partialVolumeCorrection.RdThis function performs a partial volume correction for ASL images by dividing the observed CBF by the gray matter and white matter probabilities, as described in Johnson et al., Radiology 2005: CBF_corrected = CBF_observed / (GM_prob + 0.4 * WM_prob)
partialVolumeCorrection(img, img.gm, img.wm, mask = NULL, proportion = 0.4)
| img | Low-resolution image to be corrected. All input images can be either of type antsImage or numeric vectors (if numeric vectors, the mask is ignored). |
|---|---|
| img.gm | Gray matter probability image for partial volume correction. |
| img.wm | White matter probability image for partial volume correction. |
| mask | Brain mask for image. |
| proportion | Ratio of activity for white matter to gray matter. Assumed to be 0.4. |
Returns partial volume corrected antsImage.
Method: Pattern of cerebral hypoperfusion in Alzheimer disease and mild cognitive impairment measured with arterial spin-labeling MR imaging: initial experience. Johnson NA, Jahng GH, Weiner MW, Miller BL, Chui HC, Jagust WJ, Gorno-Tempini ML, Schuff N. Radiology 2005.
Ratio of GM to WM activity: Quantitative magnetic resonance imaging of human brain perfusion at 1.5 T using steady-state inversion of arterial water. Roberts DA, Detre JA, Bolinger L, Insko EK, Leigh JS Jr. PNAS 1994.
activity.gm <- 10 activity.wm <- activity.gm * 0.4 percent.gm <- matrix(seq(0.1, 1, by=0.1), nrow=2) percent.wm <- -percent.gm + 1 activity.obs <- percent.gm * rnorm(n=length(percent.gm), mean=activity.gm, sd=5) + rnorm(n=length(percent.wm), mean=activity.wm, sd=5) activity.corrected <- partialVolumeCorrection(activity.obs, percent.gm, percent.wm)