@article{3120253,
    title = "Fluid-fluid levels in musculoskeletal tumor imaging",
    author = "Tsukamoto, S. and Errani, C. and Facchini, F. and Papagelopoulos, P. and Mavrogenis, A.F.",
    journal = "Current Medical Imaging Reviews",
    year = "2021",
    volume = "17",
    number = "2",
    pages = "157-165",
    publisher = "Bentham Science Publishers",
    issn = "1573-4056",
    doi = "10.2174/1573405616666200806173258",
    keywords = "adenoid cystic carcinoma;  angiosarcoma;  arthroscopy;  autopsy;  bone lesion;  brain hemorrhage;  breast carcinoma;  computer assisted tomography;  differential diagnosis;  epidermoid cyst;  erythrocyte sedimentation rate;  event free survival;  fat necrosis;  fibrous dysplasia;  fine needle aspiration biopsy;  hemangioma;  hematoma;  histiocytosis;  histopathology;  human;  image analysis;  leiomyoma;  malignant neoplasm;  musculoskeletal disease;  myositis;  needle biopsy;  neurilemoma;  neurofibroma;  nuclear magnetic resonance imaging;  osteomyelitis;  osteosarcoma;  plasmacytoma;  Review;  soft tissue tumor;  subdural hematoma;  thyroid carcinoma;  aneurysmal bone cyst;  bone tumor;  diagnostic imaging;  osteosarcoma, Bone Cysts, Aneurysmal;  Bone Neoplasms;  Humans;  Magnetic Resonance Imaging;  Musculoskeletal Diseases;  Osteosarcoma",
    abstract = "Fluid-fluid levels result from the separation of two fluids of differing densities within a cavernous space with the boundary between the two layers running in a horizontal plane at 90 de-grees to the direction of gravity. Magnetic resonance imaging is the most sensitive imaging modali-ty to identify fluid-fluid levels. Although the most common bone lesions containing fluid-fluid levels are aneurysmal bone cyst and telangiectatic osteosarcoma, fluid-fluid levels can be observed in a wide variety of bone and soft tissue lesions. Therefore, fluid-fluid levels cannot be considered diagnostic of any particular type of tumor and the diagnosis should be made on the basis of other clin-ical, radiological and pathological findings. This article summarizes the pathophysiology and imaging characteristics of fluid-fluid levels and discusses the differential diagnosis of tumors with this imaging sign. © 2021 Bentham Science Publishers."
}