Cross-sectional imaging correlates with gene expression in renal tumors

CONTEXT: The ability to correlate MR and CT results with genomic information captured with gene array technology would be an important step toward integrating both sets of diagnostic data into clinical decision making. Dr. Michael Kuo and colleagues at the University of California, San Diego compared the genomic topography of tumors mapped by complementary DNA (cDNA) microarrays with functional patterns seen with contrast-enhanced CT and MR imaging. They found that cross-sectional imaging can potentially reveal genomic patterns in renal cell carcinoma.

RESULTS: Renal tumors from 27 patients were examined with cDNA microarrays containing 23,000 elements representing 17,000 human genes, of which more than 7000 have been characterized. Of these 23,000 gene fragments, called clones, Kuo selected 1550 for analysis based on variations in their expression. The pattern of gene expression variation for each clone was plotted on a heat map covering each renal tumor. MRI and contrast-enhanced CT identified the presence or absence of hemorrhage or necrosis and characterized enhancement patterns. The patterns of enhancement and necrosis demonstrated significant correlation (p

IMAGE: A heat map of gene expression (top) tracks gene expression in a renal tumor. Red signifies gene overexpression, and green shows where the genes are underexpressed. A contrast-enhanced coronal MR image of a large renal tumor (bottom) reveals necrosis that corresponded to changes in gene expression.

IMPLICATIONS: Conventional CT and MR can potentially characterize large-scale gene regulation associated with specific biological processes. Such imaging traits may reveal early information concerning the response to cancer therapy.