Session: PD31: Renal Transplantation & Vascular Surgery II
PD31-04: First-in-human clinical trial for the assessment of kidney transplant quality using combined quantitative ultrasound and photoacoustic imaging
Introduction: While kidney transplantation has revolutionized the treatment of kidney failure, donor kidneys are in short supply. This leads physicians to accept kidneys from older and sicker donors. Many of these have pre-existing fibrosis and microvascular disease, which can cause damage and kidney function loss after transplantation. Unfortunately, current clinical tools for predicting graft outcomes fail to capture whole organ fibrosis and microvascular disease burden. Our group has developed quantitative ultrasound (US) and photoacoustic (PA) imaging to measure both collagen (the main component of fibrosis) and perfusion parameters. In this work, we investigate the use of US/PA imaging to noninvasively measure fibrosis and perfusion in human kidneys at the time of transplantation. Methods: A VevoLAZR-X US/PA imaging system operating at 15 MHz was utilized for imaging. An algorithm using US frequency information (H-scan) was developed to estimate whole kidney fibrotic burden. Oxygen saturation (sO2) and total hemoglobin (HbT) were estimated using multispectral PA imaging. Donor kidneys were imaged in the operating room before transplantation during cold storage to measure H-scan fibrosis and then after vascular anastomosis to measure PA perfusion. For the primary outcome, H-scan fibrosis scores were correlated with fibrosis determined by HPS-stained biopsies. Clinical outcomes are also being collected for up to 5 years post-transplant. Results: 46 patients have been imaged to date. These patients received either a living or deceased donor kidney transplant (LD n=23; DD n=23). As shown in Fig. 1a, the H-scan captures the increasing fibrotic burden with increasing %red pixels. Comparison with HPS-stained biopsies confirmed the accuracy of H-scan in assessing fibrosis (r=0.83, Fig. 1b). Post-perfusion, sO2 and HbT estimates were acquired (Fig. 1c), with the average sO2 increasing by approximately 20%. Conclusions: This is the first in-human study applying US/PA imaging to non-invasively and accurately measure kidney fibrovascular disease burden at the time of transplantation. Next steps will be to correlate imaging scores with clinical outcomes. Once complete, we expect our results will help optimize donor kidney selection and matching to the most appropriate recipients. SOURCE OF Funding: None
