Patient consent forms should account for broad future data sharing where appropriate. Measurement of MRI biomarker panels is expensive compared with blood and urine biomarkers. Consequently, financial concerns may prevent the uptake of MRI biomarkers, even when clinically validated. Robust health economic studies will form an important element of future research to determine whether the higher initial cost is offset by savings in health care—related costs from improved patient treatment pathways or outcomes that are enabled by the imaging biomarker s.
Obtaining regulatory approval is a lengthy process, especially in slowly progressive chronic diseases such as CKD. Hence it is critical to engage with this process early and ensure that data are collected according to the appropriate standards. In addition, the requirements of the pharmaceutical industry for drug development should be considered.
Collaboration with MRI scanner manufacturers will be essential to support the scalability of the validated imaging biomarkers, which can ultimately be achieved only if vendors agree to distribute them on their platforms; this process should also lead to reductions in scan acquisition times for multiparametric protocols.
Small and medium-sized enterprises will likely play an important role in the scalability of the biomarkers by providing software and services for centralized or local image processing and quality control. Involving them early in the setup and running of studies will ensure that imaging biomarkers are collected in a manner that is compatible with real-world conditions, shortening the route to clinical translation.
Renal MRI has enormous potential to allow assessment of pathophysiological changes in the kidney that may improve diagnosis and prognosis and guide treatment in patients with kidney disease. By issuing this position paper, we hope to support and align the growth of a body of complementary technical, preclinical and clinical research and provide a structure by which multicentre studies in this field can be accelerated, with the ultimate aim of improving clinical outcomes in patients with CKD. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.
Sign In or Create an Account. Sign In. Advanced Search. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents. Correspondence and offprint requests to: Nicholas M. Selby; E-mail: nicholas. Oxford Academic. Google Scholar. Peter J Blankestijn. Peter Boor. Christian Combe.
Kai-Uwe Eckardt. Eli Eikefjord. Nuria Garcia-Fernandez. Xavier Golay. Isky Gordon. Nicolas Grenier. Paul D Hockings. Jens D Jensen.
Use of Radiological Tools for Evaluating Kidney Disease
Jaap A Joles. Philip A Kalra. Patrick B Mark. Iosif A Mendichovszky. Olivera Nikolic.
Differentiation of renal masses
Aghogho Odudu. Albert C M Ong. Alberto Ortiz. Menno Pruijm. Giuseppe Remuzzi. Sophie de Seigneux. Roslyn J Simms. Janka Slatinska. Paul Summers. Maarten W Taal. Harriet C Thoeny. University of Bern, Inselspital, Bern, Switzerland. Marcos Wolf. Anna Caroli. Steven Sourbron. Cite Citation. Permissions Icon Permissions. Abstract Functional renal magnetic resonance imaging MRI has seen a number of recent advances, and techniques are now available that can generate quantitative imaging biomarkers with the potential to improve the management of kidney disease.
Table 1. Kidney length and volume and their change over time are key measure in patients with ADPKD but may also be important in CKD progression, primary and secondary hyperfiltration in diabetic nephropathy, renal transplants, renal artery stenosis, vesicoureteric reflux. Cortical thickness may be more variable within a given kidney, limiting reproducibility. Exploits the different properties of moving versus static protons in a magnetic field. Increased renal resistance to flow due to downstream microvascular obstruction, large-vessel arterial disease or changes in systemic haemodynamics.
Cortical perfusion, which can be affected by a number of pathophysiological processes in acute and chronic renal disease. Any changes in the renal microstructure, especially in the interstitium, for instance, renal fibrosis, cellular infiltration inflammatory or tumorous or oedema, changes in renal perfusion and in water handling in the tubular compartment. Allows assessment of the degree of organization in space of oriented tissues. Any changes in the microstructure that lead to a change in the preferred direction of water diffusion, for instance, tubular dilatation, tubular obstruction or a loss in the organization of medullary tubules.
Changes in renal oxygenation or changes in the microstructure of the capillary bed. T 1 is a tissue-specific time variable that can distinguish different tissues. Changes in the molecular environment, for example, water content, viscosity, temperature, fibrosis due to the association of collagen with supersaturated hydrogel and inflammation interstitial oedema, cellular swelling.
Changes with tissue water content. Limited experience in human kidney disease to date. Allows measurement of perfusion and GFR. Concerns exist when using gadolinium for research in advanced CKD hence not discussed in this paper. Perfusion and filtration per unit tissue, vascularity and tubular transit times. The fraction of large macromolecules or immobilized cell membranes in tissue; in the kidney, shown to correlate with fibrosis. These include but are not limited to elastography, hyperpolarization, and sodium MRI. Open in new tab Download slide.
Global kidney health and beyond: a roadmap for closing gaps in care, research, and policy. Search ADS. Estimating the financial cost of chronic kidney disease to the NHS in England. New magnetic resonance imaging index for renal fibrosis assessment: a comparison between diffusion-weighted imaging and T1 mapping with histological validation. Diffusion-weighted imaging and diffusion tensor imaging detect delayed graft function and correlate with allograft fibrosis in patients early after kidney transplantation.
Visualization of kidney fibrosis in diabetic nephropathy by long diffusion tensor imaging MRI with spin-echo sequence. Could MRI be used to image kidney fibrosis? A review of recent advances and remaining barriers.
Computed Tomography (CT or CAT) Scan of the Kidney | Johns Hopkins Medicine
Diffusion-weighted magnetic resonance imaging to assess diffuse renal pathology: a systematic review and statement paper. Renal blood oxygenation level-dependent magnetic resonance imaging to measure renal tissue oxygenation: a statement paper and systematic review. Arterial spin labelling MRI to measure renal perfusion: a systematic review and statement paper.
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Imaging classification of autosomal dominant polycystic kidney disease: a simple model for selecting patients for clinical trials. Renal arterial blood flow measurement by breath-held MRI: accuracy in phantom scans and reproducibility in healthy subjects. Longitudinal assessment of renal perfusion and oxygenation in transplant donor-recipient pairs using arterial spin labeling and blood oxygen level-dependent magnetic resonance imaging.
Multislice perfusion of the kidneys using parallel imaging: image acquisition and analysis strategies. Measurement of kidney perfusion by magnetic resonance imaging: comparison of MRI with arterial spin labeling to para-aminohippuric acid plasma clearance in male subjects with metabolic syndrome. Renal perfusion imaging with two-dimensional navigator gated arterial spin labeling.
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Screening strategies for chronic kidney disease in the general population: follow-up of cross sectional health survey. Randomised placebo-controlled trial of effect of ramipril on decline in glomerular filtration rate and risk of terminal renal failure in proteinuric, non-diabetic nephropathy. A predictive model for progression of chronic kidney disease to kidney failure.
Multinational assessment of accuracy of equations for predicting risk of kidney failure: a meta-analysis. Reduced cortical oxygenation predicts a progressive decline of renal function in patients with chronic kidney disease. Arterial spin labeling MRI is able to detect early hemodynamic changes in diabetic nephropathy. Kidney volume to GFR ratio predicts functional improvement after revascularization in atheromatous renal artery stenosis. Effects of losartan on renal and cardiovascular outcomes in patients with type 2 diabetes and nephropathy.
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Clinical utility of biomarkers of AKI in cardiac surgery and critical illness. Urinary peptide-based classifier CKD towards clinical application in chronic kidney disease. The importance of total kidney volume in evaluating progression of polycystic kidney disease. For commercial re-use, please contact journals. Issue Section:. Download all figures. Comments 0.
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Advance article alerts. Article activity alert. Receive exclusive offers and updates from Oxford Academic. Related articles in Web of Science Google Scholar. Related articles in PubMed Short-interval intracortical inhibition is decreased in restless legs syndrome across a range of severity. The diagnosis of various renal diseases such as chronic renal failure, renal artery stenosis, and ureteral obstruction can benefit from measuring the diffusion characteristics of the kidney [ 4 ]. Diffusion-weighted DW MR imaging of the kidneys is able to provide information on renal function and can be suggestive of the presence and degree of obstruction or inflammation.
The apparent diffusion coefficient ADC , a quantitative parameter calculated from the DW MR images, combines the effects of capillary perfusion and water diffusion in the extracellular extravascular space. Thus, DW MR imaging provides information on perfusion and diffusion simultaneously [ 5 ]. Hydration is an important factor to increase global ADC values [ 6 ], whereas renal artery stenosis or ureteral obstruction decrease those values [ 7 , 8 ].
In case of acute or chronic renal failure, the cortical and medullary ADC values are significantly decreased when compared with normal kidneys and the cortical value decrease seems to be well correlated with serum creatinine levels [ 8 ]. In a rat study, the intravenous administration of the high-viscosity iodinated contrast agent iodixanol was found to significantly decrease the ADC, this effect occurring earlier in the cortex and lasting less than in the medulla [ 9 ]. MRI is able to non-invasively provide a functional assessment of the kidney, such as glomerular filtration rate GFR , tubular concentration and transit, blood volume and perfusion, diffusion, and oxygenation.
For this purpose, T1 of blood was measured in the infrarenal inferior vena cava and renal veins prior and after injection of the contrast agent. A significant linear correlation was found between extraction fraction measured with MRI vs. Grenier et al. There was a good correlation between MR and nuclear renography, although captopril-induced changes were not seen in all patients shown to have the disease. Renal perfusion is one of the most common useful methods to detect renal impairment.
It can be evaluated with contrast agents, based on tracer kinetic methods such as scintigraphy [ 13 ]. Fast acquisition techniques such as T1-weighted gradient echo or echo planar sequences allow sufficient temporal resolution to monitor intrarenal signal changes during the first pass of the agent through the kidneys fig.
Images obtained at the arterial a , venous b , tubular c , and excretory d phase. Currently-available non-specific contrast agents have been used to investigate renal perfusion in ARF and some studies have shown a loss of CMD that was suggested to reflect changing differential perfusion patterns between the cortex and medulla in such pathological states [ 15 ].
There is an obvious need for new, validated techniques for a better and more reliable evaluation of renal perfusion alterations during ARF. Blood pool contrast agents may demonstrate some usefulness in this setting. These Gd compounds accumulate in the proximal tubules after early glomerular filtration. They act as positive contrast agents. Animal studies using 3D acquisitions with microMR devices showed various level concentrations between cortex, outer and inner medulla that disappear in case of acute as well as chronic renal injury.
The main characteristics of dendrimer-enhanced MRI make it as a contrast medium specific of proximal tubule dysfunction [ 1 , 16 ]. Unlike ferromagnetic substances and because of their size, superparamagnetic agents have no magnetic properties outside an external magnetic field. These nanoparticles have in common their specific uptake by macrophages, explaining, even if they are not entirely captured by liver and spleen, why they are widely evaluated as MRI markers for diagnosis of inflammatory and degenerative disorders associated with high macrophage phagocytic activity.
At low concentration, they act as positive contrast agents such as gadolinium , but at higher concentrations they result in a negative enhancement. It is currently agreed that two main categories of superparamagnetic agents must be distinguished: 1 SPIOs i. They consequently remain in the blood circulation for a relatively long time. Because of their long blood half-life and T1-shortening effect, these agents have been evaluated as blood pool agents for indications such as measurement of cerebral perfusion [ 17 ], myocardial or renal perfusion [ 18 ], angiography [ 19 ], or detection of vascular hepatic lesions [ 20 ].
These compounds are classically referred to as slow-clearance blood pool agents. Their renal clearance is consequently much lower than the normal GFR. These blood pool characteristics provide a much longer time window for data acquisition during radiological procedures, with little loss of intravascular signal intensity. In a model of medullary ischemia induced by glycerol, the decrease in blood volume was clearly demonstrated within the outer medulla [ 18 , 21 ]. In radiocontrast nephrotoxicity, the degree of renal enhancement after iron oxide injection seems to be correlated with the reversibility of lesions [ 22 , 23 ].
Intravenous injection of puromycin aminonucleoside in the rat is classically regarded as a good model of nephrotic syndrome secondary to glomerular epithelial cell lesions associated with glomerular and tubulointerstitial infiltration by macrophages [ 24 ]. This effect was correlated with the presence of macrophages containing iron oxide nanoparticles at histology [ 25 ].
Interestingly, the same USPIO was also found to decrease signal intensity in the cortex in a model of nephritic nephropathy by injection of sheep anti-rat glomerular basement membrane serum. Conversely, in a rat model of obstructive nephropathy, which is known to induce diffuse interstitial lesions with macrophage infiltration in all kidney structures, the USPIO induced a decrease in signal intensity in all compartments [ 26 ].
Renal allograft rejection is associated with a massive inflammatory infiltration [ 27 ]. In a rat renal allograft model, USPIO, when injected on the fourth day following transplantation, induced a decrease in MR signal intensity at 24 h in some rejecting allografts whereas isografts and allografts with immunosuppressive treatment were not associated with signal reduction [ 28 ]. Promising results were obtained in a preliminary clinical study performed in 7 patients with suspected proliferative glomerulonephritis and in 5 patients with suspected renal graft rejection imaged 72 h following injection of ferumoxtran From this clinical study, it was concluded that USPIO-enhanced MRI may allow acute tubular necrosis to be distinguished from other acute nephropathies in native and transplanted kidneys and may also allow active proliferative nephropathies to be differentiated from chronic ones [ 29 ].
Of course, such preliminary clinical data obtained in a small number of patients need to be confirmed by other studies. A good agreement between renal graft perfusion and histopathological changes associated with graft rejection suggests that USPIO-enhanced dynamic MRI may be used to evaluate acute allograft rejection [ 30 ].
Iodinated contrast agents can be nephrotoxic in at-risk patients by inducing medullary hypoxia [ 31 ]. Intravenous injection of USPIO has been used in a validated rat model of contrast-induced nephropathy to assess renal lesions induced by the iodinated contrast agent as well as their reversibility fig. Interestingly, the degree of renal enhancement after iron oxide injection seemed to be correlated with the reversibility of lesions [ 22 , 23 ]. The same images obtained in a rat with radiocontrast-induced nephropathy show a lack of decreased enhancement b.
At the present time, the vast majority of studies reported in the literature on USPIOs have been done on animals and few data are available on its real usefulness in clinical practice. The main issues of MRI in the near future will be to provide an accurate diagnosis of the underlying causes of acute or chronic renal failure, thus avoiding renal biopsy.
Compared to this invasive procedure that harvests only samples within a single area of the kidney, MRI can provide repeatedly a complete view of both kidneys and monitor non-invasively progression or regression of diseases. MRI already allows non-invasive and non-nephrotoxic evaluation of renal or non-renal arteries.
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MR angiography or venography is useful in the uremic patients who bear the highest risk of radiocontrast nephrotoxicity. During pregnancy, MRI may be used to analyze fetal uropathy. Obstructive uropathy is a common etiology of renal failure in adults; in this setting, conventional IVU may be replaced by magnetic resonance urography to demonstrate ureter calculi or tumors.
The CRISP cohort study has established the value of MRI in determining the respective volumes of kidney parenchyma and cysts in patients with polycystic kidney disease; interestingly, these parameters were significantly and inversely correlated with renal function parameters as assessed with creatinine value and MRI-based measures of renal blood flow and GFR [ 32 ].
In patients with familial medullary cystic disease, or with lithium-induced chronic nephropathy, MRI allows visualization of renal medullary cysts as small as 1—3 mm [ 33 , 34 ]. Diffusion-weighted imaging seems to have great potential in the renal consequences of renal artery stenosis, a condition in which the ADC is decreased.
However, further observational studies are needed since this sign does not seem specific; it is also encountered in various causes of renal failure interstitial fibrosis, tubular atrophy and glomerular disease as well as in inflammatory conditions such as pyelonephritis [ 6 ].