Fig. 6

False negative (a–c) and false positive (d–f) abscesses on axial fat-suppressed T2-weighted images (a, d), post-contrast T1-weighted images (b, e), and ADC maps (c, f) (arrows). False negative, top row (a–c): in a patient with a sore throat, a T2-hyperintense non-enhancing collection with ADC values were interpreted as high rather than low (no purulence). However, surgery found an abscess. False positive, bottom row (d–f): in a patient with neck swelling, MRI shows lymphadenitis and one enlarged submandibular lymph node with no enhancement and low ADC, and suppurative lymphadenitis (intranodal abscess) was diagnosed. However, surgery demonstrated necrosis but no purulence. Image modified from ref. [2]