Fig. 4

Locus coeruleus in MRI. a Brainstem schema in midsagittal ex vivo MRI, localizing LC. Scale bar = 1 cm. b The three LC rostrocaudal sublevels: light blue–rostral, blue–middle, dark blue–caudal. c–f 3D label reconstructions in aged control (BB 0) and earliest stages of Alzheimer’s disease neuropathologic change (BB I-III) in samples #3, 13, 18, and 21. Median volumes (g–j) and lengths (k–n) for whole LC and its rostral, middle, and caudal portions, respectively, with interquartile range shown. Significant differences between BB 0 and BB II observed in whole (Panel g, p = 0.0381, Mann–Whitney U test) and rostral LC volumes (Panel h, p = 0.0381, Mann–Whitney U test). Plus ( +) symbols indicate mean. Scale bar = 2 mm