[Magnetic resonance imaging findings on the eyelids of Japanese cadavers for anatomical studies and a comparative examination of their histological pictures].

Objective: To clarify ambiguous areas in interpreting MR images of Japanese eyelids, a histological examination was conducted on cadavers after the MRI for a comparative evaluation.

Subjects And Methods: Orbital sections including the unilateral upper and lower palpebrae of two Japanese cadavers (an 87-year-old woman and a 49-year-old man) were examined. Following MRI, the specimens of the same cadavers were examined histologically for a comparative evaluation.

Results: In both cadavers, a high signal intensity area with a hazy appearance unlike the orbital fat--fibroadipose tissue rich with connective tissue--was recognized between the orbicularis muscle and orbital septum. The same high signal intensity area that appeared to encase the posterior section of the descending orbital fat was also composed of fibroadipose tissue. Because of the presence of this intervening fibroadipose tissue, the posterior surface of the orbicularis muscle and the orbital septum could not come into contact with each other.

Conclusion: Although limited to only two subjects, the current observation proved that fibroadipose tissue exists not only in the superficial layer of the orbital fat but that it further descends to surround the lowest portion of the orbital fat. As already reported, it was mainly the fibroadipose tissue, but not the orbital fat, that descends into the palpebral space.