PMC6243341_01
CT scan (a) and MRI [(b) axial T1 weighted; (c) axial STIR; (d) axial diffusion-weighted imaging with background suppression) show a juxtatonsillar left parapharyngeal mass with central calcification and fat tissue peripherally. Hounsfield units in the CT scan ranged between -80 and -116 (a), while fat saturation by means of STIR technique (c) confirmed the presence of fatty tissue. CT scan after ontrast media showed no enhancement (not shown). STIR, short tau inversion-recovery.
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PMC6243341_01_bjrcr.20150183.g001.jpg
fig1
Fat identification by means of regions of interest drawn on CT images (Figure 1a), allows attenuation differences of different tissues to be found. On MRI, fat identification relies on hyperintensity visible on T1 weighted images (Figure 1b) together with the fat supression technique (Figure 1c), which nulls the magnetization of fat at certain times during acquisition. We also performed a diffusio-weighted acquisition by means of "diffusion-weighted imaging with background suppression" pulse sequence acquired at four different crescent values of the "b" coefficient (maximum b = 800 s mm-2) to assess if the tissue had pathologic restriction of molecular water movement; no pathologic restriction was found (Figure 1d).