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Pituitary tumours account for~16% of central nervous system tumors and they are the second most frequently reported histology in this group. Due to their small size, pituitary surgery is challenging and precise lesion localization through imaging is therefore a critical factor for a successful outcome. Simultaneous positron emission tomography and magnetic resonance imaging is well suited for lesion identification and localization but it requires accurate attenuation correction (AC) to ensure optimal positron emission imaging (PET) imaging. Atlas-based AC methods are often used for this purpose, as they overcome the difficulty of estimating bone tissue density with conventional MR sequences. However, atlas methods can only partially account for interpatient variability. The goal of this paper was to investigate whether direct bone measurement, by means of a zero echo time MR sequence, can significantly improve the accuracy of pituitary tumor imaging with PET.

This work demonstrates the effect of radiofrequency transmit field (B1+) nonuniformity on the relaxation properties in normal breast tissue and malignant lesions and illustrates the necessity of B1+correction to prevent error propagation in subsequent pharmacokinetic analysis.