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Fig 1. A representative case showing the procedure of thrombus volume measurement. A, Maximum intensity projection images of thin-section noncontrast CT in a patient with occlusion in both M1 and M2 segments on the right (arrows). B, All pixels are segmented with a threshold of 50–100 HU to select the thrombus (azure areas). After selecting the function of 3D region growing, we drew a region of interest around the thrombus on an axial image and then automatically segmented the whole thrombus (indigo areas). Note that the thrombus does not approximate the border of the probable thrombus. C, Pixel dilation with a single iteration for the segmented thrombus is performed at a threshold of 40–100 HU. The thrombus approximates its border more than does the thrombus on B (indigo areas). D, The volume and mean Hounsfield unit of the thrombus are calculated. MinValue indicates minimal value; MeanValue, mean value; MaxValue, maximal value.
