Diffusion-weighted imaging does not seem to be a predictor of consistency in pituitary adenomas

Purpose To prospectively evaluate the usefulness of T1-weighted imaging (T1WI) and diffusion-weighted imaging (DWI) sequences in predicting the consistency of macroadenomas. In addition, to determine their values ​​as prognostic factors of surgical outcomes. Methods Patients with pituitary macroadenoma and surgical indication were included. All patients underwent pre-surgical magnetic resonance imaging (MRI) that included the sequences T1WI before and after contrast administration and DWI with the apparent diffusion coefficient (ADC) map. Post-surgical MRI was performed at least 3 months after surgery. The consistency of the macroadenomas was evaluated at surgery, and they were grouped into soft and intermediate/hard adenomas. Mean ADC values, signal on T1WI and the ratio of tumor ADC values ​​to pons (ADC R ) were compared with tumor consistency and grade of surgical resection. Results A total of 80 patients were included. A softened consistency was found at surgery in 53 patients and hardened in 27 patients. The median ADC in the soft consistency group was 0.532 × 10 –3 mm 2 /sec (0.306 – 1.096 × 10 –3 mm 2 /sec), and in the intermediate/hard consistency group was 0.509 × 10 –3 mm 2 /sec (0.308 − 0.818 × 10 –3 mm 2 /sec). There was no significant difference between the median values ​​of ADC, ADC R and signal on T1W between the soft and hard tumor groups, or between patients with and without tumor residue. Conclusion Our results did not show usefulness of the DWI and T1WI for assessing the consistency of pituitary macroadenomas, nor as a predictor of the degree of surgical resection.