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Fig 3. 74-year-old woman with frontal sinus mucocele. Axial postcontrast MR image (A) shows the voxel of interest placed completely within the right frontal mucocele. Dural contrast enhancement (arrow) confirms the extra-axial location of the mucocele. There is no visible contamination of the voxel by normal brain tissue or scalp fat. In vivo proton MR spectrum (B) shows dominant peaks at 2.0 ppm (arrow) and 1.2 ppm (arrowhead), the latter assigned as lipid breakdown products. In vitro 1D NMR spectrum (C) of the mucocele sample after surgery confirms the main metabolite peak at 2.0 ppm (arrow). The 2D COSY spectra (D) show an N-acetyl compound at 2.0 ppm (asterisk), as well as cross-peaks for leucine (Leu), isoleucine (Iso) and valine (Val).
