7T

7T refers to magnetic resonance imaging systems that operate at a magnetic field strength of 7 tesla. This makes 7T one of the highest field strengths used for human MRI, offering a higher signal-to-noise ratio and the potential for finer spatial resolution than conventional 1.5T or 3T scanners. In practice, 7T can enable submillimeter imaging and more detailed visualization of brain structures, including cortical layers and small nuclei.

Most 7T installations are head-only systems used for research and specialized clinical investigations. While whole-body 7T systems exist, they are far less common due to technical challenges such as radiofrequency field inhomogeneity and increased safety considerations. Thus, 7T imaging is predominantly found in academic medical centers and dedicated imaging facilities.

Technically, the higher field strength improves SNR by roughly two to three times compared with 3T, enabling higher spatial and, in some cases, faster imaging. However, 7T introduces stronger susceptibility effects and B0 inhomogeneities, which can distort images and complicate sequences near air-tissue interfaces like the sinuses. These artifacts are mitigated through advanced shimming, parallel transmission, and specialized coils, but they remain a defining challenge of 7T imaging.

Applications of 7T MRI include high-resolution structural imaging, ultra-detailed functional MRI, and advanced diffusion imaging for tractography. It supports research into brain organization, cognitive function, and neurological diseases such as epilepsy and brain tumors. Safety considerations include stricter screening for implants, higher RF heating (SAR) limits, and the need for dedicated infrastructure and training.