Vävnadstäthet

Vävnadstäthet refers to the density of tissues within a biological specimen, commonly used in medical imaging, particularly in radiology. It describes how much matter, such as bone or fluid, is present within a given volume. This property is crucial for interpreting images produced by techniques like X-ray, CT scans, and MRI.

In X-ray imaging, different tissues absorb radiation to varying degrees based on their vävnadstäthet. Denser tissues, like bone, absorb more radiation and appear white or light gray on the image, while less dense tissues, like air in the lungs, absorb less and appear dark. CT scans use a quantitative measure of vävnadstäthet called Hounsfield units (HU) to differentiate between tissues with greater precision. For example, water has an HU of 0, air has negative HU, and bone has positive HU, often exceeding 1000.

MRI, while not directly measuring radiation absorption, also relies on differences in tissue properties that correlate with density. Different types of tissues have varying relaxation times (T1 and T2) which are influenced by their molecular composition and arrangement, indirectly reflecting their density and water content. Understanding vävnadstäthet is fundamental for diagnosing conditions such as fractures, tumors, fluid collections, and degenerative changes, as these often manifest as alterations in tissue density on medical scans.