Impact of ischemia duration on MRI-derived perfusion parameters in a mouse kidney transplant model.

Abstract

OBJECTIVES: Cold ischemia during kidney transplantation induces ischemia-reperfusion injury with endothelial dysfunction, capillary leak, and impaired perfusion. Its duration critically determines graft outcome. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) enables noninvasive assessment of renal microcirculation and may indicate ischemic injury. We evaluated the impact of ischemia duration on DCE-MRI-derived perfusion parameters in renal transplants in mice. MATERIALS AND METHODS: Procedures were approved by the local institutional animal care and use committee. A total of 15 C57BL/6 mice underwent kidney transplantation and were assigned to a short or prolonged cold ischemia group. DCE-MRI was performed to assess renal perfusion. Imaging was conducted at a mean of 268 ± 30 days (mean ± standard deviation) after transplantation. Perfusion parameters were calculated using the Patlak model, which provides the plasma volume fraction (v), reflecting renal blood volume and perfusion, and the volume transfer constant (K), characterizing the rate of contrast agent extravasation from capillaries into the extravascular extracellular space. RESULTS: Significant differences were observed in the Kparameter of transplanted kidneys between groups. The median K(mL/100 mL/min) was significantly higher in the 16-h group (2.87, interquartile range 2.45-3.03) versus the 30-min group (0.91, 0.90-1.42; p = 0.008). Median v(mL/100 mL/min) was non-significantly lower in the 16-h group (21.89, 17.28-23.22) versus the 30-min group (29.02, 24.99-37.15; p = 0.151). CONCLUSION: Cold ischemia with 16-h duration was associated with significantly higher Kvalues in kidney transplants, reflecting significantly increased vascular permeability. DCE-MRI provides a sensitive tool for detecting ischemia-induced microvascular dysfunction. RELEVANCE STATEMENT: Quantitative DCE-MRI detects microvascular injury after 16-h cold ischemia in kidney transplants in mice, supporting its potential as a noninvasive tool to assess graft integrity and guide interventions aimed at improving long-term transplant outcomes. KEY POINTS: The duration of ischemia critically affects endothelial integrity and perfusion characteristics in a mouse kidney transplant model. Prolonged 16-h ischemia leads to increased vascular permeability, indicating more severe endothelial and microcirculatory injury in transplanted kidneys. DCE-MRI enables sensitive detection of subtle ischemia-related microvascular alterations, supporting its value for noninvasive graft assessment.