Risk factors for developing gadolinium-induced nephrogenic systemic fibrosis

An AND Logic Gate for Magnetic-Resonance-Imaging-Guided Ferroptosis Therapy of Tumors

To improve the magnetic resonance imaging (MRI) efficiency and ferroptosis therapy efficacy of exceedingly small magnetic iron oxide nanoparticles (IO, <5 nm) for tumors via enhancing the sensitivity of tumor microenvironment (TME) responsiveness, inspired by molecular logic gates, a self-assembled IO with an AND logic gate function is designed and constructed. Typically, cystamine (CA) is conjugated onto the end of poly(2-methylthio-ethanol methacrylate) (PMEMA) to generate PMEMA-CA. The PMEMA-CA is grafted onto the surface of brequinar (BQR)-loaded IO to form IO-BQR@PMEMA. The self-assembled IO-BQR@PMEMA (SA-IO-BQR@PMEMA) is obtained due to the hydrophobicity of PMEMA. The carbon-sulfur single bond of PMEMA-CA can be oxidized by reactive oxygen species (ROS) in the TME to a thio-oxygen double bond, resulting in the conversion from being hydrophobic to hydrophilic. The disulfide bond of PMEMA-CA can be broken by the glutathione (GSH) in the TME, leading to the shedding of PMEMA from the IO surface. Under the dual actions of ROS and GSH in TME (i.e., AND logic gate), SA-IO-BQR@PMEMA can be disassembled to release IO, Fe2+/3+ , and BQR. In vitro and in vivo results demonstrate the AND logic gate function and mechanism, the high T1 MRI performance and exceptional ferroptosis therapy efficacy for tumors, and the excellent biosafety of SA-IO-BQR@PMEMA.

A tumor microenvironment dual responsive contrast agent for contrary contrast-magnetic resonance imaging and specific chemotherapy of tumors

Development of magnetic resonance imaging (MRI) contrast agents (CAs) is still one of the research hotspots due to the inherent limitations of T₁- or T₂-weighted CAs and T₁/T₂ dual-mode CAs. To dramatically enhance the MRI contrast between tumors and normal tissues, we propose a new concept of contrary contrast-MRI (CC-MRI), whose specific definition is that CC-MRI CAs present a positive or negative signal at normal tissues, but show contrary signals at diseased tissues. To realize CC-MRI of tumors, we designed and developed a tumor microenvironment (TME) dual responsive CA (i.e., SA-FeGdNP-DOX@mPEG), which is almost not responsive under normal physiological conditions, but highly responsive to the acidic and reductive TME. Our SA-FeGdNP-DOX@mPEG shows a negative MRI signal under normal physiological conditions due to the high r₂ value (336.9 mM^-1 s^-1) and high r₂/r₁ ratio (18.4), but switches to a positive MRI signal in the TME because of the high r₁ value (20.32 mM^-1 s^-1) and low r₂/r₁ ratio (7.2). Our TME dual responsive SA-FeGdNP-DOX@mPEG significantly enhanced the contrast of MR images between tumors and livers, and the ΔSNR difference reached 501%. In addition, our SA-FeGdNP-DOX2@mPEG2 with tumor targetability and controlled DOX release responding to the TME was also used for tumor-specific chemotherapy with reduced side effects.

Nephrogenic systemic fibrosis: A frivolous entity

Gadolinium-based contrast agents (GBCAs) used in magnetic resonance imaging are vital in providing enhanced quality images, essential for diagnosis and treatment. Nephrogenic systemic fibrosis (NSF) with GBCAs has been a deterrent for the physician and has led to avoidance of these agents in patients with impaired kidney function. NSF is a progressive debilitating multisystem condition described classically in patients with renal insufficiency exposed to gadolinium contrast media. It is characterized by an induration and hardening of the skin. NSF is described to first involve the extremities and can imperceptibly involve internal organs. Lack of therapeutic interventions to treat NSF makes it more challenging and warrants deep insight into the pathogenesis, risk factors and treatment strategies.

Maltodextrin-Conjugated Gd-Based MRI Contrast Agents for Specific Diagnosis of Bacterial Infections

Bacterial infections are one of the most serious health risks worldwide, and their rapid diagnosis remains a major challenge in clinic. To enhance the relaxivity and bacterial specificity of magnetic resonance imaging (MRI) contrast agents, here, a kind of gadolinium-based nanoparticles (NPs) of impressive biocompatibility is constructed as a contrast agent for maltodextrin-mediated bacteria-targeted diagnosis. To realize this, positively charged ultrasmall gadolinium oxide (Gd₂O₃, 2-3 nm) NPs are embedded in mesoporous silica NPs (MSN) with pore size around 6.38 nm. The resulting Gd₂O₃@MSN exhibits enhanced r₁ value and T₁-weighted MRI performance. Interestingly, upon conjugation of Gd₂O₃@MSN with maltodextrin to produce Gd₂O₃@MSN-Malt NPs, a remarkable decrease in internalization by osteosarcoma cells, alongside an increased adsorption toward E. coli and S. aureus, is achieved. It is therefore conceivable that the bacteria-targeted Gd₂O₃@MSN-Malt might be a promising MRI contrast agent for effective discrimination of bacterial infections from tumor.

Improving diagnostic performance of differentiating ocular adnexal lymphoma and idiopathic orbital inflammation using intravoxel incoherent motion diffusion-weighted MRI

PURPOSE

To investigate the utility of intravoxel incoherent motion diffusion-weighted MRI (IVIM-DWI) derived diffusion and perfusion parameters in differentiating ocular adnexal lymphoma (OAL) from idiopathic orbital inflammation (IOI), and to assess whether IVIM-DWI provides improved diagnostic performance for the distinction.

METHOD

Twenty-one patients with OAL and 24 patients with IOI underwent IVIM-DWI. Apparent diffusion coefficient (ADC) and IVIM-DWI parameters including true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) were measured in lesions by two independent radiologists. The MRI parameter differences between OAL and IOI were tested using two-sample t-test. The receiver operating characteristic (ROC) analysis curves were used to determine the diagnostic performance of significant parameters for differentiation between OAL and IOI.

RESULTS

The ADC, D, and f were lower in OAL than those in IOI (ADC = 0.78 ± 0.12 vs. 0.99 ± 0.16 × 10^-3 mm²/s, P < 0.001; D = 0.34 ± 0.15 vs. 0.76 ± 0.25 × 10^-3 mm²/s, P < 0.001; f = 0.31 ± 0.06 vs. 0.41 ± 0.08 × 100 %, P < 0.001). There was no significant difference in D* between OAL and IOI (P = 0.235). The optimal cut-off values of ADC, D, and f in differentiating OAL from IOI were 0.83 × 10^-3 mm²/s, 0.56 × 10^-3 mm²/s, and 0.36 × 100 %, respectively. No significant differences were found in areas under the curve (AUCs) among ADC, D and f (all P > 0.05). The combination of D and f provided significantly higher AUC than ADC (AUC = 0.984 vs. 0.838, Z = 2.128, P = 0.033), and had higher sensitivity of 95.24 %, specificity of 95.83 %, and accuracy of 95.56 %.

CONCLUSIONS

IVIM-DWI is valuable in differentiating OAL from IOI, and D combined f can improve the performance of differential diagnosis.

[T1-weighted magnetic resonance imaging contrast agents and their theranostic nanoprobes]

Magnetic resonance imaging (MRI) is an important imaging modality for clinical disease diagnosis, and nearly 50% of clinical MRI examinations require contrast agents to enhance the diagnostic sensitivity. This review provides a summary of the major MRI contrast agents and their classification, and the advantages and limits of the commercially available MRI contrast agents, and elaborates on the exceedingly small magnetic iron oxide nanoparticles (ES-MIONs), dotted core-shell iron and gadolinium hybrid nanoparticles (FeGd-HN) and exceedingly small gadolinium oxide nanoparticles (ES-GON). These nanoparticles can greatly improve the efficiency of T₁-weighted MRI due to their high r₁ value and low r₂/r₁ ratio, and are expected to be translated into clinical contrast agents for T₁-weighted MRI. The authors also review the diagnostic and therapeutic integration system that combines MRI contrast agents with various tumor therapies, such as MRI-guided ferroptosis therapy, radiosensitization therapy, and photothermal therapy, which allow efficient treatment as well as real-time monitoring of tumors and serve as potential cancer therapy strategies. The possible future research directions in the field of MRI-based multifunctional diagnostic and therapeutic formulations are also discussed.

Characterization of Malignant Portal Vein Thrombosis with Contrast-Enhanced Ultrasonography

We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ = 0.903 (p < 0.0001), sensitivity = 91% and specificity = 100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease.

Diagnostic performances of intravoxel incoherent motion and conventional diffusion-weighted imaging in the differential diagnosis of benign and malignant portal vein thrombus

PURPOSE

To evaluate the diagnostic accuracy of intravoxel incoherent motion (IVIM) and diffusion-weighted imaging (DWI) parameters in the differential diagnosis of portal vein thrombus (PVT).

METHODOLOGY

Thirty-five patients with PVT were enrolled in this retrospective study. Precontrast axial in-phase and out-of-phase T1-weighted (W) turbo field echo (TFE), axial and coronal T2-W single-shot turbo spin echo, IVIM with b values between 0 and 1300 s/mm² and conventional DWI with b factors of 50, 400, and 800 s/mm² with single-shot echo-planar imaging, and postcontrast dynamic T1-W volumetric interpolated breath-hold examination images obtained with 1.5 T MR unit were evaluated. For quantitative analysis of conventional DWI, an ADC map was reconstructed from conventional DWI using all b values. For quantitative evaluation of IVIM, the SI was calculated from each b value. A specific software program was applied to calculate D (true diffusion coefficient), D* (pseudodiffusion coefficient associated with blood flow), and f (perfusion fraction). The differentiation between benign and malignant PVT was based on the criteria outlined in the study by Catalano et al. (Radiology 254:154-162, 2010).

RESULTS

The ADC values of the malignant PVT were significantly lower than those of benign PVTs (p = 0.005). Malignant PVTs had a tendency to show higher f values in comparison with benign PVTs without statistical significance (p = 0.750). The best discriminative parameter was ADC values, which demonstrated a sensitivity of 80.0% and a specificity of 72.7% with cut-off value of 1.00 × 10^-3 mm²/s.

CONCLUSION

ADC values might be more superior tool than IVIM parameters in differentiation between malignant and benign PVT.

Advanced imaging modalities to detect cardiotoxicity

Recent advances in cancer treatments have significantly improved survival rates, reemphasizing the focus on reducing the potential complications associated with some therapies. Cardiovascular disease associated with chemotherapies is a major cause of morbidity and mortality in cancer survivors. Early detection of cardiotoxicity improves cardiac outcomes among cancer patients. The review will focus on imaging modalities used to assess cardiotoxicity - the cardiovascular consequences of chemotherapies. The review will discuss the benefits and limitations associated with each technique, as well as the guidelines available to help identify at risk patients. We will discuss novel techniques that may help detect earlier signs of cardiotoxicity, directing management that may improve clinical outcomes.

Acute Kidney Injury in Patients with Cirrhosis

Acute kidney injury (AKI) occurs commonly in patients with advanced cirrhosis and negatively impacts pre- and post-transplant outcomes. Physiologic changes that occur in patients with decompensated cirrhosis with ascites, place these patients at high risk of AKI. The most common causes of AKI in cirrhosis include prerenal injury, acute tubular necrosis (ATN), and the hepatorenal syndrome (HRS), accounting for more than 80% of AKI in this population. Distinguishing between these causes is particularly important for prognostication and treatment. Treatment of Type 1 HRS with vasoconstrictors and albumin improves short term survival and renal function in some patients while awaiting liver transplantation. Patients with HRS who fail to respond to medical therapy or those with severe renal failure of other etiology may require renal replacement therapy. Simultaneous liver kidney transplant (SLK) is needed in many of these patients to improve their post-transplant outcomes. However, the criteria to select patients who would benefit from SLK transplantation are based on consensus and lack strong evidence to support them. In this regard, novel serum and/or urinary biomarkers such as neutrophil gelatinase-associated lipocalin, interleukins-6 and 18, kidney injury molecule-1, fatty acid binding protein, and endothelin-1 are emerging with a potential for accurately differentiating common causes of AKI. Prospective studies are needed on the use of these biomarkers to predict accurately renal function recovery after liver transplantation alone in order to optimize personalized use of SLK.

Differentiating malignant from benign thrombosis in hepatocellular carcinoma: contrast-enhanced ultrasound

BACKGROUND

To determine the accuracy of contrast-enhanced ultrasonography (CEUS) in differentiating malignant and benign venous thrombosis complicating hepatocellular carcinoma (HCC).

METHODS

Fifty patients (M:F = 41:9; age range 46-83 years) with HCC and venous thrombosis [portal vein (PV) in 45 and hepatic vein (HV) in 5] detected on CT or MR scan were evaluated with CEUS. Reference standard of malignant and benign thrombosis was based on serial clinicoradiologic follow-up (n = 43) or pathology (n = 7). Two independent, blinded readers retrospectively recorded the enhancement features of the venous thrombosis and diagnosed as benign or malignant thrombosis with a five-point confidence scale. Receiver operating characteristic (ROC) curves were calculated to determine the diagnostic performance of CEUS in differentiating malignant from benign thrombosis. Confidence level ratings were also used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the diagnosis of malignant thrombosis. Inter-reader agreement was calculated using κ statistics in each assessed finding. Gray scale and Doppler characteristics of primary tumor and thrombosis were also assessed.

RESULTS

Of the 50 patients, 37 were malignant (33 with PV thrombosis and 4 with HV thrombosis) and 13 were benign (12 with PV thrombosis and 1 with HV thrombosis). In ROC curve analysis for differentiating malignant from benign thrombosis, Az was 0.947 (CI 0.841-0.991) for reader 1 and 0.958 (CI 0.861-0.995) for reader 2 with excellent inter-reader agreement (κ = 0.86). When the confidence level ratings of 1 or 2 were considered malignant thrombosis, the sensitivity, specificity, PPV, and NPV in differentiating malignant from benign thrombosis were 100%, 83%, 95%, and 100% for reader 1 and 100%, 92%, 97%, and 100% for reader 2.

CONCLUSION

CEUS is useful to differentiate malignant and benign venous thrombosis associated with HCC with high diagnostic accuracy.

Engineering Gd-loaded nanoparticles to enhance MRI sensitivity via T(1) shortening

Magnetic resonance imaging (MRI) is a noninvasive imaging technique capable of obtaining high-resolution anatomical images of the body. Major drawbacks of MRI are the low contrast agent sensitivity and inability to distinguish healthy tissue from diseased tissue, making early detection challenging. To address this technological hurdle, paramagnetic contrast agents have been developed to increase the longitudinal relaxivity, leading to an increased signal-to-noise ratio. This review focuses on methods and principles that enabled the design and engineering of nanoparticles to deliver contrast agents with enhanced ionic relaxivities. Different engineering strategies and nanoparticle platforms will be compared in terms of their manufacturability, biocompatibility properties, and their overall potential to make an impact in clinical MR imaging.

Correlation of apparent diffusion coefficient measured by diffusion-weighted MRI and clinicopathologic features in pancreatic cancer patients

BACKGROUND/PURPOSE

The aim of this study was to evaluate the clinical usefulness of diffusion-weighted magnetic resonance imaging (DWI) in patients with pancreatic cancer by comparing the apparent diffusion coefficient (ADC) value with clinicopathologic features.

METHODS

Twenty-two consecutive patients (12 men, 10 women; mean age 64.4 years) with pancreatic cancer underwent DWI before surgery. We retrospectively investigated the correlations between tumor ADC value and clinicopathologic features.

RESULTS

Apparent diffusion coefficient value was significantly lower for pancreatic cancer than for noncancerous tissue (P < 0.001). Receiver operating characteristic analysis yielded an optimal ADC cutoff value of 1.21 × 10(-3) mm(2)/s to distinguish pancreatic cancer from noncancerous tissue. There was a significant negative correlation between ADC value and tumor size (r = -0.59, P = 0.004) and between ADC value and number of metastatic lymph nodes (r = -0.56, P = 0.007). Tumors with low ADC value had a significant tendency to show high portal venous system invasion (P = 0.02) and extrapancreatic nerve plexus invasion (P = 0.01).

CONCLUSIONS

Apparent diffusion coefficient value appears to be a promising parameter for detecting pancreatic cancer and evaluating the degree of malignancy of pancreatic cancer.

Understanding nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is a rare and a debilitating disease noted uncommonly in patients with impaired renal function when exposed to low-stability gadolinium-based contrast agents (Gd-CAs). According to experimental studies, cytokines released by the stimulation of effector cells such as skin macrophages and peripheral blood monocytes activate circulating fibroblasts which play a major role in the development of NSF lesions. The presence of permissive factors, presumably, provides an environment conducive to facilitate the process of fibrosis. Multiple treatment modalities have been tried with variable success rates. More research is necessary to elucidate the underlying pathophysiological mechanisms which could potentially target the initial steps of fibrosis in these patients. This paper attempts to collate the inferences from the in vivo and in vitro experiments to the clinical observations to understand the pathogenesis of NSF. Schematic representations of receptor-mediated molecular pathways of activation of macrophages and fibroblasts by gadolinium and the final pathway to fibrosis are incorporated in the discussion.

Myocardial Perfusion Reserve Assessed by T2-Prepared Steady-State Free Precession Blood Oxygen Level–Dependent Magnetic Resonance Imaging in Comparison to Fractional Flow Reserve

Background—

Blood oxygen level–dependent (BOLD) cardiac magnetic resonance imaging (CMR) has been shown to be able to detect myocardial perfusion differences. However, validation of BOLD CMR against fractional flow reserve (FFR) is lacking. The aim of our study was to analyze the potential diagnostic accuracy of BOLD CMR in comparison to invasively measured FFR, which served as gold standard for a hemodynamic significant coronary lesion.

Methods and Results—

BOLD image was performed at rest and during adenosine infusion in a 1.5-T CMR scanner. Thirty-six patients were analyzed for relative BOLD signal intensity increase according to the 16-segment model. Invasive FFR measurements were performed in the 3 major coronary arteries during adenosine infusion in all patients. An FFR≤0.8 was regarded to indicate a significant coronary lesion. Relative BOLD signal intensity increase was significantly lower in myocardial segments supplied by coronary arteries with an FFR≤0.8 compared with segments with an FFR>0.8 (1.1±0.2 versus 1.5±0.2; P <0.0001). Sensitivity and specificity yielded 88.2% and 89.5%, respectively.

Conclusions—

CMR BOLD imaging reliably detects hemodynamic significant coronary artery disease and is, thus, an alternative to contrast–enhanced perfusion studies.

Hyperphosphataemia sensitizes renally impaired rats to the profibrotic effects of gadodiamide

BACKGROUND AND PURPOSE

Hyperphosphataemia is common in patients with nephrogenic systemic fibrosis (NSF). NSF has been linked to administration of gadolinium (Gd) chelates (GCs) and elevated serum phosphate levels accelerate the release of Gd from linear, non-ionic GCs but not macrocyclic GCs. Hence, we determined whether hyperphosphataemia is a cofactor or risk factor for NSF by investigating the role of hyperphosphataemia in renally impaired rats.

EXPERIMENTAL APPROACH

Firstly, the clinical, pathological and bioanalytical consequences of hyperphosphataemia were investigated in subtotal nephrectomized (SNx) Wistar rats following i.v. administration of the non-ionic, linear GC gadodiamide (5 × 2.5 mmol·kg(-1) ·day(-1) ). Secondly, the effects of several GCs were compared in these high-phosphate diet fed rats. Total Gd concentration in skin, femur and plasma was measured by inductively coupled plasma mass spectrometry (ICP-MS) and free Gd(3+) in plasma by liquid chromatography coupled to ICP-MS. Relaxometry was used to measure dissociated Gd in skin and bone.

KEY RESULTS

Four out of seven SNx rats fed a high-phosphate diet administered gadodiamide developed macroscopic and microscopic (fibrotic and inflammatory) skin lesions, whereas no skin lesions were observed in SNx rats treated with saline, the other GCs and free ligands or in the normal diet, gadodiamide-treated group. Unlike the other molecules, gadodiamide gradually increased the r(1) relaxivity value, consistent with its in vivo dissociation and release of soluble Gd.

CONCLUSIONS AND IMPLICATIONS

Hyperphosphataemia sensitizes renally impaired rats to the profibrotic effects of gadodiamide. Unlike the other GCs investigated, gadodiamide gradually dissociates in vivo. Our data confirm that hyperphosphataemia is a risk factor for NSF.

Nephrogenic systemic fibrosis: review of 370 biopsy-confirmed cases

Discovery of an association between gadolinium-based contrast agents (GBCAs) and nephrogenic systemic fibrosis (NSF) has led to less use of GBCA-enhanced magnetic resonance imaging in dialysis patients and patients with severe renal failure at risk of NSF, and the virtual elimination of new cases of NSF. But shifting patients with renal failure to alternative imaging methods may subject patients to other risks (e.g., ionizing radiation or iodinated contrast). This review paper examines 370 NSF cases reported in 98 articles to analyze NSF risk factors. Eliminating multiple risk factors by limiting GBCA dose to a maximum of 0.1 mmol/kg, dialyzing patients undergoing dialysis quickly following GBCA administration, delaying GBCA in acute renal failure until after renal function returns or dialysis is initiated, and avoiding nonionic linear GBCA in patients with renal failure especially when there are proinflammatory conditions may substantially reduce the risk of NSF.

Nephrogenic systemic fibrosis: review of 408 biopsy-confirmed cases

Nephrogenic systemic fibrosis (NSF) has now been virtually eliminated by the discovery of its association with gadolinium-based contrast agents (GBCAs) and the consequent reduced use of GBCA-enhanced magnetic resonance imaging (MRI) in severe renal failure patients. This review of 408 biopsy-confirmed cases shows how to minimize NSF risk when performing GBCA-enhanced MRI or magnetic resonance angiography. The absence of any NSF cases in patients less than 8 years old or greater than 87 years old suggests that infants and elderly patients are already protected. Limiting GBCA dose to a maximum of 0.1 mMol/kg, dialyzing dialysis patients quickly following GBCA administration, delaying administration of GBCA in acute renal failure until after renal function returns or dialysis is initiated, and avoiding nonionic linear GBCA in renal failure patients, especially when there are pro-inflammatory conditions, appear to have reduced NSF risk to the point where safe GBCA-enhanced MRI is possible in most patients.

Correlation between arterial blood volume obtained by arterial spin labelling and cerebral blood volume in intracranial tumours

OBJECTIVE

To compare measurements of the arterial blood volume (aBV), a perfusion parameter calculated from arterial spin labelling (ASL), and cerebral blood volume (CBV), calculated from dynamic susceptibility contrast (DSC) MRI. In the clinic, CBV is used for grading of intracranial tumours.

MATERIALS AND METHODS

Estimates of aBV from the model-free ASL technique quantitative STAR labelling of arterial regions (QUASAR) experiment and of DSC-CBV were obtained at 3T in ten patients with eleven tumours (three grade III gliomas, four glioblastomas and four meningiomas, two in one patient). Parametric values of aBV and CBV were determined in the tumour as well as in normal grey matter (GM), and tumour-to-GM aBV and CBV ratios were calculated.

RESULTS

In a 4-pixel ROI representing maximal tumour values, the coefficient of determination R (2) was 0.61 for the comparison of ASL-based aBV tumour-to-GM ratios and DSC-MRI-based CBV tumour-to-GM ratios and 0.29 for the comparison of parametric values of ASL-aBV and DSC-CBV, under the assumption of proportionality. Both aBV and CBV showed a non-significant tendency to increase when going from grade III gliomas to glioblastomas to meningiomas.

CONCLUSION

These results suggest that measurement of aBV is a potential tool for non-invasive assessment of blood volume in intracranial tumours.

Risk factors for NSF: a literature review

Emerging evidence linking gadolinium-based contrast agents (GBCAs) to nephrogenic systemic fibrosis (NSF) has changed medical practice patterns toward forgoing GBCA-enhanced magnetic resonance imaging (MRI) or substituting other imaging methods, which are potentially less accurate and often radiation-based. This shift has been based on reports of high NSF incidence at sites where a confluence of risk factors occurred in patients with severe renal dysfunction. This review article explores the factors that affect NSF risk, compares risks of alternative imaging procedures, and demonstrates how risk can be managed by careful selection of GBCA dose, timing of injection with respect to dialysis, and other factors. Nearly half of NSF cases are a milder form that does not cause contractures or reduce mobility. It appears that eliminating even a single risk factor can reduce NSF incidence/risk at least 10-fold. Elimination of multiple risk factors by using single-dose GBCA, dialyzing dialysis patients quickly following GBCA administration, avoiding GBCA in acute renal failure while serum creatinine is rising, and avoiding nonionic linear GBCA in renal failure patients may reduce NSF risk more than a thousand-fold, thereby allowing safe GBCA-enhanced MRI in virtually all patients. J. Magn. Reson. Imaging 2009;30:1298-1308. (c) 2009 Wiley-Liss, Inc.

Differentiation of malignant thrombus from bland thrombus of the portal vein in patients with hepatocellular carcinoma: application of diffusion-weighted MR imaging

PURPOSE

To investigate the utility of diffusion-weighted (DW) imaging in distinguishing bland thrombus from neoplastic thrombus in the portal vein in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

In this retrospective institutional review board-approved HIPAA-complaint study, the imaging results in 25 patients (16 men [average age, 62.3 years; range, 35-75 years] and nine women [average age, 58.4 years; range, 32-69 years]; overall average age, 60.1 years; range, 32-75 years) with HCC and portal vein thrombosis who were examined with both contrast material-enhanced computed tomography (CT) and 1.5-T magnetic resonance (MR) imaging were reviewed. Axial echo-planar two-dimensional DW imaging was performed by using b values of 50, 400, and 800 sec/mm(2). A thrombus was considered neoplastic if it expanded the vessel or enhanced on the dynamic CT and MR images; otherwise it was considered bland. The signal intensity (SI) of the thrombus and HCC lesions in the same patients was compared on DW images. The results were evaluated by using the Fisher exact test. The apparent diffusion coefficients (ADCs) of HCC and thrombus were used to compute the ratio of the ADC of the thrombus to the ADC of the tumor.

RESULTS

On DW images, 15 of 19 neoplastic thrombi demonstrated same SI and four showed lower SI than the primary HCC. Each of the six bland thrombi had lower SI than the primary HCC (P < .001). The mean ADC of HCC and thrombus in the neoplastic thrombus group was 0.87 x 10(-3) mm(2)/sec and 0.88 x 10(-3) mm(2)/sec, respectively (P = .45). The ADC of the bland thrombus was 2.89 x 10(-3) mm(2)/sec, significantly higher than the ADC of the HCC (1.0 x 10(-3) mm(2)/sec, P < .0003). The ratio of the ADC of the thrombus to the ADC of the tumor in the bland thrombus group was 2.9 compared with 0.998 in the neoplastic group (P = .0003).

CONCLUSION

DW imaging enables discrimination between bland and neoplastic portal vein thrombi when the ratio of the ADC of the thrombus to the ADC of HCC was lower than 2 and when the thrombi showed similar SI as the primary HCC when qualitative analysis was performed.

Toxicity of MRI and CT contrast agents

Anatomical and physiological imaging using CT and MRI are playing a critical role in patients' diagnosis, disease characterization and treatment planning. CT- and MRI-based protocols increasingly require an injection of iodinated CT and gadolinium (Gd)-based MRI contrast media. Although routinely used in clinical practice, iodinated and to a less extent Gd-based contrast media possess side effects: life-threatening contrast-induced nephropathy (CIN) is associated with CT and nephrogenic systemic fibrosis (NSF) with MRI contrast agents. CIN is defined as an acute decline in renal functions (serum creatinine increase > 0.5 mg/dl) after administration of iodinated contrast media. Patients with moderate-to-severe chronic kidney disease are considered the highest risk group for development of CIN. CIN is more common with ionic high-osmolar contrast CT media. NSF is a rare condition characterized by the formation of connective tissue in the skin and systemically in the lung, liver, heart and kidney. Patients with end stage kidney disease, acute kidney injury and stage 4-5 chronic kidney disease are at a high risk for NSF. The nonionic linear Gd-chelates are associated with the highest risk of NSF. This review summarizes the incidence, symptoms, safety profile of various CT and MRI contrast agents based on their physiochemical properties.

Nephrogenic systemic fibrosis and its impact on abdominal imaging

The objective of this article is to review the current knowledge about nephrogenic systemic fibrosis (NSF) and how to prevent it. More than 300 cases of NSF in patients with severe chronic renal insufficiency or acute renal failure or in patients undergoing dialysis have been reported in the peer-reviewed literature, with an overwhelming majority occurring within weeks to months after injection of a gadolinium-based contrast agent (GBCA). Because administration of a high dose of a GBCA is a primary risk factor and because most high-dose magnetic resonance (MR) imaging applications involve abdominal imaging (eg, liver and abdominal MR angiography), NSF cases have been associated with abdominal MR imaging. Additional major risk factors for developing NSF include proinflammatory conditions, failure to perform dialysis promptly after GBCA administration, use of nonionic linear contrast agents, hyperphosphatemia, and younger age. Recent recommendations to use GBCAs with caution in patients with acute renal failure, patients receiving dialysis, or patients with an estimated glomerular filtration rate of less than 30 mL/min have resulted in virtually no new NSF cases being reported with onset in 2008 or 2009 in spite of a high level of awareness about this entity. In conclusion, NSF has been virtually eliminated by using caution in administering GBCAs to patients known to have severe or acute renal failure. In these patients, avoid high doses; and for patients undergoing dialysis, schedule MR imaging to occur just before a dialysis session to ensure rapid elimination of gadolinium.

Nephrogenic systemic fibrosis: an unusual scleroderma-like fibrosing disorder

Nephrogenic systemic fibrosis (NSF) is a fibrosing disorder, recently described in patients with advanced chronic kidney disease, usually after exposure to gadolinium (Gd)-based contrast agents, characterized by progressive fibrotic involvement mainly of the skin. At clinical examination, the cutaneous findings of NSF may partly resemble those of systemic sclerosis. However, the different topographic distribution of the skin thickening and hardening, usually involving the limbs and trunk, whilst sparing the face, the lack of serologic abnormalities and the distinctive histopathological findings allow this new disease entity to be distinguished from systemic sclerosis and other scleroderma-like fibrosing disorders (scleromyxedema, scleredema, eosinophilic fasciitis, etc.). Herein, we describe what, to best of our knowledge, is the first, biopsy proven, Italian case of NSF, which highlights the issue of the differential diagnosis between NSF and scleroderma-like fibrosing disorders.

Features of nephrogenic systemic fibrosis on radiology examinations

OBJECTIVE

The objective of this article is to illustrate the spectrum of imaging findings with photographic and histopathologic correlation in patients with biopsy-proven nephrogenic systemic fibrosis (NSF).

CONCLUSION

Features of NSF may be evident on the patient's skin as well as on routine imaging studies, although these imaging findings are nonspecific and are more likely to occur with other diseases.

Monitoring kidney and renal cyst volumes applying MR approaches on a rapamycin treated mouse model of ADPKD

OBJECT

The aim of our study was to determine total cystic volume in a mouse model of PKD using MR imaging to monitor therapeutic effects in vivo.

MATERIALS AND METHODS

We imaged eight female pcy-mice in two groups: four belonged to an untreated control group and four were treated with the anticystic agent rapamycin, which has proven to be effective in reducing cystogenesis in animal models. The mice were imaged using a 9.4 Tesla animal scanner. MRI measurements were taken at six time points during the therapy. Total renal volumes and total cyst volumes were calculated using a thresholding approach.

RESULTS

During the course of the treatment, the total cyst volume increased significantly faster than the total renal volume in the untreated group, indicating that growth of the total renal volume in the untreated group was primarily due to the growth of the cysts, rather than the parenchyma. The measured total renal volume in the control (placebo) group was significantly higher than the volume in the treated group.

CONCLUSION

Using MRI, we were able to monitor the cystic volume in a mouse model of PKD to assess the therapeutic effect of anticystic treatment.

Extracorporeal photopheresis improves nephrogenic fibrosing dermopathy/nephrogenic systemic fibrosis: three case reports and review of literature

Nephrogenic fibrosing dermopathy/nephrogenic systemic fibrosis (NFD/NSF) is a recently recognized systemic fibrosing disorder that develops in the context of renal insufficiency. Its predominant manifestation is severe cutaneous fibrosis, often causing disabling contractures of neighboring joints. No therapy is consistently effective, and etiology and pathogenesis remain obscure. However, gadolinium-containing contrast agents used in magnetic resonance imaging or angiography have recently been strongly linked to the development of fibrosis in NSF. We report a clinical response to treatment with extracorporeal photopheresis (ECP) using the Therakos UVAR XTS system in three cases of NFD/NSF associated with flexion contractures affecting all four limbs. All three patients were receiving renal replacement therapy for longstanding end-stage renal failure. All three showed clinical response with softening of skin plaques at the end of four cycles, and improved range of movement in all four limbs on completion of treatment. The first patient, with NFD/NSF of 4.5 year's duration, was able to resume most activities of daily living although still chairbound, while a second patient with more recent onset of NSF was able to walk short distances with the help of Zimmer frames by the end of 16-18 cycles of treatment, having been chairbound pretreatment. A third patient with milder initial symptoms also experienced significant improvement after a shorter course of ECP treatment. Our experience with these three patients confirms previous case reports, suggesting that ECP may be effective in NFD/NSF.

Gadolinium-based contrast agents and nephrogenic systemic fibrosis: a systematic review and meta-analysis

BACKGROUND

In the past decade, more than 200 cases of nephrogenic systemic fibrosis (NSF) have been identified, primarily among patients with advanced kidney disease. Multiple studies have suggested an association between gadolinium-based contrast agents (GBCAs) and NSF. We performed a systematic review and meta-analysis to examine this potential association.

METHODS

A systematic review of studies examining the association between any GBCA and NSF was performed. A search for controlled studies was conducted in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. If controlled data for a GBCA was not available, we searched for case reports and series. Relevant data were extracted and meta-analyses were performed.

RESULTS

Seven of 144 identified studies met inclusion criteria; gadodiamide was the sole or predominant GBCA in four of these; one study exclusively examined gadopentetate. Other GBCAs were not specifically examined in controlled or uncontrolled studies. Meta-analysis of controlled trials demonstrated a significant association between GBCA exposure and NSF [odds ratio (OR) 26.7; 95% confidence interval (CI) 10.3-69.4] and gadodiamide and NSF (OR 20.0; 95% CI 3.7-107.8). Examination of the evidence using established criteria suggested that this association was causal.

CONCLUSIONS

The current state of evidence suggests an association and potentially causal link between the use of GBCAs and the development of NSF among patients with advanced kidney disease. Additional study is warranted to clarify the potential association of GBCAs other than gadodiamide with NSF.

Ultrastructural evidence of dermal gadolinium deposits in a patient with nephrogenic systemic fibrosis and end-stage renal disease

BACKGROUND AND OBJECTIVES

The pathogenesis of acquired nephrogenic systemic fibrosis recently described for patients with renal insufficiency and a history of exposition to gadolinium-based magnetic resonance contrast agents is not completely understood. A role for circulating fibroblasts in the fibrosing tissue is hypothetical, and the mechanism of the assumed trigger function of gadolinium remains elusive.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A skin lesion on a 76-yr-old man with symptoms of nephrogenic systemic fibrosis lasting 5 mo was studied at the ultrastructural level. After confirmation of he diagnosis by histopathologic methods, the presence and distribution of gadolinium, iron, calcium, and magnesium by energy filtering transmission electron microscopy was also examined.

RESULTS

The performed electron spectroscopic imaging and electron energy loss spectroscopic analyses on deparaffinized samples revealed deposition of gadolinium in irregular small aggregates that adhered to cell profiles and collagen fibers of the connective tissue, forming a perivascular "gadolinium-deposit zone" in the skin. Traces of iron signal were demonstrated in singular gadolinium-positive deposits, and iron presence was found in adjacent connective tissue. The ultrastructural cell analysis of the lesion showed among numerous poorly differentiated fibrocytes also higher differentiated cells with myofibroblastic characteristics, including bundles of intermediate filaments and attachment plaques in the cell periphery, indicating an ability of lesional fibroblasts to differentiate into myofibroblastic cells.

CONCLUSIONS

These findings support the pivotal role of gadolinium chelates in the development of nephrogenic systemic fibrosis.

Management of hepatorenal syndrome

Hepatorenal syndrome is a form of acute or sub-acute renal failure which develops in patients with chronic liver disease. In contrast to other forms of acute renal failure it may be reversible using pharmacological agents. The pathogenesis involves splanchnic vasodilatation and intense renal vasoconstriction. Increasing intravascular volume and prolonged treatment with vasoconstrictor drugs reverses renal failure in a significant proportion of patients. Agents currently used include the vasopressin analogues terlipressin and the alpha1-adrenoceptor agonist midodrine. The somatostatin analogue octreotide has been used in combination therapy but is ineffective as monotherapy. Intravenous albumin is an important adjunctive treatment both in the prevention and treatment of hepatorenal syndrome. Increasing intravascular volume using TIPS (transjugular intrahepatic stent shunt) is effective in some patients and may be useful in maintaining patients who have initially responded to pharmacological therapy. Despite improvements in survival, long term prognosis is still poor and generally depends on the degree of reversibility of the underlying liver disease or access to liver transplantation.

Drug-induced morphea: report of a case induced by balicatib and review of the literature

Drug-induced scleroderma has been rarely reported, mostly with the features of diffuse scleroderma or acrosclerosis, and exceptionally with the characteristics of morphea. We report the case of an adult white woman, enrolled in a double-blind, placebo-controlled, multicentric trial evaluating the efficacy and safety of the cathepsin K inhibitor balicatib for osteoporosis. Typical morphea lesions developed on the patient's trunk 9 months after the beginning of therapy. Lesions completely resolved after drug withdrawal and a single brief course of systemic steroids. No recurrence occurred in a 2-year follow-up. Fifteen cases of drug-induced morphea could be retrieved from the literature. Drug withdrawal determined complete remission in only a few patients. Different drug classes have been implicated. Some of these, including balicatib, alter directly connective tissue metabolism.