Imaging or Diagnostic Imaging Europe magazine.