Perform partial volume correction for ASL images.

This 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)

Arguments

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.

Value

Returns partial volume corrected antsImage.

References

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.

Author

Kandel BM

Examples

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)