Detecting kidney fibrosis using H-scan

Kidney fibrosis plays a significant role in determining the outcome of kidney transplantation. Accurate measurement of kidney fibrosis is thus important not only in the diagnosis of chronic kidney disease but also in the assessment of donor grafts. Currently, biopsy is only procedure used to assess kidney fibrosis. Thus, the development of non-invasive and accurate imaging tools would be advantageous. This study aims to demonstrate the ability of H-scan to quantify kidney fibrosis. We performed an ex vivo murine study using the unilateral ureteral obstruction (UUO) model to induce renal fibrosis. 15 mice in total were used in this study. 10 mice underwent UUO surgery on the left ureter, with the right kidneys serving as controls. The kidneys were extracted on day 7 (n = 5) and day 14 (n = 5). The other 5 healthy mice served as sham controls, and their kidneys were also extracted. Ultrasound imaging of the extracted kidneys was performed using a 15 MHz center frequency transducer. After imaging, the kidneys were stained with picrosirius red to quantify fibrosis levels. H-scan was applied to the whole kidneys. The percentage of lower frequency scattering encoded as red (% red) was used as the H-scan quantification, and these results were compared to the histology fibrosis score. We demonstrated that H-scan imaging provided differentiated color images for normal and fibrotic kidneys. Fibrotic kidneys tended to contain more red, indicating increased collagen fiber arising during the buildup of kidney fibrosis. Furthermore, quantification of fibrosis using the H-scan and histology was compared, showing a strong correlation of R = 0.99. Overall, we demonstrated that the H-scan can accurately detect the buildup of kidney fibrosis, suggesting its potential use for renal fibrosis assessment as an alternative to biopsy.