Evaluation Of Pituitary Adenoma Consistency With MRI And Its Relation With Collagen Content

Objective To study the relation between consistency, collagen content,preoperative T₂-weighted imaging（T₂WI）, diffusion-weighted imaging（DWI）, size,invasion, resection rate of pituitary adenoma with analysing the signal intensity（SI） onMRI and calculating collagen content in pituitary adenoma, then estimate the value ofT₂WI and DWI in detecting the consistency of pituitary adenoma, simultaneously,discuss the influence factors in tumor excision.Methods Thirty-eight patients harboring pituitary adenomas paticipated in thestudy. The MRI were obtained using a3.0-tesla MR scanner with a head birdcasetransmit/received coil preoperatively. As well as regular T₁-weighted imagings（T₁WI），T₂WI and DWI used, a GRE （gradient echo，GRE） sequence was used fora T₁-weighted post-contrast imagings. SI on T₂WI of tumor （T₂tumor） and SI onapparent diffusion coefficient（ADCtumor） imagings of tumor was collected, SI on T₂WIof tumor to SI on T₂WI of pons（RT₂） and SI on ADC imagings of tumor to SI on ADCimagings of pons（RADC） was calculated.The MRI indicators were compared to theconsistency of tumor. Then estimate the value of MRI indicators in detecting theconsistency of pituitary adenoma. Meanwhile,the sizes of tumors before and aftersurgery were figured out with “platform-like volume calculation formula”．Picric acidstaining was applied to observe the collagen component. Finally, we analysed therelation between consistency, collagen content, MRI indicators, size, invasion and resection rate of pituitary adenomas.Results1. In38patients, the tumor consistency at surgery was classified as softin13patients, intermediate in17patients, and hard in8patients. The collagencomponent could clearly be differentiated from tumor cells by picric acid staining.2. The MRI indicators of pituitary adenomas of different consistency werestatistically significant（P＜0.05）.3. By receiver operating characteristic（ROC） curve, we get the area under theROC curve （AUC） for T₂tumor, ADCtumor, RT₂, RADCin detecting different consistencyof pituitary adenoma. The AUC of MRI indicators for soft tumor was0.723,0.763,0.790,0.774, and0.524,0.681,0.555,0.654for tumors of the intermediate group. For tumors of the hard group, the AUC was0.524,0.681,0.555,0.654.Then we calculatedthe cutoff point for MRI indicators with AUC above0.7, results are shown below:（1）When detecting the soft tumor, we took0.562×10-3mm²/sec,0.856×10-3mm²/sec,1.77,1.23as cutoff point for T2tumor, ADCtumor, RT2, RADCrespectively. Thesensitivity（Sen） was84.6%,69.2%,76.9%,69.2%, the specificity（Spe） was60.0%,72.0%,76.0%,76.0%, the positive predictive value（PPV） was52.4%,56.3%,62.5%,60.0%, the negative predictive value（NPV） was88.2%,81.8%,86.4%,82.6%, and theKappa value was0.389,0.391,0.501,0.436. There were statistic difference betweenMRI indicators and the tumor consistency（P＜0.05）.（2） When detecting the hardtumor, we took0.650×10-3mm²/sec,1.031×10-3mm²/sec,1.72,0.85as cutoff pointfor T2tumor, ADCtumor, RT2, RADCrespectively. The sensitivity（Sen） was100.0%,100.0%,100.0%,37.5%, the specificity（Spe） was50.0%,23.3%,56.7%,93.3%, thepositive predictive value（PPV） was34.8%,25.8%,38.1%,42.9%, the negativepredictive value （NPV） was100.0%,100.0%,100.0%,78.8%， and the Kappa valuewas0.379,0.245,0.401,0.118， There were statistic difference between MRIindicators and the tumor consistency（P＜0.05）.4. The mean collagen content in soft group was1.51%±0.91%,7.34%±3.10%inthe intermediate group and15.45%±8.58%in the hard group. There were statisticdifference between the groups. We took3.74%as cutoff point for collagen content indetecting the soft tumors, the sensitivity（Sen） was100.0%, the specificity（Spe） was92.0%, the positive predictive value （PPV） was86.7%, the negative predictivevalue（NPV） was100.0%, and the Kappa value was0.887， There were statisticdifference between collagen content and the tumor consistency（P＜0.05）. We took8.93%as cutoff point for collagen content in detecting the hard tumors, thesensitivity（Sen） was87.5%, the specificity（Spe） was83.3%, the positive predictivevalue（PPV） was58.3%, the negative predictive value（NPV） was96.2%, and theKappa value was0.599，There were statistic difference between collagen content andthe tumor consistency（P＜0.05）.5. The mean size in the total removal group was （7.90±9.77）cm3and（31.62±22.30）cm3in the incomplete resection group. The mean size of pituitaryadenomas of different group were statistically significant （P＜0.05）.6. The mean resection rate in the group of Knosp grade0to2is72.88%±25.97, and97.27%±7.75in the group of Knosp grade3and4, there was a significantdifference between the two groups （P＜0.05）.Conclusion1. The collagen component was displayed clearly by picric acidstaining which was a reliable staining method to observe the collagen component.2. The SI on T₂WI and ADC imagings of tumor was connected with theconsistency of tumor. The MRI indicators on T₂WI and ADC had a certain value inprognosis the consistency of tumor.3. The consistency of tumor was connected with collagen content. The collagencontent was lower than3.74%in most of the soft tumors,and above8.93%in most ofthe hard tumors.4. Besides the consistency, the size of tumor and cavernous sinus invasion（CSI）also had effects on removing the tumour.