Measuring signal-to-noise ratios in MR imaging.

Abstract

The signal-to-noise ratio (S/N) in magnetic resonance imagining is one of the variables that must be measured when comparing the relative performance of different techniques. Although various investigators and official groups have proposed different methods for measuring S/N, these are generally not practical for use by a physician working in a clinical situation. The authors present a simple method that should serve for estimating S/N in most cases.

Diffusion Tensor MR Imaging of the Neurologically Intact Human Spinal Cord

“…Individual subject scan times were determined from the start of the first FLASH locator image to the last DWI image. We calculated T2-weighted SNR for every section in every subject and then averaged across spinal levels for each subject by using the method outlined by Kaufman et al 20 This resulted in 1 SNR distribution per subject per level.…”

Efficient and robust computation of PDF features from diffusion MR signal

“…The energy is low when E ≈Ê and increases with their dissimilitudes. Note that σ has to be known a priori and can be either retrieved from multiple images [69,38] or a single image as described in [37,70,71]. Combining Eq.…”

Quadrature coil design for high‐resolution carotid artery imaging scores better than a dual phased‐array coil design with the same volume coverage

“…An estimation of noise was derived from the standard deviation (SD air ) of circular ROIs placed on the air surrounding the phantom outside regions that exhibited image artifacts (e.g., Gibbs ringing, T2 smearing in the readout/phase encoding directions). The SNR was calculated using the formula: (0.655 ϫ signal)/ SD air (7,8). The mean SNR at each depth was calculated from the SNR at the center and off-center in the three slices (nine observations).…”