Editorial: Gadolinium Use in Patients with Kidney Disease: A Cause for Concern

The value of contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine for predicting decompensation and transplant-free survival in chronic liver disease

OBJECTIVES

To investigate the value of contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine for predicting clinical outcomes in patients with chronic liver disease (CLD).

METHODS

Three hundred and fourteen CLD patients who underwent gadobenate dimeglumine-enhanced hepatic magnetic resonance imaging were stratified into three groups: nonadvanced CLD (n = 116), compensated advanced CLD (n = 120), and decompensated advanced CLD (n = 78) groups. The liver-to-portal vein contrast ratio (LPC) and liver-spleen contrast ratio (LSC) at the hepatobiliary phase were measured. The value of LPC for predicting hepatic decompensation and transplant-free survival was assessed using Cox regression analysis and Kaplan-Meier analysis.

RESULTS

The diagnostic performance of LPC was significantly better than LSC in evaluating the severity of CLD. During a median follow-up period of 53.0 months, the LPC was a significant predictor for hepatic decompensation (p < 0.001) in patients with compensated advanced CLD. The predictive performance of LPC was higher than that of the model for end-stage liver disease score (p = 0.006). With the optimal cut-off value, patients with LPC ≤ 0.98 had a higher cumulative incidence of hepatic decompensation than patients with LPC > 0.98 (p < 0.001). The LPC was also a significant predictive factor for transplant-free survival in patients with compensated advanced CLD (p = 0.007) and those with decompensated advanced CLD (p = 0.002).

CONCLUSIONS

Contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine is a valuable imaging biomarker for predicting hepatic decompensation and transplant-free survival in CLD patients.

KEY POINTS

• The liver-to-portal vein contrast ratio (LPC) significantly outperformed liver-spleen contrast ratio in evaluating the severity of chronic liver disease. • The LPC was a significant predictor for hepatic decompensation in patients with compensated advanced chronic liver disease. • The LPC was a significant predictor for transplant-free survival in patients with compensated and those with decompensated advanced chronic liver disease.

Gadolinium-Based Contrast Media Nephrotoxicity in Kidney Impairment: The Physio-Pathological Conditions for the Perfect Murder

Gadolinium-based contrast media (GBCM) toxicity in patients with kidney disease is a concern for the possible development of systemic nephrogenic fibrosis and possible renal complications. This review focuses on the pathological mechanisms underlying the potential kidney toxicity of gadolinium. Gadolinium, as a free compound (Gd3+), is highly toxic in humans because it competes with divalent calcium (Ca2+) and magnesium (Mg2+) ions, interfering in some relevant biologic processes. Its toxicity is blunted by the complexing of Gd3+ with a carrier, allowing its use in magnetic resonance imaging. The binding reaction between gadolinium and a carrier is thermodynamically reversible. Consequently, under some conditions, gadolinium can be released in the interstitial space as a free Gd3+ compound with the possibility of toxicity. Other metals such as iron, copper, and calcium can interfere with the binding between gadolinium and its carrier because they compete for the same binding site. This process is known as transmetallation. In patients with kidney impairment, conditions such as low clearance of the Gd-carrier complex, acid-base derangements, and high serum phosphorous can increase the presence of free Gd3+, leading to a higher risk for toxicity.

Biosafety of Non-Return Valves for Infusion Systems in Radiology

Cross-infection in contrast injectors is still a subject under discussion with little understanding. This study evaluated the biosafety of non-return valves (NRVs). Initially, the maximum pressure during backflow of intact and disrupted flexible diaphragms (FDs) from NRVs, as well as the functionality of connectors with NRVs were verified. The performance of air columns interposed by water in connectors with NRVs was analyzed, and the diffusion distance of crystal violet through connectors with NRVs was measured. The efficacy of NRVs as a barrier to bacterial contamination from backflow was evaluated. Finally, a clinical study of bacteriological contamination from syringes was conducted. There were differences among the maximum tolerated pressure by intact and disrupted FDs. Disrupted FDs showed no failures in the functionality of connectors with NRVs based on the lack of air bubbles released. Air columns could move through connectors with NRVs with intact and disrupted FDs. The longest diffusion distance of crystal violet was 6 cm of connector length, and NRVs showed efficacy as a barrier to bacterial contamination. In the clinical study, there was no bacterial growth in any of the evaluated samples. In conclusion, biosafety depends on the functionality of NRVs as well as proper practical clinical performance.

Imaging for the diagnosis and response assessment of renal tumours

PURPOSE

Imaging plays a key role throughout the renal cell carcinoma (RCC) patient pathway, from diagnosis and staging of the disease, to the assessment of response to therapy. This review aims to summarise current knowledge with regard to imaging in the RCC patient pathway, highlighting recent advances and challenges.

METHODS

A literature review was performed using Medline. Particular focus was paid to RCC imaging in the diagnosis, staging and response assessment following therapy.

RESULTS

Characterisation of small renal masses (SRM) remains a diagnostic conundrum. Contrast-enhanced ultrasound (CEUS) has been increasingly applied in this field, as have emerging technologies such as multiparametric MRI, radiomics and molecular imaging with 99mtechnetium-sestamibi single photon emission computed tomography/CT. CT remains the first-line modality for staging of locoregional and suspected metastatic disease. Although the staging accuracy of CT is good, limitations in determining nodal status persist. Response assessment following ablative therapies remains challenging, as reduction in tumour size may not occur. The pattern of enhancement on CT may be a more reliable indicator of treatment success. CEUS may also have a role in monitoring response following ablation. Response assessments following anti-angiogenic and immunotherapies in advanced RCC is an evolving field, with a number of alternative response criteria being proposed. Tumour response patterns may vary between different immunotherapy agents and tumour types; thus, future response criteria modifications may be inevitable.

CONCLUSION

The diagnosis and characterisation of SRM and response assessment following targeted therapy for advanced RCC are key challenges which warrant further research.

Cutaneous Manifestations of Scleroderma and Scleroderma-Like Disorders: a Comprehensive Review

Scleroderma refers to an autoimmune connective tissue fibrosing disease, including three different subsets: localized scleroderma, limited cutaneous systemic sclerosis, and diffuse cutaneous systemic sclerosis with divergent patterns of organ involvement, autoantibody profiles, management, and prognostic implications. Although systemic sclerosis is considered the disease prototype that causes cutaneous sclerosis, there are many other conditions that can mimic and be confused with SSc. They can be classified into immune-mediated/inflammatory, immune-mediated/inflammatory with abnormal deposit (mucinoses), genetic, drug-induced and toxic, metabolic, panniculitis/vascular, and (para)neoplastic disorders according to clinico-pathological and pathogenetic correlations. This article reviews the clinical presentation with emphasis on cutaneous disease, etiopathogenesis, diagnosis, and treatment options available for the different forms of scleroderma firstly and for scleroderma-like disorders, including scleromyxedema, scleredema, nephrogenic systemic fibrosis, eosinophilic fasciitis, chronic graft-versus-host disease, porphyria cutanea tarda, diabetic stiff-hand syndrome (diabetic cheiroartropathy), and other minor forms. This latter group of conditions, termed also scleroderma mimics, sclerodermiform diseases, or pseudosclerodermas, shares the common thread of skin thickening but presents with distinct cutaneous manifestations, skin histology, and systemic implications or disease associations, differentiating each entity from the others and from scleroderma. The lack of Raynaud's phenomenon, capillaroscopic abnormalities, or scleroderma-specific autoantibodies is also important diagnostic clues. As cutaneous involvement is the earliest, most frequent and characteristic manifestation of scleroderma and sclerodermoid disorders, dermatologists are often the first-line doctors who must be able to promptly recognize skin symptoms to provide the affected patient a correct diagnosis and appropriate management.

Gadolinium-Based Contrast Agents in Kidney Disease: A Comprehensive Review and Clinical Practice Guideline Issued by the Canadian Association of Radiologists

PURPOSE OF REVIEW

Use of gadolinium-based contrast agents (GBCA) in renal impairment is controversial, with physician and patient apprehension in acute kidney injury (AKI), chronic kidney disease (CKD), and dialysis because of concerns regarding nephrogenic systemic fibrosis (NSF). The position that GBCA are absolutely contraindicated in AKI, category G4 and G5 CKD (estimated glomerular filtration rate [eGFR] < 30 mL/min/1.73 m2), and dialysis-dependent patients is outdated and may limit access to clinically necessary contrast-enhanced magnetic resonance imaging (MRI) examinations. This review and clinical practice guideline addresses the discrepancy between existing Canadian guidelines regarding use of GBCA in renal impairment and NSF.

SOURCES OF INFORMATION

Published literature (including clinical trials, retrospective cohort series, review articles, and case reports), online registries, and direct manufacturer databases were searched for reported cases of NSF by class and specific GBCA and exposed patient population.

METHODS

A comprehensive review was conducted identifying cases of NSF and their association to class of GBCA, specific GBCA used, patient, and dose (when this information was available). Based on the available literature, consensus guidelines were developed by an expert panel of radiologists and nephrologists.

KEY FINDINGS

In patients with category G2 or G3 CKD (eGFR ≥ 30 and < 60 mL/min/1.73 m2), administration of standard doses of GBCA is safe and no additional precautions are necessary. In patients with AKI, with category G4 or G5 CKD (eGFR < 30 mL/min/1.73 m2) or on dialysis, administration of GBCA should be considered individually and alternative imaging modalities utilized whenever possible. If GBCA are necessary, newer GBCA may be administered with patient consent obtained by a physician (or their delegate) citing an exceedingly low risk (much less than 1%) of developing NSF. Standard GBCA dosing should be used; half or quarter dosing is not recommended and repeat injections should be avoided. Dialysis-dependent patients should receive dialysis; however, initiating dialysis or switching from peritoneal to hemodialysis to reduce the risk of NSF is unproven. Use of a macrocyclic ionic instead of macrocyclic nonionic GBCA or macrocyclic instead of newer linear GBCA to further prevent NSF is unproven. Gadopentetate dimeglumine, gadodiamide, and gadoversetamide remain absolutely contraindicated in patients with AKI, those with category G4 or G5 CKD, or those on dialysis. The panel agreed that screening for renal disease is important but less critical when using macrocyclic and newer linear GBCA. Monitoring for and reporting of potential cases of NSF in patients with AKI or CKD who have received GBCA is recommended.

LIMITATIONS

Limited available literature (number of injections and use in renal impairment) regarding the use of gadoxetate disodium. Limited, but growing and generally high-quality, number of clinical trials evaluating GBCA administration in renal impairment. Limited data regarding the topic of Gadolinium deposition in the brain, particularly as it related to patients with renal impairment.

IMPLICATIONS

In patients with AKI and category G4 and G5 CKD (eGFR < 30 mL/min/1.73 m2) and in dialysis-dependent patients who require GBCA-enhanced MRI, GBCA can be administered with exceedingly low risk of causing NSF when using macrocyclic agents and newer linear agents at routine doses.

Gadolinium-Based Contrast Agents in Kidney Disease: Comprehensive Review and Clinical Practice Guideline Issued by the Canadian Association of Radiologists

Use of gadolinium-based contrast agents (GBCAs) in renal impairment is controversial, with physician and patient apprehension in acute kidney injury (AKI), chronic kidney disease (CKD), and dialysis because of concerns regarding nephrogenic systemic fibrosis (NSF). The position that GBCAs are absolutely contraindicated in AKI, CKD stage 4 or 5 (estimated glomerular filtration rate [eGFR] <30 mL/min/1.73 m²) and dialysis-dependent patients is outdated, and may limit access to clinically necessary contrast-enhanced MRI examinations. Following a comprehensive review of the literature and reported NSF cases to date, a committee of radiologists and nephrologists developed clinical practice guidelines to assist physicians in making decisions regarding GBCA administrations. In patients with mild-to-moderate CKD (eGFR ≥30 and <60 mL/min/1.73 m²), administration of standard doses of GBCA is safe and no additional precautions are necessary. In patients with AKI, with severe CKD (eGFR <30 mL/min/1.73 m²), or on dialysis, administration of GBCAs should be considered individually and alternative imaging modalities utilized whenever possible. If GBCAs are necessary, newer GBCAs may be administered with patient consent obtained by a physician (or their delegate), citing an exceedingly low risk (much less than 1%) of developing NSF. Standard GBCA dosing should be used; half or quarter dosing is not recommended and repeat injections should be avoided. Dialysis-dependent patients should receive dialysis; however, initiating dialysis or switching from peritoneal to hemodialysis to reduce the risk of NSF is unproven. Use of a macrocyclic ionic instead of macrocyclic nonionic GBCA or macrocyclic instead of newer linear GBCA to further prevent NSF is unproven. Gadopentetate dimeglumine, gadodiamide, and gadoversetamide remain absolutely contraindicated in patients with AKI, with stage 4 or 5 CKD, or on dialysis. The panel agreed that screening for renal disease is important but less critical when using macrocyclic and newer linear GBCAs. Monitoring for and reporting of potential cases of NSF in patients with AKI or CKD who have received GBCAs is recommended.

Effects of gadolinium-based MRI contrast agents on liver tissue

BACKGROUND

MRI with contrast is often used clinically. However, recent studies have reported a high accumulation of gadolinium-based contrast agents (GBCAs) in kidney, liver, and spleen tissues in several mouse models.

PURPOSE

To compare the effects on liver tissue of gadolinium-based MRI contrast agents in the light of biochemical and histopathological evaluation.

STUDY TYPE

Institutional Review Board (IRB)-approved controlled longitudinal study.

ANIMAL MODEL

In all, 32 male Sprague-Dawley rats were divided into a healthy control group subjected to no procedure (Group 1), a sham group (Group 2), a gadodiamide group (Group 3), and a gadoteric acid group (Group 4).

FIELD STRENGTH/SEQUENCE

Not applicable.

ASSESSMENT

Liver tissues removed at the end of the fifth week and evaluated pathologically (scored Knodell's histological activity index [HAI] method by two histopathologists) immunohistochemical (caspase-3 and biochemical tests (AST, ALT, TAS, TOS, and OSI method by Erel et al) were obtained.

STATISTICAL TESTS

Differences between groups were analyzed using the nonparametric Kruskal-Wallis test followed by the Tamhane test, and one-way analysis of variance (ANOVA) followed by Turkey's HSD test.

RESULTS

An increase was observed in histological activity scores in sections from rats administered gadodiamide and gadoteric acid, and in caspase-3, AST and ALT values (P < 0.05). In contrast, we determined no change in TOS (P = 0.568 and P = 0.094, respectively), TAS (P = 0.151 and P = 0.055, respectively), or OSI (P = 0.949 and P = 0.494, respectively) values.

DATA CONCLUSION

These data suggest that gadodiamide and gadoteric acid trigger hepatocellular necrosis and apoptosis by causing damage in hepatocytes, although no change occurs in total antioxidant and antioxidant capacity.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:1367-1374.

Comparison of nephrotoxicity between two gadolinium-contrasts, gadodiamide and gadopentetate in patients with mildly diminished renal failure

Although gadolinium (Gd)-based contrast media have been found to be nephrotoxic, their nephrotoxicity, and the dependence of nephrotoxicity on chelate types, have not been assessed in patients with normal or mildly diminished renal failure. This prospective, randomized study compared the nephrotoxicity of low doses of the nonionic Gd-based contrast medium gadodiamide (Omniscan®) and the ionic Gd-based contrast medium gadopentetate (Magnevist®) in patients with serum creatinine < 1.6 mg/dL. Patients aged 20 to 80 years, weighing 45 to 70 kg and with normal or < 1.6 mg/dL Serum-creatinine in the 3 months prior to undergoing magnetic resonance imaging (MRI) of brain, were enrolled. Patients were randomized to receive 0.1 mol/kg gadodiamide or gadopentetate. Serum-creatinine, serum cystatin-C, estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease (MDRD) formula, and estimated creatinine clearance rate (eCCr) using the Cockcroft-Gault formula were measured just before and 16-80 hr after MRI. Groups were compared statistically by Mann-Whitney U-tests and Wilcoxon signed-rank tests. There were no significant differences in clinical characteristics between the gadodiamide (n = 43) and gadopentetate (n = 59) groups. Serum-creatinine, eGFR and eCCr before and 16-80 hr after MRI did not differ significantly within either group or between the two groups. Serum cystatin-C was significantly higher 16-80 hr after than before MRI only in the gadodiamide group (0.79 ± 0.21 vs. 0.74 ± 0.14 mg/L, p = 0.028). The ionic contrast medium, gadopentetate, did not affect renal function during MRI, whereas the nonionic contrast medium, gadodiamide, affected renal function transiently.

Ultrasound features of hepatocellular adenoma and the additional value of contrast-enhanced ultrasound

BACKGROUND

Hepatocellular adenoma (HCA) is a rare benign tumor of the liver. It is of clinical importance to differentiate HCA from other liver tumors, especially hepatocellular carcinoma (HCC). This study aimed to evaluate the characteristic features of HCA by conventional ultrasound and contrast-enhanced ultrasound (CEUS) findings.

METHODS

Twenty-six patients (10 males and 16 females; mean age 36.2+/-5.0 years) with 26 histopathologically proven HCAs were retrospectively identified. According to the maximum diameter of HCAs, they were divided into three groups: <30 mm, 30-50 mm, and >50 mm. Ultrasound examinations were performed with C5-2 broadband curved transducer of Philips iU22 unit (Philips Bothell, WA, USA). For each lesion, a dose of 2.4 mL SonoVue® (Bracco Imaging Spa, Milan, Italy) was injected as a quick bolus into the cubital vein. Lesions' echogenicity, color-Doppler flow imaging and contrast enhancement patterns were recorded.

RESULTS

Grayscale ultrasound revealed that most of HCAs were hypoechoic (73.1%, 19/26). Spotty calcifications were detected in 26.9% (7/26) of the lesions. Color-Doppler flow imaging detected centripetal bulky color flow in 46.2% (12/26) of the HCAs. CEUS showed that 73.1% (19/26) of the HCAs displayed as rapid, complete and homogenous enhancement, and 53.8% (14/26) showed decreased contrast enhancement in the late phase. There was no significant difference in enhancement patterns among different sizes of HCAs (P>0.05). Centripetal enhancement with subcapsular tortuous arteries was common in larger HCAs.

CONCLUSIONS

CEUS combined with grayscale and color-Doppler flow imaging helped to improve preoperative diagnosis of HCAs. The characteristic imaging features of HCAs included: rapid homogeneous enhancement and slow wash-out pattern on CEUS; heterogeneous echogenicity on grayscale ultrasound; and centripetal enhancement with subcapsular tortuous arteries in large HCAs.

Contrast-enhanced ultrasound (CEUS): an excellent tool in the follow-up of small renal masses treated with cryoablation

Strict imaging follow-up is mandatory after cryoablation of small renal masses (SRMs). Although it uses ionizing radiation and nephrotoxic iodinated contrast, computed tomography (CT) is still the gold standard test. Contrast-enhanced ultrasound (CEUS) is a novel technique that informs in real time about renal perfusion avoiding radiation and nephrotoxicity. The objective of this study is to compare outcomes between CEUS and CT in the follow-up of SRMs treated with cryoablation, as well as to assess degree of agreement between them. This is a prospective observational study (May 2012 to December 2013) comparing CEUS and CT in 16 patients with SRMs cryoablated. The on-going protocol of the study includes a CT and CEUS 3 months after treatment and then every 6 months during 5 years. Local relapse was defined as the presence of contrast enhancement in the mass. All the CEUS were performed by a single experienced observer (E.S.). Degree of agreement was measured with kappa index. CEUS detected contrast enhancement in three patients (3/16, 18.8%) and CT in two patients (2/16, 12.5%). Degree of agreement between CEUS and CT, according to Landis-Koch classification, was 0.76 (CI 0.33-1.19; p = 0.0165), which is excellent and higher than expected by random. Sensitivity of the test is 93.75% (15/16). Median time of follow-up after cryoablation is 22 months (15.5-36.5). CEUS has an excellent agreement with CT and a high sensitivity in the follow-up of SRMs treated with cryosurgery, demonstrating its usefulness. Due to these encouraging results, it could become a reference test in the near future for monitoring SRMs after ablative treatment.

Nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is a relatively new fibrosing disorder which has caught the attention of various specialities in the past decade. NSF is an extremely disabling and often painful condition, affecting up to 13% of the individuals with chronic kidney disease. The administration of a gadolinium chelate contrast agent has been reported to induce the development of NSF, particularly in patients who have acute or chronic renal disease with a glomerular filtration rate (GFR) lower than 30-mL/min/1.73 m(2) and in those with acute renal insufficiency. Mass spectroscopy studies have demonstrated particles of gadolinium in the lesional tissue. The exact pathogenesis of this curious sclerosing condition is unknown. The role of the aberrant targeting of 'circulating fibrocytes' to the peripheral tissues and viscera has been hypothesized. NSF has distinct clinicopathological features in the setting of renal failure and needs to be looked upon as a new entity on the block. The condition is characterized by irregular indurated plaques, with amoeba-like projections and islands of sparing, chiefly on the trunk and extremities. Flexion contractures of fingers, knees, and elbow joints are known to occur in advanced cases of NSF. The course is frequently associated with painful episodes and loss of ambulation. Histopathology shows haphazard arrangement of thickened bundles of collagen, varying amount of mucin, and increased population of fibroblast-like cells in the dermis. Immunohistochemistry shows increased deposition of type-I procollagen and CD 34+ cells having fibroblastic activity. The condition is refractory to treatment with corticosteroids and immunosuppressive agents. Various modalities of therapy such as UVA1 phototherapy, imatinib mesylate, photodynamic therapy, plasmapheresis, extracorporeal photochemotherapy, and high-dose intravenous immunoglobulin have shown a moderate degree of improvement in skin thickness scores. A prudent option is restoration of renal function to normalcy via renal transplantation but to date the outcome of renal transplantation is unknown.

Nephrogenic systemic fibrosis: concepts and perspectives

Nephrogenic systemic fibrosis is a chronic, progressive condition that develops in some patients with renal impairment after exposure to gadolinium-based contrast agents used in magnetic resonance imaging. Thickening of the skin is typical, usually affecting the extremities. Visceral organs can also be affected. The diagnosis of the disease requires careful clinicopathological correlation. Treatment aims at restoring renal function, which is associated with delayed progression and, eventually, remission of skin changes. Reduction and prevention of nephrogenic systemic fibrosis cases are based on limiting the use of gadolinium-based contrast agents in patients with kidney disorders (especially in patients with advanced renal failure at stages 4 and 5), and restricting their use to situations in which they are essential to diagnosis/follow-up. Other than limiting exposure to gadolinium based contrast agents, no effective preventive methods have been reported. Due to increased awareness about the disease among radiologists and nephrologists, the incidence of nephrogenic systemic fibrosis is declining.

In an animal model nephrogenic systemic fibrosis cannot be induced by intraperitoneal injection of high-dose gadolinium based contrast agents

AIM AND OBJECTIVE

Nephrogenic systemic fibrosis (NSF) has been reported in humans to be most likely induced by gadolinium based contrast agents (GBCA), namely by gadodiamide, gadopentetate dimeglumine, and gadoversetamide, rarely by other GBCA. The pathogenesis of NSF remains unclear; different hypotheses are under discussion. The objective of the study is to assess if in the animal model human-like NSF changes can be induced by high-dose, intraperitoneal GBCA injections over four weeks.

MATERIALS AND METHODS

After approval by the institutional animal ethics committee, six rats each were randomly assigned to groups, and treated with seven different GBCA. Intraperitoneal (IP) injections - proven in the animal model to be effective - were chosen to prolong the animals' exposure to the respective GBCA. GBCA doses of previous intravenous (IV) animal studies were applied. After five weeks all rats were sacrificed. Sham controls were treated with IP saline injections, employing the same regimen.

RESULTS

No findings comparable with human NSF were observed in all animals after IP treatment with all seven GBCA at daily doses of 2.5 and 5.0 mmol/kg body weight (BW). No histopathological abnormalities of all examined organs were noted. Weight loss was stated in weeks three and four with GBCA injections at doses of 5.0 mmol/kg BW, but rats regained weight after cessation of GBCA treatment.

CONCLUSIONS

NSF-comparable pathological findings could not be induced by high dose intraperitoneal injection of seven GBCA.

Diagnostic accuracy of contrast-enhanced ultrasound in differentiating benign and malignant focal liver lesions: a retrospective study

PURPOSE

The purpose of this study was to assess the diagnostic accuracy of our early experience with contrast-enhanced ultrasound (CEUS) in the characterisation of focal liver lesions (FLLs) using histopathology, contrast-enhanced computed tomography (CT), magnetic resonance imaging (MRI) or other imaging follow-up as the standard of reference.

MATERIALS AND METHODS

Seventy-three patients with 82 FLLs who underwent liver CEUS from January 2006 to December 2008 were retrospectively reviewed. CEUS was performed with up to 4.8 mL of SonoVue® (Bracco, Milan, Italy) using a low mechanical index mode. The CEUS findings were compared with histopathology, or where histopathology was not available, clinical and imaging follow-up over at least 12 months was used as the standard of reference.

RESULTS

Of the 82 FLLs, 50 were malignant and 32 were benign at final diagnosis. CEUS correctly identified 43 malignant FLLs, with final diagnosis confirmed by histopathology in 13 lesions and clinico-radiological follow-up in 30 lesions. Twenty-nine lesions were correctly identified as benign on CEUS, with all these lesions confirmed on clinico-radiological follow-up. CEUS demonstrated a sensitivity of 86.0% and a specificity of 90.6% in the characterisation of liver lesions as malignant, with an overall accuracy of 87.8% (P < 0.05).

CONCLUSION

Our early experience has shown that CEUS can be accurate in differentiating malignant from benign FLLs and may become a useful first-line imaging tool where CT or MRI are not available or contra-indicated.

Screening patients to assess renal function before administering gadolinium chelates: assessment of the Choyke questionnaire

OBJECTIVE

The purpose of our study was to determine the efficacy of using the Choyke questionnaire to stratify the potential risk for nephrogenic systemic fibrosis (NSF) before a gadolinium-enhanced MRI examination and to compare the economic impact of such an approach with universal blood sampling before gadolinium-enhanced MRI.

MATERIALS AND METHODS

We retrospectively reviewed the records of 1,086 consecutive outpatients referred for gadolinium-enhanced MRI. For inclusion, patients were required to have an estimated glomerular filtration rate (eGFR) result within 30 days before gadolinium-enhanced MRI and a completed Choyke questionnaire, first when the order was placed and again at the point of service. Questionnaire results were dichotomized into "No" (all no responses in both questionnaires) or "Yes" (one or more yes responses in either questionnaire) response groups for comparison with the corresponding eGFR. An economic impact assessment for using the questionnaire to identify "at risk" patients was performed using a decision-analytic model.

RESULTS

Entry criteria were met in 665 of 1,086 (61.2%) patients. Zero patients in the No (n = 287) and seven in the Yes (1.9%) group (n = 378) had an eGFR of less than 30 mL/min/1.73 m(2). Using the 100% sensitivity achieved in identifying higher risk patients (seven patients; 95% CI, 59-100%), the questionnaire could save $4.52 per patient. At the lower boundary of the 95% CI for sensitivity, the savings incurred would come at the expense of administering gadolinium to 0.4% of patients with an eGFR less than 30 mL/min/1.73 m(2).

CONCLUSION

The Choyke questionnaire effectively stratifies patients for NSF risk before gadolinium-enhanced MRI, offering potential cost savings and streamlined care.

Under-recognized renal insufficiency in hospitalized patients: implications for care

BACKGROUND

The consequences of undetected low glomerular filtration rate (GFR) are important in hospitalized patients who receive potentially nephrotoxic drugs or undergo major surgery. This study estimated the prevalence of estimated GFR (eGFR) <60mL/min/1.73m(2) in hospitalized patients.

METHODS

This cross-sectional descriptive study included 14,658 adults hospitalized at 10 centers in Spain. Serum samples were analyzed for hemoglobin, creatinine, albumin and urea nitrogen. eGFR was estimated using Modification of Diet in Renal Disease (MDRD) 4 or MDRD IDMS, and MDRD 6 when serum albumin and BUN were included (n=8611). Individuals were classified as having GFR>or=60mL/min/1.73m(2), stages 3, 4 and 5 (GFR 30-59, 15-29 and <15mL/min/1.73m(2), respectively). Additionally, stages 3a and 3b (GFR 45-59 and 30-44mL/min/1.73m(2), respectively) were assessed.

RESULTS

MDRD 4 eGFR showed that 28.3% of patients had renal insufficiency stages 3-5 and 14.2% had stages 3b, 4 or 5, which represents important-severe renal deterioration. Forty-three percent of patients with stages 3-5 had hemoglobin <or=11g/dL, compared with 27.9% of patients with eGFR>or=60mL/min/1.73m(2). A good correlation was observed between eGFR MDRD 4 and MDRD 6.

CONCLUSIONS

A high percentage of hospitalized patients in Spain have deteriorated renal function stages 3-5. Using eGFR equations to assess eGFR could identify more hospitalized patients with renal insufficiency, potentially leading to improved care.

Effects of aging on glomerular function and number in living kidney donors

To elucidate the pathophysiologic changes in the kidney due to aging, we used physiological, morphometric, and imaging techniques to quantify GFR and its determinants in a group of 24 older (≥ 55 years) compared to 33 younger (≤ 45 years) living donors. Mathematical modeling was used to estimate the glomerular filtration coefficients for the whole kidney (K(f)) and for single nephrons (SNK(f)), as well as the number of filtering glomeruli (N(FG)). Compared to younger donors, older donors had a modest (15%) but significant depression of pre-donation GFR. Mean whole-kidney K(f), renocortical volume, and derived N(FG) were also significantly decreased in older donors. In contrast, glomerular structure and SNK(f) were not different in older and younger donors. Derived N(FG) in the bottom quartile of older donors was less than 27% of median-derived N(FG) in the two kidneys of younger donors. Nevertheless, the remaining kidney of older donors exhibited adaptive hyperfiltration and renocortical hypertrophy post-donation, comparable to that of younger donors. Thus, our study found the decline of GFR in older donors is due to a reduction in K(f) attributable to glomerulopenia. We recommend careful monitoring for and control of post-donation comorbidities that could exacerbate glomerular loss.

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.

Left ventricular infarct size assessed with 0.1 mmol/kg of gadobenate dimeglumine correlates with that assessed with 0.2 mmol/kg of gadopentetate dimeglumine

OBJECTIVE

To determine myocardial infarct (MI) size during cardiovascular magnetic resonance at 1.5 Tesla using 0.1 mmol/kg body weight of gadobenate dimeglumine (Gd-BOPTA) and 0.2 mmol/kg body weight of gadopentetate dimeglumine (Gd-DTPA).

METHODS

Twenty participants (16 men, 4 women), aged 58 +/- 12 years, with a prior chronic MI were imaged in a crossover design. Participants received 0.2 mmol/kg body weight of Gd-DTPA and 0.1 mmol/kg body weight of Gd-BOPTA on 2 occasions separated by 3 to 7 days.

RESULTS

The correlations were high between Gd-DTPA and Gd-BOPTA measures of infarct volume (r = 0.93) and the percentage of infarct relative to left ventricular myocardial volume (r = 0.85). The size and location of the infarcts were similar (P = 0.9) for the 2 contrast agents. Interobserver correlation of infarct volume (r = 0.91) was high.

CONCLUSIONS

In chronic MI, late gadolinium enhancement identified with a single 0.1 mmol/kg body weight dose of Gd-BOPTA is associated in volume and location to a double (0.2 mmol/kg body weight) dose of Gd-DTPA. Lower doses of higher relaxivity contrast agents should be considered for determining left ventricular myocardial infarct size.

Current status of gadolinium toxicity in patients with kidney disease

Gadolinium-based contrast (GBC) agents have recently been the subject of intense interest for physicians across numerous specialties. These agents are widely used as contrast for magnetic resonance imaging and have been generally considered safe. Early on, phase III trials and small studies in low-risk patients suggested a benign renal profile; however, more recent studies raised the possibility of nephrotoxicity, although it is not clear whether it approaches the incidence of nephropathy associated with iodinated radiocontrast. In 2006, reports of a rare systemic fibrosing condition called nephrogenic systemic fibrosis (NSF) were recently linked to exposure of patients with advanced kidney disease to GBC agents. Analysis of the data suggests that certain GBC agents are more likely to be associated with NSF. Also, not all patients with kidney disease are at risk for developing NSF, only those with advanced acute or chronic kidney disease. Avoidance of GBC exposure is the best approach for high-risk patients. When GBC is required to obtain optimal images, use of low dosages of more stable macrocyclic agents is safer and preferred. This article reviews the current status of GBC agents as nephrotoxins and causes of NSF and provides opinions on how to use these agents in patients with underlying kidney disease.

Gadolinium-enhanced magnetic resonance imaging for renovascular disease and nephrogenic systemic fibrosis: critical review of the literature and UK experience

PURPOSE

To examine the positive reporting bias regarding the link with gadolinium (Gd) exposure and nephrogenic systemic fibrosis (NSF) in patients with renal impairment. This link has impacted strongly the international radiology safety guidelines. We believe that positive reporting bias has prevailed in the literature and that very few patients with a glomerular filtration rate (GFR) 15-29 mL/min (stage 4 chronic kidney disease [CKD]) should be regarded as high risk.

MATERIALS AND METHODS

To examine this, we conducted the following steps: 1. A critical literature search on NSF. 2. An analysis of our centers magnetic resonance angiography (MRA) experience since 1999. 3. A survey of participating centers of the multicenter ASTRAL trial to assess whether any patients screened or enrolled into ASTRAL had developed NSF.

RESULTS

The vast majority (90%) of NSF cases reported in the literature have occurred in patients with endstage renal disease treated with dialysis; very have had stable stage 4 or 5 (nondialysis) CKD. In all, 562 patients were followed up at our center: 30.4% were CKD4, 14.4% CKD5, 5.3% on dialysis, and 0.2% had renal transplants when imaged. No patients developed any symptoms or signs of NSF. In all, 347 patients were enrolled into ASTRAL on the basis of MRA (32% CKD4/5). One patient out of 45 centers (CKD5, received two Gd scans) developed NSF. Approximately 5 times as many patients were screened as were entered into ASTRAL.

CONCLUSION

No cases of NSF were observed at our center. By extrapolation, 1/1735 patients screened for the ASTRAL trial developed NSF, giving a crude incidence rate of 0.06%. We would argue that patients with CKD4 can safely undergo Gd-MRA, albeit using a minimal dose of a macrocyclic agent and avoiding repeat doses.

Skin problems in chronic kidney disease

Skin disorders associated with chronic kidney disease (CKD) can markedly affect a patient's quality of life and can negatively impact their mental and physical health. Uremic pruritus, which is frequently encountered in patients with CKD, is considered to be an inflammatory systemic disease rather than a local skin disorder. Biomarkers of inflammation are increased in patients with uremic pruritus and an imbalance of the endogenous opioidergic system might be involved in the complex pathogenesis of the disease. Treatment options for uremic pruritus include emollients, topical capsaicin cream, ultraviolet B phototherapy, gabapentin, oral activated charcoal and nalfurafine, a kappa-opioid-receptor agonist. Calcific uremic arteriolopathy is triggered by an imbalance of promoters and inhibitors of vascular calcification, caused by the inflammatory changes that occur in uremia. Promising therapeutic strategies for calcific uremic arteriolopathy include bisphosphonates and intravenous sodium thiosulfate. Nephrogenic systemic fibrosis is a devastating condition associated with the use of gadolinium-based contrast agents in patients with CKD. At present, no therapies are available for this complication. Preventive measures include use of iodine-based contrast agents, particularly in patients with CKD stage 4 and 5. If gadolinium contrast is necessary, administration of low volumes of the more stable macrocyclic ionic types of gadolinium-based contrast agent is advocated. Hemodialysis following gadolinium exposure might offer benefits but evidence is lacking.

Inhibition of chloride outward transport by gadolinium in cultured rat spinal cord neurons

Gadolinium is a rare-earth lanthanide metal ion and is used as organic gadolinium complexes in magnetic resonance imaging (MRI). Although gadolinium-based MRI agents are thought to be safe in clinical use, the in vivo release of the toxic free inorganic gadolinium (Gd3+) has been reported in some patients with kidney disease. In central nervous system neurons, the inhibitory action of GABA is a consequence of relatively hyperpolarized Cl- equilibrium potential (ECl), which results from the activity of K+-Cl- co-transporter (KCC). The lanthanide ions are reported to affect GABAA receptors. However, little is known about the effect of Gd3+ on GABAA receptor function with intact intracellular Cl- concentration. In the present study, we investigated the effect of Gd3+ on GABAA receptor-mediated currents using gramicidin perforated patch recording method in cultured rat spinal cord neurons. The application of muscimol, a GABAA receptor agonist, caused outward current at a holding potential of -50 mV. Gd3+ inhibited the muscimol-induced outward current in a concentration-dependent and reversible manner. Gd3+ inhibited the maximum muscimol response but had no effect on the half-maximum concentration. The Gd3+ inhibition was accompanied by a depolarizing shift of the reversal potential. The Gd3+ action was blocked by furosemide, a blocker of both KCC and Na+-K+-Cl- co-transporter (NKCC), but not bumetanide, a specific blocker of NKCC. Gd3+ failed to inhibit the muscimol-induced outward currents recorded by conventional whole-cell patch-clamp method which cannot retain intact intracellular Cl- concentration. These results suggest that Gd3+ inhibits a KCC function and gives rise to increase in intracellular Cl- concentration. The reduction of outward chloride transport could be related to the neurotoxic effects of Gd3+.

The prevention of acute kidney injury: an in-depth narrative review Part 1: volume resuscitation and avoidance of drug- and nephrotoxin-induced AKI

This narrative clinical review in two parts discusses the prevention of clinical acute kidney injury (AKI). The first part focuses on general prevention measures, including identification of individuals at high risk for AKI, and on the role of volume expansion and fluid therapy. The latter discusses the timing, the goals, the selection of the fluids and the haemodynamic management of the patient receiving parenteral fluids for the prevention of AKI. In addition, this part summarizes the interaction of intensivist-nephrologist in the ICU with attention to tight glycaemia control and the use of low doses of corticoids in the septic shock patients. Finally, the avoidance of drug- and nephrotoxin-induced AKI is discussed. The second part of this review will summarize the possible pharmacological interventions in the patient at risk.

Descending Thoracic Aortic Dissection: Evaluation and Management in the Era of Endovascular Technology

Acute aortic dissection is a relatively uncommon but highly lethal condition. Without proper treatment, devastating consequences can occur due to aortic rupture, cardiac tamponade, or irreversible ischemia involving the spinal cord or the visceral organs. The treatment strategy of this condition is in part influenced by the location and the severity of aortic dissection as immediate surgical intervention is necessary in acute ascending aortic dissection, whereas medical therapy is the initial treatment approach in uncomplicated descending aortic dissection. Recent advances of endovascular technology have broadened the potential application of this catheter-based therapy in aortic pathologies, including descending thoracic aortic dissection. In this article, the etiology, pathogenesis, and classification of this condition are discussed. The diagnostic benefits of various imaging modalities for descending aortic dissection are also discussed. Current treatment strategies, including medical, surgical, and catheter-based interventions, are reviewed. Lastly, clinical experiences of endovascular treatment for descending aortic dissection and various endovascular devices potentially applicable for this condition are discussed.

Pyelonephritis presenting with severe acute renal failure

We describe an unusual case of an 8-yr-old child presenting with low grade fever and acute renal failure. Investigations showed blood urea 246 mg/dl, serum creatinine 6.4 mg/dl, microscopic hematuria and 2+ proteinuria. Renal biopsy was done in view of rapidly worsening kidney function and showed dense lymphoplasmacytic infiltrate and neutrophils with focal areas of interstitial necrosis, confirming acute pyelonephritis. Ultrasonography and MRI demonstrated multiple renal abscesses. He was managed with antimicrobial therapy and hemodialysis.

Nephrogenic systemic fibrosis: chronic imaging findings and review of the medical literature

Nephrogenic systemic fibrosis (NSF) is a systemic fibrosing disorder which has been strongly associated with exposure to gadolinium-based contrast media (GBCM) in the setting of renal insufficiency. Although this disorder primarily affects the skin, it can result in severe joint contractures, disabilities and even death. However, to date, there have been no published studies reporting chronic imaging findings of NSF. In this report we present three biopsy-proven cases of NSF with the associated chronic MRI, radiographic and bone scintigraphy findings. Two of the patients had been exposed to gadodiamide, and one had been exposed to gadopentetate dimeglumine prior to the onset of NSF. Two are newly reported cases. One patient's subacute imaging findings have previously been reported, but significant chronic images will now be presented. This patient became severely disabled from contractures and developed long bone smooth periosteal reaction, extensive intra-articular and periarticular calcifications, musculotendinous heterotopic ossification and ankylosis of several joints. One of the patients underwent renal transplantation 6 months after GBCM exposure, with near complete resolution of the skin fibrosis. The third patient had persistent MRI findings of skin thickening, with low T1 and high T2 signal intensity 5 years after exposure to gadodiamide. A review of the medical literature is provided, emphasizing the association of NSF with various GBCM. These cases broaden our understanding of the long-term imaging findings and complications of NSF and the stratified risk of NSF with various GBCM.

A follow-up of four cases of nephrogenic systemic fibrosis: is gadolinium the specific trigger?

We originally reported four patients with nephrogenic systemic fibrosis (NSF) in the British Journal of Dermatology in 2003, and now present an update of their outcome. All four patients (three females and one male) presented within a six month period at our institution, and had received gadolinium contrast agents prior to disease onset. Two patients with functioning renal transplants had limited cutaneous disease, two patients maintained on haemodialysis had more severe disease and died one year after disease onset. Gadolinium deposition was demonstrated in lesional skin of one patient using electron microscopy and energy dispersive spectroscopy.