The purpose of this study was to assess the potential of shear wave elastography (SWE) as an indicator of abnormal kidney function defined by radiolabeled glomerular filtration rate (GFR). Fifty-seven patients referred for 51Cr-ethylenediaminetetraacetic acid GFR and 99mTc-dimercaptosuccinic acid renal scintigraphy were included. Young's modulus (YM) measured with SWE and kidney length, volume, cortical thickness and parenchymal echogenicity measured with conventional ultrasound were correlated with patients' GFR and renal scintigraphy results. Spearman correlation coefficients between SWE and GFR were negative for the right (r = -0.635, p < 0.0001) and left (r = -0.817, p < 0.0001) kidneys. Positive correlations between left renal cortical thickness (r = 0.381, p = 0.04) and left kidney volume (r = 0.356, p = 0.019) with GFR were reported. SWE correctly predicted the dominant functioning kidney in 94.7% of cases. The area under the receiver operating characteristic curve for SWE (0.800) was superior to that for conventional ultrasound (0.252-0.415). The cutoff value of ≥5.52 kPa suggested a kidney function ≤60 mL/min/1.73 m2 (82.4% sensitivity and 76.2% specificity). SWE has advantages over conventional ultrasound in assessing kidney function and distinguishing the dominant functioning kidney.
Estimation of glomerular filtration rate (GFR) in renal transplant patients is often assessed by application of creatinine-based equations. The aim was to correlate the estimated GFR (eGFR) using creatinine-based equations [Cockroft-Gault, Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Nankivell] with gold standard 51Cr-EDTA in kidney transplant patients in the Asian population. This is a single-center, cross-sectional study involving adult renal transplant patients. Background demographic data, medications, office blood pressure, and baseline investigations were taken. Correlations between measured GFR and eGFR were analyzed and Pearson's correlation coefficients, bias, and accuracy were assessed. Thirty-seven renal transplant patients with a mean age of 46 ± 13 years were recruited. Majority were Chinese (68%), Malay (24%), and Indian (8%). The median duration of the transplant was 84 (interquartile range 60,132) months. The mean measured GFR was 71 ± 21 mL/min/1.73 m2. Cockroft-Gault and CKD-EPI has the best correlation with 51Cr-EDTA with Pearson correlation coefficients of 0.733 (P <0.001) and 0.711 (P < 0.001), respectively. All formulae showed >80% accuracy with eGFR lies between 30% of the measured value. CKD-EPI and MDRD had the greatest accuracy with 89.2% each. Clinician may use any of these three serum creatinine-based equations to estimate GFR in kidney transplant recipients.