Kidney Week

Abstract: TH-PO0026

Multiparametric MRI Evaluation of Renal Flow Reserve in Response to Oral Protein Loading

Session Information

• Bioengineering: MPS, Flow, and Delivery
  November 06, 2025 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Bioengineering

• 400 Bioengineering

Authors

• Margain, Corina, The University of Texas System, Austin, Texas, United States

Corina Margain, BSE

• Wang, Jiachen, The University of Texas System, Austin, Texas, United States

Jiachen Wang, PhD

• Bush, Adam, The University of Texas System, Austin, Texas, United States

Adam Bush, PhD

Group or Team Name

• Translational Cardiovascular Imaging Laboratory.

Background

Renal flow reserve (RFR), the capacity of the kidneys to increase renal blood flow (RBF) under stress, is a promising marker of early renal dysfunction. While stress testing is well-established in other organs, no standardized kidney stress test exists in clinical practice. Acute protein loading can activate RFR, but current assays rely on global estimates or invasive tests that lack spatial and temporal resolution. This study evaluated the feasibility of using multiparametric MRI to noninvasively characterize the kidney hemodynamic response to an oral protein load in healthy adults and assess its ability to detect RFR activation.

Methods

Fifteen adults (29±12 years, 10 females) underwent MRI before ( ≥10-hour fasting, 400mL water intake) and after consuming 0.7 g/kg of tuna(n=15) or tofu (n=5). Imaging was performed on a 3T Siemens Vida, including MRA, 2D PC-MRI, IVIM(D, D*, f), T1, and T2* mapping. In a tuna subset (n=5), renal perfusion was assessed with 3D-pCASL.

Results

PC-MRI showed a significant post-tuna RBF increase (+11.8±4.5%, p=0.001), while tofu showed no change (+3.1±13.6%, p=0.62). RFR (peak tuna ΔRBF) correlated with age (R²=0.28,p=0.04) and eGFR (R²=0.29,p=0.04). Medullary D increased (+10.1±1.94%,p=0.001) post-tuna but not in the cortex or with tofu; D* and f did not change significantly. Cortical T2* increased 60-90min post-tuna (+8.5±18.9%,p=0.04) but did not change in the medulla or with tofu. T1 increased only in the cortex 90–120min post-tuna (+4.0±4.5%,p=0.03). Kidney volumes remained stable (+3.4±6.6%,p=0.31). In the pCASL subset, RBF change was not significant (–6.10±8.81%,p=0.11).

Conclusion

MRI-based renal stress testing with an oral protein load is feasible and noninvasive. Animal protein elicited hyperemia consistent with RFR activation. Hyperemia occurred without a drop in T2*, suggesting preserved oxygen supply-demand balance. No response was seen with tofu. RFR correlations with age and eGFR suggest sensitivity to subclinical kidney disease. This approach may support future applications in living donor evaluation, CKD staging, and imaging biomarker development.

Postprandial RBF Change(left). RFR vs. eGFR Correlation(right)

Funding

• Other NIH Support

Digital Object Identifier (DOI)

• doi: 10.1681/ASN.20254zd44f3b