Ultrasonographic quantitative evaluation of acute and chronic renal disease using the renal cortical thickness to aorta ratio in dogs

Abstract

The renal cortical thickness (RCT) has been correlated with renal function. Previous studies have also reported that the RCT:Abdominal aorta(Ao) ratio is constant in normal dogs with various physical factors. This multi‐center, retrospective, analytical study aimed to determine if there are differences between actual RCT and predicted value of RCT considering physical factors in dogs with acute or chronic renal disease. We also aimed to demonstrate whether the RCT and Ao ratio index would be useful for evaluating renal pathology. A total of 54 dogs with acute or chronic renal disease and 30 normal healthy dogs were included in this study. The RCT was measured at the center of the renal pyramid as the shortest distance perpendicular to the renal capsule from the base of the renal medullary pyramid at three points. The diameter of the Ao was measured just caudal to the branch of the left renal artery in the sagittal plane in systole. The RCT:Ao ratio of chronic kidney disease (CKD) patients was 0.50 ± 0.11 (mean ± standard deviation). The RCT:Ao ratio in normal dogs was 0.67 ± 0.07. The RCT:Ao ratio in patients with acute kidney injury (AKI) was 0.83 ± 0.05. There was a statistically significant difference between normal dogs and dogs with CKD (P < 0.001) and between normal dogs and dogs with AKI (P < 0.001). In conclusion, findings from the current study supported using the RCT:Ao ratio as a non‐invasive quantitative method for characterizing kidney pathology in dogs with acute or chronic renal disease.

Quantitative studies on B‐mode ultrasound and point shear wave elastography of kidneys in nonazotemic dogs

“…In the current study, the RCT: Ao ratio was higher compared with values reported in earlier studies. 8,29 This difference in values could be attributed to the lower mean body weight of the subjects in previous reports. The RCT:Ao ratio exhibited a negative correlation with body weight.…”

“…These observations were recorded in the present study as per Bragato et al 1 The quantitative parameters, including length (L), breadth (B), height (H), the thickness of the renal cortex (RCT), the thickness of the renal medulla (RMT), and the diameter of the aorta (Ao) in centimeters (cm) caudal to the origin of the left renal artery, were recorded as per earlier reports (Figure 1). 6,8,28,29 At least two measurements were taken for L, B, H, RCT, and RMT, and the average of the respective measurements was recorded for further calculations. From these measurements, L:Ao, B:Ao, H:Ao, cortico-medullary (CM), and RCT:Ao ratios were derived.…”

“…This technique allows for the assessment of internal structural changes, contour alterations, and dimensional measurements, albeit with some limitations in its scope. 1,[6][7][8] Renal biopsy 9 and fine needle aspiration cytology 10 are considered superior methods to assess the progression of renal affections but are invasive in nature and considered not practical for continuous monitoring. 11,12 Therefore, noninvasive methods are preferred over the above techniques to assess the progression of renal affections.…”

“…However, ultrasonographic evaluation provides certain advantages in the diagnosis of renal diseases. This technique allows for the assessment of internal structural changes, contour alterations, and dimensional measurements, albeit with some limitations in its scope 1,6–8 . Renal biopsy 9 and fine needle aspiration cytology 10 are considered superior methods to assess the progression of renal affections but are invasive in nature and considered not practical for continuous monitoring 11,12 .…”