Plural of spectrum. Spectra are components of the MR signal according to frequencies. Spectroscopy uses NMR spectral components to identify the metabolites, e.g. of the brain.

The mapping of a CSI spectral matrix to an anatomical image. It shows the regional changes in metabolites as superimposed contours.

A spectral line is a particular distinct frequency or narrow band of a frequency set. The resonance of this frequency occurs corresponding to a particular chemical shift. Theoretically, the frequency of a pure sine wave displays sharp spectral lines at the point of Larmor frequency. In reality, the spectral lines spread into a blurred peak, caused by field inhomogeneities and spin-spin effect.

The overall width in hertz needed to observe a particular NMR spectrum. This width is generally set using the Nyquist limit; namely, that the temporal sampling rate must be equal to twice the maximum spread in frequencies.

From Siemens Medical Systems;
Received FDA clearance in 2012.
The MAGNETOM Spectra is a cost-optimized high field MRI system with Tim 4G and Dot technologies. The system consumes less energy compared to other 3 Tesla scanners. The magnet-cooling helium is contained in a closed loop, which prevents the gas from escaping and reduces the need for refills. TimTX includes innovative techniques in the radio frequency excitation hardware as well as new application and processing features enabling uniform RF distribution in all body regions.