MRItechnologie

MRI technology uses a strong static magnetic field, gradient fields, and radiofrequency pulses to generate detailed images of internal structures. Hydrogen nuclei align with the magnetic field and, when perturbed by RF pulses, emit signals that are spatially encoded and reconstructed into cross-sectional images by a computer. The method provides high soft-tissue contrast without ionizing radiation, making it especially valuable for the brain, spine, joints, and many abdominal organs.

Key components are a superconducting magnet, gradient coils, RF transmit/receive coils, and a computing system. Field strengths commonly used clinically are 1.5 tesla and 3 tesla. Various imaging sequences produce different contrasts, including T1- and T2-weighted imaging, diffusion-weighted imaging (DWI/DTI), perfusion imaging, MR spectroscopy, functional MRI (fMRI), and MR angiography (MRA).

Advantages include excellent soft-tissue detail and no ionizing radiation; limitations include longer scan times, sensitivity to motion and metal artifacts, and claustrophobic or acoustic discomfort. Safety considerations cover the strong magnetic field, which can interact with ferromagnetic implants, and the RF energy that can cause heating (SAR). Gadolinium-based contrast agents are used in some protocols and carry a risk of nephrogenic systemic fibrosis in patients with impaired kidney function or rare allergic reactions.

Applications span neurology and neurosurgery, musculoskeletal imaging, oncology, cardiology, and abdominal imaging. The technology originated in research in the 1950s–1970s; Paul Lauterbur and Peter Mansfield were awarded the Nobel Prize in 2003 for its development, and clinical MRI became widely available in the 1980s and 1990s.