Evaluation of magnetic resonance diffusion and spectroscopy measurements as predictive biomarkers in stage 1 cervical cancer
To establish whether ADC and total choline were significantly different between cervical tumors with different histological characteristics (type, degree of differentiation, presence or absence of lymphovascular invasion, lymph-node involvement) in order to establish their role as predictive biomarkers. 62 patients with stage 1 cervical cancer were scanned at 1.5 T. T2-weighted imaging (TR/TE = 4500/80 ms), to identify tumor and normal cervix, was followed by diffusion-weighted imaging (TR/TE = 2500/69 ms; 5 b-values 0, 100, 300, 500 and 800 s/mm2) and MR spectroscopic imaging (15 mm slice, 7.5 mm in-plane resolution, TR = 888 ms). Regions of interest in normal cervix and tumor were drawn on apparent diffusion coefficient (ADC) maps by an expert observer with reference to the T2-weighted images. ADCs were calculated using a monoexponential fit of data from all b-values. MR spectra in voxels designated as tumor (> 30% tumor) or non-tumor were quantified using LCModel and referenced to tissue water. There was a statistically significant difference between the ADC of tumor regions (1117 ± 183 × 10− 6 mm2/s) and of selected normal regions (1724 ± 198 × 10− 6 mm2/s; p < 0.001), and between tumors that were well/moderately differentiated (1196 ± 181 × 10− 6 mm2/s) compared with those that were poorly differentiated (1038 ± 153 × 10− 6 mm2/s; p = 0.016). There was no significant difference between the ADCs of the tumors when separated by other characteristics (tumor type, lymphovascular invasion, lymph-node metastases), or between measured total choline in any of the groups. ADCs are lower in cancer compared to normal cervical tissue, with degree of tumor differentiation contributing to this difference.