To analyze regional heterogeneity in Young's modulus of the kidney following acute renal vein occlusion and identify optimal regions for diagnosis.

A total of 20 New Zealand White rabbits were used as the study subjects. At 2 hours after ligation of the left renal vein, Young's modulus was measured and compared across different sides (healthy side vs affected side), anatomical locations (upper pole vs mid portion vs lower pole), and organizational structures (cortex vs medulla vs renal sinus) of the kidney. The point-biserial correlation coefficient was employed to analyze the correlation between Young's modulus in various renal regions and the status of acute renal vein occlusion. The intraclass correlation coefficient (ICC) was used to assess the reproducibility of the Young's modulus measurements.

Regarding anatomical locations, in the healthy side group, the differences in Young's modulus were statistically significant between the upper pole and mid portion, and between the mid portion and lower pole (P＜0.05). In the affected side group, no statistically significant differences in Young's modulus were observed among the upper pole, mid portion, and lower pole (P＞0.05). Regarding organizational structures, in the healthy side group, the differences in Young's modulus were statistically significant between the cortex and renal sinus, and between the medulla and renal sinus (P＜0.05). In the affected side group, the differences in Young's modulus among the cortex, medulla, and renal sinus were all statistically significant (P＜0.05). Three-way ANOVA revealed that the three-way interaction effect (acute renal vein occlusion status × anatomical location × organizational structure) was not statistically significant (F=1.575, P=0.190). The Young's modulus values in the affected side group were consistently higher than those in the healthy side group for identical anatomical locations and organizational structures, and all these differences were statistically significant (P＜0.05). Among these comparisons, the mid-portion cortex demonstrated the most prominent effect size (Cohen's d=2.770), eexhibited the strongest correlation with acute renal vein occlusion (r=0.867), and showed the optimal measurement reproducibility (ICC=0.987).

Renal elasticity in normal kidneys shows regional heterogeneity and undergoes remodeling under pathological conditions. Acute renal vein occlusion causes a significant increase in stiffness, identifying the mid-portion cortex as the optimal diagnostic region.