Value of apparent diffusion coefficient (ADC) in evaluating response of carcinoma of the cervix treated with chemoradiotherapy.

Objective. To determine whether the apparent diffusion coefficient (ADC) value obtained by diffusion-weighted magnetic resonance imaging (DW-MRI) can be used as a reliable detector of response of carcinoma of the cervix treated with chemoradiotherapy, compared with conventional T2-weighted MRI. Design. A prospective cohort study was performed. Setting. Department of Oncology, Universitas-National Hospital Complex, Bloemfontein. Subjects. Seventeen women with advanced cervical cancer, FIGO staging IIB - IVB, were selected for chemoradiation. Outcome measures. Patients underwent pelvic MRI before therapy, 14 days after onset of therapy, and in the last week of treatment (5th/6th week). Axial and sagittal conventional T2 was followed by DW-MRI in the axial plane from which a tumour region of interest (ROI) was manually drawn to calculate ADC values using b-values of 500 and 1 000 s/mm². Results. ADC values for cervical carcinoma increased after treatment with chemoradiation. The most significant observation was seen 14 days after treatment was started. The mean ADC value increased with 20% (b=500 s/mm²) and 24% (b=1 000 s/mm2) (statistically significant, p<0.05) compared with a decrease in tumour size of only 8%, which was not statistically significant (p=0.075). Responders showed a larger change in ADC values than non-responders. Conclusion. The study showed considerable promise in the ability of ADC to identify early tumour response to therapy. DW-MRI is a non-invasive functional imaging technique that may in future change management in oncology by early identification of non-responders, hence avoiding unnecessary treatment. [ABSTRACT FROM AUTHOR]

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