Clinical Study On Evaluating Pituitary Adenoma Texture By Preoperative MR Signal Intensity

Background: Pituitary adenoma is one of the most common benign intracranial tumors. The incidence of pituitary adenoma is about 1/100000, which accounts for 10 percent of brain tumor and has an increasing trend year by year. Although there are many assistant treatments for pituitary adenoma, surgical tumor resection is still the main way. Transsphenoidal approach (micrurge or nerval endoscope )for pituitary adenoma (no significant expansion around the saddle area) resection is the first choice instead of open surgery. However, there are about 10% of tumors can't be totally excised through transsphenoidal approach due to its tough texture. Furthermore, for some tough pituitary tumors which are large or middle-size and oppress the optic nerve and chiasma are more difficulty to be resected through transsphenoidal approach, thus, approaches through coronale and pterion might be a better choice to resect the tumor and release the tumor oppression on optic nerve and chiasma.Magnetic Resonance Imaging (MRI) possesses many merits including direct multidimensional imaging, high soft tissue resolution, and no false imaging of the skull base bone that could show a clear imaging about the saddle and its surrounding structures in the brain. Thus, the preoperative MRI of pituitary adenoma is very important for surgeons to determine surgical approach. However, it is still controversial about whether MRI could predict the texture of pituitary adenoma preoperatively. So that further study on evaluating pituitary adenoma texture by MRI in order to determine the optimal surgical approach and improve the prognosis is necessary.Objective: to study the possibility of preoperative texture evaluation of pituitary adenoma by MRI.Method: 70 cases of pituitary adenoma confirmed by surgery and pathology were divided into three groups based on tumor texture: soft-texture group (group A, 36 cases), the moderate-texture group (group B, 22 cases) and firm-texture group (Group C, 12 cases). All of the cases conduct MRI examination preoperatively. T1WI tumor/white matter signal intensity, T2WI tumor/white matter signal intensity signal as well as T1WI before/after contrast medium administration tumor signal intensity were calculated to compare with the tumor texture determined by surgery.Result: T1WI tumor/white matter signal intensity (TGSIR) in three groups were 1.32±0.18, 0.89±0.32 and 0.76±0.26 respectively and there was no significant statistical difference (P>0.05). Similarly,T1WI before/after contrast medium administration tumor signal intensity in the three groups were 1.25±0.28,1.48±0.33 and 1.91±0.45 respectively and there was no significant statistical difference(P>0.05). However, T2WI tumor/white matter signal intensity signal in there groups were 2.29±0.25, 1.87±0.12 and 1.38±0.23 respectively and there was significant statistical difference between each group(P<0.01).Conclusion: MIR is an uncomplicated and accurate measure to predict pituitary adenoma texture preoperatively and helpful in surgical approach selection. T2WI tumor/white matter signal intensity > 2.0 indicates a soft-texture tumor, between 2.0 and 1.7 indicates a middle-soft-texture tumor and <1.7 indicates a rough-texture tumor.