Detection of nephrocalcinosis using ultrasonography, micro-computed tomography, and histopathology in cats

Tang, PK; Geddes, RF; Chang, YM; Jepson, RE; van den Broek, DHN; Lötter, N; Elliott, J

Abstract

BackgroundIdentification of nephrocalcinosis in cats with chronic kidney disease (CKD) is of clinical interest but the ability of ultrasonography to detect nephrocalcinosis is uncertain.ObjectivesTo compare ultrasonography, micro-computed tomography (mu CT) and histopathology for identification of nephrocalcinosis.AnimalsTwelve kidneys from 7 euthyroid client-owned cats with CKD.MethodsDescriptive study. Renal ultrasonography was performed ante-mortem for nephrocalcinosis detection. Kidneys were grouped based on nephrocalcinosis: present, suspected, or absent. When cats died, necropsy was performed. Renal tissue was evaluated using mu CT for macroscopic nephrocalcinosis, and nephrocalcinosis volume-to-kidney tissue ratio (macro-VN:KT) and sagittal nephrocalcinosis area-to-kidney tissue ratio (macro-AN:KT) were calculated. Each kidney subsequently was bisected longitudinally, formalin-fixed, and paraffin-embedded for microscopic nephrocalcinosis assessment using von Kossa and Alizarin red staining with AN:KT (VK-micro-AN:KT and AR-micro-AN:KT) quantified using ImageJ. Data are presented as median (range). Relationships between macroscopic and microscopic AN:KT were assessed using Spearman's correlation.ResultsNephrocalcinosis by ultrasonography was considered to be absent in 3, suspected in 3, and present in 5 kidneys; 1 kidney had nephrolithiasis with nephrocalcinosis. The macro-VN:KT was 0.001%, 0.001%, and 0.019%, and the macro-AN:KT was 0.08%, 0.30%, and 1.47%, respectively. Histologically, VK-micro-AN:KT was 0.21%, 2.85%, and 4.56%, and AR-micro-AN:KT was 1.73%, 5.82%, and 8.90% for kidneys where ultrasonographic macro-nephrocalcinosis was absent, suspected, or present, respectively. A strong correlation was identified between macroscopic (macro-AN:KT) and microscopic (VK-micro-AN:KT) nephrocalcinosis (rs = 0.76; P = .01).Conclusions and Clinical ImportanceUltrasonographically diagnosed nephrocalcinosis correlates well with macroscopic and microscopic nephrocalcinosis at necropsy despite their separation in time.

Citation

Tang, P., Geddes, R., Chang, Y., Jepson, R., van den Broek, D., Lötter, N., & Elliott, J. (2024). Detection of nephrocalcinosis using ultrasonography, micro-computed tomography, and histopathology in cats. Journal of Veterinary Internal Medicine, https://doi.org/10.1111/jvim.17011

• Journal Article Type: Article
• Acceptance Date: Jan 26, 2024
• Online Publication Date: Feb 13, 2024
• Publication Date: 2024
• Deposit Date: Feb 28, 2024
• Publicly Available Date: Feb 28, 2024
• Print ISSN: 0891-6640
• Electronic ISSN: 1939-1676
• Publisher: Wiley Open Access
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1111/jvim.17011
• Keywords: calcification; chronic kidney disease; CKD-MBD; feline; mineralization; CHRONIC KIDNEY-DISEASE; CALCIUM-OXALATE; CLINICAL-SIGNIFICANCE; IDENTIFICATION; CALCIFICATION; ULTRASOUND; ALIZARIN; CHLORIDE; CALCULI; DOGS