Quantitative MR derived imaging parameters as a predictor of secretory & histological phenotype in pituitary adenoma.
| Abstract: |
- Background: Accurate pre-treatment differentiation between pituitary adenoma subtypes sometimes poses a diagnostic challenge, complicating treatment decisions in patients with these tumours. In this retrospective, single centre study we sought to investigate if quantitative differences in tumour MR signal intensity could be used to non-invasively predict the secretory and histological phenotype of pituitary adenoma.
- Methods: Clinically acquired MR images were retrospectively analysed in 85 patients with pituitary tumours: 36 resected non-functioning pituitary adenomas (NFPA), 33 resected growth hormone (GH) secreting adenomas; and 16 medically treated prolactinomas. Absolute mean T1 and T2-weighted signal intensity (SI) values were derived for each tumour along with relative T1W and T2W SI ratio values normalised to either centrum semiovale white matter (WM) or CSF. Inter-group differences in absolute SI values, relative SI ratios, tumour T2W/T1 W SI ratio and relative T1 W post-contrast enhancement ratio between non-functioning and secretory tumours were compared. Subgroup analysis of 20 resected somatotroph adenomas was also undertaken to compare the effect of tumour granulation status on these quantitative MR parameters.
- Results: Prolactin secreting tumours displayed significantly higher relative T1W SI (p=0.02) and significantly lower mean T2W/T1W SI ratio values (p=0.007) compared to nonfunctioning tumours (Mann-Whitney U test). GH secreting tumours also displayed significantly lower relative T2W SI (p<0.001), significantly higher relative T1W SI (p<0.001), and significantly lower T2W/T1W SI ratio values compared to nonfunctioning tumours (Mann-Whitney U test). Within GH secreting tumours, sparsely granulated somatotrophs had significantly higher mean relative T2W SI (p=0.004) compared to densely granulated tumours. ROC analysis demonstrated that relative T1 W SI ratios had the greatest ability to discriminate non-functioning tumours from GH (AUC=0.786) and prolactin secreting tumours (AUC=0.707), and distinguish densely from sparsely granulated somatotrophs (AUC=0.681).
- Conclusion: Quantitative signal intensity based MR parameters display the ability to noninvasively discriminate the secretory status of pituitary adenomas and the granulation status of pre-treatment somatotroph adenomas.
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- Analysis of existing data
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