Evaluate SCC or SPM Detection Performance

Computes Sensitivity, Specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) by comparing detected points with ground truth ROI points. This function is used to assess the accuracy of SCC- or SPM-based detection in neuroimaging analysis.

Usage

calculateMetrics(detectedPoints, truePoints, totalCoords, regionName)

Arguments

detectedPoints

A data frame containing detected coordinates (x, y). SCC-detected points should be obtained using getPoints. SPM-detected points should be obtained using getSPMbinary.

truePoints

A data frame with ground truth ROI coordinates (x, y), extracted via processROIs.

totalCoords

A list with the full voxel grid dimensions, created by getDimensions. Must include named elements xDim and yDim.

regionName

A character string used to label the output region.

Value

A data frame with the following evaluation metrics

• region: Name of the analyzed region.

• sensitivity: True positive rate (TP / (TP + FN) * 100).

• specificity: True negative rate (TN / (TN + FP) * 100).

• PPV: Positive predictive value (TP / (TP + FP) * 100).

• NPV: Negative predictive value (TN / (TN + FN) * 100).

Details

This function requires three precomputed objects

• detectedPoints: SCC-detected points from getPoints or SPM-detected points from getSPMbinary.

• truePoints: Ground truth ROIs extracted using processROIs.

• totalCoords: Full voxel coordinate grid from getDimensions.

See also

getPoints for SCC-detected regions.
getSPMbinary for binary SPM-detected points.
processROIs for defining ground truth ROIs.
getDimensions for generating the coordinate grid.

Examples

# Load precomputed inputs for the example
data("calculateMetricsExample", package = "neuroSCC")

# Evaluate SCC and SPM detection performance
with(calculateMetricsExample, {
  metricsSCC <- calculateMetrics(detectedSCC, trueROI, totalCoords, "Region2_SCC")
  metricsSPM <- calculateMetrics(detectedSPM, trueROI, totalCoords, "Region2_SPM")

  print(metricsSCC)
  print(metricsSPM)
})
#>        region sensitivity specificity      PPV      NPV
#> 1 Region2_SCC    85.12872    95.62596 97.22839 78.10603
#>        region sensitivity specificity      PPV      NPV
#> 1 Region2_SPM    75.14124    96.31291 96.33654 75.01638