RPS 1207 - Imaging of benign kidney diseases and renal transplantation

Author Block: C. Lyu, Z. Liao, Z. Li; Wuhan/CN
Purpose: Functional MRI offers promise for noninvasive detection of renal allograft injury, but conventional models lack biological specificity. This study aimed to evaluate the clinical utility of time-dependent diffusion MRI (td-dMRI) for detecting rejection and fibrosis in kidney transplant recipients.
Methods or Background: In this prospective observational study at a tertiary center in China, adult renal allograft recipients undergoing indication biopsies between April 2024 to June 2025 were enrolled. Microstructural maps from td-dMRI based on a Bayesian method, DWI, intravoxel incoherent motion, diffusion kurtosis imaging, stretched exponential model, fractional order calculus, and continuous-time random-walk model. The diagnostic performances of these microstructural parameters in differentiating different degrees of renal allograft fibrosis (mild, moderate and severe fibrosis) and rejection (no-rejection, acute and chronic rejection) were evaluated by areas under the receiver operating characteristic curves (AUC).
Results or Findings: A total of 100 patients (67 males, 33 females) were analyzed. Among them, 41 had acute rejection and 13 had chronic rejection; 67 had mild fibrosis, 19 moderate, and 14 severe fibrosis. td-dMRI-derived diameter significantly distinguished fibrosis grades, while cellularity identified early fibrotic changes. For rejection, diameter, fin, and fp differentiated acute rejection, and D-CTRW, fin, fp, and diameter distinguished chronic rejection. Combining td-dMRI metrics with clinical variables yielded high AUCs (0·968 for acute, 0·913 for chronic rejection).
Conclusion: This study supports td-dMRI as a biologically meaningful, one-stop contrast-free imaging approach for transplant kidney surveillance. It enables noninvasive detection of structural and cellular changes associated with rejection and fibrosis, even when conventional markers are inconclusive. Integrating td-dMRI with serum biomarkers may improve diagnostic accuracy and reduce unnecessary biopsies, promoting personalized immunosuppression and earlier intervention.
Limitations: It was a single-center study with a moderate sample size, which may limit generalizability.
Funding for this study: the National Natural Science Foundation of China. (No. 82371942 and No. 82071889）
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This prospective study was approved by the ethic committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology

Author Block: C. Lyu, Z. Liao, Z. Li; Wuhan/CN
Purpose: This study aims to develop a noninvasive comprehensive diagnostic protocol based on diffusion weighted imaging (DWI) and clinical indicators to achieve accurate and efficient identification of high-risk complications (rejection, acute kidney injury, viral infection, moderate to severe fibrosis) after renal transplantation.
Methods or Background: This prospective study enrolled 120 renal allograft recipients. Quantitative parameters of DWI, intravoxel incoherent motion (IVIM), diffusion kurtosis imaging (DKI), stretched exponential model (SEM), fractional order calculus (FROC) and continuous-time random walk (CTRW) were measured. Clinical and pathological features were also recorded. Univariate and multivariate logistic regression analyses were performed to identify independent clinical and imaging predictors of high-risk complications group. Receiver operating characteristic (ROC) curves were used to evaluate diagnostic performance. Internal validation of the combined model was performed using stratified 5-fold cross-validation and bootstrap resampling to assess model stability and generalizability.
Results or Findings: Finally, 101 patients were included. Diffusion coefficients differed significantly between superior and inferior graft function groups across models. DDC_SEM_cortex and HCO₃⁻ emerged as independent predictors in multivariate analysis. The AUCs for HCO3-, DDC_SEM_cortex, and their combined model in identifying patients requiring clinical management changes were 0.888, 0.898, 0.941. Internal validation confirmed strong performance (cross-validation AUC 0.938; bootstrap AUC 0.940, 95% CI 0.931–0.943)
Conclusion: DDC_SEM_cortex and serum HCO3- levels are promising noninvasive imaging biomarkers for identifying renal allograft recipients with high-risk complications. It provides a powerful noninvasive tool for clinical decision-making and is expected to guide individualized kidney transplant management.
Limitations: It was a single-center study with a moderate sample size, which may limit generalizability. MRI was acquired in free-breathing mode, making image quality susceptible to motion artifacts despite the iliac fossa location
Funding for this study: This study has received funding by the National Natural Science Foundation of China. (No. 82371942 and 82071889）
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This prospective study was approved by the ethic committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology

Author Block: X. Zhang, H. Sun, G. Zhang, C. HUANG; Beijing/CN
Purpose: To evaluate structural and quantitative multiparametric MRI (mpMRI) features across the lupus nephritis (LN) disease continuum—active LN, clinically stable LN, and healthy controls—and to investigate correlations with clinical indices.
Methods or Background: In this prospective study, 40 patients with active LN, 40 with stable LN, and 21 matched healthy volunteers underwent renal MRI at 3.0T, including structural sequences, multi-b-value diffusion-weighted imaging (DWI/IVIM/DKI)and T1/T2 mapping. Structural abnormalities were qualitatively assessed, and quantitative parameters were compared across groups. Correlations with proteinuria, eGFR, complement levels, and disease activity scores were analyzed.
Results or Findings: Morphological abnormalities were observed in 40% of active LN and 30% of stable LN, versus none in controls. Exudative lesions were significantly more common in active LN than in stable LN (45.0% vs. 7.5%, p < 0.001). Quantitatively, active LN showed markedly reduced cortical ADC (1.74 ± 0.24 ×10⁻³ mm²/s vs. 2.05 ± 0.21 in controls, p < 0.001) and elevated parenchymal T1 (1632 ± 123 ms vs. 1408 ± 95, p < 0.001). Stable LN showed partial normalization of cortical ADC (p = 0.022 vs. active LN) and T1 (p = 0.007), but parenchymal ADC and medullary ADC remained depressed (p < 0.01 vs. controls). Proteinuria correlated negatively with cortical diffusion (r = –0.33, p = 0.038) while eGFR correlated positively with ADC (r up to 0.48, p = 0.002).
Conclusion: Multiparametric renal MRI sensitively detects structural and functional changes across active LN, clinical remission, and health. Crucially, it identifies persistent microstructural injury in clinically stable patients, underscoring its potential as a noninvasive tool for monitoring treatment response and guiding long-term management.
Limitations: The lack of direct histopathological limits ability to precisely link imaging findings to specific microscopic changes
Funding for this study: Gumuyang Zhang received funding from Peking Union Medical College Hospital Talent Cultivation Program (Category D); GrantID UHB11588.
Hao Sun received funding from the CAMS lnnovation Fund for Medical Sciences(ClFMS); GrantID2024-12M-C&T-C-0041;
Hao sun received funding from the CAMs innoyation Fund for Medical sciences(ClFMS): Grant ID2025-12M-C&T-C-001.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Pecking Union College Hospital Institutional Review Board approval was obtained

Author Block: E. Şahin, F. Alpaslan, T. Y. Kılıç, E. İsmailov, M. F. Kazanbaş, T. Banaz, B. Tütüncüoğlu, M. Kadıoğlu, S. Baş Özkök; Istanbul/TR
Purpose: To evaluate renal T1 and T2 mapping characteristics in patients with biopsy-proven renal amyloidosis and to explore their correlation with clinical severity and renal function indices.
Methods or Background: Renal amyloidosis is characterized by extracellular amyloid deposition that leads to progressive organ dysfunction. Non-invasive CMR-based renal mapping techniques may provide insight into disease activity and stage. Twenty-eight patients with biopsy-confirmed renal amyloidosis (mean age 53.2±12.8 years; 43% female) underwent renal T1 and T2 mapping using a 1.5 Tesla scanner. Disease severity was staged (GRADE I–V) according to clinical and histopathologic criteria. Standard renal function tests (urea, creatinine, eGFR) were obtained. Spearman’s rank correlation was used to assess associations between renal mapping parameters, disease grade, and renal function. Healthy volunteers (n=20) served as controls.
Results or Findings: Median renal T1 values were significantly higher in the amyloidosis group compared with controls (1245 ms, IQR 1150–1410 vs. 1020 ms, IQR 985–1065; p<0.01). Similarly, median renal T2 values were elevated (82 ms, IQR 71–91 vs. 65 ms, IQR 61–70; p<0.01). A strong positive correlation was observed between disease grade and renal T1 (ρ=0.62, p<0.001), while renal T2 demonstrated a weaker but significant association (ρ=0.38, p<0.05). Renal T1 correlated positively with serum creatinine (ρ=0.45, p<0.05) and urea (ρ=0.41, p<0.05), and negatively with eGFR (ρ=–0.52, p<0.01). Renal T2 values showed a similar but less consistent pattern.
Conclusion: Renal T1 and T2 mapping values are elevated in renal amyloidosis and correlate with both disease severity and renal function impairment. These parameters may serve as useful non-invasive biomarkers for staging and monitoring renal involvement, complementing histopathology and laboratory measures.
Limitations: Relatively small, single-centre sample size.
Funding for this study: Not receive any financial support
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the Başakşehir Çam and Sakura City Hospital Ethical Board. Application was submitted and registered

Author Block: M. I. Scheuer¹, C. S. Böttger¹, C. Liang², E. Bechler¹, A. Ljimani¹; ¹Düsseldorf/DE, ²Thuebingen/DE
Purpose: Metabolic syndrome is a collection of multifactorial conditions associated with combined cardiovascular pathologies and renal dysfunction. Novel therapies such as SGLT2 inhibitors show nephroprotective effects, but their clinical use is limited by the absence of noninvasive tools to monitor renal fat and treatment response. This study investigates MRI-based fat quantification as a method for assessing renal lipid accumulation.
Methods or Background: A total of 58 patients from a metabolic outpatient clinic underwent 1.5 T MRI scans (Avanto, Siemens Healthineers, Germany). Participants were divided into two groups by BMI (<30 vs. >30). Renal fat fraction (RFF) was quantified alongside visceral (VAT), subcutaneous (SAT), and abdominal muscle (AM) areas at L1–L2, as well as hepatic fat fraction (HFF). Correlations between renal and abdominal fat depots were analyzed to evaluate the potential of RFF as a biomarker.
Results or Findings: Results demonstrated significantly higher RFF in participants with BMI >30 compared to BMI <30. No significant correlations were observed between RFF and HFF, VAT, SAT, or AM.
These findings suggest that renal fat accumulation occurs independently of other fat depots. MRI-based renal fat quantification emerges as a promising noninvasive biomarker for monitoring renal lipid content in patients with metabolic syndrome. The observed group differences highlight its potential to detect renal fat burden, while the lack of correlation with hepatic or abdominal fat supports its unique role. A second MRI scan is planned after the treatment by new SGLT2 inhibitors within the study.
Conclusion: MRI-based renal fat quantification may serve as a valuable biomarker for monitoring the effectiveness of nephroprotective therapies in patients with metabolic syndrome.
Limitations: None.
Funding for this study: None.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study was approved by the Ethics Committee of the Medical Faculty of Heinrich Heine University Düsseldorf (study number 5891R, approval date August 28, 2018)

Author Block: E. Almar Munoz¹, E. Colliander², S. Tupper², M. Lansner Kielberg², M. L. Liu², A. Mayr¹, R. Mirón Mombiela²; ¹Innsbruck/AT, ²Herlev/DK
Purpose: n patients with autosomal dominant kidney disease (ADPKD), total kidney volume (TKV) is the gold standard biomarker for assessing the risk of progression and the need for drug therapy. However, it is a time-consuming process. In this systematic review, we evaluate the current state of deep learning (DL) algorithms for automatic kidney volume segmentation.
Methods or Background: All original research, including the search terms ADPKD, diagnostic imaging, DL, and TVK, was identified in PubMed, Embase, and Ovid MEDLINER databases from January 2000 to October 13, 2024. Articles with insufficient information to assess methodological quality were excluded. The quality was assessed using the QUADAS-2 and Checklist for Artificial Intelligence in Medical Imaging (CLAIM) tools. We focused on Dice Similarity Coefficient (DSC), bias differences, and time efficiency as outcomes.
Results or Findings: Nineteen studies were included, with an overall good quality; however, the mean adherence to the CLAIM checklist was 64%. The average DSC was 95 ± 2.89% (95% CI: 94.62–94.85) with relatively low bias for TKV in 5,622 ADPKD patients (mean age, 46.1 years; 45% male) and 9,180 scans (79% MRI). The average segmentation time was decreased by 75% compared to the ground truth. Performance differences were evident among imaging modalities, but 3D models did not outperform their 2D counterparts. No statistically significant evidence of small-study effects or publication bias was detected.
Conclusion: DL models for TKV in ADPKD patients demonstrated high precision compared to manual segmentation in a large, pooled sample with heterogeneous study designs and methods. Therefore, clinical implementation is feasible.
Limitations: Risk of data and model drift over time. High computational and environmental costs. Lack of task-specific evaluation standards (addressable by a tailored PRISMA for AI). Potential automation bias. Workflow/institutional variability. Regulatory and compliance challenges.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information:

Author Block: W. M. Fernández Rios, N. Lopez-Galiacho, E. Sifre Gómez, L. P. Cervera Bravo, S. Descalzo García, F. C. Mejia Galvis, M. N. Vicente de Vera, T. Vicente García, N. Carreres Creus; Alabcete/ES
Purpose: To describe the normal ultrasonographic findings of the renal graft and to review the radiological semiology of the most frequent complications through a series of cases from our department, both in the immediate postoperative period and during long-term follow-up.
Methods or Background: Renal transplantation is the most common solid-organ replacement procedure and represents the definitive treatment for chronic kidney disease. Advances in surgical technique, immunosuppression, surveillance imaging, and histopathological diagnosis of rejection have significantly improved graft survival. The increasing number of recipients and the use of higher-risk donors make thorough radiological assessment essential. The radiologist plays a pivotal role throughout the process—from baseline evaluation to the assessment of graft dysfunction and the guidance of interventional procedures.
Results or Findings: Doppler ultrasound is the first-line imaging modality in the immediate postoperative period, providing a reference examination and enabling early detection of complications. In cases of dysfunction, contrast-enhanced ultrasound or magnetic resonance imaging can provide greater diagnostic specificity. Complications are classified by timing and aetiology: immunological (rejection), vascular, urological, infectious, surgical/iatrogenic, and neoplastic. The heterotopic placement of the graft in the iliac fossa results in a characteristic spectrum of imaging findings.
Conclusion: Detailed knowledge of normal anatomy, vascular variations, surgical techniques, and donor and recipient risk factors is essential for accurate diagnosis and timely management. Ultrasound remains the cornerstone in the evaluation of renal transplantation, both in the early and late postoperative periods.
Limitations: No limitations
Funding for this study: No disclosure
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: