diff --git a/Modules/Filtering/ImageCompose/test/itkComposeBigVectorImageFilterTest.cxx b/Modules/Filtering/ImageCompose/test/itkComposeBigVectorImageFilterTest.cxx
index db3f6b66655..84b15225a43 100644
--- a/Modules/Filtering/ImageCompose/test/itkComposeBigVectorImageFilterTest.cxx
+++ b/Modules/Filtering/ImageCompose/test/itkComposeBigVectorImageFilterTest.cxx
@@ -58,22 +58,23 @@ itkComposeBigVectorImageFilterTest(int, char *[])
   VectorImageType::Pointer img = composeFilter->GetOutput();
   std::cout << "Compose filter executed." << std::endl;
 
+
+  itk::ImageRegion<3> sliceRegion = img->GetLargestPossibleRegion();
+  sliceRegion.SetSize(2, 1); // Set the size of the z-dimension to 1
+
   for (unsigned int i = 0; i < nchannels; ++i)
   {
     itk::IndexValueType                  z = i;
     std::map<unsigned int, unsigned int> values;
 
-    for (itk::IndexValueType y = 0; y < size; ++y)
+    sliceRegion.SetIndex(2, z); // Set the index of the z-dimension to the current slice
+
+    itk::ImageRegionConstIterator<VectorImageType> it(img, sliceRegion);
+    for (it.GoToBegin(); !it.IsAtEnd(); ++it)
     {
-      for (itk::IndexValueType x = 0; x < size; ++x)
+      if (it.Get()[i] != i % 250)
       {
-        itk::Index<3> idx = { { x, y, z } };
-
-        auto pixel = img->GetPixel(idx);
-        if (pixel[i] != i % 250)
-        {
-          ++values[pixel[i]];
-        }
+        ++values[it.Get()[i]];
       }
     }