Computed tomographic measurements of pancreatic thickness in clinically normal dogs

Abstract

Pancreatic thickness is an indicator for evaluating pancreatic diseases. The transverse and cross-sectional pancreatic thickness observed on computed tomography (CT) may differ. This study aimed to provide a normal reference range for pancreatic thickness on the transverse plane based on body weight (BW) and assess pancreatic thickness to aorta (P/Ao) ratio. In addition, we aimed to establish the normal short and long dimensions of the pancreas based on cross-sectional image through the long axis of the pancreas using multiplanar reconstruction (MPR). The short dimension to aorta (S/Ao) and long dimension to aorta (L/Ao) ratios were also established in clinically normal dogs. The pancreatic thickness was measured using CT results of 205 clinically normal dogs. The pancreatic thickness on the transverse plane and the short and long dimensions in the cross-sectional image of the pancreas were measured using MPR. The diameter of the Ao was measured on the transverse plane and the P/Ao, S/Ao, and L/Ao ratios were calculated. Our study showed that the mean normal pancreatic thicknesses (mean ± standard deviation [SD]) of the pancreatic body, left and right lobe in the transverse plane were 10.92 ± 2.54 mm, 8.92 ± 2.26 mm and 9.96 ± 2.24 mm, respectively. The P/Ao ratios of the pancreatic body, left and right lobes were 1.85 ± 0.33, 1.50 ± 0.27 and 1.68 ± 0.29, respectively. The mean short dimension (mean ± SD) in the cross-sectional image of the pancreatic body, left and right lobe were 8.98 ± 1.97 mm, 7.99 ± 1.89 mm and 8.76 ± 2.03 mm, respectively. In conclusion, pancreatic thickness increased with BW, while the P/Ao, S/Ao, and L/Ao ratios could be used regardless of BW.

Keywords: CT; canine; dimension; pancreas; size.

Figure 1

Measurements of the pancreatic body. Schematic illustration of pancreas (A), transverse plane (B), dorsal plane (C) and oblique sagittal MRP plane (D). The thickness of the pancreatic body was measured at the thickest location adjacent to the duodenal flexure (DF) (B). On the dorsal plane (C), long axis (blue line) of pancreas was set to be parallel to the pancreas and through the middle. MPR was performed perpendicular (yellow line) to the long axis (blue line) of the pancreatic body connecting to the left lobe at the thickest part. In the oblique sagittal MPR plane (D), which is cross sectional image at the yellow line, short and long dimensions perpendicular to each other were measured at their longest length (Green, short dimension; Purple, long dimension). PV, portal vein; DF, duodenal flexure; DD, descending duodenum; GDV, gastroduodenal vein (arrowhead); SV, splenic vein.

Figure 2

Measurements of the left pancreatic lobe. Schematic illustration of pancreas (A), transverse plane (B), dorsal plane (C) and oblique sagittal MPR plane (D). The thickness of the left lobe was measured at the thickest location along the length of the left lobe (white arrow, splenic vein) (B). On the dorsal plane (C), long axis (blue line) of pancreas was set to be parallel to the pancreas and through the middle. MPR was performed perpendicular (yellow line) to the long axis (blue line) of the left lobe at the thickest part. In the oblique sagittal MPR plane (D) which is cross sectional image at the yellow line, short and long dimensions perpendicular to each other were measured at their longest length (Green, short dimension; Purple, long dimension). PV, portal vein; DF, duodenal flexure; DD, descending duodenum; GDV, gastroduodenal vein; SV, splenic vein (white arrow).

Figure 3

Measurements of the right pancreatic lobe. Schematic illustration of pancreas (A), transverse plane (B), dorsal plane (C) and oblique transverse MPR plane (D). The thickness of the right lobe was measured at the thickest location in the region that runs along the descending duodenum (DD) (B). On the dorsal plane (C), long axis (yellow line) of pancreas was set to be parallel to the pancreas and through the middle. MPR was performed perpendicular (blue line) to the long axis (yellow line) of the right lobe at the thickest part. In the oblique transverse MPR plane (D) which is cross sectional image at the blue line, short and long dimensions perpendicular to each other were measured at their longest length (Green, short dimension; Purple, long dimension). PV, portal vein; DF, duodenal flexure; DD, descending duodenum; GDV, gastroduodenal vein; SV, splenic vein; RK, right kidney.

Figure 4

The diameter of the aorta (red double arrow) was measured in the transverse plane horizontally at the level where the pancreatic body (PD) was measured. PD, pancreatic body.

Figure 5

Correlation between pancreatic thickness and body weight (BW) and between pancreatic thickness to Ao (P/Ao) ratios and BW. The thickness of pancreatic body (A), left lobe (C), and right lobe (E) measured on the transverse plane. All pancreatic thickness showed a linear positive correlation with BW. P/Ao ratio of the pancreatic body (B), P/Ao ratio of the left lobe (D), and P/Ao ratio of the right lobe (F). P/Ao ratios of pancreas showed no correlation with BW. BW, body weight; P/Ao, pancreatic thickness measured on the transverse plane to aorta.

Figure 6

Correlation between short dimensions of pancreas and body weight (BW) and between short dimension to Ao (S/Ao) ratios and BW. Short dimension of pancreatic body (A), left lobe (C), and right lobe (E). The short dimensions of the pancreas showed a linear positive correlation with BW. S/Ao ratio of pancreatic body (B), left lobe (D), and right lobe (F). S/Ao ratios of the pancreas showed no correlation with BW. BW, body weight; S/Ao, short dimension measured in the cross-sectional image to Ao.

Figure 7

Correlation between long dimension of pancreas and body weight (BW) and between long dimensions to Ao (L/Ao) ratios and BW. Long dimension of pancreatic body (A), left lobe (C), and right lobe (E). The long dimensions of the pancreas showed a linear positive correlation with BW. L/Ao ratio of pancreatic body (B), left lobe (D), and right lobe (F). L/Ao ratios of the pancreas showed no correlation with BW. BW, body weight; L/Ao, long dimension measured in the cross-sectional image to Ao.