Magnetic Resonance Imaging (MRI). MRI_axial: (A) Axial T1-weighted Spin Echo (SE) MRI shows circumferential thickening of the trachea (white arrow) with intermediate signal intensity of the thickened mucosa/submucosa. (B) T2-weighted Turbo SE MRI at the same level. Note the pathological high signal intensity of the thickened mucosa/submucosa, which corresponds to mucosal inflammation. MRI_sag: (C) Sagittal T1-weighted SE MRI shows irregular narrowing of the airway (white arrow). (D) Sagittal T2-weighted Turbo SE MRI of the subglottic trachea shows thickening of the tracheal lumen with high signal intensity due to inflammation.