Fig. 4
From: Ventilation and perfusion MRI at a 0.35 T MR-Linac: feasibility and reproducibility study
The small and large ROI positions. The positions and numbering of the ROIs, whose mean ventilation value is used for the normalization of the ventilation-weighted maps, are displayed. In A the small ROIs with a size of \(8\times 8\) pixels and in B the large ROIs with \(12\times 12\) pixels are shown in blue with their assigned numbers starting from the top right lung. For presentation purposes, the ventilation maps were filtered using a Gaussian and then logarithmically plotted