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Diffusion-weighted MRI may offer a new non-invasive marker to differentiate between indolent and aggressive prostate cancer, UK researchers have proposed. "Diffusion-weighted MRI (DW-MRI) may offer a new non-invasive marker to differentiate between indolent and aggressive prostate cancer, UK researchers have proposed.

The decision to follow the path of active surveillance or radical prostatectomy can be a difficult one, and risk is conventionally assessed using serum levels of prostate specific antigen (PSA), Gleason score and clinical T stage.

However, biopsies to assess Gleason score are invasive and sampling errors may occur. While endorectal T2-weighted (T2W) MRI is used to image prostate cancer, both sensitivity and specificity can be poor.

The research group reviewed apparent diffusion coefficients (ADCs) of DW-MRI in 44 patients with clinically localized prostate cancer over a six-month period, in addition to biopsies and standard T2W MRI.

Twenty-six patients, with 36 tumour lesions, were classed as having low-risk disease (stage T1/T2a, Gleason score less than seven and PSA less than ten), whilst the remaining 18 patients with 23 lesions were assessed as having either intermediate- or high-risk disease.

The authors reported significant differences between the two groups in both ADC fast - 1778 vs 1583 x 10-6mm2/sec - and ADC slow - 1379 vs 1196 x 10-6mm2/sec.

They concluded: "DW-MRI offers potential as a non-invasive marker of biologically aggressive cancer. Tumour volume and the slow diffusion component appear to be discriminators of higher-risk disease."

"DW-MRI is simple to implement and the time penalty when added to a standard endorectal staging MRI examination is less than two minutes," they added.

However, they noted that further work to determine ADC cut-off values was needed.


Diffusion-weighted magnetic resonance imaging: a potential non-invasive marker of tumour aggressiveness in localized prostate cancer
Clin Radiol 2008; Articles in press"