36 - Imaging Fibrosis in Pediatric Kidney Transplantation: A Pilot Study
Saturday, April 23, 2022
3:30 PM – 6:00 PM US MT
Poster Number: 36 Publication Number: 36.235
Mohamed Elsingergy, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States; Hansel J. Otero, Children's Hospital of philadelphia, Wynnewood, PA, United States; Suraj Serai, The Children's Hospital of Philadelphia, Philadelphia, PA, United States; Tricia Bhatti, The Children's Hospital of Philadelphia and Perelman School of Medicine, Philadelphia, PA, United States; Sandra Amaral, CHOP, Philadelphia, PA, United States; Erum A. Hartung, Children's Hospital of Philadelphia, Philadelphia, PA, United States; Bernarda Viteri, Childrens Hospital of Philadelphia, Philadelphia, PA, United States
Physician Childrens Hospital of Philadelphia Philadelphia, Pennsylvania, United States
Background: Non-invasive assessment of interstitial fibrosis and tubular atrophy (IFTA), a major determinant of kidney transplant injury, remains profoundly limited, and invasive percutaneous biopsies is still the gold standard. Elastography is a non-invasive technique that propagates shear waves across tissues to measure their stiffness; each imaging modality uses a specific energy level to trigger tissue excitement and require modality and technique specific cut off values.
Objective: We compared ultrasound elastography (USE) and MR elastography (MRE) stiffness measurements between pediatric transplant recipients and healthy controls and investigated the ability of elastography to detect pathologic IFTA in kidney allografts.
Design/Methods: In this prospective study, we performed kidney USE and MRE in pediatric kidney transplant recipients who underwent allograft biopsy (for cause or protocol) and healthy controls. No biopsy was performed on controls. USE and MRE mean stiffness values were compared between controls, normal/“stable” allografts, and IFTA allografts using one-way ANOVA. Pearson coefficient was used to determine the correlation between MRE and USE. Area under the receiver operating characteristic curves (AUROC) were used to determine MRE and USE cut-off values with highest sensitivity and specificity to differentiate stable from IFTA allografts using pathology as the reference standard.
Results: 10 transplant recipients [80% males, median (IQR) age 16 (12.5-18) years] and 8 controls [25% males, median (IQR) age 16.5 (13.5-19) years] were enrolled. Three transplant recipients had “stable” allografts with no IFTA on pathology and 7 had Banff Grade 1 IFTA. Mean stiffness of IFTA allografts (20.6 ± 4.5kPa USE and 5.6 ± 0.8kPa MRE) was significantly (p < 0.05) higher than stable allografts (13.2 ± 2.6kPa USE and 4.4 ± 0.5kPa MRE) and controls (9.6 ± 2kPa USE and 3.6 ± 0.5kPa MRE). USE and MRE stiffness values were closely correlated (r=0.98; p< 0.01). AUROC to predict presence of fibrosis in transplanted kidneys was high for both modalities (0.91 USE and 0.89 MRE). Stiffness cut-off values for USE and MRE were 13.8kPa and 4.6kPa, respectively. Both values yielded a sensitivity of 100% but the specificity of USE (72%) was slightly higher than MRE (67%).Conclusion(s): Both MR and US elastography show potential as non-invasive imaging tools for quantitative measurement of renal stiffness and differentiating fibrotic from stable allografts. Larger sampling will be conducted next to examine the reproducibility and generalizability of these results.