Quantification of Pancreatic Islet Morphology

Representative sections of ANHH and control specimens were digitized using whole-slide imaging (WSI) (Nanozoomer RS or Nanozoomer S360; Hamamatsu Photonics KK, Hamamatsu, Japan). The number, maximum diameter, perimeter, and area of each islet in each specimen were measured using an image analysis system (NIS-Element D software program, version 5.30.00; Nikon, Tokyo, Japan). Islets of any size were evaluated. The measurement method is shown in the schematic illustration (Fig. 2A). The cross-sectional area of pancreatic parenchyma was measured in the same manner. The circularity ranged from 0 to 1.0, with a higher circularity meaning that the shape of the given islet was closer to a circle [9 (link)–11 (link)]. In this study, circularity was calculated using the following formula: 4π × (area of islet) / (perimeter of islet)². We adopted 0.71 as a threshold value because it was the value that generated the largest statistically significant difference.
Fig. 2

Measurement procedure of the islets (A), representative images with each circularity value (B) and representative images showing an irregular shape of the islets in ANHH cases compared to controls (insulin immunostaining) (C)