Is There Any Congruity Between Tumor Consistency in Pituitary Macroadenomas and Preoperative Diffusion Weighted Imaging and Apparent Diffusion Coefficient (ADC) Map?

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Background: Pituitary adenomas are the most common space-occupying lesions in the sellar region. Pituitary adenomas are usually soft, but 5 to 13% of macroadenomas are fibrous. The resection of firm tumors by curettage or suction is challenging. Therefore, preoperative knowledge of the pituitary adenomas consistency could help neurosurgeons plan more appropriate surgical procedures. In this regard, predicting fibrous adenomas by magnetic resonance imaging (MRI) is typically difficult and the results are controversial. We evaluated the correlation of pituitary adenoma consistency during tumor resection with preoperative diffusion-weighted images (DWI) findings and apparent diffusion coefficient (ADC) values. Methods: 45 consecutive patients (21 male, 24 female, mean age 43 ± 10) with pituitary macroadenoma were prospectively enrolled. Radiological evaluation with conventional MR and DWI images was done for all patients. Tumor consistency was evaluated at surgery and classified as soft, intermediated, and hard. Histological examination was performed on tumor specimens. Results: Based on the surgical findings, 12 (26.7%) tumors were classified as soft-, 30 (66.6%) as intermediate-, and 3 (6.7%) as hard-consistency macroadenomas. Although the collagen content showed an association with tumor consistency, neither tumor consistency nor collagen content and secretory status were correlated with conventional MRI measures and ADCs in different b values and planes. Conclusions: Preoperative DW MRI was not useful to predict the tumor consistency, collagen content, and hormone-secreting status of pituitary macroadenomas.