Keywords: Kidney, Kidney

Motivation: Previous studies have demonstrated a correlation between kidney fibrosis and corticomedullary difference in apparent diffusion coefficient (ADC). However, separately measuring ADC in cortex and medulla is challenging due to the low contrast between the tissues. 

Goal(s): To facilitate measurement of corticomedullary ADC. 

Approach: T1-weighted, distortion-matched echo planar imaging (EPI) with high corticomedullary contrast were acquired in addition to diffusion weighted EPI. Regions-of-interest were performed in the T1-weighted images and propagated to the distortion-matched ADC maps to obtain measurements. 

Results: Corticomedullary ADC differences were obtained in four datasets from two healthy volunteers with values within the range of previously published values. 

Impact: T1-weighted, distortion-matched EPI with high corticomedullary contrast greatly facilitates measurements of cortex and medulla in diffusion weighted EPI.  

Keywords: Kidney, Kidney, ASL, DWI, ADC, Perfusion, Age, BMI

Motivation: The demand for accurate and non-intrusive renal function evaluation methods.

Goal(s): To discern how age and BMI affect:

• Renal perfusion measured with ASL (Arterial spin labeling).
• Renal diffusion measured with Apparent diffusion coefficient (ADC) from DWI (Diffusion-weighted images).

Approach:

1. Recruit and scan healthy volunteers.
2. Create a database with the results.
3. Apply statistics:

• Evaluating correlations (Spearman coefficient).
• Evaluating differences between groups (Mann-Whitney U test).

Results:  
ASL:

• Negative significant age-related perfusion and significant differences between age groups.
• Negative significant correlations of BMI with perfusion in inner regions of the kidneys.

• No significant correlation with age.
• Negative significant correlations of BMI with ADC maps.

Impact: These findings provide insights for the MRI community, enhancing tailored renal understanding and diagnostic precision. Personalized approaches, using age and BMI, have the potential to enhance patient outcomes. This study encourages focused research, promoting personalized medicine and refining renal imaging.

Keywords: Kidney, Quantitative Imaging, type 2 diabetes mellitus; IDEAL-IQ; proton-density fat fraction; diabetic kidney disease

Motivation: Renal parenchymal fat deposits play a crucial role in the development of diabetic kidney disease (DKD). Noninvasive measurement of renal parenchymal fat deposits using functional MRI provides valuable insights into the pathogenesis of DKD.

Goal(s): Exploring the reproducibility of IDEAL-IQ imaging in quantifying renal lipid deposition and to investigate the differences observed in DKD patients.

Approach: A total of 26 healthy participants underwent two IDEAL-IQ scans without repositioning and 96 type 2 diabetes mellitus (T2DM) patients underwent a single IDEAL-IQ scan.

Results: IDEAL-IQ imaging is a reproducible technique for noninvasively quantifying renal lipid deposition. Furthermore, the technique shows promising performance in staging DKD.

Impact: This study highlights the potential benefits of IDEAL-IQ imaging in evaluating renal lipid deposition in DKD patients. It contributes to a better understanding of the pathogenesis and progression of DKD, to improved diagnostic and management strategies for T2DM patients.

Keywords: Kidney, Genetic Diseases, ARPKD, Pediatric Genetic Disease

Motivation: There are no clinically available therapies for ARPKD.

Goal(s): We evaluated the ability of T₁ and T₂ from MR Fingerprinting (MRF) to assess kidney cystic burden and Arterial Spin Labeling (ASL) to assess kidney perfusion to detect and stage ARPKD kidney disease.

Approach: 12 ARPKD patients and 10 healthy adult volunteers were scanned on a Siemens 3T with kidney MRF and ASL MRI methods to generate kidney cortical perfusion maps.

Results: Significant increases in kidney T₁ and T₂, and reduced perfusion were observed between ARPKD patients and healthy volunteers (p<0.001) and between ARPKD patients with early and mild-to-moderate CKD based on eGFR (p<0.03).

Impact: The multi-modal MRI biomarkers in combination evaluated were able to distinctly stratify all three cohorts, including the two ARPKD patient cohorts, demonstrating the utility of a multi-modal MRI approach during future clinical trials aimed at limiting ARPKD kidney disease progression.

Keywords: Kidney, Quantitative Susceptibility mapping, Autosomal polycystic kidney disease, ADPKD, complex cysts, hemorrhage, renal calcifications

Motivation: Current MRI-based approaches for assessment of the complications related to the ADPKD (hemorrhage and calcifications) suffer from low specificity due to the complex and nonlinear dependence of T1/T2 relaxation times on tissue composition.

Goal(s): The aim of this study is to assess QSM as an enrichment biomarker suited for unambiguous differentiation of various complex ADPKD cysts.

Approach: We perform a cross-sectional study in ADPKD subjects categorizing complex cysts based on their appearance on QSM and assessing their prevalence in patient population.

Results: The results of our imaging study demonstrate that QSM can provide complimentary characterization of cyst composition and visualize calcifications within kidneys.

Impact: Our results indicate that QSM can identify unique susceptibility properties of complex cysts unattainable with traditional imaging approaches, which may serve as an enrichment biomarker for ADPKD progression and the development of cyst complications.

Keywords: Kidney, Kidney, Multi-parameter magnetic resonance imaging; Clear cell likelihood score; Clear cell renal cell carcinoma; Pseudocapsule

Motivation: Clear cell likelihood score version 2.0 (ccLS v2.0) is not yet able to predict malignancy in small renal masses (SRMs). Pseudocapsule may provide added value with ccLS v2.0

Goal(s): To develop a modified clear cell likelihood score based on pseudocapsule (m-ccLS) for predicting malignancy in SRMs

Approach: Receiver operating characteristic curve (ROC), net reclassification index (NRI), and integrated discrimination improvement (IDI) were used to compare diagnostic value of m-ccLS and ccLS v2.0

Results: Area under curve (AUC), NRI and IDI of m-ccLS were superior to those of ccLS v2.0 for the diagnosis of malignancy. The likelihood of malignancy increased with higher m-ccLS scores

Impact: M-ccLS achieved predict malignancy of small renal masses (SRMs). M-ccLS may be a valuable tool for expanding the clinical application of this scoring system and contributing to its further promotion and dissemination

Keywords: Kidney, Kidney

Motivation: To observe the renal oxygenation in patients with primary aldosteronism (PA).

Goal(s): To explore the renal oxygenation in patients with PA by blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) compared with healthy controls (HCs).

Approach: A total of 40 participants were included and underwent renal BOLD-MRI. The correlation between renal BOLD parameters and clinical indicators was analyzed by Pearson correlation analysis or Spearman correlation analysis. A ROC curve was used to distinguish the PA patients and HCs.

Results: The cortical R2* of the PA patients was higher than that of the HCs, suggesting that the cortices of PA patients were relative hypoxia.

Impact: Our results suggested that BOLD-MRI could detect the oxygenation level of the renal cortex and medulla of PA patients and may have the potential to noninvasively assess renal status.

Keywords: Kidney, Cancer, Hyperpolarised MRI, renal cancer, VERDICT

Motivation: Accurate differentiation of renal tumour subtype and grade is not currently possible using standard of care imaging.

Goal(s): To use combined functional and microstructural MRI in the form of diffusion weighted imaging with VERDICT, proton density fat fraction and hyperpolarised [1-13C]pyruvate to detect the different histological and metabolic features of different renal tumours.
Two patients with histologically proven renal tumours (grade 2 clear cell and grade 3 papillary) underwent MRI imaging.

Approach: Two patients with histologically proven renal tumours (grade 2 clear cell and grade 3 papillary) underwent MRI imaging.

Results: Combined function and microstructural MRI differentiated tumour types and normal kidney.

Impact: This study demonstrates the first combined use of VERDICT, PDFF and hyperpolarised [1-13C]pyruvate. The differentiation of renal tumours has proven difficult on imaging and this combination is a promising approach to this significant clinical problem.

Keywords: Urogenital, Kidney

Motivation: In renal tumors, it is often difficult to differentiate between benign and malignant tumors, which could reduce unnecessary biopsies and surgeries.

Goal(s): To differentiate between angiomyolipoma (AML) and renal cell carcinoma (RCC).

Approach:  Imaging with two types of diffusion-weighted images (DWI) with different Echo times (TE) and comparing T2 signals in AML and RCC at DWI (b=0) and DWI (b=1200).

Results: T2 signals at high diffusion restriction DWI (b=1200) were significantly lower in AML compared to RCC.

Impact:  There is potential to preoperatively differentiate AML non-invasively, which previously due to the difficulty in differentiation, led to invasive diagnostic methods such as biopsies and unnecessary surgeries.

Keywords: Kidney, Kidney

Motivation: As the current diagnostic tools are insensitive to early kidney damage in radiation nephropathy, there is a clinical need for improved biomarkers that can be used to noninvasively assess tubulointerstitial changes in RN.

Goal(s): To verify whether MRI-based T2 mapping can detect microstructural changes in renal parenchyma resulting from radiation-induced kidney damage.

Approach: We performed T2 mapping in two mouse models of radiation nephropathy, one involving external beam irradiation and the other utilizing internal irradiation with α-particle-emitting actinium (²²⁵Ac) radiolabeled antibody.

Results: Increased T2 values were found in the cortex and outer medulla of the treated mice compared to the healthy controls.

Impact: MRI-based T2 values could serve as a quantitative biomarker for detecting microstructural changes specific to EBRT and αRPT.

Keywords: Kidney, Tumor, Carcinoma, Renal Cell; Lymphatic Metastasis; Nephrectomy; Magnetic resonance imaging; Prognosis.

Motivation: The prognostic property of regional lymph node metastasis (RLNM) has been widely recognized, but the diagnostic workup has stagnated for renal cell carcinoma (RCC).

Goal(s): This study aimed to assess the diagnostic performance of MRI-based Node Reporting and Data System (Node-RADS) for RLNM and to explore its prognostic impact on patients with RCC.

Approach: A single-center retrospective comparative study.

Results: MRI-based Node-RADS presented better diagnostic performance for RLNM than the size criteria and previous clinical models (AUC, 0.91 vs 0.79–0.85; all P<.05), and exhibited a substantial prognostic value for RCCs regarding progress-free survival and overall survival (both P<.001).

Impact: Node-RADS, a concept that combines size, texture, margin, and shape, is a promising approach for lymph node metastasis in RCCs, which may contribute to improving clinical node staging and guiding clinical decision making.

Keywords: Kidney, Kidney

Motivation: 4D flow MRI provides volumetric time-resolved blood flow measurements in short scan times. Nevertheless, 4D Flow MRI techniques have not been clinically applied to abdominal neoplasms invading into the vasculature, altering blood flow and posing unique surgical problems. 

Goal(s): Describe the clinical implementation of 4D Flow MRI for treatment planning of RCC patients with venous tumor thrombus undergoing nephrectomy and thrombectomy. 

Approach: Our institution has established a 4D flow MRI workflow for blood flow assessment based on multidisciplinary collaboration and several other factors. 

Results: Clinical 4D flow for treatment planning of RCC patients has been successfully implemented at our institution.

Impact: 4D flow MRI allows for comprehensive non-invasive assessment of the abdominal circulation in the clinical setting. The methodology presented here has provided unvaluable input to the care team of patients with complicated cases of advanced RCC during treatment planning. 

Keywords: Pelvis, Body

Motivation: Setting up a noninvasive and accurate method to predict tumor grade preoperatively is urgently needed. However, the comparison between the potential of the bpMRI-based radiomics model and that of traditional MRI model in estimating the grade of BCa have not yet been investigated.

Goal(s): The purpose of this study was to construct a radiomics model based on bp-MRI for the preoperative prediction of BCa grade and compare it with traditional MRI model.

Approach:  A logistic regression  classifier was used to develop the radiomics signatures. 

Results: Radiomics model was outperformed the traditional MRI model in distinguishing high-grade and low-grade bladder cancer. 

Impact: The bp-MRI radiomics model was useful in distinguishing high-grade and low-grade bladder cancer. Radiomics model was outperformed the traditional MRI model.

Keywords: Pelvis, Bladder, cancer

Motivation: NacVI-RADS based on mpMRI, was exclusively constructed to evaluate the response to systemic therapy and provided a reference for further treatment for patients with muscle-invasive bladder cancer (MIBC).

Goal(s): To examine the feasibility of the nacVI-RADS criteria in driving the therapeutic decision. 

Approach: Patients received bladder sparing treatment were retrospectively retrieved. Pre-treatment and follow-up MRI were independently reviewed by two readers using the nacVI-RADS. We observed the pathological results from salvage RC and oncological outcomes for patients continuing systemic treatment with different nacVI-RADS category.

Results: We confirmed the consistency between the nacVI-RADS score and outcomes to initial treatment both pathologically and oncologically.

Impact: We preliminarily verified the feasibility of mpMRI in determining continuing or quitting bladder-sparing strategy after initial systemic therapy for MIBC. Besides, we modified nacVI-RADS, which showed a significantly improved performance in predicting the oncological outcomes after undergoing bladder sparing strategy.

Keywords: Urogenital, Bladder, Uro-Dynamic MRI

Motivation: Current standards for assessing the lower urinary tract (LUT) provide limited anatomical information. Uro-Dynamic MRI proves to be a valuable non-invasive tool for LUT biomechanics analysis. Bladder shape has been studied in static imaging but not in dynamic imaging.

Goal(s): Build a comprehensive, non-invasive framework to study bladder biomechanics in healthy and diseased subjects.

Approach: Uro-Dynamic MRI was implemented and used in five healthy and five BPH subjects. Novel MRI-derived bladder shape metrics were developed and quantified in all subjects.

Results: We observe quantifiable differences on correlation coefficients of flowrates and calculated bladder shape metrics between healthy and patients with benign prostatic hyperplasia.

Impact: Uro-Dynamic MRI allows biomechanical and shape analysis of the lower urinary tract(LUT), allowing comparisons between healthy and diseased subjects. Higher correlation values with flowrates observed on healthy subjects. Coupled Bladder biomechanical and shape analysis allows potential characterization of LUT disease. 

Keywords: Urogenital, MR Fingerprinting

Motivation: Azoospermia care often requires performing microdissection procedures for sperm extraction that are unsuccessful in 50% of men. 

Goal(s): Investigate the feasibility of a combined MRF and diffusion mapping protocol of the testicles, as well as quantify the normal ADC, T1 and T2 values of the left and right testicles.

Approach: Regions of interest were annotated on ADC and T1 maps, these were copied to T2 maps.

Results: Mean ADC, axial T1 and T2 values were similar between left and right testicles. Mean coronal T1 and T2 values of the left testicles were higher than those of the right testicles.

Impact: The acquisition of a dedicated protocol for combined MRF and diffusion mapping of the testicles is feasible. This work paves the way for prospective studies investigating non-invasive characterization of the testicles in patients with obstructive and non-obstructive azoospermia.