patchDetection {imcRtools}

R Documentation

Function to detect patches containing defined cell types

Description

Function to detect spatial clusters of defined types of cells. By defining a certain distance threshold, all cells within the vicinity of these clusters are detected as well.

Usage

patchDetection(
  object,
  patch_cells,
  colPairName,
  min_patch_size = 1,
  name = "patch_id",
  expand_by = 0,
  coords = c("Pos_X", "Pos_Y"),
  convex = FALSE,
  img_id = NULL,
  BPPARAM = SerialParam()
)

Arguments

object	a SingleCellExperiment or SpatialExperiment object
patch_cells	logical vector of length equal to the number of cells contained in object. TRUE entries define the cells to consider for patch detection (see Details).
colPairName	single character indicating the colPair(object) entry containing the neighbor information.
min_patch_size	single integer indicating the minimum number of connected cells that make up a patch before expansion.
name	single character specifying the colData entry storing the patch IDs in the returned object.
expand_by	single numeric indicating in which vicinity range cells should be considered as belonging to the patch (see Details).
coords	character vector of length 2 specifying the names of the colData (for a SingleCellExperiment object) or the spatialCoords entries of the cells' x and y locations.
convex	should the convex hull be computed before expansion? Default: the concave hull is computed.
img_id	single character indicating the colData(object) entry containing the unique image identifiers.
BPPARAM	a BiocParallelParam-class object defining how to parallelize computations.

Value

An object of class(object) containing a patch ID for each cell in colData(object)[[name]].

Detecting patches of defined cell types

This function works as follows:

1. Only cells defined by patch_cells are considered for patch detection.

2. Patches of connected cells are detected. Here, cell-to-cell connections are defined by the interaction graph stored in colPair(object, colPairName). At this point, patches that contain fewer than min_patch_size cells are removed.

3. If expand_by > 0, a concave (default) or convex hull is constructed around each patch. This is is then expanded by expand_by and cells within the expanded hull are detected and assigned to the patch. This expansion only works if a patch contains at least 3 cells.

The returned object contains an additional entry colData(object)[[name]], which stores the patch ID per cell. NA indicate cells that are not part of a patch.

Author(s)

Tobias Hoch

adapted by Nils Eling (nils.eling@dqbm.uzh.ch)

References

Hoch, T. et al., Multiplexed Imaging Mass Cytometry of Chemokine Milieus in Metastatic Melanoma Characterizes Features of Response to Immunotherapy., bioRxiv 2021

Examples

library(cytomapper)
data(pancreasSCE)

# Visualize cell types
plotSpatial(pancreasSCE, img_id = "ImageNb", node_color_by = "CellType")

# Build interaction graph
pancreasSCE <- buildSpatialGraph(pancreasSCE, img_id = "ImageNb", 
                                 type = "expansion", threshold = 20)

# Detect patches of "celltype_B" cells
pancreasSCE <- patchDetection(pancreasSCE, 
                              patch_cells = pancreasSCE$CellType == "celltype_B",
                              colPairName = "expansion_interaction_graph")
                              
plotSpatial(pancreasSCE, img_id = "ImageNb", node_color_by = "patch_id")

# Include cells in vicinity
pancreasSCE <- patchDetection(pancreasSCE, 
                              patch_cells = pancreasSCE$CellType == "celltype_B",
                              colPairName = "expansion_interaction_graph",
                              expand_by = 20, 
                              img_id = "ImageNb")

plotSpatial(pancreasSCE, img_id = "ImageNb", node_color_by = "patch_id")
  

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