Pituitary macroadenomas: preoperative evaluation of consistency with diffusion-weighted MR imaging--initial experience

Purpose: To prospectively evaluate use of diffusion-weighted (DW) magnetic resonance (MR) images and apparent diffusion coefficient (ADC) maps for determination of the consistency of macroadenomas. Materials and Methods: The study protocol was approved by the institutional ethics committee, and informed consent was obtained from all patients. Twenty-two patients with pituitary macroadenoma (10 men, 12 women; mean age, 54 years ± 17.09 [standard deviation]; range, 21-75 years) were examined. All patients underwent MR examination, which included T1-weighted spin-echo and T2-weighted turbo spin-echo DW imaging with ADC mapping and contrast material-enhanced T1-weighted spin-echo imaging. Regions of interest (ROIs) were drawn in the macroadenomas and in normal white matter on DW images, ADC maps, and conventional MR images. Consistency of macroadenomas was evaluared at surgery and was classified as soft, intermediate, or hard. Histologic examination was performed on surgical specimens of macroadenomas. Mean ADC values, signal intensity (SI) ratios of tumor to white matter within ROIs on conventional and DW MR images, and degree of enhancement were compared with tumor consistency and with percentage of collagen content at histologic examination by using analysis of variance for linear trend. Results: The mean value of ADC in the soft group was (0.663 ± 0.109) × 10-3 mm2/sec; in the intermediate group, (0.842 ± 0.081) × 10-3 mm2/sec; and in the hard group, (1.363 ± 0.259) × 10-3 mm 2/sec. Statistical analysis revealed a significant correlation between tumor consistency and ADC values, DW image SI ratios, T2-weighted image SI ratios, and percentage of collagen content (P <"001, analysis of variance). No other statistically significant correlations were found. Conclusion: Findings in this study suggest that DW MR images with ADC maps can provide information about the consistency of macroadenomas.