# landing_vignette

    library(neuroSCC)

# Introduction

This vignette guides you through the initial data preparation steps necessary to use the neuroSCC package for analyzing neuroimaging data with Simultaneous Confidence Corridors (SCC).

# 1. Loading and Inspecting Neuroimaging Data

We’ll begin by loading a sample PET neuroimaging file included with the package and inspecting its structure.

    niftiFile <- system.file("extdata", "syntheticControl1.nii.gz", package = "neuroSCC")

    # Load and clean data using neuroCleaner
    petData <- neuroCleaner(niftiFile)

    # Inspect the data
    head(petData)
    #>   z x y pet
    #> 1 1 1 1   0
    #> 2 1 1 2   0
    #> 3 1 1 3   0
    #> 4 1 1 4   0
    #> 5 1 1 5   0
    #> 6 1 1 6   0
    str(petData)
    #> 'data.frame':    902629 obs. of  4 variables:
    #>  $ z  : int  1 1 1 1 1 1 1 1 1 1 ...
    #>  $ x  : int  1 1 1 1 1 1 1 1 1 1 ...
    #>  $ y  : int  1 2 3 4 5 6 7 8 9 10 ...
    #>  $ pet: int  0 0 0 0 0 0 0 0 0 0 ...

# 2. Creating a Database from Multiple PET Images

Now, let’s demonstrate how to create a structured database using multiple PET files available in the package.

    # Create database for control subjects
    controlPattern <- "^syntheticControl.*\\.nii.gz$"
    databaseControls <- databaseCreator(pattern = controlPattern, control = TRUE, quiet = FALSE)
    #> Processing CN_number 1 - File 1 of 2
    #> Processing CN_number 2 - File 2 of 2

    # Inspect the created database
    head(databaseControls)
    #>   CN_number z x y pet
    #> 1         1 1 1 1   0
    #> 2         1 1 1 2   0
    #> 3         1 1 1 3   0
    #> 4         1 1 1 4   0
    #> 5         1 1 1 5   0
    #> 6         1 1 1 6   0
    table(databaseControls$CN_number)
    #>
    #>      1      2
    #> 902629 902629

# 3. Creating the Data Matrix

We’ll transform the PET database into a matrix format suitable for SCC analysis.

    # Create matrix for Z-slice 35
    matrixControls <- matrixCreator(databaseControls, paramZ = 35, quiet = FALSE)
    #> Processing Subject 1
    #> Processing Subject 2

    # Inspect matrix structure
    dim(matrixControls)
    #> [1]    2 9919
    str(matrixControls)
    #>  num [1:2, 1:9919] 0 0 0 0 0 0 0 0 0 0 ...

# 4. Normalizing the Data Matrix

Normalization adjusts for global intensity differences between subjects.

    # Perform mean normalization
    normalizedMatrix <- meanNormalization(matrixControls, returnDetails = FALSE)
    #>
    #>  Mean before normalization: 4.345851
    #>
    #>  Normalization completed.

# 5. Extracting Contours for Triangulation

Contours from the neuroimage are used to set boundaries for SCC computations.

    # Extract contours from sample data
    contours <- neuroContour(niftiFile, paramZ = 35, levels = 0, plotResult = TRUE)

    # Check contours structure
    length(contours)
    #> [1] 1
    str(contours[[1]])
    #> 'data.frame':    600 obs. of  2 variables:
    #>  $ x: num  8 9 9 9 9 9 9 9 9 9 ...
    #>  $ y: num  44 43 43 42 42 41 41 40 40 39 ...

# 6. Conditional Triangulation Setup (optional)

The triangulation step requires the external `Triangulation` package, currently not on CRAN. Ensure you have this package installed. If not, install it using:

    remotes::install_github("FIRST-Data-Lab/Triangulation")

Conditional example for triangulation:

    if (!requireNamespace("Triangulation", quietly = TRUE)) {
      cat("Triangulation package is not installed.\nInstall it using: remotes::install_github('FIRST-Data-Lab/Triangulation')\n")
    } else {
      # Perform triangulation with the first contour
      mesh <- Triangulation::TriMesh(n = 15, contours[[1]])

      # Inspect mesh
      print(mesh[["V"]][1:10, ])
      print(mesh[["Tr"]][1:10, ])
    }
    #> Warning in tri.mesh(X, Y): success: collinearities reduced through jitter
    #> Warning in tri.mesh(X, Y): dataset started with 3 colinear points, jitter
    #> added!

    #>              X        Y
    #>  [1,] 13.06667 38.40000
    #>  [2,] 13.06667 43.46667
    #>  [3,] 13.06667 48.53333
    #>  [4,] 13.06667 53.60000
    #>  [5,] 13.06667 58.66667
    #>  [6,] 13.06667 63.73333
    #>  [7,] 18.13333 28.26667
    #>  [8,] 18.13333 33.33333
    #>  [9,] 18.13333 38.40000
    #> [10,] 18.13333 43.46667
    #>       node1 node2 node3
    #>  [1,]     1   205   206
    #>  [2,]     1   206   207
    #>  [3,]     1   207   209
    #>  [4,]     1   209   210
    #>  [5,]     1   210   213
    #>  [6,]     1   213   215
    #>  [7,]     1   215     8
    #>  [8,]     1     8     9
    #>  [9,]     1     9    10
    #> [10,]     1    10     2

# What’s Next?

You’re now ready to perform Simultaneous Confidence Corridor analyses:

- Single-group SCC analysis (see `one_group_scc` vignette)
- Two-group comparison SCC (see `two_group_comparison` vignette)
- Single patient vs. group analysis (see `one_vs_group` vignette)

Feel free to explore these vignettes to continue your analysis journey with neuroSCC.