Fig. 2.

Workflow for the diameter detection subroutine (BMode.m). Solid and dashed boxes indicate user and algorithm actions, respectively. In step 1a, the user selects the diameter region of interest (ROI) to begin the processing sequence. In step 1b, the ROI is cropped and transposed to allow the user to select the vessel center (green circle) and wall angle (orange line). In step 2a, a Gaussian filter is applied to the image to improve detection of the vessel walls via the (step 2b) Canny edge detection method. After repeating these steps for each image frame in the digital video, an aggregate diameter-time series is displayed (blue line) with ±10% error limits (dashed lines) (step 3). If the diameter values appear erroneous, the operator can choose to reselect the ROI or (step 4) record the subroutine output.