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Researchers have combined MR neuroimaging and DNA microarray analysis to create a multidimensional map of previously acquired gene-expression patterns in glioblastoma multiforme.

"Researchers have combined magnetic resonance neuroimaging and DNA microarray analysis to create a multidimensional map of previously acquired gene-expression patterns in glioblastoma multiforme (GBM).

The map "provided clinically relevant insights into tumor biology" non-invasively, the researchers note in the March 24th Early Edition of Proceedings of the National Academy of Sciences.

In the introduction, the authors note that genomic heterogeneity typifies GMB, and histologically similar tumors may exhibit different clinical behaviors. "Interestingly, histologically similar tumors often demonstrate highly distinct imaging profiles on MRI."

By analyzing pretreatment MRI studies for 22 GBMs, Dr. Michael D. Kuo from University of California San Diego School of Medicine and colleagues found five distinct MRI phenotypes that were significantly associated with several known gene-expression patterns.

"Most notably, an 'infiltrative' imaging phenotype was identified that predicted patient outcome," the researchers report.

Patients with the infiltrative imaging phenotype were more apt to have multiple tumor foci. The median survival was 216 days for the infiltrative phenotype versus 390 days for the edematous phenotype.

Overexpression of epidermal growth factor receptor (EGFR), a "potential therapeutic target, was also directly inferred by neuroimaging and was validated in an independent set of tumors by immunohistochemistry," Dr. Kuo and colleagues report.

"For the first time, we have shown that the activity of specific molecular programs in these tumors can be determined based on MRI scans alone," Dr. Kuo said in a written statement.

"It is likely that identification of imaging phenotypes tied to distinct molecular phenotypes will help to advance individualized patient care," Dr. Kuo and colleagues conclude.

Proc Natl Acad Sci USA 2008."