Résumé
Elastography is any of a class of medical imaging modalities that map the elastic properties and stiffness of soft tissue. The main idea is that whether the tissue is hard or soft will give diagnostic information about the presence or status of disease. For example, cancerous tumours will often be harder than the surrounding tissue, and diseased livers are stiffer than healthy ones. The most prominent techniques use ultrasound or magnetic resonance imaging (MRI) to make both the stiffness map and an anatomical image for comparison. Palpation is the practice of feeling the stiffness of a person's or animal's tissues with the health practitioner's hands. Manual palpation dates back at least to 1500 BC, with the Egyptian Ebers Papyrus and Edwin Smith Papyrus both giving instructions on diagnosis with palpation. In ancient Greece, Hippocrates gave instructions on many forms of diagnosis using palpation, including palpation of the breasts, wounds, bowels, ulcers, uterus, skin, and tumours. In the modern Western world, palpation became considered a respectable method of diagnosis in the 1930s. Since then, the practice of palpation has become widespread, and it is considered an effective method of detecting tumours and other pathologies. Manual palpation has several important limitations: it is limited to tissues accessible to the physician's hand, it is distorted by any intervening tissue, and it is qualitative but not quantitative. Elastography, the measurement of tissue stiffness, seeks to address these challenges. There are numerous elastographic techniques, in development stages from early research to extensive clinical application. Each of these techniques works in a different way. What all methods have in common is that they create a distortion in the tissue, observe and process the tissue response to infer the mechanical properties of the tissue, and then display the results to the operator, usually as an image. Each elastographic method is characterized by the way it does each of these things.
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Concepts associés (9)
Cirrhose
La cirrhose (du grec ancien : « roux ») est une maladie grave du foie, résultant d’agressions biochimiques répétées, le plus souvent par la consommation chronique d’alcool ou par des virus hépatotropes mais pouvant aussi résulter de l’accumulation de graisses dans le foie, de maladies auto-immunes, de déficits enzymatiques ou autres. Elle est définie selon des critères morphologiques de fibrose et de transformation de l’architecture normale du foie en nodules structurellement anormaux dont la couleur roussâtre a inspiré le nom actuel de la maladie à René Laennec.
Foie
vignette|Le foie est en rouge sur cette représentation du système digestif humain. Le foie est le plus gros organe abdominal et fait partie de l'appareil digestif sécrétant la bile et remplissant plus de vitales, notamment les trois suivantes : une fonction d'épuration, une fonction de synthèse et une fonction de stockage. Il s'agit d'une glande amphicrine permettant la synthèse de la bile (rôle exocrine) ainsi que celle de plusieurs glucides et lipides (rôle endocrine). Il joue aussi un rôle important dans l'hémostase.
Steatosis
Steatosis, also called fatty change, is abnormal retention of fat (lipids) within a cell or organ. Steatosis most often affects the liver – the primary organ of lipid metabolism – where the condition is commonly referred to as fatty liver disease. Steatosis can also occur in other organs, including the kidneys, heart, and muscle. When the term is not further specified (as, for example, in 'cardiac steatosis'), it is assumed to refer to the liver.
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