Renal Apparent Diffusion Coefficient Research Articles

Decreased renal apparent diffusion coefficient after COVID-19 associated acute kidney injury

Study objective: To investigate if there are any differences in total renal blood flow, regional renal perfusion, renal oxygenation or renal tissue properties, studied by non-invasive MRI, in patients having recovered from severe COVID-19 with different grades of acute kidney injury (AKI). Hypothesis: We hypothesize that the decrease in renal blood flow and perfusion that our research group have previously found in severe COVID-19 patients with AKI 1 may persist together with possible renal edema and development of fibrosis. Material and methods: We identified patients with AKI grade 3 from a cohort of patients previously treated in the intensive care unit for severe COVID-19 with respiratory failure. These patients were matched to possible extent regarding age, sex, height, weight, body mass index (BMI) and body surface area (BSA) with patients from the same cohort that had AKI grade 1 and patients that did not have AKI. A total of 22 patients were included. Because of common occurrence of oliguria without a reduction of glomerular filtration, AKI grade was determined using the Kidney Disease Improving Global Outcome (KDIGO) creatinine criteria only. All patients had a record of a plasma creatinine inside normal range within two years prior to ICU care, and had no history of renal disease. Comorbidities were common in the study population. Follow up examination was performed approximately five months after the patients were admitted the ICU. Results: Significant differences in cortical and medullary ADC were demonstrated between the study groups. Both cortical and medullary ADC was significantly reduced in the ‘AKI grade 3’ group compared to the ‘no AKI’ group and the ‘AKI grade 1’ group. Total renal blood flow was significantly lower in the ‘AKI grade 3’ group compared to the ‘no AKI’ group and global renal perfusion was significantly lower in the ‘AKI grade 3’ group compared to the ‘no AKI’ and ‘AKI grade 1’ groups. No significant differences in either cortical or medullary perfusion were seen between the groups. Cortical and medullary oxygenation and renal vein oxygen saturation did not differ significantly between the groups. Conclusion: In this study we demonstrates that, approximately five months after intensive care for severe COVID-19, patients that had high grades of AKI during hospitalization have reduced cortical and medullary ADC together with reduced total renal blood flow and global renal perfusion compared to similar patients that did not have AKI. These findings might indicate development of renal fibrosis. No differences regarding renal oxygenation were observed between the studied groups. 1. Luther T, Eckerbom P, Cox E, Lipcsey M, Bulow S, Hultstrom M, et al. Decreased renal perfusion during acute kidney injury in critical COVID-19 assessed by magnetic resonance imaging: a prospective case control study. Crit Care. 2022;26(1):262. Public and private funding sources. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The role of diffusion-weighted imaging in the diagnosis of early kidney damage

Objective: This study aimed to determine a threshold value for distinguishing early-stage chronic kidney disease (CKD) from moderate and advanced stages as well as patients with early-stage CKD from those with normal renal function using apparent diffusion coefficient (ADC) and normalized ADC values. Methods: This retrospective study enrolled 257 patients. Diffusion-weighted images were obtained with a set of b = 50,400,800 values. In each patient, six ADC values were measured from upper, middle, and lower areas of both kidneys, and three ADC values were measured from the spleen. Patients with CKD were classified into five subgroups and healthy patients were classified into two subgroups according to their glomerular filtration rate (GFR). Results: The renal ADC values were found to be positively correlated with GFR (r = 0.790, p < 0.001) and negatively correlated with creatinine levels (r = −0.709, p < 0.001). The mean ADC values of the stage 1 and 2 CKD groups were found to be significantly higher than those of advanced-stage CKD groups (p < 0.001), and these values were significantly lower in the stage 1 and 2 CKD groups than in the healthy group (p < 0.001). With a cut-off value of ≥1.791 for ADC, the sensitivity was 76.5% and the specificity was 85% while distinguishing between patients with early- and advanced-stage CKD. Conclusion: Renal and normalized ADC values are strongly correlated with CKD stages, and with the use of appropriate threshold values, the difference between early and advanced stages of CKD can be predicted.

Effect of Iodized contrast substances used in computed tomography examination on kidney apparent diffusion coefficient (ADC) value

Aim: In this prospective study, our goal is to evaluate the effect of iodine-based contrast agent on renal Apparent Diffusion Coefficient (ADC) before and after the contrast agent in patients with normal and abnormal Glomerulary Filtration Rate (GFR) values using computed tomography (CT) imaging.Methods: The patients who applied for CT examination at an age older than 40 years and met the inclusion criteria of patient and control groups were included. DWI was evaluated by two radiologist in the same session. The range of interest (ROI) was adjusted to be less than 1.5 cm².The Spearman correlation test was used for statistical analysis.Results: A total of 48 subjects (23 and 25 subjects for patient and control groups, respectively) with two DWI scans were included. ADC values were compared for both kidneys before and after the administration of the contrast agent and a significant decrease in post-ADC values was observed in the control group (right kidney pre-ADC: 2,11±0,17 x10ˉ³, post-ADC 2,07±0,15 x10ˉ³ mm²/s, p=0,016; left kidney pre-ADC: 2,11±0,17 x10ˉ³ mm²/s, post-ADC 2,04±0,14 x10ˉ³ mm²/s, p=0,011). However, there was no significant difference between the patient groups according to the administration of contrast agent (right kidney pre-ADC: 1,97±0,22 x10ˉ³ mm²/s, post-ADC: 1,97±0,24 x10ˉ³ mm²/s, p=0,95; left kidney pre-ADC: 1,96±0,23 x10ˉ³ mm²/s, post-ADC: 1,98±0,22 x10ˉ³ mm²/s, p=0,64). Moreover, pre-ADC values in the patient group were relatively low. Pre-ADC values in both groups for the right kidney were 1,97±0,22 x10ˉ³ mm²/s and 2,11±0,17 x10ˉ³ mm²/s, respectively (p=0,016). Pre ADC values in both groups for the left kidney were 1,96±0,23 x10ˉ³ mm²/s and 2,11±0,17 x10ˉ³ mm²/s, respectively (p=0,018). No significant differences in the post-ADC values were observed between the two groups.Conclusion: No decrease in ADC values was observed after the administration of iodine-based contrast agent in patients with a GFR less than 60, whereas there was a relatively high decrease in patients with normal GFR.

Evaluation of interstitial fibrosis in chronic kidney disease by multiparametric functional MRI and histopathologic analysis.

To investigate the diagnostic value of functional MRI to assess renal interstitial fibrosis in patients with chronic kidney disease (CKD). We prospectively recruited 80 CKD patients who underwent renal biopsies and 16 healthy volunteers to undergo multiparametric functional MRI examinations. The Oxford MEST-C classification was used to score the interstitial fibrosis. The diagnostic performance of functional MRI to discriminate interstitial fibrosis was evaluated by calculating the area under the receiver operating characteristic (ROC) curves. IgA nephropathy (60%) accounted for the majority of pathologic type in the CKD patients. Apparent diffusion coefficient (ADC) from diffusion-weighted imaging (DWI) was correlated with interstitial fibrosis (rho = -0.73). Decreased renal blood flow (RBF) derived from arterial spin labeling (rho = -0.78) and decreased perfusion fraction (f) derived from DWI (rho = -0.70) were accompanied by increased interstitial fibrosis. The T1 value from T1 mapping correlated with interstitial fibrosis (rho = 0.67) (all p < 0.01). The areas under the ROC curve for the discrimination of ≤ 25% vs. > 25% and ≤ 50% vs. > 50% interstitial fibrosis were 0.87 (95% confidence interval, 0.78 to 0.94) and 0.93 (0.86 to 0.98) by ADC, 0.84 (0.74 to 0.91) and 0.94 (0.86 to 0.98) by f, 0.93 (0.85 to 0.98) and 0.90 (0.82 to 0.96) by RBF, and 0.91 (0.83 to 0.96) and 0.77 (0.66 to 0.85) by T1, respectively. Functional MRI parameters were strongly correlated with the interstitial fibrosis of CKD. Therefore, it might a powerful tool to assess interstitial fibrosis of CKD noninvasively. • In CKD patients, the renal cortical ADC value decreased and T1 value increased significantly compared with healthy volunteers. • Functional MRI revealed significantly decreased renal perfusion in CKD patients compared with healthy volunteers. • The renal cortical ADC, f, RBF, and T1 values were strongly correlated with the interstitial fibrosis of CKD.

Pancreas and kidney changes in type 2 diabetes patients: the role of diffusion-weighted imaging

Background/aim The aim of this study was to compare renal and pancreatic apparent diffusion-coefficient (ADC) values of diabetic patients and control subjects and to examine their potential association with several diabetes-related clinical parameters.Materials and methods A total of 80 sex- and age-matched patients were included in the study. Of them, 40 were patients with type 2 diabetes and 40 were nondiabetic participants. Abdominal diffusion-weighted MRIs of both groups were retrospectively reviewed. Diabetes-related clinical parameters were recorded.Results The difference between the mean ADC values of the patient group and the control group was significant (p = 0.012). It was also found that the mean pancreatic ADC values of diabetic patients and the control group significantly differed (p = 0.02). Besides, there were positive correlations between the mean pancreatic ADC values and age, Hb1Ac level, treatment type, and disease duration (p < 0.05). While eGFR values positively correlated with the mean renal ADC values (p < 0.05), there were negative correlations between such values and age, serum creatinine level, and disease duration (p < 0.05).Conclusion Renal and pancreatic ADC values of diabetic patients could potentially play a role, as markers of renal and pancreatic functions, in clinical decisions in the follow-up of such patients.

Pathological assessment of chronic kidney disease with DWI: Is there an added value for diffusion kurtosis imaging?

Chronic kidney disease (CKD) is a worldwide health problem, precise functional and pathological assessment is beneficial to better treatment. Diffusion kurtosis imaging (DKI) can evaluate non-Gaussian diffusion and may help to assess renal pathology and function. To assess pathological and functional alterations in CKD using DKI compared with diffusion-weighted imaging (DWI). Prospective study. 70 CKD patients and 20 healthy volunteers. 1.5 T. All participants underwent DKI, and apparent diffusion coefficient (ADC), mean diffusivity (MD), and mean kurtosis (MK) of renal parenchyma were acquired. Correlation between renal parenchymal ADC, MD, MK, and estimated glomerular filtration rate (eGFR), pathological scores were assessed. The diagnostic efficacy of ADC, MD, and MK for assessing the degree of renal pathological injury were compared. ANOVA, Spearman correlation analysis, and ROC curve analysis. The cortical ADC, MD were significantly higher than medulla for all participants, whereas medullary MK was significantly higher than cortex (P < 0.01). Whether eGFR reduced or not, renal parenchymal MK were significantly higher in patients than controls (P < 0.05). Positive correlation was found between eGFR and ADC (cortex, r=0.562; medulla, r=0.527), and negative correlation between eGFR and MK (cortex, r=-0.786; medulla, r=-0.709) (all P < 0.001). There was positive correlation between MK and glomerular injury (cortex, r=0.681; medulla, r=0.652), tubulointerstitial lesion (cortex, r=0.650; medulla, r=0.599) (all P < 0.001). For discrimination between mild and m-s renal injury group, the AUC values of ADC, MD, MK were cortex: 0.723, 0.655, 0.864 and medulla: 0.718, 0.581, 0.829. The AUC values of ADC, MD, MK were cortex: 0.708, 0.679, 0.770 and medulla: 0.713, 0.830, 0.780 for differentiating control group from mild renal injury group. DKI is practicable for noninvasive assessment of renal pathology and function of CKD, DKI offer better diagnostic performance than DWI. Evidence Level 1 Technical Efficacy 2.

Does diffusion-weighted magnetic resonance imaging help in the detection of renal parenchymal disease and staging/prognostication in chronic kidney disease?

PurposeDiffusion-weighted imaging (DWI) in renal diseases is an upcoming modality, and its utility as an additional marker is yet to be proven. This study was intended to find the relationship between apparent diffusion coefficient (ADC) values with renal function tests and stages of chronic kidney disease (CKD) to assess renal dysfunction, and to label a cut-off for normal renal function and dysfunction.Material and methodsA prospective diagnostic study was conducted on 120 patients: 60 with deranged renal function tests (RFT) and 60 with normal RFT. DWI using a 1.5-Tesla MRI (at b-values of 0 and 500 s/mm2) was done. A region of interest of size 1-2 cm2 was placed on renal parenchyma in the region of medulla, one each, over the superior, mid, and lower regions of each kidney separately. ADC values were recorded for renal parenchyma and compared.ResultsIn patients with renal dysfunction ADC values were significantly lower than in patients with normal function (1.75 ± 0.25 vs. 2.28 ± 0.21 of right kidney and 1.79 ± 0.17 vs. 2.29 ± 0.21 of left kidney [×10−3 mm2/s]; p = 0.001). ADC values of different stages of CKD showed a decreasing trend with increasing stage.ConclusionsADC values taken at all poles to get focal involvement of the kidney can be used to measure each kidney separately, and values can be individually correlated with the elevated renal parameters. The cut-off value of the mean ADC for individual kidneys was > 2.28 (×10−3 mm2/s) in normal renal function and < 2.00 (×10−3 mm2/s) in renal dysfunction.

The Role of Diffusion-Weighted MRI and Apparent Diffusion Coefficient in Assessment of Diabetic Kidney Disease: Preliminary Experience Study.

BackgroundDiabetic kidney disease is the most common cause of ESRD. There is poor correlation between the degree of renal fibrosis and current screening markers. A noninvasive imaging technique is needed to assess the degree of structural changes in the kidney. The aim of this study was to assess the role of apparent diffusion coefficient (ADC) in the diagnosis of diabetic kidney disease. Forty adult diabetic patients with chronic kidney disease as well as 20 age- and sex-matched adult healthy controls were recruited from Nephrology Department of our University Hospital. All patients underwent renal MR-DWI and ADC mapping on a 1.5-T scanner (Philips Achieva) using phased array body coil.ResultsAmong the studied 40 diabetic patients, five groups of patients were resulted 8 patients for each and the ADC values were inversely correlated with advancement in renal parenchymal affection, ie, in late stages of the disease the ADC values were lower than in early stages. The mean ADC values of renal parenchyma in patients with diabetic kidney disease were considerably lower than that of healthy controls with normal renal function (2.1±0.3x10−3 mm2/s vs 2.4±0.1x10−3 mm2/s with p<0.001).ConclusionADC value is a possible noninvasive technique in evaluating the stage of renal dysfunction with assessment of disease progression.

Validity of diffusion-weighted magnetic resonance imaging in the evaluation of acute pyelonephritis in comparison with contrast-enhanced computed tomography.

PurposeApplications of diffusion-weighted magnetic resonance imaging outside the brain have gained increasing importance in recent years, and recent studies have shown the usage of diffusion-weighted (DW) imaging in diagnosing pyelonephritis based on renal cortical and medullary apparent diffusion coefficient (ADC) values. The aim of this study was to assess the validity of DW magnetic resonance (MR) imaging in comparison with contrast-enhanced computed tomography (CECT) in diagnosing pyelonephritis.Material and methodsA cross-sectional observational study was conducted for a period of six months in a tertiary hospital in Coimbatore. All patients with clinical and laboratory diagnosis of acute pyelonephritis, who were referred for radiological imaging (CECT), were taken into the study. Out of 112 patients with a clinical and laboratorial diagnosis of acute pyelonephritis (APN), who underwent both DW MR and CECT, diagnosis of APN was made in 100 patients based on CECT, while in 12 cases the investigation (CECT) was negative. Finally, these 100 patients were included in the study. The validity of DW MR imaging in diagnosing APN was assessed by deriving sensitivity, specificity, and positive and negative predictive value in comparison with CECT findings.ResultsThe validity report of DW MR imaging in the detection of APN showed a very high sensitivity (96-100%) and specificity (86-90%) and very low false positives (6-10%) and negatives (< 5%), and it also showed that in the areas of affected renal parenchyma ADC values were consistently lower compared to unaffected renal parenchyma.ConclusionBased on the generated hypothesis, DW MR imaging of the kidneys seems to be highly sensitive and specific for the detection of focal or diffuse infections within the kidney in comparison with CECT.

Combination of renal apparent diffusion coefficient and renal parenchymal volume for better assessment of split renal function in chronic kidney disease

ObjectiveTo investigate the value of the combination of the split renal apparent diffusion coefficient (ADC) and renal parenchyma volume (RPV) by diffusion-weighted imaging (DWI) for assessment of split renal function in patients with chronic kidney disease (CKD). MethodsForty-eight eligible participants (36 CKD patients and 12 healthy individuals) were included in the study. All of them underwent DWI (b = 0 and 800 s/mm2) examination with a 1.5 T MRI scanner to determine the split renal ADC and RPV. Glomerular filtration rate (GFR) was measured by 99Tcm-DTPA scintigraphy using Gates’ method and used as the reference standard. All statistical tests were performed using SPSS 20.0 and MedCalc 10.0 statistical software packages. ResultsSplit renal ADC, RPV, and their product were significantly correlated with GFR (γ = 0.493, p < 0.0001; γ = 0.337, p = 0.018; γ = 0.708, p < 0.0001, respectively). The product of split renal ADC and RPV had a significantly higher correlation with GFR (γ = 0.708) than split renal ADC (p = 0.0002) and RPV (p = 0.016). ROC curve analysis showed that the product of split renal ADC and RPV was a significantly better indicator of reduced split renal function (AUC = 0.893) compared to split renal ADC (p = 0.0455) and RPV (p = 0.0326). ConclusionThe combination of split renal ADC and RPV obtained by DWI can significantly improve the assessment of split renal function in CKD patients.

Synergistical action of the β2 adrenoceptor and fatty acid binding protein 2 polymorphisms on the loss of glomerular filtration rate in Chinese patients with type 2 diabetic nephropathy.

Since altered sympathetic nerve activity and insulin resistance are implicated in the pathogenesis of type 2 diabetic nephropathy, we investigated the effect of polymorphic Arg16Gly and Gln27Glu in the β2 adrenoceptor gene and Ala54Thr in the fatty acid binding protein 2 gene on the estimated glomerular filtration rate (eGFR) in Chinese patients with the above disease. A total of 552 diabetic subjects recruited from annual health examinations were studied. The eGFR was calculated from the Modification of Diet in Renal Disease equation for the Chinese. Plasma norepinephrine level and genotype were determined by high-performance liquid chromatography-tandem mass spectrometry and TaqMan method, respectively. Holter-derived heart rate viability (HRV) and the MRI-generated renal apparent diffusion coefficient (ADC) were evaluated. The Gly16Gly and Thr54Thr homozygotes had significantly higher microalbuminuria and lower eGFR against other genotypes in their individual polymorphism. Besides, the Gly16Gly variant exhibited markedly elevated norepinephrine level, whereas indicative of insulin resistance was increased in the Thr54Thr one. Multiple linear regression analysis further confirmed the independent genetic effect on the eGFR. Moreover, multifactor dimensionality reduction method detected a gene-gene synergistic action that subjects with the Gly16Gly/Thr54Thr genotype were exposed to higher risk of eGFR loss. Finally, these findings were accompanied by lower HRV and ADC, indicating sympathetically mediated hemodynamic changes. By uncovering the genetic component of the coherent interplay between the elevated sympathetic nerve activity and metabolic disorders, our observations might promote the development of novel personalized prevention and management strategies against the diabetic nephropathy, especially in the genetically susceptible individuals.

Diffusion-weighted imaging and pathology of chronic kidney disease: initial study.

To investigate the value of diffusion-weighted imaging (DWI) for assessing histopathologic changes observed in chronic kidney disease (CKD). Fifty-two patients with CKD underwent DWI before renal biopsy. The renal apparent diffusion coefficient (ADC) values and histopathologic changes were analyzed. The pathologic changes were scored using a semi-quantitative method (no lesion as 0, mild lesion as 1, moderate lesion as 2, and severe lesion as 3). The relationships between renal histopathologic scores, types, classification, and right renal ADCs were analyzed using ANOVA and Pearson's or Spearman's correlation tests. Negative correlations were found between the right renal ADCs and scores of tubulointerstitial lesions (r=-0.354, P=0.012), the severity of tubular atrophy (r=-0.439, P=0.002), and the severity of interstitial fibrosis (r=-0.272, P=0.049). There were no correlations between the ADCs and scores of glomeruli and peritubular vessel lesions (P>0.05). There were significant differences among groups based on pathology types (P=0.009). There was no significant relationship between renal ADCs and the pathologic classification (P>0.05). DWI may be helpful to detect tubulointerstitial injury, including tubular atrophy and interstitial fibrosis. DWI may have the potential to serve as an effective auxiliary method to help nephrologists to evaluate patients with CKD.

Renal Adiposity Confounds Quantitative Assessment of Markers of Renal Diffusion With MRI: A Proposed Correction Method.

Recent studies have indicated that excessive fat may confound assessment of diffusion in organs with high fat content, such as the liver and breast. However, the extent of this effect in the kidney, which is not considered a major fat deposition site, remains unclear. This study tested the hypothesis that renal fat may impact diffusion-weighted imaging (DWI) parameters, and proposes a 3-compartment model (TCM) to circumvent this effect. Using computer simulations, we investigated the effect of fat on assessment of apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM), and TCM-derived pure-diffusivity. We also investigated the influence of magnetic resonance repetition (TR) and echo time (TE) on DWI parameters as a result of variation in the relative contribution of the fat signal. Apparent diffusion coefficient, IVIM and TCM DWI parameters were calculated in domestic pigs fed a high-cholesterol (obese group) or normal diet (lean group), and correlated to renal histology. Intravoxel incoherent motion-derived pure-diffusivity was also compared among 15 essential hypertension patients classified by body mass index (BMI) (high vs normal). Finally, pure-diffusivity was calculated and compared in 8 patients with atherosclerotic renal artery stenosis (ARAS) and 5 healthy subjects using IVIM and TCM. Simulations showed that unaccounted fat results in the underestimation of IVIM-derived pure diffusivity. The underestimation increases as the fat fraction increases, with higher pace at lower fat contents. The underestimation was larger for shorter TR and longer TE values due to the enhancement of the relative contribution of the fat signal. Moreover, TCM, which incorporates highly diffusion-weighted images (b > 2500 s/mm), could correct for fat-dependent underestimation. Animal studies in the lean and obese groups confirmed lower ADC and IVIM pure-diffusivity in obese versus lean pigs with otherwise healthy kidneys, whereas pure-diffusivity calculated using TCM were not different between the 2 groups. Similarly, essential hypertension patients with high BMI had lower ADC (1.9 vs 2.1 × 10 mm/s) and pure-diffusivity (1.7 vs 1.9 × 10 mm/s) than those with normal BMI. Pure-diffusivity calculated using IVIM was not different between the ARAS and healthy subjects, but TCM revealed significantly lower diffusivity in ARAS. Excessive renal fat may cause underestimation of renal ADC and IVIM-derived pure-diffusivity, which may hinder detection of renal pathology. Models accounting for fat contribution may help reduce the variability of diffusivity calculated using DWI.

Diffusion tensor imaging of the renal cortex in diabetic patients: correlation with urinary and serum biomarkers.

To demonstrate role of diffusion tensor imaging of the kidney in diabetic patients and to correlate renal fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the renal cortex with urinary and serum biomarkers of diabetes. Prospective study was conducted upon 42 diabetic patients (28 males, 14 females; mean age=33years) and 17 age- and sex-matched volunteers. Diabetic patients were micro-normoalbuminuric (n=27) and macroalbuminuric (n=15). Patients and volunteers underwent diffusion tensor imaging of the kidney. The FA and ADC of the renal cortex were calculated from 3 regions of interests of both kidneys. The mean FA and ADC of the renal cortex in diabetic patients (0.36±0.10 and 1.74±0.16×10-3mm2/s) was significantly different (p=0.001) from that of volunteers (0.26±0.02 and 1.88±0.03×10-3mm2/s). The cut-off renal FA and ADC used to differentiate diabetic patients from volunteers were 0.28 and 1.89×10-3mm2/s with AUC of 0.791 and 0.773 and accuracy of 71% and 76%. The FA and ADC calculated in the renal cortex in patients with macroalbuminuria (0.43±0.10 and 1.63±0.19×10-3mm2/s) was significantly different (p=0.001) from that of patients with micro-normoalbuminuria (0.35±0.12 and 1.80±0.18×10-3mm2/s). The FA and ADC of the renal cortex in diabetic patients correlated with urinary albumin (r=0.530; p=0.001, r=-0.421; p=0.006), urinary NAG (r=0.376; p=0.014, r=-0.245; p=0.01), urinary TGF-β1 (r=0.287; p=0.065, r=-0.214; p=0.175), and serum creatinine (r=0.381; p=0.013, r=-0.349; p=0.023). The FA and ADC of the renal cortex may help in differentiation of diabetic kidney from volunteers and prediction of the presence of macroalbuminuria in diabetic patients and correlated with some of the urinary and serum biomarkers of diabetes.

Evaluation of upper abdominal organs with DWI in patients with familial Mediterranean fever

To investigate the diagnostic efficiency of diffusion-weighted magnetic resonance imaging (DWI) for the evaluation of functional changes that can occur in upper abdominal organs in patients with familial Mediterranean fever (FMF). The study included 50 controls, 45 patients with FMF, and 14 patients with FMF who had accompanying proteinuria. Measurement of apparent diffusion coefficient (ADC) was performed using DWI sections obtained from liver, spleen, kidney, and pancreas parenchyma with 1.5T MRI using b=500 and b=1000s/mm2 values both in patients and control groups. Mean ADC values were compared between patient and control groups. Renal ADC values were lower in the patient groups compared to the control group. Additionally, renal ADC values showed further decrease in the patient group in the presence of accompanying proteinuria, when compared to the FMF group without proteinuria (p<0.001). Based on the ROC analysis, calculated cutoff values for the determination of FMF and FMF accompanied by proteinuria were 2.26×10-3 and 2.04×10-3mm2/s, respectively. Liver, spleen, and pancreas ADC values did not show remarkable change between patient and control groups. Present findings indicate that the presence of FMF and its clinical progression expressed by proteinuria can be differentially determined with renal DWI.

Correction of Gradient Nonlinearity Bias in Quantitative Diffusion Parameters of Renal Tissue with Intra Voxel Incoherent Motion.

Spatially nonuniform diffusion weighting bias as a result of gradient nonlinearity (GNL) causes substantial errors in apparent diffusion coefficient (ADC) maps for anatomical regions imaged distant from the magnet isocenter. Our previously described approach effectively removed spatial ADC bias from 3 orthogonal diffusion-weighted imaging (DWI) measurements for monoexponential media of arbitrary anisotropy. This work evaluates correction feasibility and performance for quantitative diffusion parameters of the 2-component intravoxel incoherent motion (IVIM) model for well-perfused and nearly isotropic renal tissue. Sagittal kidney DWI scans of a volunteer were performed on a clinical 3T magnetic resonance imaging scanner near isocenter and offset superiorly. Spatially nonuniform diffusion weighting caused by GNL resulted both in shifting and broadening of perfusion-suppressed ADC histograms for off-center DWI relative to unbiased measurements close to the isocenter. Direction-average diffusion weighting bias correctors were computed based on the known gradient design provided by the vendor. The computed bias maps were empirically confirmed by coronal DWI measurements for an isotropic gel-flood phantom. Both phantom and renal tissue ADC bias for off-center measurements was effectively removed by applying precomputed 3D correction maps. Comparable ADC accuracy was achieved for corrections of both b maps and DWI intensities in the presence of IVIM perfusion. No significant bias impact was observed for the IVIM perfusion fraction.

Renal function and diffusion-weighted imaging: a new method to diagnose kidney failure before losing half function

To diagnose earlier kidney failure, we investigated renal functions with diffusion-weighted imaging (DWI). We evaluated the DWI of 62 patients with chronic kidney disease (CKD) and compared it with creatinine clearance provided by daily urine collection. The apparent diffusion coefficient (ADC) values were compared with the five stages of CKD. For each stage of CKD, the ADC values were found to be significantly different (p<0.01) and allowed the differentiation of stage 1 of the disease from the other stages. Renal ADC values show a significant correlation with the clinical stages of CKD. DWI may detect renal failure prior to a rise in creatinine.

Renal Apparent Diffusion Coefficient Values in Patients with Obstructive Uropathy and High Values of Creatinine.

Purpose: Diffusion weighted magnetic resonance imaging (DW-MRI) of the kidneys provides noninvasive information on renal function in healthy volunteers, and it is feasible in severely ill patients. It may provide information on the degree of kidney dysfunction.The purpose of this study is to evaluate apparent diffusion coefficient (ADC) values using DW-MRI in patients with obstructive uropathy and elevated serum creatinine levels.Methods: Fifty patients with high serum creatinine levels and diagnoses of chronic urinary obstruction detected by ultrasonography were included in this study.DW-MRIs were obtained from 50 patients with hydronephrotic kidneys and 26 healthy volunteers using a 1.5T whole-body MR scanner.Results: ADC measurements of renal parenchyma in hydronephrotic kidneys were significantly lower compared to normal kidneys (p < 001).Conclusion: The measurement of ADC values has potential value in the evaluation of the functional status of hydronephrotic kidneys.

Apparent diffusion coefficient measurement by diffusion weighted magnetic resonance imaging is a useful tool in differentiating renal tumors.

BackgroundTo determine the clinical value of apparent diffusion coefficient (ADC) measurement by diffusion weighted magnetic resonance imaging (DW-MRI) in differentiating renal tumors.MethodsElectronic databases were searched using combinations of keywords and free words relating to renal tumor, ADC and DW-MRI. Based on carefully selected inclusion and exclusion criteria, relevant case–control studies were identified and the related clinical data was acquired. Statistical analyses were performed using STATA 12.0 (Stata Corporation, College station, TX).ResultsSixteen case–control studies were ultimately included in the present meta-analysis. These 16 high quality studies contained a combined total of 438 normal renal tissues and 832 renal tumor lesions (597 malignant and 235 benign). The results revealed that ADC values of malignant renal tumor tissues were markedly lower than normal renal tissues and benign renal tumor tissues. ADC values of benign renal tumor tissues were also significantly lower than normal renal tissue.ConclusionsADC measurement by DW-MRI provided clinically useful information on the internal structure of renal tumors and could be an important radiographic index for differentiation of malignant renal tumors from benign renal tumors.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1221-1) contains supplementary material, which is available to authorized users.

Diffusion-weighted MRI does not reflect kidney fibrosis in a rat model of fibrosis.

To assess the apparent diffusion coefficient (ADC) derived from diffusion-weighted (DW) magnetic resonance imaging (MRI) as a specific marker of renal fibrosis in rats with unilateral ureteral obstruction (UUO). Thirteen rats were analyzed in group 1 (n = 4), group 2 (n = 3), and group 3 (n = 6) and measured using a clinical 3.0T MR scanner. Groups 1 and 2 were used to establish the final imaging protocols for group 3. DW imaging with four b-values (0, 50, 300, 800 s/mm(2) ) was conducted before UUO, at days 3 and 5 after UUO, after release of the obstruction, and after sacrifice. Renal cortical ADCs were correlated with histological and ultrastructural analyses. ADC values of group 3 are shown as mean ± standard deviation of [10(-3) mm(2) /s]. On day 5, in vivo cortical ADC of obstructed fibrotic kidneys was significantly reduced compared to unobstructed kidneys (1.4 ± 0.086 vs. 1.535 ± 0.087, P = 0.0018). Postmortem ADC dropped by 50% and was significantly increased in obstructed vs. unobstructed kidneys (0.711 ± 0.094 vs. 0.566 ± 0.049, P = 0.0046). Histopathology of obstructed kidneys showed tubular dilation, tubular cell atrophy, and expansion of the interstitial space. Postmortem ADC correlated tightly with tubular lumen area (r = 0.9, P < 0.001), fibronectin (r = 0.8, P = 0.003), collagen type I (r = 0.73, P = 0.007), and interstitial expansion (r = 0.69, P = 0.013). Compared to the in vivo measurements, postmortem renal ADCs were considerably reduced and, unlike in vivo, fibrotic kidneys exhibited consistently higher ADC compared to healthy kidney parenchyma. Our data suggest that in vivo ADC is unlikely to be a direct measure of renal fibrosis.