Magnetic susceptibility artefact on MRI mimicking lymphadenopathy: description of a nasopharyngeal carcinoma patient

This report describes a case involving a 34-year-old male patient with nasopharyngeal carcinoma (NPC) who exhibited the manifestation of lymph node enlargement on magnetic resonance (MR) images due to a magnetic susceptibility artefact (MSA). Initial axial T1-weighted and T2-weighted images acquired before treatment showed a round nodule with hyperintensity in the left retropharyngeal space that mimicked an enlarged cervical lymph node. However, coronal T2-weighted images and subsequent computed tomography (CT) images indicated that this lymph node-like lesion was an MSA caused by the air-bone tissue interface rather than an actual lymph node or another artefact. In addition, for the subsequent MR imaging (MRI), which was performed after chemoradiotherapy (CRT) treatment for NPC, axial MR images also showed an enlarged lymph node-like lesion. This MSA was not observed in a follow-up MRI examination when different MR sequences were used. This finding suggests that when performing lymph node staging for patients with head and neck carcinomas such as NPC, the possibility of an MSA should be considered to avoid misinterpretation and excessive treatment.