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Dynamic contrast-enhanced (DCE)-MRI in combination with diffusion-weighted imaging (DWI)-MRI is better than either modality alone in detecting local tumor progression after high-intensity focused ultrasonic ablation of localized prostate cancer, new research shows.

As reported in the American Journal of Roentgenology for May, Dr. Chan Kyo Kim, from Samsung Medical Center in Seoul, Korea, and colleagues evaluated these imaging modalities in 27 patients with increased PSA levels after treatment. Local tumor progression was defined as the presence of cancer foci on endorectal biopsy.

Eighteen patients had local progression after treatment, the report indicates.

DCE-MRI was more sensitive than DWI-MRI in detecting local progression. For the first blinded reader, DCE-MRI and DWI-MRI (T2-weighted) were 80 and 63 per cent sensitive (p = 0.004), respectively. The corresponding sensitivities for the second reader were 87 and 70 per cent (p = 0.004).

By contrast, DWI-MRI was more specific than DCE-MRI in detecting tumor progression. With the first reader, the corresponding specificities were 78 and 68 per cent (p = 0.002) and with the second reader were 74 and 63 per cent (p < 0.001). The accuracy rates of each modality for both readers were roughly 72 per cent.

For reader one, the areas under the receiver operating characteristic curve for DCE-MRI and DWI-MRI were 0.77 and 0.77, respectively. The corresponding values for reader two were 0.85 and 0.81.

"After high-intensity focused ultrasonic ablation, the normal anatomy of the prostate gland is completely lost or deformed, making it difficult to distinguish benign tissue from cancer," Dr. Kim said in a statement. The present findings suggest that the combination of DCE-MRI and DWI-MRI, which only takes about seven minutes to perform, is best for this purpose.