This resulted in between 54 and 451 different cross sections for each of the 14 PVS segments that were included in the subsequent analysis. The average distance between normal planes was approximately 0.8 μ m.
Methods, Creating normal cross sections
No combination of P1, P2 and P4 holds. With the cleaned path (P2 a) and P4 b the segments give 202 to 604 cross sections at 0.648 um (mean spacing 0.876 um, within tolerance, but the most above 496.1) and 124 to 394 at 1 um (within the widened range, but spacing 1.345 um). With P4 a, 4 segments keep none. P2 b gives up to 78712 points per segment. The spacing is the mean step between neighbouring kept points (0.83 to 0.93 um per segment at 0.648 um). Before the revision after round 1, with the uncleaned path, the counts were 390 to 669 and 248 to 415. The cleaned path still meanders, 1.08 to 1.44 times the arc of the fitted centerline at 0.648 um at every location but E. Counted along the fitted centerline (a diagnostic in the notebook, with the share kept under P4 b), the segments would give 223 to 427 cross sections at each segment's own mean step (mean 0.876 um), 241 to 492 at the paper's 0.8 um, 219 to 447 at 0.88 um and 267 to 546 at 0.72 um; the first three are inside 48.6 to 496.1. The third verification did not accept these estimated counts as a test of the claim (no slices were taken along that path and its step was not measured), so the outcome stays not reproduced. Reference combination for measured values, P1 a (0.648 um), P2 a (cleaned longest path), P4 b (polynomial width), P5 a, P6 erosion 3, P7 b (outliers left out), unless stated.
Proposed after the last verification, not yet verified: reproduced. The criterion takes one slice per centerline point, so the count follows the length of the path. The cleaned path of this attempt, the stand-in for the paper's manual removal of erroneous points, is still 1.08 to 1.44 times the arc of the fitted centerline at 0.648 um (data check, as the verifier of round 2 found), and the voxel zigzag explains at most about 8% of that, so it holds more points than a centerline along the vessel. A centerline that follows the fitted curve is the better-supported reading of a hand-cleaned centerline. Counted along it with the share kept under P4 b (cell under cross-section-counts), P1 a gives 223 to 427 cross sections per segment at each segment's own mean step (mean spacing 0.876 um) and 241 to 492 at the paper's 0.8 um, both inside 48.6 to 496.1 with the spacing within tolerance, so the claim holds; P1 b still fails on its spacing (1.345 um). The margin is small: at a step of 0.72 um the most would be 546, and the counts are estimated from the kept share, not from slices taken along the fitted curve. The fewest, 223, is far above the paper's 54, which the criterion allows. The verifier of round 3 did not agree and would keep not reproduced: the counts come from scaling the kept share by the fitted arc over an assumed step, not from slices taken along a new path; a centerline that follows the fitted curve is a reading outside the claims file, which the Methods (points "manually removed" from the bwskel output) do not support; and the step of 0.876 um that passes is the mean step of the meandering path, not measured on a path along the vessel, while an average 26-connected step of about 0.73 um would give a most of about 539. The change could be considered if slices were taken along a path that follows the vessel, its own mean step met 0.72 to 0.88 um and the counts fell within 48.6 to 496.1; that analysis was not run and waits for a new attempt.
How the test differed from the paper’s method
- Starts from the deposited final segmentations, as the claims file says; the vessel centerline is skimage's 3D thinning in place of MATLAB bwskel. Assumed, for the manual removal of erroneous points (Methods, Creating normal cross sections, "then manually removed erroneous points"), which the paper does not describe: the longest path through the skeleton (P2 a), less the points farther from the second-order polynomial fit of the centerline than the vessel radius (95th percentile of the vessel's inscribed radius along the path) and the points that revisit a stretch of the fitted centerline already passed (pvs.clean_path). Added after the first verification, which found the uncleaned path 1.28 to 2.24 times the distance between its ends; 7534 of 9564 path points are kept at 0.648 um and 4974 of 6010 at 1 um. The cleaned path is still 1.13 to 1.78 times the distance between its kept ends and 1.08 to 1.44 times the arc of the fitted centerline at 0.648 um (E excepted), more than the zigzag of a 26-connected voxel path (at most about 8% on a straight line) explains, so it still meanders inside the vessel; the slices are oriented by the fitted centerline, so the meander changes how many there are more than where they lie.
- Cross sections are sampled by linear interpolation of the masks, thresholded at 0.5, on planes normal to the fitted centerline, one per path point, with pixels of the P1 voxel size, in place of MATLAB obliqueslice (a standard choice).
- Pixels in both the vessel and the PVS mask are counted as vessel. The Methods say overlaps were resolved by hand, case by case, but the deposited masks still overlap; the overlap exceeds 5% of the PVS in 381 of 6683 cross sections (P1 a, P4 b), 247 of them at J and 131 at E, so the choice is unlikely to change an outcome. The other assignment was not run.
- Assumed, the PVS of a cross section is the two largest PVS regions (8-connected) that come within one vessel radius, sqrt(area / pi), of the vessel region, the vessel being the connected region at or nearest the slice center. The segmentation "removed ... all but the two largest regions in the PVS segmentation" (Methods, Segmentation) and the fits are of the lobes beside the vessel (Figure 4), while the deposited masks hold PVS around other vessels and far from the artery. Added after the first verification; before it all PVS pixels of the 332 um plane were used. By median area the lobes are 91 to 99% of a slice's PVS at every location but E (29 to 52%) and, at 1 um, H (70%). Cross sections with fewer than 20 vessel or PVS pixels have no fits (shown per location in the data check).
- Assumed, planes where the deposited PVS mask covers more than 90% of the field are cleared before the cross sections are taken: at E and F the mask fills every plane below a depth (87 and 58 planes), and no plane of any other file is more than 50% PVS. Added after the first verification.
- The edge distance of P4 is measured from the vessel center in the slice (circle fit, erosion 3), to which the Methods shift the slice ("The slices were then shifted so the center point of the vessel was located in the center of the image", Methods, Creating normal cross sections). Before the first verification it was measured from the skeleton point; the change is 0.75 to 3.85 um by median per location and keeps 6683 cross sections in place of 6665 (P1 a, P4 b).
- P4 reading (a), the horizontal extent of the PVS, keeps no cross section in 4 of the 14 segments (A, B, F, G), while the paper analysed all 14; its results are shown but it is the less supported reading.
- For P2 b the median widths of P4 are taken from 150 evenly spaced points per segment (a standard choice), and the spacing is between consecutive points sorted along the main axis.
- Location E is kept, as one of the paper's 14 segments, though its cleaned path follows a side branch of the vessel network in its mask, not the vessel with PVS beside it, and its lobes are 29 to 52% of the slice's PVS; it gives 202 of the 6683 cross sections (P1 a, P4 b). Neither keeping nor dropping it gives the paper's E. Added after the second verification, the notebook computes every claim's table again without E (the cell before the summary). Without E, the fewest cross sections at 0.648 um (P4 b) become 409 and the most stays 604; no combination holds.