Measurement of renal cortical thickness using ultrasound in normal dogs: a reference range study considering bodyweight and body condition score

Abstract

The renal cortical thickness (RCT) reflects the pathological condition of the kidney, and measuring this parameter can help diagnose renal fibrosis in dogs. The normal reference range of RCT in dogs is broad (3-8 mm) because of the extreme diversity in body size. Therefore, this retrospective, reference interval, and observational design study aimed to establish a normal reference range for RCT in dogs measured using ultrasound by considering bodyweight (BW), body surface area (BSA), body condition score (BCS), and abdominal aorta (Ao) diameter. A total of 60 dogs met the inclusion criteria, and abdominal ultrasound images and medical records of these dogs were analyzed. RCT was measured at 1-3 points where the renal capsule and broad base of the medullary pyramid were clearly observed. Ao diameter was measured caudal to the branch of the left renal artery in the mid-sagittal view. The RCT showed positive correlations with BW and BSA and a negative correlation with BCS, which can be described as follows: RCT (mm) = 0.131 × BW − 0.166 × BCS + 3.580. The RCT:Ao ratio was 0.70 ± 0.09 (mean ± standard deviation). No significant differences were found in the RCT:Ao ratio depending on BW or BCS. In conclusion, the RCT:Ao ratio and relative RCT considering both BW and BCS are potentially useful for evaluating the normality of the renal cortex on ultrasound examination in dogs with various physiques.

A deep learning model for CT-based kidney volume determination in dogs and normal reference definition

“…In this study, the BW and BW/BCS index were significantly positively correlated with kidney volume, which is consistent with the results of previous studies showing a significantly positive linear relationship between BW, BW/BCS index, and kidney size (32,43,44). In a previous study (32), the BW/BCS index showed a stronger correlation with renal cortical thickness than BW. However, our correlations between kidney volume and BW/BCS index and BW were not significantly different, even though BW had a positive correlation and BCS a negative correlation.…”

“…In this study, the BW and BW/BCS index were significantly positively correlated with kidney volume, which is consistent with the results of previous studies showing a significantly positive linear relationship between BW, BW/BCS index, and kidney size ( 32 , 43 , 44 ). In a previous study ( 32 ), the BW/BCS index showed a stronger correlation with renal cortical thickness than BW.…”

“…In human medicine, several studies have used CT images to demonstrate correlations between kidney volume, body weight (BW), and age ( 2 , 12 ). In veterinary medicine, previous studies have examined the relationship between kidney length and BW using CT images ( 31 ) and the relationship between renal cortical thickness and BW using ultrasound ( 32 ), but none have evaluated the relationships between kidney volume, BW, and age using CT images. In addition, there is no established reference range for kidney volume measured from CT images in dogs.…”

ACVR and ECVDI consensus statement for the standardization of the abdominal ultrasound examination

“…The length of the kidney should be obtained at its greatest dimension in a longitudinal (either sagittal or dorsal) plane 30–31 . Published methods and normal values are available using renal length/aorta or L5/6 measurements, renal cortical thickness, renal cortex to aorta ratios, and cortex/medulla ratios 32–34 . It is the opinion of the panel, however, that these measurements are not necessary to routinely obtain in every patient but can be used when indicated.…”

“…[30][31] Published methods and normal values are available using renal length/aorta or L5/6 measurements, renal cortical thickness, renal cortex to aorta ratios, and cortex/medulla ratios. [32][33][34] It is the opinion of the panel, however, that these measurements are not necessary to routinely obtain in every patient but can be used when indicated. The shape, cortical echogenicity, and corticomedullary distinction of each kidney should be evaluated and recorded.…”