typename FixedImageType::Pointer m_FixedImage;
typename FixedImageMaskType::ConstPointer m_FixedImageMask;
-#ifdef ITK_USE_OPTIMIZED_REGISTRATION_METHODS
+#if defined(ITK_USE_OPTIMIZED_REGISTRATION_METHODS) || ITK_VERSION_MAJOR >= 4
FixedImagePixelType m_FixedImageSamplesIntensityThreshold;
bool m_UseFixedImageSamplesIntensityThreshold;
#endif