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BACKGROUND:At present,results of a few studies demonstrate that preoperative magnetic resonance imagling (MRI)examination reveals the texture of pituitary adenoma,I.e.on the T2-weighted image,solid pituitary adenoma shows weak signal and soft one shows strong signal.Also,solid pituitary adenoma is caused by fibrosis,which is confirmlea.However,some key problems are still in question and disputation,such as how to exactly quantize MRI signal intensity,which signal is used as prediction index,and the relationship of MRI signal and collagen content which reflects the texture of pituitary adenoma,and so on.OBJECTIVE:To observe the relationship of MRI signal intensity of different textures of pituitary adenoma and its collagen content,and investigate the best prediction index of the texture of pituitary adenoma.DESIGN:Case-control observation.SETTING:Department of Neurosurgery,Third Hospital Affiliated to Sun Yat-sen University;Department of Neurosurgery,Xiangya Hospital,Central South University.PARTICIPANTS:Fifty-seven patients with pituitary adenoma,including 32 males and 25 females,aged 20 to 65 years,who received treatment in the Department of Neurosurgery,Xiangya Hospital,Central South University during June 2003 to January 2004.The involved patients were all diagnosed by MRI and confirmed by pathological resection.Informed consents were obtained from all the patients.The samples of above-mentioned patients resected by operation were fixed with 40 g/L formaldehyde for sirius red staining.METHODS:①Accordling to the texture of pituitary adenoma observed in the operation:The 57 samples of pituitary adenoma were divided into 2 groups:non-flbrosis group(n=49)and fibrosis group(n=8).In the non-fibrosis group,the texture of pituitary adenoma was soft,I.e.pituitary adenoma tissue automatically flew out,and could be aspirated by aspirater or erased by curette,and the superior part of saddle could fall in the saddle,In the fibrosis group,pituitary adenoma tissue could be difficultly erased by curette,very strong drag power exiSted while pituitary adenoma was taken out,and supedor part of saddle could not fall in the saddle,could be resected in small pieces with the help of repeated electric coagulation or sharp instrument.②All the patients underwent MRI examination.The signal intensity ratio of pituitary adenoma to grey matter and white matter(pituitary adenoma/grey matter,pituitary adenoma/white matter)in T1-weighted image(T1w1),T2-weighted jmage (T2WI)and enhanced T1-weighted image (T1+WI)were measured;The samples were performed sirius red staining for measurling collagen content,and analyzed by automatic image analysis system (Kontron Ibas 2.5,Germany).Five visual fields were randomly chosen from each section to calculate the relative area occupied bv collagen(%) and the mean value was obtained.t test and linear correlation analysis were performed.MAIN OUTCOME MEASURES:①Signal intensity ratio of pituitary adenoma to grey matter and pituitary adenoma to white matter in T1WI,T1WI and T2WI.②Collagen content of pituitary adenoma samples.RESULTS:①Signal intensity ratio of pituitary adenoma to grey matter and pituitary adenoma to white matter in T1WI,T1WI and T2VI:T2 WI pituitary adenoma/grey matter and T2WI pituitary adenoma/white matter in the fibrosis group was lower than that in the non-fibrosis group,respectively(1.15±0.26 vs.1.57±0.46;1.48±0.39vs,2.10±0.61,P＜0.05-0.01).②Collagen content of pituitary adenoma samples:Collagen content of pituitary adenoma in the fibrosis group was higher than that in the non-fibresis group [(20.03±7.99)%vs.(7.87±4.82)%,P＜0.01].③The relationship of MRI signal intensity and collagen content:The correlation coefficient of T2WI pituitary adenoma/grey matter,T2WI pituitary adenoma/white matter and the total content of collagen was -0.531 and-0.726,respectively(P＜0.01).There were no obvious correlations between other signal intensity ratios and the total content of pituitary adenoma(r=0.124,P＞0.05).CONCLUSION:①There were obvious differences in the signal intensity ratio of T2WI pituitary adenoma and grey matter,white matter in MRI of different textures of pituitary adenoma.The difference of pituitary adenoma/white matter in T2WI was more obvious and better as predication index.When pituitary adenoma/white matter in T2wI was＜1.9,the texture of pituitary adenoma was solid.②T2WI pituitary adenoma/white matter and T2WI pituitary adenoma/grey matter in MRI of different textures of pituitary adenoma could reflect collagen content.