Guidelines and Good Clinical Practice Recommendations for Contrast Enhanced Ultrasound (CEUS) in the Liver - Update 2020 - WFUMB in Cooperation with EFSUMB, AFSUMB, AIUM, and FLAUS

The present, updated document describes the fourth iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS), first initiated in 2004 by the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB). The previous updated editions of the guidelines reflected changes in the available contrast agents and updated the guidelines not only for hepatic but also for non-hepatic applications.The 2012 guideline requires updating as previously the differences of the contrast agents were not precisely described and the differences in contrast phases as well as handling were not clearly indicated. In addition, more evidence has been published for all contrast agents. The update also reflects the most recent developments in contrast agents, including the United States Food and Drug Administration (FDA) approval as well as the extensive Asian experience, to produce a truly international perspective.These guidelines and recommendations provide general advice on the use of ultrasound contrast agents (UCA) and are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis to improve the management of patients.

[Diagnostic Value of Contrast-enhanced Ultrasound in Extrathyroidal Extension of Papillary Thyroid Carcinoma]

Objective To evaluate the diagnostic value of contrast-enhanced ultrasound(CEUS)in thyroid extrathyroidal extension(ETE)of papillary thyroid carcinoma(PTC).Methods Totally 172 PTC patients(184 thyroid nodules)were examined by conventional ultrasound(US)and CEUS before operation.Sonographic features of thyroid nodules and the relationship between nodules and thyroid capsule were retrospectively evaluated.The diagnostic efficacy of these two methods for ETE was compared,and the effect of nodule enhancement level on the diagnosis of ETE was analyzed.Results The sensitivity,specificity,and accuracy of CEUS were 78.9%,89.4% and 84.2% in diagnosing ETE,while those of US were 60.0%,86.2%,and 73.4%,respectively.Among them,the sensitivity(P=0.000)and accuracy(P=0.009)of CEUS in diagnosing ETE were significantly higher than those of US,but there was no statistically significant difference in specificity(P=0.375).The area under the receiver operator characteristic curve of CEUS(0.84)was significantly larger than that of US(0.73)(Z=2.24,P=0.01).The diagnostic value of CEUS in ETE was related to the enhancement level of nodules.The sensitivity,specificity,and accuracy of CEUS in the diagnosis of ETE were highest in hypo-enhanced nodules,followed by hyper-enhanced nodules and the iso-enhanced nodules.Conclusion CEUS has higher performance than US in detecting ETC of PTC.

Single-layer boron-doped graphene quantum dots for contrast-enhanced in vivo T1-weighted MRI

Gadolinium (Gd)-based chelates are used as clinical T1 contrast agents for magnetic resonance imaging (MRI) due to their demonstrated high sensitivity and positive contrast enhancement capability. However, there has been an increasing safety concern about their use in medicine because of the toxicity of the metal ions released from these contrast agents when used in vivo. Although significant effort has been made in developing metal-free MRI contrast agents, none have matched the magnetic properties achieved by the gold standard clinical contrast agent, Gd diethylene penta-acetic acid (Gd-DTPA). Here, we report the development of a single-layer, boron-doped graphene quantum dot (termed SL-BGQD) that demonstrates better T1 contrast enhancement than Gd-DTPA. The SL-BGQD is shown to provide significantly higher positive contrast enhancement than the Gd-DTPA contrast agent in imaging vital organs, including kidneys, liver, and spleen, and especially, vasculatures. Further, our results show that the SL-BQGD is able to bypass the blood-brain barrier and allows sustained imaging for at least one hour with a single injection. Hematological and histopathological analyses show that the SL-BGQD demonstrates a non-toxic profile in wild-type mice and may, therefore, serve as an improved, safer alternative to currently available clinical MRI contrast agents.

Nanoparticle-Based Paramagnetic Contrast Agents for Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a noninvasive medical imaging modality that is routinely used in clinics, providing anatomical information with micron resolution, soft tissue contrast, and deep penetration. Exogenous contrast agents increase image contrast by shortening longitudinal (T 1) and transversal (T 2) relaxation times. Most of the T 1 agents used in clinical MRI are based on paramagnetic lanthanide complexes (largely Gd-based). In moving to translatable formats of reduced toxicity, greater chemical stability, longer circulation times, higher contrast, more controlled functionalisation and additional imaging modalities, considerable effort has been applied to the development of nanoparticles bearing paramagnetic ions. This review summarises the most relevant examples in the synthesis and biomedical applications of paramagnetic nanoparticles as contrast agents for MRI and multimodal imaging. It includes the most recent developments in the field of production of agents with high relaxivities, which are key for effective contrast enhancement, exemplified through clinically relevant examples.

Recall strategies for patients found to have a nodule in cirrhosis: is there still a role for CEUS?

Development of liver tumors and their evolution to hepatocellular carcinoma (HCC) is a multi-step process in which different HCC-etiologies induce continuous rounds of hepatocyte damage and regeneration. Over an extended time, this triggers cirrhosis which is a pathological state of the liver in which lesions can progress to become dysplastic nodules. Later, these nodules may evolve into HCC and occasionally generate metastatic events. To provide optimal care, patients with liver cancer should be managed using a multidisciplinary approach in specialized centers in which all the diagnostic and therapeutic resources are available. Among the different imaging modalities the introduction on contrast agents for ultrasound use has opened new further applications in different clinical settings. In fact, contrast enhanced ultrasound (CEUS) has been applied for more than ten years and plays increasingly important roles in the management of HCC. Since early 2000, international societies including the American Association for the Study of Liver Diseases (AASLD), the European Association for the Study of the Liver (EASL), the Asian Pacific association for the Study of the Liver (APASL), the Japanese society of Hepatology (JSH), the Italian society for the study of the liver (AISF), the World Federation for Ultrasound in Medicine and Biology (WFUMB), and the European Federation of Societies for Ultrasound in Medicine and Biology (EFUSMB) have discussed the important role of CEUS in the diagnosis of HCC. In the present review an update of the literature and a detailed discussion of the present Guidelines regarding the role of CEUS in the evaluation of nodules in cirrhotic patients is offered.

Quantitative guidelines for the prediction of ultrasound contrast agent destruction during injection

Experiments and theory were undertaken on the destruction of ultrasound contrast agent microbubbles on needle injection, with the aim of predicting agent loss during in vivo studies. Agents were expelled through a variety of syringe and needle combinations, subjecting the microbubbles to a range of pressure drops. Imaging of the bubbles identified cases where bubbles were destroyed and the extent of destruction. Fluid-dynamic calculations determined the pressure drop for each syringe and needle combination. It was found that agent destruction occurred at a critical pressure drop that depended only on the type of microbubble. Protein-shelled microbubbles (sonicated bovine serum albumin) were virtually all destroyed above their critical pressure drop of 109 ± 7 kPa Two types of lipid-shelled microbubbles were found to have a pressure drop threshold above which more than 50% of the microbubbles were destroyed. The commercial lipid-shelled agent Definity was found to have a critical pressure drop for destruction of 230 ± 10 kPa; for a previously published lipid-shelled agent, this value was 150 ± 40 kPa. It is recommended that attention to the predictions of a simple formula could preclude unnecessary destruction of microbubble contrast agent during in vivo injections. This approach may also preclude undesirable release of drug or gene payloads in targeted microbubble therapies. Example values of appropriate injection rates for various agents and conditions are given.

[Contrast agents in radiology: current agents approved, recommendations, and safety aspects]

The manuscript summarizes current approved contrast media and their indications. Contrast agents that are discussed include iodinated contrast agents, magnetic resonance (MR) contrast agents, and ultrasound contrast agents. Allergic and non-allergic renal adverse events are described. The clinical issue of metformin and the administration of contrast agents are updated. Nephrogenic systemic fibrosis (NSF) is discussed and safety issues of available MR contrast agents are analyzed. The most recent changes in European Society of Urogenital Radiology (ESUR) guidelines are also presented.

Guidelines and good clinical practice recommendations for Contrast Enhanced Ultrasound (CEUS) in the liver - update 2012: A WFUMB-EFSUMB initiative in cooperation with representatives of AFSUMB, AIUM, ASUM, FLAUS and ICUS

Initially, a set of guidelines for the use of ultrasound contrast agents was published in 2004 dealing only with liver applications. A second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some non-liver applications. Time has moved on, and the need for international guidelines on the use of CEUS in the liver has become apparent. The present document describes the third iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS) using contrast specific imaging techniques. This joint WFUMB-EFSUMB initiative has implicated experts from major leading ultrasound societies worldwide. These liver CEUS guidelines are simultaneously published in the official journals of both organizing federations (i.e., Ultrasound in Medicine and Biology for WFUMB and Ultraschall in der Medizin/European Journal of Ultrasound for EFSUMB). These guidelines and recommendations provide general advice on the use of all currently clinically available ultrasound contrast agents (UCA). They are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis and improve the management of patients worldwide.

Dynamic contrast enhanced ultrasound assessment of the vascular effects of novel therapeutics in early stage trials

Imaging is key in the accurate monitoring of response to cancer therapies targeting tumour vascularity to inhibit its growth and dissemination. Dynamic contrast enhanced ultrasound (DCE ultrasound) is a quantitative method with the advantage of being non-invasive, widely available, portable, cost effective, highly sensitive and reproducible using agents that are truly intravascular. Under the auspices of the initiative of the Experimental Cancer Medicine Centre Imaging Network, bringing together experts from the UK, Europe and North America for a 2-day workshop in May 2010, this consensus paper aims to provide guidance on the use of DCE ultrasound in the measurement of tumour vascular support in clinical trials. Key Points • DCE ultrasound can quantify and extract specific blood flow parameters, such as flow velocity, relative vascular volume and relative blood flow rate. • DCE ultrasound can be performed repeatedly and is therefore ideally suited for pharmacokinetic and pharmacodynamic studies evaluating vascular-targeted drugs. • DCE ultrasound provides a reproducible method of assessing the vascular effects of therapy in pre-clinical and early clinical trials, which is easily translatable into routine clinical practice.

Gadolinium in pediatric cardiovascular magnetic resonance: what we know and how we practice

BACKGROUND

The association of gadolinium-based contrast agents (GBCAs) with nephrogenic systemic fibrosis (NSF) has led to a heightened awareness towards patients' renal function. Whereas detailed guidelines exist for the use of GBCAs in adult patients, best practice is less well defined in children, especially in the very young. We aimed at identifying current practice with regards to the use of GBCAs in children who undergo cardiovascular magnetic resonance.

METHODS

We conducted a worldwide survey among cardiac imagers with pediatric expertise. The questionnaire contained 21 questions covering the imagers' work environments, GBCAs used, monitoring of renal function, and a special emphasis was placed on the practice in neonates.

RESULTS

The survey yielded 70 replies. The single most commonly used GBCA was gadopentetate dimeglumine 34/70 (49%). Among the respondents, the choice of GBCA was more importantly based on availability 26/70 (37%) and approval by a pharmaceutical licensing body that most closely reflects the indication 16/70 (23%) than image quality 7/70 (10%) and side effect profile 8/70 (11%). 55/70 (79%) of respondents performed scans in neonates <1 week of age and 52/55 (95%) of them used GBCA in neonates. 65/70 (93%) respondents at least assess some of their patients' renal functions. Formula-based estimate of glomerular filtration rate is the most popular assessment method 35/65 (54%). In patients with a glomerular filtration rate < 30 ml/min/1.73 m(2) 62/70 (89%) of respondents do not administer gadolinium at all. The single most common side effect of gadolinium was noted to be nausea/emesis 34/57 (60%) followed by discomfort at injection site 17/57 (30%).

CONCLUSIONS

Cardiac imagers are aware of the immature renal function and physiological differences of their pediatric patients that place them at risk for NSF. Epidemiological data is needed for pediatric cardiovascular licensure of gadolinium compounds and for the creation of practice guidelines which will replace current-day practice based on individual clinical judgment.

Optimizing imaging quality in endourology with the Uro Dyna-CT: contrast agent dilution matters

BACKGROUND AND PURPOSE

The implementation of the Uro Dyna-CT (Siemens Healthcare Solutions, Erlangen, Germany) with interventional 3D- and cross-sectional imaging necessitates the development of new standards for endourologic procedures such as the customized use of diluted contrast agent. Our aim was to find the ideal contrast agent dilution (CAD) for the interventional use of the Uro Dyna-CT in a standardized setting and prove the experimental findings in a clinical case.

MATERIALS AND METHODS

Retrograde pyelographies were performed with 10 different CADs of Imeron 300 (Bracco, Konstanz, Germany) in 10 different pig's urinary tracts. Fluoroscopy, X-ray, 3D- and slice-image reconstruction was performed with the Uro Dyna-CT. Image quality was evaluated, blinded and randomized by 5 observers. Small plastic jars were filled with the CADs and 2 artificial stones (Plaster of paris). Images were evaluated by two observers. The ex vivo findings were transferred to a clinical setting in a complex percutaneous lithotomy procedure. Unweighted and weighted kappa coefficients were calculated to indicate the degree of observers' agreement.

RESULTS

Twenty percent diluted contrast agent provides the best image quality and stone detection when interventional cross-sectional imaging is considered without limitations in fluoroscopy or X-ray quality. This was proved in a percutaneous lithotomy of an obese patient.

CONCLUSIONS

Image quality of the Uro Dyna-CT can be optimized by the use of 20 % diluted contrast agent. This knowledge helps to provide high-quality 3D imaging in the endourological operation room.

Precise measurement of renal filtration and vascular parameters using a two-compartment model for dynamic contrast-enhanced MRI of the kidney gives realistic normal values

OBJECTIVE

To model the uptake phase of T(1)-weighted DCE-MRI data in normal kidneys and to demonstrate that the fitted physiological parameters correlate with published normal values.

METHODS

The model incorporates delay and broadening of the arterial vascular peak as it appears in the capillary bed, two distinct compartments for renal intravascular and extravascular Gd tracer, and uses a small-vessel haematocrit value of 24%. Four physiological parameters can be estimated: regional filtration K ( trans ) (ml min(-1) [ml tissue](-1)), perfusion F (ml min(-1) [100 ml tissue](-1)), blood volume v ( b ) (%) and mean residence time MRT (s). From these are found the filtration fraction (FF; %) and total GFR (ml min(-1)). Fifteen healthy volunteers were imaged twice using oblique coronal slices every 2.5 s to determine the reproducibility.

RESULTS

Using parenchymal ROIs, group mean values for renal biomarkers all agreed with published values: K ( trans ): 0.25; F: 219; v ( b ): 34; MRT: 5.5; FF: 15; GFR: 115. Nominally cortical ROIs consistently underestimated total filtration (by ~50%). Reproducibility was 7-18%. Sensitivity analysis showed that these fitted parameters are most vulnerable to errors in the fixed parameters kidney T(1), flip angle, haematocrit and relaxivity.

CONCLUSIONS

These renal biomarkers can potentially measure renal physiology in diagnosis and treatment.

KEY POINTS

• Dynamic contrast-enhanced magnetic resonance imaging can measure renal function. • Filtration and perfusion values in healthy volunteers agree with published normal values. • Precision measured in healthy volunteers is between 7 and 15%.

Gadolinium-enhanced cardiovascular magnetic resonance: administered dose in relationship to United States Food and Drug Administration (FDA) guidelines

PURPOSE

Myocardial late gadolinium enhancement was originally validated using higher than label-recommended doses of gadolinium chelate. The objective of this study was to evaluate available evidence for various gadolinium dosing regimens used for CMR. The relationship of gadolinium dose warnings (due to nephrogenic systemic fibrosis) announced in 2008 to gadolinium dosing regimens was also examined.

METHODS

We conducted a meta-analysis of peer reviewed publications from January, 2004 to December, 2010. Major subject search headings (MeSh) terms from the National Library of Medicine's PubMed were: contrast media, gadolinium, heart, magnetic resonance imaging; searches were limited to human studies with abstracts published in English. Case reports, review articles, editorials, MRA related papers and all reports that did not indicate gadolinium type or weight-based dose were excluded. For all included references, full text was available to determine the total administered gadolinium dose on a per kg basis. Average and median dose values were weighted by the number of subjects in each study.

RESULTS

399 publications were identified in PubMed; 233 studies matched the inclusion criteria, encompassing 19,934 patients with mean age 54.2 ± 11.4 (range 9.3 to 76 years). 34 trials were related to perfusion testing and 199 to myocardial late gadolinium enhancement. In 2004, the weighted-median and weighted-mean contrast dose were 0.15 and 0.16 ± 0.06 mmol/kg, respectively. Median contrast doses for 2005-2010 were: 0.2 mmol/kg for all years, respectively. Mean contrast doses for the years 2005-2010 were: 0.19 ± 0.03, 0.18 ± 0.04, 0.18 ± 0.10, 0.18 ± 0.03, 0.18 ± 0.04 and 0.18 ± 0.04 mmol/kg, respectively (p for trend, NS). Gadopentetate dimeglumine was the most frequent gadolinium type [114 (48.9%) studies]. No change in mean gadolinium dose was present before, versus after the Food and Drug Administration (FDA) black box warning (p > 0.05). Three multi-center dose ranging trials have been published for cardiac MRI applications.

CONCLUSION

CMR studies in the peer-reviewed published literature routinely use higher gadolinium doses than regulatory agencies indicated in the package leaflet. Clinical trials should be supported to determine the appropriate doses of gadolinium for CMR studies.

ASCI 2010 contrast media guideline for cardiac imaging: a report of the Asian Society of Cardiovascular Imaging cardiac computed tomography and cardiac magnetic resonance imaging guideline working group

The use of contrast media for cardiac imaging becomes increasing as the widespread of cardiac CT and cardiac MR. A radiologist needs to carefully consider the indication and the injection protocol of contrast media to be used as well as the possibility of adverse effect. There are several guidelines for contrast media in western countries. However, these are focusing the adverse effect of contrast media. The Asian Society of Cardiovascular Imaging, the only society dedicated to cardiovascular imaging in Asia, formed a Working Group and created a guideline, which summarizes the integrated knowledge of contrast media for cardiac imaging. In cardiac imaging, coronary artery evaluation is feasible by non-contrast MR angiography, which can be an alternative examination in high risk patients for the use of iodine contrast media. Furthermore, the body habitus of Asian patients is usually smaller than that of their western counterparts. This necessitates modifications in the injection protocol and in the formula for calculation of estimated glomerular filtration rate. This guideline provided fundamental information for the use of contrast media for Asian patients in cardiac imaging.

Comments and illustrations regarding the guidelines and good clinical practice recommendations for contrast-enhanced ultrasound (CEUS)--update 2008

The recently published EFSUMB guidelines and recommendations provide general advice for the use of ultrasound contrast agents to improve the management of patients. They are the subject of this pictorial essay, comments and analysis of the literature. CEUS has become the most important imaging method for focal liver diseases. Its uses are discussed in detail, especially the characterization of liver tumors and the monitoring of local treatment. The recommendations also deal with the uses of ultrasound contrast agents for the evaluation of the microvasculature and macrovasculature of the kidneys, including the characterization of focal renal lesions, the detection of lesions and the monitoring of local treatment. CEUS and contrast-enhanced endoscopic ultrasound can be used to characterize lesions. Ductal adenocarcinoma as the most common tumor of the pancreas is typically hypoenhanced compared to the adjacent pancreatic tissue in all phases. Neuroendocrine tumors and serous microcystic adenoma of the pancreas are characterized by hypervascularization appearing typically hyperenhanced during CEUS. This is of importance for a differential diagnosis. Vesicoureteric reflux and blunt abdominal trauma are also mentioned. Other parts or chapters of the guidelines are described in a separate paper of this supplement.

Comprehensive investigation of the non-covalent binding of MRI contrast agents with human serum albumin

Three techniques, electrospray mass spectrometry, ultrafiltration, and proton relaxometry, are compared in the context of the quantitative analysis of non-covalent binding between human serum albumin (HSA) and MRI contrast agents. The study of the affinity by proton relaxometry reveals the association constant and the number of interaction sites assuming that all sites are identical and independent. Ultrafiltration was adapted for the study of paramagnetic complexes. This technique confirmed the results obtained by relaxometry. Electrospray mass spectrometry, an original method able to study non-covalent binding because of its soft ionization process that allows for the survival of weak binding, provides qualitative and quantitative results. Electrospray mass spectrometry confirmed the affinity measured by proton relaxometry and ultrafiltration. This technique requires very small amounts of products and directly gives the stoichiometry of the association, information not easily obtained by classic techniques. Nevertheless, proton relaxometry remains a useful and mandatory technique for determining the enhancement of the relaxation subsequent to the binding although it demands large amounts of compounds. It is to be pointed out that even if the three techniques lead to a similar ranking of the affinity of the contrast agents for HSA, the absolute values of the association constants disagree as a result of the difference in the experimental conditions (presence of salt, native protein or desalted one, approximations in the fitting of the data, liquid or gas phases).

Determinants of amount of contrast utilized in patients undergoing percutaneous coronary procedures

OBJECTIVE

To determine predictors of contrast amount during coronary angiography and percutaneous coronary intervention.

BACKGROUND

Contrast-induced nephropathy is a leading cause of hospital-acquired acute renal insufficiency. During percutaneous coronary procedures, contrast amount is a major risk factor incriminated in development of contrast-induced nephropathy.

METHODS

Demographic and procedural details were obtained for consecutive patients undergoing percutaneous coronary procedures between January 2002 and October 2005 (N=962, mean+/-standard error of contrast amount: 216.6+/-3.0 ml) at a tertiary care hospital.

RESULTS

A significant difference (P value <0.05) in unadjusted mean contrast volume was observed between subgroups of percutaneous coronary intervention vs. coronary angiography, patients with a history of coronary artery bypass grafting, patients undergoing additional procedures and multivessel and multisite percutaneous coronary interventions. On General Linear Model analysis, independent predictors (beta coefficient, 95% confidence interval, P value) of increased contrast amount during percutaneous coronary procedures were history of coronary artery bypass grafting (44.4, 30.6-58.2, <0.001), type of coronary procedure (85.2, 73.4-97.0, <0.001 for percutaneous coronary intervention vs. coronary angiography), number of interventions and number of additional procedures performed. Among additional procedures, rotablation, intravascular ultrasound and Angiojet were associated with increased contrast use. No significant independent effect on the contrast amount was observed with percutaneous coronary intervention location (right coronary artery vs. left anterior descending artery vs. circumflex artery) site (ostial vs. proximal vs. mid vs. distal) of percutaneous coronary intervention or with interventions on chronic total occlusions on the contrast amount.

CONCLUSION

Data from our study could guide the coronary angiographer in moderating the volume of contrast utilized as well as assist with the elective planning of complex therapeutic procedures.

Does perfusion CT enable differentiating Alzheimer's disease from vascular dementia and mixed dementia? A preliminary report

The purpose of the study was to evaluate the usefulness of perfusion CT (pCT) in differentiating Alzheimer's disease (AD) from vascular dementia (VaD) and mixed dementia (MixD). pCT was performed in 41 patients (mean age, 68.3 years): 24 with AD, 8 with VaD, and 9 with MixD. Regional perfusion parameters (rCBF, rCBV, and rMTT) were calculated from 31 ROIs in the grey and white matter of the frontal and temporal lobes, basal ganglia, and internal capsules bilaterally. The obtained data for the subgroups of AD, VaD, and MixD patients were compared statistically.

CONCLUSIONS

On the basis of rCBF and rCBV values, pCT may be a valuable method of distinguishing between AD and VaD but it seems to be of little significance in differentiating MixD from VaD and of no usefulness in distinguishing between AD and MixD.

Three-dimensional anisotropy contrast imaging of pontine gliomas: 2 case reports

BACKGROUND

Magnetic resonance imaging can provide a preoperative diagnosis of pontine glioma, but the findings sometimes do not correspond with the clinical symptoms. We describe 2 cases of pontine gliomas who did not present with motor and sensory disturbance.

CASE REPORT

Three-dimensional anisotropy contrast (3DAC) imaging was used to assess the neuronal tracts in 2 patients with pontine gliomas. Conventional MR imaging depicted markedly abnormal findings of abnormally high or heterogeneous signal intensity in the pons in 2 cases. In contrast, 3DAC imaging obviously showed the corticospinal and spinothalamic tracts and cerebellar peduncles without destruction by tumors.

CONCLUSION

Three-dimensional anisotropy contrast imaging provides more information about damage to the neuronal tracts in cases of pontine gliomas than other MR imaging techniques. This technique may be used for preoperative mapping of the tumor and its relationship to the tracts, thus, providing an accurate road map for tumor resection.

European Society of Urogenital Radiology guidelines on contrast media application

PURPOSE OF REVIEW

The present review covers the European Society of Urogenital Radiology guidelines for safe use of contrast media of importance for referring urologists.

RECENT FINDINGS

During the recent years contrast medium-induced nephropathy has become a hot topic. It is of importance to reduce its incidence. First of all, the patients at risk should be identified prior to the administration of a contrast medium, so that appropriate measures can be taken. Before intravenous administration of an iodinated agent but not before gadolinium-based and ultrasound agents, all patients should be questioned about the potential renal dysfunction at the time of referral, and only those who answer affirmative to at least one question should have their serum creatinine level determined. Before intraarterial injection, the serum creatinine should always be measured. In case of an abnormal level, another imaging procedure should be considered. If impossible, hydration should be instituted and administration of nephrotoxic drugs should be stopped. After administration, delayed reactions such as nephrogenic systemic fibrosis, thyreotoxicosis, skin rash, etc. may be seen. Interaction with isotope studies and biochemical analysis occurs too.

SUMMARY

The awareness regarding the potential adverse reactions due to contrast media and the necessary precautions to be taken are of utmost importance both for radiologists and referring physicians. This is the only way to reduce their incidence.

Arterial contamination: a useful indirect sign of cerebral sino-venous thrombosis

BACKGROUND

Various imaging findings of cerebral sino-venous thrombosis (CSVT) have been described on magnetic resonance venography (MRV).

OBJECTIVE

The purpose of this study was to evaluate the significance of visualization of the arterial system on cerebral MRV, also described as arterial contamination, as an indirect sign of CSVT.

METHODS

Forty patients with a clinical suspicion of venous sinus thrombosis underwent MR imaging of the brain, followed by MRV sequence, based on 2D time of flight technique in the coronal oblique plane. Patient's clinical symptoms and signs were noted with particular interest for papilloedema. Twenty-seven patients were diagnosed to have cerebral venous thrombosis on MRV, and of these, arterial contamination was visualized in 16 patients. In the remaining 13 cases, in which there was no evidence of venous sinus thrombosis, arterial contamination was absent. The sensitivity of this finding was 59.25% (n = 16/27), specificity was 100%, positive predictive value was 100% and negative predictive value was 54.2%. Of these 16 patients with arterial contamination, 12 patients had evidence of increased intracranial pressure in the form of papilloedema.

CONCLUSION

Visualization of the arterial system is a useful indirect sign of CSVT, and may be an indicator of increased intracranial pressure in these patients.

Using the Magnetic Resonance Three-Dimensional Volume Rendering for Tissues Technique in the Planning of Craniotomy Flaps with Linear Scalp Incision

Preoperative three-dimensional images with surface venous anatomy may be used in the planning of a linear scalp incision and the opening site of the dura mater for protection of surface veins during surgical dissection, and to find the splitting site of the brain according to the lesion. In 45 patients who had a brain tumor, linear scalp incision planning was done by regarding the three-dimensional images derived from post-contrast time-of-flight (TOF) sequence raw data. The findings of correspondence and the quality of routine contrast-enhanced magnetic resonance imaging (MRI) and three-dimensional volume rendering for tissues (VRT) images were analyzed separately with the surgical findings according to a visual grading system. Our experience revealed that the surgical findings correlated well with the three-dimensional VRT images. According to a visual surgical grading system, a grade III correlation was found in 20 (45%), grade II in 15 (33%), grade I in 7 (15%), and grade 0 in 3 (7%) patients in our study population. At the end of our research we conclude that this method is useful in terms of the preoperative determination of brain surface anatomy and may be used in the determination of the site of a linear scalp incision according to the localization of an intracranial lesion.

CT arteriography for orbital tumors: diagnostic and surgical value

The aim of this study is to investigate the efficacy of dynamic computed tomography (CT) during selective angiography (CT-arteriography) of orbital tumors in the evaluation of intratumoral vascular anatomy, feeding artery territory, and histological diagnosis. Among 35 consecutive cases with various orbital lesions, those cases showing tumor staining or pooling of the contrast medium on digital subtraction angiography (DSA) were evaluated by CT-arteriography (n = 14). The information obtained by CT-arteriography was compared with that provided by enhanced MRI (n = 31) and dynamic MRI (n = 21), in which the contrast medium was injected intravenously. In addition to the visualization of fine vascular anatomy, CT-arteriography emphasized areas of nodular enhancement and non-enhancing cystic/necrotic components as well as the intratumoral feeding arteries. Patterns of CT-arteriography were categorized into three subgroups: homogeneous enhancement (benign lymphoid lesion), partial enhancement (schwannomas and carcinomas), and patchy multinodular enhancement (specific for cavernous angiomas). In addition, CT-arteriography with selective arterial catheterization clearly delineated the feeding artery territories. CT-arteriography, with a minimal dose of contrast medium, can offer significant advantages over intravenously injected dynamic neuroimaging, and provides additional valuable preoperative information about the orbital tumor under investigation.

ESUR guidelines on contrast media

Since 1996 the Contrast Media Safety Committee of the European Society of Urogenital Radiology has released 15 guidelines regarding safety in relation to the use of radiographic, ultrasonographic, and magnetic resonance contrast media. The guidelines have been well received by the radiologic community in Europe and all over the world and comprise current standards for good practice at many institutions. The present report is an overview of the work accomplished by the European Society of Urogenital Radiology over the past 8 years. The committee has covered renal and nonrenal adverse events and other aspects of contrast media.

Contrast-enhanced transcranial Doppler ultrasound for diagnosis of patent foramen ovale

The suspected cause of clinical manifestations of patent foramen ovale (PFO) is a transient or a permanent right-to-left shunt (RLS). Contrast-enhanced transcranial Doppler ultrasound (c-TCD) is a reliable alternative to transesophageal echocardiography (TEE) for diagnosis of PFO, and enables also the detection of extracardiac RLS. The air-containing echo contrast agents are injected intravenously and do not pass the pulmonary circulation. In the presence of RLS, the contrast agents bypass the pulmonary circulation and cause microembolic signals (MES) in the basal cerebral arteries, which are detected by TCD. The two main echo contrast agents in use are agitated saline and D-galactose microparticle solutions. At least one middle cerebral artery (MCA) is insonated, and the ultrasound probe is fixed with a headframe. The monitored Doppler spectra are stored for offline analysis (e.g., videotape) of the time of occurrence and number of MES, which are used to assess the size and functional relevance of the RLS. The examination is more sensitive, if both MCAs are investigated. In the case of negative testing, the examination is repeated using the Valsalva maneuver. Compared to TEE, c-TCD is more comfortable for the patient, enables an easier assessment of the size and functional relevance of the RLS, and allows also the detection of extracardiac RLS. However, c-TCD cannot localize the site of the RLS. Therefore, TEE and TCD are complementary methods and should be applied jointly in order to increase the diagnostic accuracy for detecting PFO and other types of RLS.

Technology Insight: imaging amyloid plaques in the living brain with positron emission tomography and MRI

Alois Alzheimer first imaged amyloid plaques in 1906 by examining dead tissue under the microscope, but their clinical significance has remained undetermined. Now, nearly a century later, investigators are beginning to image amyloid plaques in living brains using both positron emission tomography and MRI. In this article, we review the studies that report on these recent technical advances, and discuss their potential importance in clarifying the diagnostic and pathogenic relevance of amyloid plaques to Alzheimer's disease.

Regulatory compliance associated with contrast media

A basic understanding of the role of regulatory agencies in governing the healthcare environment and their influence over contrast media use is required of radiographers and imaging administrators to meet the many standards of compliance. In addition, radiology management teams must consider cost effectiveness, departmental efficiency, workplace safety, and compliance in choosing to implement new products. Regulatory agencies may be classified into 2 groups, voluntary and involuntary. Involuntary agencies are governmental agencies mandating regulatory compliance by local, state, or federal laws. Voluntary agencies are precisely that, those agencies an institution voluntarily chooses to participate with, to demonstrate the quality of care they provide. Failure to follow involuntary regulatory guidelines or to participate in voluntary best practice standards jeopardizes patient safety and the quality of care provided, and exposes the institution and the individual to liability risks. Severe penalties may result from a failure to maintain regulatory compliance, including the possibility of large fines, criminal indictments, and loss of third-party reimbursement. Achieving regulatory compliance is never an easy venture with the number of regulatory agencies and standards needing to be addressed. Combining regulatory compliance with the effects of doing business provides quite a challenge for today's imaging departments. A solid knowledge base in regulatory standards along with continuous investigation of new standards will allow departments to evaluate their own processes involved in providing patient care. Recognition of areas of high risk/high volume, including contrast media use, will assist in directing the departments' focus appropriately. A thorough evaluation of the products used and their respective handing and administration, in regard to patient and workplace safety, and appropriate documentation of workplace injuries due to contrast media packaging, will assist in maintaining a high level of compliance.

Assessment of CE-MRA for the rapid detection of supra-aortic vascular disease

BACKGROUND

Contrast-enhanced MR angiography (CE-MRA) using a combined head and neck coil permits non-invasive imaging of the vasculature from the aortic arch through to the Circle of Willis in less than 2 minutes.

OBJECTIVE

To determine the accuracy of CE-MRA for the detection of vascular pathology, in particular vascular stenoses, using digital subtraction angiography (DSA) as the gold standard.

METHODS

In a prospective study of 81 patients referred for DSA, CE-MRA and DSA studies were performed within 72 hours of each other. CE-MRA was performed on a 1.5 Tesla clinical MRI scanner using a five-channel neurovascular array (head and neck coil), with dynamic tracking of the IV gadolinium bolus. CE-MRAs and DSA films were read by two interventional neuroradiologists blinded to the clinical presentation of the patient.

RESULTS

On DSA, there were 77 vascular stenoses > or =50% identified, 51 extracranial and 26 intracranial. The overall sensitivity of CE-MRA using the neurovascular array for the detection of vascular stenoses > or =50% was 57% (95% CI: 46 to 68%) with a specificity of 98% (97 to 99%). The sensitivity for the detection of extracranial vascular stenoses > or =50% was 82% (72 to 93%) with a specificity of 97% (96 to 98%). However, the sensitivity for the detection of intracranial vascular stenoses > or =50% was only 8% (0 to 18%), with a specificity of 99% (98 to 100%).

CONCLUSIONS

At this stage Contrast-enhanced MR angiography using a neurovascular coil shows promise as a rapid, specific, and noninvasive screening method for extracranial vascular disease, but not for intracranial vascular disease.

Contrast enhanced harmonic ultrasound for differentiating breast tumors - first results

PURPOSE

To investigate the extent to which indeterminate lesions of the breast can be differentiated in the early and late phase after bolus injection of the ultrasound contrast medium Optison.

MATERIALS AND METHODS

Fifty female patients (mean age: 49 years) with a altogether 53 preoperatively impalpable indeterminate breast tumors, 20 fibroadenomas and 33 carcinomas, were examined by B-mode imaging and contrast medium-enhanced ultrasound with power Doppler (three patients had multifocal carcinomas). The tumors had a diameter of 5-15 mm (mean diameter: 9 mm). Histological confirmation was performed in all lesions by vacuum biopsies and/or surgical preparation. All examinations were performed with a multifrequency linear array probe (5-10 MHz, Logiq9 and Logiq 7, GE). Power Doppler (PD) and B-mode imaging as well as tissue harmonic imaging (THI) were employed. A bolus of 0.5 ml Optison was injected intravenously and spreading of the contrast enhancement and washout in the tumors were followed for at least 20 minutes. A low mechanical index was chosen to avoid early destruction of the microbubbles. Maximum tumor size was measured and tumors vessels were evaluated in digital cine ultrasound sequences.

RESULTS

Without CM administration, 14 of 19 tumor lesions smaller than 10 mm could be distinguished better from the surrounding tissue with THI compared to fundamental B-mode imaging. Both benign (17/20) and malignant (30/33) tumors exhibited increased tumor marginal vessels or intratumoral vessels in the early phase after CM injection. A diffuse contrast medium accumulation was observed in the late phase (8-18 min, mean: 12 min) in 30 of 33 malignant tumors, but in none of the benign tumors. The diagnostic confirmation for this late enhancement was there with 90% for the malignant tumors.

CONCLUSION

After intravenous bolus administration of Optison, breast carcinomas appear to have a prolonged diffuse enhancement of central tumor vasularity in the late phase compared to an earlier marginal vascularity of fibroadenomas.

A standard for radiopacity of root-end (retrograde) filling materials is urgently needed

AIM

To assess the radiopacity of materials used, or recommended for use, as apical root-end (retrograde) fillings.

METHODOLOGY

The radiopacity of 14 materials falling into the category of root-end filling materials was measured in equivalent millimetres of aluminium (mm Al) using a new computerized method. These included temporary or intermediate sealing materials; composite, compomer and GIC filling materials; EBA-derived cements; amalgam, etc. Gutta-percha cone material was added as a control. Samples of 1 mm thickness were radiographed on periapical film alongside an aluminium step wedge calibrated in millimetres, and the opacity of the materials, in greyscale or pseudo-colour, was compared with the equivalent step.

RESULTS

The radiopacity ranged from 1.75 mm Al to >10 mm Al. The lower range appears insufficient for routine clinical detection when it is compared with the minimal requirement for intracanal fillings.

CONCLUSIONS

Because of the proliferation of root-end filling materials with a broad range of radiopacity, an international standard stipulating the required minimal radiopacity, as well as other properties, is needed urgently. It should be based on in vitro results and on large-scale clinical radiographic surveys.

Methylcellulose gel is a superior contrast agent for ultrasound examination of the cervix in obstetric patients

OBJECTIVE

To determine the superior contrast agent for cervical sonography: water-soluble methylcellulose gel vs. normal saline.

METHODS

Women with an indication for cervical sonography underwent placement of 10 mL water-soluble methylcellulose gel or normal saline. Assessment of cervical dimensions and contour was performed via transperineal sonography prior to and after contrast placement.

RESULTS

Twenty-five patients with similar demographic characteristics and indications for ultrasonography were enrolled into each group. Administration of contrast improved the ability to visualize the external os or vaginal fornices in 18 women in the gel group vs. six in the saline group (P = 0.002). In the gel group, 17 patients had easier identification of the external os and visualization of the fornices was enhanced in 13 patients. The assessment of cervical length prior to and after contrast administration was not statistically different with the use of either of these agents.

CONCLUSION

Intravaginal soluble gel is superior to normal saline as a cervical contrast agent. Intravaginal contrast may allow for easier identification of cervical anatomy during ultrasonographic examination in selected patients.

Dialysis and contrast media

In a previous survey we revealed uncertainty among responders about (a) whether or not to perform hemodialysis in patients with severely reduced renal function who had received contrast medium; and (b) when to perform hemodialysis in patients on regular treatment with hemodialysis or continuous ambulatory dialysis who received contrast medium. Therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and to issue guidelines. The committee performed a Medline search. Based on this, a report and guidelines were prepared. The report was discussed at the Ninth European Symposium on Urogenital Radiology in Genoa, Italy. Hemodialysis and peritoneal dialysis safely remove both iodinated and gadolinium-based contrast media. The effectiveness of hemodialysis depends on many factors including blood and dialysate flow rate, permeability of dialysis membrane, duration of hemodialysis and molecular size, protein binding, hydrophilicity, and electrical charge of the contrast medium. Generally, several hemodialysis sessions are needed to removal all contrast medium, whereas it takes 3 weeks for continuous ambulatory dialysis to remove the agent completely. There is no need to schedule the dialysis in relation to the injection of iodinated or MR contrast media or the injection of contrast agent in relation to the dialysis program. Hemodialysis does not protect poorly functioning kidneys against contrast-medium-induced nephrotoxicity. Simple guidelines are given.

Comparison between GdDTPA and two gadolinium polyoxometalates as potential MRI contrast agents

Two gadolinium polyoxometalates, Gd(2)P(2)W(18)O(62) and K(15)[(GdO)(3)(PW(9)O(34))(2)], have been evaluated by in vivo as well as in vitro experiments as the candidates of tissue-specific magnetic resonance imaging (MRI) contrast agents. T(1)-relaxivities of 28.4 mM(-1).s(-1) for Gd(2)P(2)W(18)O(62) and 11.2 mM(-1).s(-1) for K(15)[(GdO)(3)(PW(9)O(34))(2)] (400 MHz, 25 degrees C) were higher than that of the commercial MRI contrast agent (GdDTPA). Their relaxivities in bovine serum albumin and human serum transferrin were also reported. The favorable liver-specific contrast enhancement and renal excretion capability in in vivo MRI with Sprague-Dawley rats after i.v. administration of K(15)[(GdO)(3)(PW(9)O(34))(2)] was demonstrated. In vivo and in vitro assay showed that K(15)[(GdO)(3)(PW(9)O(34))(2)] is a promising liver-specific MRI contrast agent. However, Gd(2)P(2)W(18)O(62) did not show the favorable quality in vivo as expected from its high relaxivity in vitro, which was attributed to low bioavailability, indicating that it is of limited value as tissue-specific MRI contrast agent.

Differential conjugation of tat peptide to superparamagnetic nanoparticles and its effect on cellular uptake

Surface modification of superparamagnetic contrast agents with HIV-1 tat peptide has emerged as a promising means for intracellular magnetic labeling and noninvasive tracking of a large number of cell types with MRI. To achieve efficient intracellular delivery of the nanoparticles, we investigated the effect on cellular uptake of superparamagnetic iron oxide particles by varying the number of attached tat peptides. First, we report here a modified P2T method in measuring the numbers of surface attachments per particle through disulfide linkage. The method was shown to have desirable simplicity and reproducibility. With the P2T method as a tool, conjugates with progressively higher ratios of peptide-to-particle were synthesized. We were able to demonstrate that higher numbers of tat peptide facilitate the cellular uptake of iron oxide nanoparticles in a nonlinear fashion. Cells labeled with these optimized preparations were readily detectable by MR imaging. The increase in sensitivity could allow in vivo tracking of 100-fold lower cell concentration than currently described.

The value of contrast-enhanced color Doppler ultrasound in the detection of vascularization of finger joints in patients with rheumatoid arthritis

OBJECTIVE

A prospective study was performed to assess the usefulness of contrast-enhanced color Doppler ultrasound (CDUS) in the evaluation of intraarticular vascularization of finger joints in patients with rheumatoid arthritis (RA).

METHODS

We investigated 198 finger joints in 46 patients with RA, and 80 finger joints in 10 healthy volunteers. Joints with varying levels of clinical activity of inflammation were classified as being active, moderately active, or inactive. CDUS was performed with a high-frequency multi-D linear array transducer. A microbubble-based ultrasound (US) contrast agent (Levovist; Schering, Berlin, Germany) was intravenously infused. Doppler findings were rated on the basis of both unenhanced and contrast-enhanced CDUS images.

RESULTS

Healthy joints showed no intraarticular vascularization on either unenhanced or contrast-enhanced CDUS. Unenhanced CDUS detected intraarticular vascularization in 7 (8%) of 83 inactive joints, in 31 (52%) of 60 moderately active joints, and in 32 (58%) of 55 active joints. Contrast-enhanced CDUS detected intraarticular vascularization in 41 (49%) of 83 joints with inactive RA, in 59 (98%) of 60 joints with moderately active RA, and in all 55 joints with active RA. Detection of intraarticular vascularization was improved by administration of the microbubble-based US contrast agent (P < 0.001). Contrast-enhanced CDUS demonstrated differences in intraarticular vascularization between joints with inactive RA and those with active RA (P < 0.001), between joints with inactive RA and those with moderately active RA (P < 0.001), and between joints with moderately active RA and those with active RA (P < 0.001).

CONCLUSION

The use of a microbubble-based US contrast agent significantly improved the detection of intraarticular vascularization in the finger joints of patients with RA. This technique seems to be a useful adjunct in the assessment of disease activity.