nii.qc.snrd: Signal-to-Noise Ratio of Tissue Relative to Air

In TKoscik/nifti.qc: Quality control metrics and reports for NIFTI data

Description

Calculate the signal to noise ratio within the masked region relative to the background.

SNR_d = μ_ROI/[√((2/(4-π))σ_AIR)]

Dietrich O, Raya JG, Reeder SB, Reiser MF, Schoenberg SO. Measurement of signal<e2><80><90>to<e2><80><90>noise ratios in MR images: influence of multichannel coils, parallel imaging, and reconstruction filters. Journal of Magnetic Resonance Imaging: An Official Journal of the International Society for Magnetic Resonance in Medicine. 2007 Aug;26(2):375-85.

Usage

nii.qc.snrd(img.nii, img.vol=1L, mask.nii, mask.vol=1L, mask.dir="gt", mask.thresh=0, air.nii, air.vol=1L, air.dir="eq", air.thresh=1)

Arguments

img.nii	Full directory listing to desired nifti image (unzipped)
img.vol=1L	For multi volume images; an integer indicating the volume to load (1..N)
mask.nii	Full directory listing to desired nifti image to use for masking (unzipped). Must be identical pixel dimensions to base image.
mask.vol=1L	For multi volume images; an integer indicating the volume to load (1..N)
mask.dir="gt"	Direction to threshold the mask image to generate the desired ROI. Options include ("gt") [>] Default, "ge" [>=], "lt" [<], "le" [<=], "eq" [==]
mask.thresh=0	Value at which to threshold the mask image to generate an ROI. E.g., for binary masks, where the value 1 indicates the ROI, default of >0, will generate the appropriate mask
air.nii	Full directory listing to desired nifti image to use for identifying the air region around the head (unzipped). Must be identical pixel dimensions to base image.
air.vol=1L	For multi volume images; an integer indicating the volume to load (1..N)
air.dir="gt"	Direction to threshold the air mask image to generate the desired ROI. Options include ("gt") [>] Default, "ge" [>=], "lt" [<], "le" [<=], "eq" [==]
air.thresh=0	Value at which to threshold the air mask image to generate an ROI. E.g., for binary masks, where the value 1 indicates the ROI, default of >0, will generate the appropriate mask

Value

a numeric value indicating signal-to-noise-ratio relative to air

Author(s)

Timothy R. Koscik <[e-mail]>

TKoscik/nifti.qc documentation built on May 6, 2019, 4:30 p.m.