Fate and removal of iodinated X-ray contrast media in membrane bioreactor: Microbial dynamics and effects of different operational parameters

Iodinated X-ray contrast media (ICM) are mainly used in medical sector, and their presence in environmental waters is a cause of concern as they are capable of forming highly toxic iodinated disinfection byproducts. In the present study, the removal mechanisms of the three ICM- iohexol, iopromide, and iopamidol were elucidated in a lab-scale aerobic membrane bioreactor (MBR). At steady-state operation (solids retention time (SRT)- 70 days, organic loading rate (OLR)- 0.80 KgCOD/m³-day, nitrogen loading rate (NLR)- 0.08 KgNH₄-N/m³-day, hydraulic retention time (HRT)- 12 h), the average removal of iohexol and iopromide was found to be 34.9 and 45.2 %, respectively, whereas iopamidol proved to be highly recalcitrant in aerobic conditions of the MBR (removal <10 % in all phases of the MBR operation). Further, through batch kinetic studies and mass balance analysis, it was observed that ICM were primarily biotransformed in the MBR system and biosorption (K_d < 10 L/Kg) was negligible. The biodegradation rate coefficient values (K_biol) of the ICM were found to be <0.65 L/g-d which indicate that biotransformation rate of ICM was slow. Increased OLR (1.60 KgCOD/m³-day) and reduced SRT (20 days) were found to negatively affect the removal of the ICM. Further, the removal of ICM was found to depend on its initial concentration, and the increment in the ammonium loading (0.16 KgNH₄-N/m³-day) did not favor its removal. The dosing of ICM altered the microbial dynamics of the mixed liquor and reduced the microbial diversity and richness. Bdellovibrio, Zoogloea, and bacteria belonging to TM7-3 class, Cryomorphaceae and Hyphomonadaceae families may contribute in ICM biotransformation.

Evaluation of the accumulation of the iodinated contrast agents diatrizoic acid and iohexol in Dreissena polymorpha mollusks

Mollusks are very sensitive to aquatic environmental alterations and then, are important bio-indicators for monitoring the contamination of water bodies. Iodinated X-ray contrast media (ICMs) are ubiquitously present in the aquatic environment, primarily due to their high consumption for diagnosis purposes, high injection levels, low biodegradability, and low removal rates by wastewater treatment plants. Although these compounds are assumed to be of low toxicity, aquatic organisms are continuously exposed to these agents, which may result in adverse effects as ICMs can act as iodine source and disrupt the endocrine system. Thus, the evaluation of their environmental risk, especially on aquatic fauna is of great interest. To this end, we first compared the accumulation behavior, based on iodine analysis, of two ICM exhibiting different osmolality, diatrizoic acid and iohexol in Dreissena polymorpha bivalves exposed under laboratory conditions at concentrations of 0, 100, and 1000 μg/L during 4 and 7 days. This study was the first to provide information on iodine concentration in whole soft tissues and several organs in control zebra mussels. Moreover, it showed, after exposure, an increase of iodine content mainly in the digestive glands, followed by gills and gonads, highlighting that ICMs actually enter the organisms. Thus, bioaccumulation of ICMs studies were then performed, by liquid chromatography coupled to tandem mass spectrometry, on entire mollusks and digestive glands of organisms exposed at 0, 10, 100, and 1000 μg/L of both ICMs during 21 days, followed by 4 days of depuration. These first data on ICMs concentrations in zebra mussels, showed a clear accumulation of ICMs in mussels as a function of relative exposure level, as well as a rapid depuration. Osmolality did not seem to have a significant impact on the accumulation level, but a slight difference was observed on the accumulation pattern between both ICMs.

Magnetic Particle Imaging of Magnetotactic Bacteria as Living Contrast Agents Is Improved by Altering Magnetosome Arrangement

Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as imaging agents to differentiate between normal and diseased tissue or track cell movement. Magnetic particle imaging (MPI) detects the magnetic properties of SPIONs, providing quantitative and sensitive image data. MPI performance depends on the size, structure, and composition of nanoparticles. Magnetotactic bacteria produce magnetosomes with properties similar to those of synthetic nanoparticles, and these can be modified by mutating biosynthetic genes. The use of Magnetospirillum gryphiswaldense, MSR-1 with a mamJ deletion, containing clustered magnetosomes instead of typical linear chains, resulted in improved MPI signal and resolution. Bioluminescent MSR-1 with the mamJ deletion were administered into tumor-bearing and healthy mice. In vivo bioluminescence imaging revealed the viability of MSR-1, and MPI detected signals in livers and tumors. The development of living contrast agents offers opportunities for imaging and therapy with multimodality imaging guiding development of these agents by tracking the location, viability, and resulting biological effects.

Background-Free Proton NMR Spectroscopy with Radiofrequency Amplification by Stimulated Emission Radiation

We report on the utility of Radiofrequency Amplification by Stimulated Emission Radiation (RASER) for background-free proton detection of hyperpolarized biomolecules. We performed hyperpolarization of ≈0.3 M ethyl acetate via pairwise parahydrogen addition to vinyl acetate. A proton NMR signal with signal-to-noise ratio exceeding 100 000 was detected without radio-frequency excitation at the clinically relevant magnetic field of 1.4 T using a standard (non-cryogenic) inductive detector with quality factor of Q=68. No proton background signal was observed from protonated solvent (methanol) or other added co-solvents such as ethanol, water or bovine serum. Moreover, we demonstrate RASER detection without radio-frequency excitation of a bolus of hyperpolarized contrast agent in biological fluid. Completely background-free proton detection of hyperpolarized contrast agents in biological media paves the way to new applications in the areas of high-resolution NMR spectroscopy and in vivo spectroscopy and imaging.

Variability in hair gadolinium concentrations among decedents who received gadolinium-based contrast agents

This study utilized laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to quantify gadolinium in the hair of autopsy cases that had received gadolinium-based contrast agents (GBCAs) before death. Consecutive autopsy cases were reviewed for GBCA injections and subjects who received a single type of GBCA in the year before death were included. Hair samples were analyzed using LA-ICP-MS as a line scan technique and parameters were optimized to maximize instrument sensitivity, accuracy, and precision. Linear regression analyses between hair measures and gadolinium dose were executed. LA-ICP-MS analysis produced a time-resolved record of GCBA exposure, with the position of the gadolinium peak maxima along the hair shaft providing a good estimate for the day that GBCA injection occurred (R2 = 0.46; p = 0.0022); however, substantial within and between subject variation in the position of the GBCA peak was observed. Average area under the curve for gadolinium peaks in the hair samples was a better predictor of gadolinium dose (R2 = 0.41; p = 0.0046), compared to the average of peak maxima concentration. Correlation between area under the curve and dose suggests that LA-ICP-MS analysis of hair may be an effective method to evaluate gadolinium levels in subjects in vivo after exposure to GBCAs. This study demonstrates that analysis of human hair using techniques with high spatial resolution such as LA-ICP-MS has excellent potential to reveal time-dependent signatures of past exposures.

Molecular imaging of orthotopic prostate cancer with nanobubble ultrasound contrast agents targeted to PSMA

Ultrasound imaging is routinely used to guide prostate biopsies, yet delineation of tumors within the prostate gland is extremely challenging, even with microbubble (MB) contrast. A more effective ultrasound protocol is needed that can effectively localize malignancies for targeted biopsy or aid in patient selection and treatment planning for organ-sparing focal therapy. This study focused on evaluating the application of a novel nanobubble ultrasound contrast agent targeted to the prostate specific membrane antigen (PSMA-targeted NBs) in ultrasound imaging of prostate cancer (PCa) in vivo using a clinically relevant orthotopic tumor model in nude mice. Our results demonstrated that PSMA-targeted NBs had increased extravasation and retention in PSMA-expressing orthotopic mouse tumors. These processes are reflected in significantly different time intensity curve (TIC) and several kinetic parameters for targeted versus non-targeted NBs or LUMASON MBs. These, may in turn, lead to improved image-based detection and diagnosis of PCa in the future.

A method for material decomposition and quantification with grating based phase CT

Material decomposition (MD) is an important application of computer tomography (CT). For phase contrast imaging, conventional MD methods are categorized into two types with respect to different operation sequences, i.e., “before” or “after” image reconstruction. Both categories come down to two-step methods, which have the problem of noise amplification. In this study, we incorporate both phase and absorption (PA) information into MD process, and correspondingly develop a simultaneous algebraic reconstruction technique (SART). The proposed method is referred to as phase & absorption material decomposition-SART (PAMD-SART). By iteratively solving an optimization problem, material composition and substance quantification are reconstructed directly from absorption and differential phase projections. Comparing with two-step MD, the proposed one-step method is superior in noise suppression and accurate decomposition. Numerical simulations and synchrotron radiation based experiments show that PAMD-SART outperforms the classical MD method (image-based and dual-energy CT iterative method), especially for the quantitative accuracy of material equivalent atomic number.

Speciation analysis of Gadolinium-based contrast agents using aqueous eluent-hydrophilic interaction liquid chromatography hyphenated with inductively coupled plasma-mass spectrometry

Gadolinium chelates are widely used as contrast agents for magnetic resonance imaging (MRI). In recent decades, the amount of Gd in river water has been increasing owing to the input of Gd-based contrast agents. To identify and quantify the Gd-based contrast agents in river water, the novel technique of hydrophilic interaction liquid chromatography (HILIC) hyphenated with inductively coupled plasma-mass spectrometry (ICP-MS) was developed. To avoid deposition of carbon on the ICP-MS interface, a mobile phase consisting of an ammonium acetate buffer diluted with pure water was applied to separate Gd-based contrast agents. Despite the absence of an organic solvent in the mobile phase, six Gd-based contrast agents, Gd-DTPA, Gd-EOB-DTPA, Gd-DOTA, Gd-DTPA-BMA, Gd-BT-DO3A, and Gd-HP-DO3A, were successfully separated. This technique was applied for river water samples. As a result, Gd-DOTA, Gd-BT-DO3A, and Gd-HP-DO3A were observed from the sample near the outfall of a wastewater treatment plant (WWTP), indicating that at least some of the Gd-based contrast agents are passed through treatment in a WWTP. In addition to Gd-based contrast agents, unidentified Gd compounds were found to be present in river water. These results infer that transformation and/or dissociation of Gd chelates may be caused during the treatment procedure in a WWTP.

Deposition patterns of iatrogenic lanthanum and gadolinium in the human body depend on delivered chemical binding forms

BACKGROUND

Recently, gadolinium from linear GBCAs has been reported to deposit in various regions of the body. Besides gadolinium, other lanthanides are used in medical care. In the current study, we investigated deposition of lanthanum in two patients who received lanthanum carbonate as a phosphate binder due to chronic kidney injury and compared it to additionally found Gd deposition.

METHODS

Tissue specimens of two patients with long-term application of lanthanum carbonate as well as possible GBCA application were investigated. Spatial distribution of gadolinium and lanthanum was determined by quantitative laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) imaging of tissue sections. The deposition of gadolinium and lanthanum in different organs was compared, and the ratio of Gd concentration to La concentration (Gd-to-La-ratio) was investigated on an individual pixel base within the images.

RESULTS

Deposition of Gd and La was found in all investigated tissues of both patients. Gd and La exhibited high spatial correlation for all samples, with the main deposition being located in the middle coat (tunica media) of blood vessels. The Gd-to-La-ratio was similar in the tissues investigated (between 8 ± 4 (mean ± standard deviation) and 10 ± 2), except for the thyroid vasculature and surrounding tissue (90 ± 17) as well as the cerebellum (270 ± 18). Here, the ratio was significantly increased towards higher Gd concentration.

CONCLUSION

The results of this study demonstrate long-term deposition of La and comparable localization of additionally found Gd in various tissues of the body. La deposition was relatively low, considering the total administered amount of lanthanum carbonate of up to 11.5 kg, indicating a low absorption and/or high excretion of lanthanum. However, the total amount of deposited La is significant and raises questions about possible adverse side effects. The ratio-approach allows for the usage of the additionally generated Gd data, without detailed knowledge about possible GBCA applications. The significantly decreased Gd-to-La-ratio in the brain might be explained by the lanthanum being released and taken up as free La³⁺ ion in the stomach that impedes a crossing of the blood-brain-barrier while the intravenously injected GBCAs might dechelate first when they have already crossed the blood-brain-barrier.

Magnetic nanowires in biomedical applications

Magnetic nanostructures and nanomaterials play essential roles in modern bio medicine and technology. Proper surface functionalization of nanoparticles (NPs) allows the selective bonding thus application of magnetic forces to a vast range of cellular structures and biomolecules. However, the spherical geometry of NPs poises a series of limitations in various potential applications. Mostly, typical spherical core shell structure consists of magnetic and non-magnetic layers have little tunability in terms of magnetic responses, and their single surface functionality also limits chemical activity and selectivity. In comparison to spherical NPs, nanowires (NWs) possess more degrees of freedom in achieving magnetic and surface chemical tenability. In addition to adjustment of magnetic anisotropy and inter-layer interactions, another important feature of NWs is their ability to combine different components along their length, which can result in diverse bio-magnetic applications. Magnetic NWs have become the candidate material for biomedical applications owing to their high magnetization, cheapness and cost effective synthesis. With large magnetic moment, anisotropy, biocompatibility and low toxicity, magnetic NWs have been recently used in living cell manipulation, magnetic cell separation and magnetic hyperthermia. In this review, the basic concepts of magnetic characteristics of nanoscale objects and the influences of aspect ratio, composition and diameter on magnetic properties of NWs are addressed. Some underpinning physical principles of magnetic hyperthermia (MH), magnetic resonance imaging (MRI) and magnetic separation (MS) have been discussed. Finally, recent studies on magnetic NWs for the applications in MH, MRI and MS were discussed in detail.

Manganese-free chow, a refined non-invasive solution to reduce gastrointestinal signal for T1-weighted magnetic resonance imaging of the mouse abdomen

Commercial mouse chow is designed to provide a complete, nutrient-rich diet, and it can contain upwards of 100 mg/kg manganese, an essential mineral. Manganese acts as a relaxation time-shortening contrast agent for both T1 and T2, and where standard chow is hydrated in the gastrointestinal tract, bright signals are produced when using T1-weighted imaging (T1WI). As a result of peristalsis, gastrointestinal hyperintensities result in temporally unstable signals, leading to image ghosting and decreased resolution from that prescribed. To avoid the problem, various methods of gastrointestinal tract modulation, including the use of intestinal cleansing with laxatives and dietary modulation, have been reported. Here, dietary modulation has been extended to the use of a biologically innocuous, long-term change of diet. In this study, we report on the use of a commercially available manganese-free chow to improve the image quality of the gastrointestinal tract. This manganese-free chow, apart from the omitted manganese which is available in tap water, is a complete diet and readily available. We investigated the time-dependent, diet-related gastrointestinal intensities on short-TR T1WI magnetic resonance imaging; monitored body mass, food and water consumption and standard blood biochemistry analysis following diet change; and determined manganese concentration in blood plasma following a five-day change to manganese-free chow. We show that the manganese-free chow presents a refinement to other gastrointestinal tract modulation, as it avoids the need for invasive procedures for gut voiding and can be provided ad libitum so that animals can be maintained with no need for prescribed diet change before imaging.

Distinguishing Extravascular from Intravascular Ferumoxytol Pools within the Brain: Proof of Concept in Patients with Treated Glioblastoma

BACKGROUND AND PURPOSE

Glioblastoma-associated macrophages are a major constituent of the immune response to therapy and are known to engulf the iron-based MR imaging contrast agent, ferumoxytol. Current ferumoxytol MR imaging techniques for localizing macrophages are confounded by contaminating intravascular signal. The aim of this study was to assess the utility of a newly developed MR imaging technique, segregation and extravascular localization of ferumoxytol imaging, for differentiating extravascular-from-intravascular ferumoxytol contrast signal at a delayed 24-hour imaging time point.

MATERIALS AND METHODS

Twenty-three patients with suspected post-chemoradiotherapy glioblastoma progression underwent ferumoxytol-enhanced SWI. Segregation and extravascular localization of ferumoxytol imaging maps were generated as the voxelwise difference of the delayed (24 hours) from the early (immediately after administration) time point SWI maps. Continuous segregation and extravascular localization of ferumoxytol imaging map values were separated into positive and negative components. Image-guided biologic correlation was performed.

RESULTS

Negative segregation and extravascular localization of ferumoxytol imaging values correlated with early and delayed time point SWI values, demonstrating that intravascular signal detected in the early time point persists into the delayed time point. Positive segregation and extravascular localization of ferumoxytol imaging values correlated only with delayed time point SWI values, suggesting successful detection of the newly developed extravascular signal.

CONCLUSIONS

Segregation and extravascular localization of ferumoxytol MR imaging improves on current techniques by eliminating intrinsic tissue and intravascular ferumoxytol signal and may inform glioblastoma outcomes by serving as a more specific metric of macrophage content compared with uncorrected T1 and SWI techniques.

Two-way magnetic resonance tuning and enhanced subtraction imaging for non-invasive and quantitative biological imaging

Distance-dependent magnetic resonance tuning (MRET) technology enables the sensing and quantitative imaging of biological targets in vivo, with the advantage of deep tissue penetration and fewer interactions with the surroundings as compared with those of fluorescence-based Förster resonance energy transfer. However, applications of MRET technology in vivo are currently limited by the moderate contrast enhancement and stability of T₁-based MRET probes. Here we report a new two-way magnetic resonance tuning (TMRET) nanoprobe with dually activatable T₁ and T₂ magnetic resonance signals that is coupled with dual-contrast enhanced subtraction imaging. This integrated platform achieves a substantially improved contrast enhancement with minimal background signal and can be used to quantitatively image molecular targets in tumours and to sensitively detect very small intracranial brain tumours in patient-derived xenograft models. The high tumour-to-normal tissue ratio offered by TMRET in combination with dual-contrast enhanced subtraction imaging provides new opportunities for molecular diagnostics and image-guided biomedical applications.

Short Acquisition Time Super-Resolution Ultrasound Microvessel Imaging via Microbubble Separation

Super-resolution ultrasound localization microscopy (ULM), based on localization and tracking of individual microbubbles (MBs), offers unprecedented microvascular imaging resolution at clinically relevant penetration depths. However, ULM is currently limited by the requirement of dilute MB concentrations to ensure spatially sparse MB events for accurate localization and tracking. The corresponding long imaging acquisition times (tens of seconds or several minutes) to accumulate sufficient isolated MB events for full reconstruction of microvasculature preclude the clinical translation of the technique. To break this fundamental tradeoff between acquisition time and MB concentration, in this paper we propose to separate spatially overlapping MB events into sub-populations, each with sparser MB concentration, based on spatiotemporal differences in the flow dynamics (flow speeds and directions). MB localization and tracking are performed for each sub-population separately, permitting more robust ULM imaging of high-concentration MB injections. The superiority of the proposed MB separation technique over conventional ULM processing is demonstrated in flow channel phantom data, and in the chorioallantoic membrane of chicken embryos with optical imaging as an in vivo reference standard. Substantial improvement of ULM is further demonstrated on a chicken embryo tumor xenograft model and a chicken brain, showing both morphological and functional microvasculature details at super-resolution within a short acquisition time (several seconds). The proposed technique allows more robust MB localization and tracking at relatively high MB concentrations, alleviating the need for dilute MB injections, and thereby shortening the acquisition time of ULM imaging and showing great potential for clinical translation.

A direct injection liquid chromatography tandem mass spectrometry method for the kinetic study on iodinated contrast media (ICMs) removal in natural water

Iodinated contrast media (ICMs) are a class of X-ray contrast media worldwide utilized for radiographic procedures. Since they cannot be removed efficiently during water treatment, they can be found in surface and groundwater. In this work, a rapid and sensitive direct injection liquid chromatography-tandem (LC-MS/MS) method for the simultaneous analysis of seven ICMs media (iopamidol, ioxitalamic acid, diatrizoic acid, iothalamic acid, iohexol, iomeprol and iopromide) in complex aqueous matrices has been developed and validated. The MDLs for the analytes ranged from 0.7 to 21 ng L^-1 in ultrapure water, and recoveries ranged from 86 to 100% in drinking water, 85-103% in groundwater and 84-105% in WWTP effluent. A stereo-isomer for iopromide was separated. This analytic method was applied to investigate the removal of target ICMs by low pressure ultra violet light (LPUV) advanced oxidation processes with three oxidants, hydrogen peroxide, free chlorine and monochloramine in groundwater. Results showed that the addition of oxidants did not enhance attenuation of ICMs, since fluence-based decay apparent rate constants were similar (K_UV = 3.2 × 10^-3, K_UV-Cl2 = 3.6 × 10^-3 and K_UV-NH2 = 3.4 × 10^-3 10^-3 cm² mJ^-1). This yielded direct photolysis is the main mechanism to attenuate target ICMs.

Nephrogenic Systemic Fibrosis Risk Assessment and Skin Biopsy Quantification in Patients with Renal Disease following Gadobenate Contrast Administration

BACKGROUND AND PURPOSE

Nephrogenic systemic fibrosis following administration of intravenous gadobenate during MR imaging is rare. This study aimed to analyze any nephrogenic systemic fibrosis-related risks and quantify skin gadolinium levels in patients with impaired renal function but without nephrogenic systemic fibrosis who had received gadobenate.

MATERIALS AND METHODS

In this retrospective study with a prospective skin biopsy phase, patients with estimated glomerular filtration rates of <60 mL/min/1.73 m² undergoing contrast-enhanced MR imaging from July 2007 through June 2014 were screened for nephrogenic systemic fibrosis using a questionnaire. This was highly sensitive but not specific and reliably excluded nephrogenic systemic fibrosis if responses to at least 6 of the 8 questions were negative. If no nephrogenic systemic fibrosis was detected, a skin biopsy was requested.

RESULTS

Of 2914 patients who met these criteria, 1988 were excluded for various reasons. Of the remaining 926 patients, 860 were screened negative for nephrogenic systemic fibrosis. Of these, 17 (2%) had estimated glomerular filtration rates of <15 mL/min/1.73 m², 51 (6%) had levels of 15 < 30 mL/min/1.73 m², 234 (27%) had levels of 30 < 45 mL/min/1.73 m², and 534 (62%) had levels of 45 < 60 mL/min/1.73 m². Of the 66 who were not cleared of nephrogenic systemic fibrosis by the questionnaire, 6 patients were evaluated by a dermatologist and confirmed not to have nephrogenic systemic fibrosis (no biopsy required).

CONCLUSIONS

A diagnosis of nephrogenic systemic fibrosis was excluded in 860 patients with impaired renal function who were followed up and received gadobenate during MR imaging. In 14 such patients who underwent at least 1 gadobenate-enhanced MR imaging examination and did not have nephrogenic systemic fibrosis, gadolinium levels in the skin were exceedingly low.

The role of gadolinium in magnetic resonance imaging for early prostate cancer diagnosis: A diagnostic accuracy study

Objective

Prostate lesions detected with multiparametric magnetic resonance imaging (mpMRI) are classified for their malignant potential according to the Prostate Imaging-Reporting And Data System (PI-RADS™2). In this study, we evaluate the diagnostic accuracy of the mpMRI with and without gadolinium, with emphasis on the added diagnostic value of the dynamic contrast enhancement (DCE).

Materials and methods

The study was retrospective for 286 prostate lesions / 213 eligible patients, n = 116/170, and 49/59% malignant for the peripheral (Pz) and transitional zone (Tz), respectively. A stereotactic MRI-guided prostate biopsy served as the histological ground truth. All patients received a mpMRI with DCE. The influence of DCE in the prediction of malignancy was analyzed by blinded assessment of the imaging protocol without DCE and the DCE separately.

Results

Significant (CSPca) and insignificant (IPca) prostate cancers were evaluated separately to enhance the potential effects of the DCE in the detection of CSPca. The Receiver Operating Characteristics Area Under Curve (ROC-AUC), sensitivity (Se) and specificity (Spe) of PIRADS-without-DCE in the Pz was 0.70/0.47/0.86 for all cancers (IPca and CSPca merged) and 0.73/0.54/0.82 for CSPca. PIRADS-with-DCE for the same patients showed ROC-AUC/Se/Spe of 0.70/0.49/0.86 for all Pz cancers and 0.69/0.54/0.81 for CSPca in the Pz, respectively, p>0.05 chi-squared test. Similar results for the Tz, AUC/Se/Spe for PIRADS-without-DCE was 0.75/0.61/0.79 all cancers and 0.67/0.54/0.71 for CSPca, not influenced by DCE (0.66/0.47/0.81 for all Tz cancers and 0.61/0.39/0.75 for CSPca in Tz). The added Se and Spe of DCE for the detection of CSPca was 88/34% and 78/33% in the Pz and Tz, respectively.

Conclusion

DCE showed no significant added diagnostic value and lower specificity for the prediction of CSPca compared to the non-enhanced sequences. Our results support that gadolinium might be omitted without mitigating the diagnostic accuracy of the mpMRI for prostate cancer.

Binding of iodinated contrast media (ICM) and their transformation products with hormone receptors: Are ICM the new EDCs?

Iodinated contrast media (ICM) have been detected at high concentrations (as high as about 3 μg/L) in surface water systems, and recently in fish brains and gonad. The mismatch between the polarity of ICM and the high lipid content of brain raises questions on whether their bioaccumulation is receptor-mediated. Furthermore, the structural similarity of ICM to the natural thyroid hormones thyroxine and triiodothyronine suggest potential binding of ICM to nuclear receptors in the endocrine system. Therefore, an in silico approach based on Surflex-Dock module of SYBYL was used to investigate the molecular docking of selected ICM (diatrizoic acid, iohexol, iopamidol, and iopromide). These ICM showed interaction with nuclear receptors that play key roles in endocrine regulation, including the androgen and estrogen receptors. Furthermore, the results indicate peroxisome proliferator-activated receptor gamma (PPARg) as one of the viable targets in the endocrine disrupting potential of ICM with higher Cscores for the ICM and iopromide transformation products than the reference ligand for the receptor. The data obtained from in silico calculations showed stronger binding of iohexol to the transthyretin-binding pocket compared to the natural hormones, thyroxine and triiodothyronine, suggesting the potential of ICM to act as endocrine disrupting chemicals (EDCs) in the environment.

Exploring the tumour extracellular matrix by in vivo Fast Field Cycling relaxometry after the administration of a Gadolinium-based MRI contrast agent

¹ H Fast Field Cycling NMR (FFC-NMR) relaxometry is proposed as a powerful method to investigate tumour stroma in vivo upon the administration of a Gd-based contrast agent. To perform this study, an FFC-NMR equipment endowed with a wide bore magnet was used for the acquisition of Nuclear Magnetic Resonance Dispersion profiles on healthy muscle and tumour tissue in living mice. At magnetic field strengths < of ca. 1 MHz, the differences in the relaxation rates of the intra and extracellular compartment become of the same order of magnitude of the exchange rate across the cellular membranes. Under this condition, the water exchange rate between the two compartments yields to a biexponential magnetization recovery that can be analysed by fitting the experimental data with the two-Site eXchange (2SX) model. Using this model, it was possible to obtain, for the two compartments, both relaxation properties and water kinetic constants for water exchange across cell membranes. The method allowed us to determine the effect of the "matrix" on the water proton relaxation times and, in turn, to get some insights of the composition of this compartment, till now, largely unknown.

Iohexol-measured glomerular filtration rate in children and adolescents with chronic kidney disease: a pilot study comparing venous and finger stick methods

BACKGROUND

Measurement of glomerular filtration rate by iohexol disappearance (iGFR) has become a gold standard in the pediatric chronic kidney disease (CKD) population. The need for serial phlebotomy can be difficult and minimizing venipunctures would be beneficial. Furthermore, finger stick collection for dried blood spot (DBS) may be more tolerable in the pediatric population, and equivalence between these two methods may further simplify the process.

METHODS

This was a cross-sectional study in children and adolescents 1 to 21 years with stages I-IV CKD. Iohexol was infused and blood drawn 10, 30, 120, and 300 min later. Blood spots on filter paper were collected by finger stick after each of the latter two blood draws. The rate of iohexol plasma disappearance was used to calculate GFR. Pearson's correlation coefficient and bias, Students t test, and Bland-Altman graphical representations were used to compare methods.

RESULTS

Forty-one patients were recruited. The mean creatinine was 1.13 mg/dL (SD 0.45), the mean 4-point iGFR was 73.2 ml/min/1.73m² (SD 27.5) and the mean 2-point iGFR was 75.6 ml/min/1.73m² (SD 27.3). Correlation between 2-point and 4-point venous GFR was r = 0.97; p < 0.001. The correlation between the DBS and the 2-point venous GFR was r = 0.95; p < 0.001, with no significant bias. Ninety-four percent of the 2-point GFR's were within 10% of the 4-point GFR's and 80% of DBS-GFRs were within 10% of the 2-point GFR's.

CONCLUSIONS

The 2-point iGFR was highly correlated and agreed well with the 4-point iGFR. The same was true for the DBS method and the 2-point venous method. DBS sampling by finger stick sampling at 2 time points after iohexol infusion gave an acceptably accurate measurement of GFR.

Detection of artificial sweeteners and iodinated X-ray contrast media in wastewater via LC-MS/MS and their potential use as anthropogenic tracers in flowing waters

The detection of wastewater impact on stream chemistry is often hindered by high background concentrations of ubiquitous solutes. In the present study we tested the applicability of artificial sweeteners (AS) and iodinated X-ray contrast media (ICM) as tracers to detect this impact by examining wastewater treatment plant (WWTP) effluents and surface water samples. The developed direct injection LC-MS/MS method enabled the detection of these anthropogenic micropollutants in aqueous samples down to trace level concentrations. The 2-h-composite sampling of WWTP effluent revealed fluctuating ICM concentrations between and within days with highest concentrations at the end of the week. Diatrizoic acid (DTZ) and iopromide (IOP) were the predominant ICM with concentrations up to 7 μg/L. Concentrations of the AS acesulfame (ACE) fluctuated between 0.5 μg/L and 1 μg/L. Concentrations of AS and ICM in surface water were both associated with wastewater impact. DTZ contamination was more widespread whereas some sampling points exhibited a more pronounced contamination with non-ionic ICM. Surface water was frequently contaminated with AS. Particularly ACE was detected in every surface water sample indicating that it is chemically stable and that inputs to the aquatic environment via WWTP effluents are widespread. The broad application of ACE as food additive enables its application as a tracer throughout Germany. Furthermore, the developed LC-MS/MS method enables rapid detection of ACE down to the low ng/L-range. Nonetheless, DTZ or IOP could be used in addition to ACE to verify anthropogenic influences on natural waters.

Noninvasive Imaging of Endothelial Damage in Patients With Different HbA1c Levels: A Proof-of-Concept Study

The aim of this study was to compare endothelial permeability, which is considered a hallmark of coronary artery disease, between patients with different HbA_1c levels using an albumin-binding magnetic resonance (MR) probe. This cross-sectional study included 26 patients with clinical indication for X-ray angiography who were classified into three groups according to HbA_1c level (<5.7% [<39 mmol/mol], 5.7-6.4% [39-47 mmol/mol], and ≥6.5% [48 mmol/mol]). Subjects underwent gadofosveset-enhanced coronary magnetic resonance and X-ray angiography including optical coherence within 24 h. Contrast-to-noise ratios (CNRs) were assessed to measure the probe uptake in the coronary wall by coronary segment, excluding those with culprit lesions in X-ray angiography. In the group of patients with HbA_1c levels between 5.7 and 6.4%, 0.30 increased normalized CNR values were measured, compared with patients with HbA_1c levels <5.7% (0.30 [95% CI 0.04, 0.57]). In patients with HbA_1c levels ≥6.5%, we found 0.57 higher normalized CNR values compared with patients with normal HbA_1c levels (0.57 [95% CI 0.28, 0.85]) and 0.26 higher CNR values for patients with HbA_1c level ≥6.5% compared with patients with HbA_1c levels between 5.7 and 6.4% (0.26 [95% CI -0.04, 0.57]). Additionally, late atherosclerotic lesions were more common in patients with high HbA_1c levels (HbA_1c ≥6.5%, n = 14 [74%]; HbA_1c 5.7-6.4%, n = 6 [60%]; and HbA_1c <5.7%, n = 10 [53%]). In conclusion, coronary MRI in combination with an albumin-binding MR probe suggests that both patients with intermediate and patients with high HbA_1c levels are associated with a higher extent of endothelial damage of the coronary arteries compared with patients with HbA_1c levels <5.7%.

Physicians' awareness of gadolinium retention and MRI timing practices in the longitudinal management of pituitary tumors: a "Pituitary Society" survey

PURPOSE

In view of mounting attention related to possible brain retention of gadolinium-based contrast agents (GBCAs) in patients with normal renal function, our purpose was to detail results from a survey of pituitary experts to assess: 1) the timing interval and frequency of pituitary magnetic resonance imaging (MRI) following surgical and/or medical and/or radiation therapy of pituitary tumors, 2) awareness of the types of GBCAs used and their possible safety issues.

METHODS

The Pituitary Society Education Committee composed a survey with 12 multiple choice questions, 8 of which specifically addressed the time interval and frequency of MRI in the longitudinal management of pituitary tumors. The survey was distributed at two meetings; the International Pituitary Neurosurgeons Society conference in San Diego, CA, on February 18th, 2018, and the Pituitary Society Membership and Career Development Forum, Chicago, IL on March 18th, 2018.

RESULTS

There is consensus among pituitary endocrinologists and neurosurgeons that long-term repeated imaging is recommended in most pituitary tumors, although the precise strategy of timing varied depending on the specialist group and the specific clinical context of the adenoma. The data also suggest that International Pituitary Neurosurgeons Society neurosurgeons, as well as Pituitary Society neuroendocrinologists, are sometimes unaware of which contrast agents are used by their institution, and many are also unaware that evidence of long-term brain retention has been reported with the use of GBCAs in patients with normal function.

CONCLUSIONS

International pituitary endocrinologists and pituitary neurosurgeons experts suggest ongoing MRIs for the management of pituitary tumors; strategies vary based on clinical context, but also on individual experience and practice.

Quantitative dried blood spot analysis for metallodrugs by laser ablation-inductively coupled plasma-mass spectrometry

A quantitative dried blood spot (DBS) method based on direct sampling by means of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is presented. Gadolinium-based contrast agents were used as model metallodrugs with a significant relevance for pharmaceutical applications. Challenges regarding the ablation of the complex blood-filter matrix were characterized and successfully addressed by a thorough adaption of the laser ablation conditions. Especially the laser fluence was optimized with respect to the particle size distribution of the generated aerosol as monitored by an optical particle counter. Thus, generation of micrometer-sized particles could be minimized in favor of smaller particles increasing the transport efficiency of the DBS ablation aerosol to the plasma and the recorded signal stability. Inhomogeneous blood drying on the porous filter paper could be compensated by the addition of an internal standard prior to blood spotting. To preserve the advantages of DBS sampling, such as small blood volumes and minimal invasiveness, the combined use of DBS and a capillary blood sampling system is demonstrated. By placing the internal standard into the capillary prior to blood sampling, a simple workflow usable for clinical application was implemented. The applicability of the developed method, achieving limits of detection and quantification in the low μg L^-1 range and covering a linear range of over four orders of magnitude, was demonstrated for blood samples containing different concentrations of the gadolinium contrast agents gadopentetate and gadoterate.

Differentiation of Hemorrhage from Iodine Using Spectral Detector CT: A Phantom Study

BACKGROUND AND PURPOSE

Conventional CT often cannot distinguish hemorrhage from iodine extravasation following reperfusion therapy for acute ischemic stroke. We investigated the potential of spectral detector CT in differentiating these lesions.

MATERIALS AND METHODS

Centrifuged blood with increasing hematocrit (5%-85%) was used to model hemorrhage. Pure blood, blood-iodine mixtures (75/25, 50/50, and 25/75 ratios), and iodine solutions (0-14 mg I/mL) were scanned in a phantom with attenuation ranging from 12 to 75 HU on conventional imaging. Conventional and virtual noncontrast attenuation was compared and investigated for correlation with calculation of relative virtual noncontrast attenuation. Values for all investigated categories were compared using the Mann-Whitney U test. Sensitivity and specificity of virtual noncontrast, relative virtual noncontrast, conventional CT attenuation, and iodine quantification for hemorrhage detection were determined with receiver operating characteristic analysis.

RESULTS

Conventional image attenuation was not significantly different among all samples containing blood (P > .05), while virtual noncontrast attenuation showed a significant decrease with a decreasing blood component (P < .01) in all blood-iodine mixtures. Relative virtual noncontrast values were significantly different among all investigated categories (P < .01), with correct hemorrhagic component size estimation for all categories within a 95% confidence interval. Areas under the curve for hemorrhage detection were 0.97, 0.87, 0.29, and 0.16 for virtual noncontrast, relative virtual noncontrast, conventional CT attenuation, and iodine quantification, respectively. A ≥10-HU virtual noncontrast, ≥20-HU virtual noncontrast, ≥40% relative virtual noncontrast, and combined ≥10-HU virtual noncontrast and ≥40% relative virtual noncontrast attenuation threshold had a sensitivity/specificity for detecting hemorrhage of 100%/23%, 89%/95%, 100%/82%, and 100%/100%, respectively.

CONCLUSIONS

Spectral detector CT can accurately differentiate blood from iodinated contrast in a phantom setting.

Preliminary Assessment of a Microwave System to Detect Contrast Enhancing Agents

This paper presents a preliminary study of the impact of potential contrast enhancing agents on a 2-port microwave imaging system. To this end, we have conducted microwave measurements inside a dual cylindrical tank, comprised of an outer and inner cylinder filled with high and low loss liquids, respectively. A third smaller cylinder inside the low loss filled tank represents a target. The target materials consisted of safflower oil, water, PEGylated zinc oxide nanoparticles dispersed in water, and saline with varying concentrations of salt. To benchmark our experimental results, we have also performed accurate numerical simulations of the system under three target scenarios: safflower oil, water, and PEGylated zinc oxide suspension. Our results show that the difference in received signal strength in scenarios with and without PEGylated zinc oxide nanoparticles in our 2-port system was comparable to measurement error. However, with the use of varying concentrations of saline solutions as a target, we have observed a significant difference in received signal strength.

Diffusion weighted and dynamic contrast enhanced MRI as an imaging biomarker for stereotactic ablative body radiotherapy (SABR) of primary renal cell carcinoma

Purpose

To explore the utility of diffusion and perfusion changes in primary renal cell carcinoma (RCC) after stereotactic ablative body radiotherapy (SABR) as an early biomarker of treatment response, using diffusion weighted (DWI) and dynamic contrast enhanced (DCE) MRI.

Methods

Patients enrolled in a prospective pilot clinical trial received SABR for primary RCC, and had DWI and DCE MRI scheduled at baseline, 14 days and 70 days after SABR. Tumours <5cm diameter received a single fraction of 26 Gy and larger tumours received three fractions of 14 Gy. Apparent diffusion coefficient (ADC) maps were computed from DWI data and parametric and pharmacokinetic maps were fitted to the DCE data. Tumour volumes were contoured and statistics extracted. Spearman’s rank correlation coefficients were computed between MRI parameter changes versus the percentage tumour volume change from CT at 6, 12 and 24 months and the last follow-up relative to baseline CT.

Results

Twelve patients were eligible for DWI analysis, and a subset of ten patients for DCE MRI analysis. DCE MRI from the second follow-up MRI scan showed correlations between the change in percentage voxels with washout contrast enhancement behaviour and the change in tumour volume (ρ = 0.84, p = 0.004 at 12 month CT, ρ = 0.81, p = 0.02 at 24 month CT, and ρ = 0.89, p = 0.001 at last follow-up CT). The change in mean initial rate of enhancement and mean Ktrans at the second follow-up MRI scan were positively correlated with percent tumour volume change at the 12 month CT onwards (ρ = 0.65, p = 0.05 and ρ = 0.66, p = 0.04 at 12 month CT respectively). Changes in ADC kurtosis from histogram analysis at the first follow-up MRI scan also showed positive correlations with the percentage tumour volume change (ρ = 0.66, p = 0.02 at 12 month CT, ρ = 0.69, p = 0.02 at last follow-up CT), but these results are possibly confounded by inflammation.

Conclusion

DWI and DCE MRI parameters show potential as early response biomarkers after SABR for primary RCC. Further prospective validation using larger patient cohorts is warranted.

Molecular imaging agents for ultrasound

Ultrasound (US) imaging is a safe, sensitive and affordable imaging modality with a wide usage in the clinic. US signal can be further enhanced by using echogenic contrast agents (UCAs) which amplify the US signal. Developments in UCAs which are targeted to sites of disease allow the use of US imaging to provide molecular information. Unfortunately, traditional UCAs are too large to leave the vascular space limiting the application of molecular US to intravascular markers. In this mini review, we highlight the most recent reports on the application of molecular US imaging in the clinic and summarize the latest nanoparticle platforms used to develop nUCAs. We believe that the highlighted technologies will have a great impact on the evolution of the US imaging field.

Magnetic particle imaging for radiation-free, sensitive and high-contrast vascular imaging and cell tracking

Magnetic particle imaging (MPI) is an emerging ionizing radiation-free biomedical tracer imaging technique that directly images the intense magnetization of superparamagnetic iron oxide nanoparticles (SPIOs). MPI offers ideal image contrast because MPI shows zero signal from background tissues. Moreover, there is zero attenuation of the signal with depth in tissue, allowing for imaging deep inside the body quantitatively at any location. Recent work has demonstrated the potential of MPI for robust, sensitive vascular imaging and cell tracking with high contrast and dose-limited sensitivity comparable to nuclear medicine. To foster future applications in MPI, this new biomedical imaging field is welcoming researchers with expertise in imaging physics, magnetic nanoparticle synthesis and functionalization, nanoscale physics, and small animal imaging applications.

Big Potential from Small Agents: Nanoparticles for Imaging-Based Companion Diagnostics

The importance of medical imaging in the diagnosis and monitoring of cancer cannot be overstated. As personalized cancer treatments are gaining popularity, a need for more advanced imaging techniques has grown significantly. Nanoparticles are uniquely suited to fill this void, not only as imaging contrast agents but also as companion diagnostics. This review provides an overview of many ways nanoparticle imaging agents have contributed to cancer imaging, both preclinically and in the clinic, as well as charting future directions in companion diagnostics. We conclude that, while nanoparticle-based imaging agents are not without considerable scientific and developmental challenges, they enable enhanced imaging in nearly every modality, hold potential as in vivo companion diagnostics, and offer precise cancer treatment and maximize intervention efficacy.

Development of a Fluid Dynamic Model for Quantitative Contrast-Enhanced Ultrasound Imaging

Contrast-enhanced ultrasound (CEUS) is a non-invasive imaging technique extensively used for blood perfusion imaging of various organs. This modality is based on the acoustic detection of gas-filled microbubble contrast agents used as intravascular flow tracers. Recent efforts aim at quantifying parameters related to the enhancement in the vascular compartment using time-intensity curve (TIC), and at using these latter as indicators for several pathological conditions. However, this quantification is mainly hampered by two reasons: first, the quantification intrinsically solely relies on temporal intensity variation, the explicit spatial transport of the contrast agent being left out. Second, the exact relationship between the acquired US-signal and the local microbubble concentration is hardly accessible. This paper introduces the use of a fluid dynamic model for the analysis of dynamic CEUS (DCEUS), in order to circumvent the two above-mentioned limitations. A new kinetic analysis is proposed in order to quantify the velocity amplitude of the bolus arrival. The efficiency of proposed methodology is evaluated both in-vitro, for the quantitative estimation of microbubble flow rates, and in-vivo, for the classification of placental insufficiency (control versus ligature) of pregnant rats from DCEUS. Besides, for the in-vivo experimental setup, we demonstrated that the proposed approach outperforms the performance of existing TIC-based methods.

Distribution and relevance of iodinated X-ray contrast media and iodinated trihalomethanes in an aquatic environment

Distribution and relevance of iodinated X-ray contrast media (ICM) and iodinated disinfection byproducts (I-DBPs) in a real aquatic environment have been rarely documented. In this paper, some ICM were proven to be strongly correlated with I-DBPs through investigation of five ICM and five iodinated trihalomethanes (I-THMs) in surface water and two drinking water treatment plants (DWTPs) of the Yangtze River Delta, China. The total ICM concentrations in Taihu Lake and the Huangpu River ranged from 88.7 to 131 ng L^-1 and 102-252 ng L^-1, respectively. While the total I-THM concentrations ranged from 128 to 967 ng L^-1 in Taihu Lake and 267-680 ng L^-1 in the Huangpu River. Iohexol, the dominant ICM, showed significant positive correlation (p < 0.01) with CHClI₂ in Taihu Lake. Iopamidol and iomeprol correlated positively (p < 0.01) with some I-THMs in the Huangpu River. The observed pronounced correlations between ICM and I-THMs indicated that ICM play an important role in the formation of I-THMs in a real aquatic environment. Characteristics of the I-THM species distributions indicated that I-THMs may be transformed by natural conditions. Both DWTPs showed negligible removal efficiencies for total ICM (<20%). Strikingly high concentrations of total I-THMs were observed in the finished water (2848 ng L^-1 in conventional DWTP and 356 ng L^-1 in advanced DWTP). Obvious transformation of ICM to I-THMs was observed during the chlorination and ozonization processes in DWTPs. We suggest that ICM is an important source for I-DBP formation in the real aquatic environment.

T1w dark blood imaging improves detection of contrast enhancing lesions in multiple sclerosis

PURPOSE

In multiple sclerosis (MS) the sensitivity for detection of contrast enhancing lesions (CEL) in T1-weighted scans is essential for diagnostics and therapy decisions. The purpose of our study was to evaluate the sensitivity of T1w MPRAGE scans in comparison to T1w dark blood technique (T1-DB) for CEL in MS.

MATERIALS AND METHODS

3T MR imaging was performed in 37 MS patients, including T2-weighted imaging, T1w MPRAGE before and after gadolinium injection (unenhanced-T1 and T1-CE) and T1-DB imaging. After gadolinium application, the T1-DB scan was performed prior to T1-CE. From unenhanced-T1 and T1-CE scans, subtraction images (T1-SUB) were calculated. The number of CEL was determined separately on T1-CE and T1-DB by two raters independently. Lesions only detected on T1-DB scans then were verified on T1-SUB. Only lesions detected by both raters were included in further analysis.

RESULTS

In 16 patients, at least one CEL was detected by both rater, either on T1-CE or T1-DB. All lesions that were detected on T1-CE were also detected on T1-DB images. The total number of contrast enhancing lesions detected on T1-DB images (n = 54) by both raters was significantly higher than the corresponding number of lesions identified on T1-CE (n = 27) (p = 0.01); all of these lesions could be verified on SUB images. In 21 patients, no CEL was detected in any of the sequences.

CONCLUSIONS

The application of T1-DB technique increases the sensitivity for CEL in MS, especially for those lesions that show only subtle increase in intensity after Gadolinium application but remain hypo- or iso-intense to surrounding tissue.

The impact of iodinated X-ray contrast agents on formation and toxicity of disinfection by-products in drinking water

The presence of iodinated X-ray contrast media (ICM) in source waters is of high concern to public health because of their potential to generate highly toxic disinfection by-products (DBPs). The objective of this study was to determine the impact of ICM in source waters and the type of disinfectant on the overall toxicity of DBP mixtures and to determine which ICM and reaction conditions give rise to toxic by-products. Source waters collected from Akron, OH were treated with five different ICMs, including iopamidol, iopromide, iohexol, diatrizoate and iomeprol, with or without chlorine or chloramine disinfection. The reaction product mixtures were concentrated with XAD resins and the mammalian cell cytotoxicity and genotoxicity of the reaction mixture concentrates was measured. Water containing iopamidol generated an enhanced level of mammalian cell cytotoxicity and genotoxicity after disinfection. While chlorine disinfection with iopamidol resulted in the highest cytotoxicity overall, the relative iopamidol-mediated increase in toxicity was greater when chloramine was used as the disinfectant compared with chlorine. Four other ICMs (iopromide, iohexol, diatrizoate, and iomeprol) expressed some cytotoxicity over the control without any disinfection, and induced higher cytotoxicity when chlorinated. Only iohexol enhanced genotoxicity compared to the chlorinated source water.

Dynamic single gold nanoparticle visualization by clinical intracoronary optical coherence tomography

The potential use of Gold Nanoparticles (GNPs) as contrast agents for clinical intracoronary frequency domain Optical Coherence Tomography (OCT) is here explored. The OCT contrast enhancement caused by GNPs of different sizes and morphologies has been systematically investigated and correlated with their optical properties. Among the different GNPs commercially available with plasmon resonances close to the operating wavelength of intracoronary OCT (1.3 µm), Gold Nanoshells (GNSs) have provided the best OCT contrast due to their largest scattering cross section at this wavelength. Clinical intracoronary OCT catheters are here demonstrated to be capable of three dimensional visualization and real-time tracking of individual GNSs. Results here included open an avenue to novel application of intravascular clinical OCT in combination with GNPs, such as real time evaluation of intravascular obstructions or pressure gradients.

Magnetic Particle Imaging: A Novel in Vivo Imaging Platform for Cancer Detection

Cancer remains one of the leading causes of death worldwide. Biomedical imaging plays a crucial role in all phases of cancer management. Physicians often need to choose the ideal diagnostic imaging modality for each clinical presentation based on complex trade-offs among spatial resolution, sensitivity, contrast, access, cost, and safety. Magnetic particle imaging (MPI) is an emerging tracer imaging modality that detects superparamagnetic iron oxide (SPIO) nanoparticle tracer with high image contrast (zero tissue background signal), high sensitivity (200 nM Fe) with linear quantitation, and zero signal depth attenuation. MPI is also safe in that it uses safe, in some cases even clinically approved, tracers and no ionizing radiation. The superb contrast, sensitivity, safety, and ability to image anywhere in the body lends MPI great promise for cancer imaging. In this study, we show for the first time the use of MPI for in vivo cancer imaging with systemic tracer administration. Here, long circulating MPI-tailored SPIOs were created and administered intravenously in tumor bearing rats. The tumor was highlighted with tumor-to-background ratio of up to 50. The nanoparticle dynamics in the tumor was also well-appreciated, with initial wash-in on the tumor rim, peak uptake at 6 h, and eventual clearance beyond 48 h. Lastly, we demonstrate the quantitative nature of MPI through compartmental fitting in vivo.

Magnetic barcode imaging for contrast agents

PURPOSE

To demonstrate a new MR imaging approach that unambiguously identifies and quantitates contrast agents based on intrinsic agent properties such as r1 , r2 , r2*, and magnetic susceptibility. The approach is referred to as magnetic barcode imaging (MBI).

METHODS

Targeted and bioresponsive contrast agents were imaged in agarose phantoms to generate T1 , T2 , T2*, and quantitative susceptibility maps. The parameter maps were processed by a machine learning algorithm that is trained to recognize the contrast agents based on these parameters. The output is a quantitative map of contrast agent concentration, identity, and functional state.

RESULTS

MBI allowed the quantitative interpretation of intensities, removed confounding backgrounds, enabled contrast agent multiplexing, and unambiguously detected the activation and binding states of bioresponsive and targeted contrast agents.

CONCLUSION

MBI has the potential to overcome significant limitations in the interpretation, quantitation, and multiplexing of contrast enhancement by MR imaging probes. Magn Reson Med 77:970-978, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Laser ablation ICP-MS: Application in biomedical research

In the last decade, the development of diverse bioanalytical methodologies based on mass spectrometry imaging has increased, as has their application in biomedical questions. The distribution analysis of elements (metals, semimetals, and non-metals) in biological samples is a point of interest in life sciences, especially within the context of metallomics, which is the scientific field that encompasses the global analysis of the entirety of elemental species inside a cell or tissue. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been efficiently employed to generate qualitative and quantitative maps of elemental distribution in thin tissue sections of a variety of biological samples, for example, brain, cartilage, spinal cord, etc. The combination of elemental with molecular mass spectrometry allows obtaining information about the elements bound to proteins, when they are previously separated by gel electrophoresis (metalloproteomics), and also adding a new dimension to molecular mass spectrometry imaging by the correlation of molecular and elemental distribution maps in definite regions in a biological tissue. In the present review, recent biomedical applications in LA-ICP-MS imaging as a stand-alone technique and in combination with molecular mass spectrometry imaging techniques are discussed. Applications of LA-ICP-MS in the study of neurodegenerative diseases, distribution of contrast agents and metallodrugs, and metalloproteomics will be focused in this review. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:47-57, 2017.

Feasibility of 10-Minute Delayed Hepatocyte Phase Imaging Using a 30° Flip Angle in Gd-EOB-DTPA-Enhanced Liver MRI for the Detection of Hepatocellular Carcinoma in Patients with Chronic Hepatitis or Cirrhosis

Objectives

To compare 10-minute (min) delayed hepatocyte phase imaging (HPI) using a 30° flip angle (FA) (10m-FA30) and 20-min delayed HPI using a 10° FA (20m-FA10) or 30° FA (20m-FA30) in Gd-EOB-DTPA-enhanced MRI in patients with chronic hepatitis or cirrhosis, in terms of lesion-to-liver contrast-to-noise ratio (CNR) for hepatocellular carcinoma (HCC) and detection sensitivity for focal hepatic lesions (FHLs).

Materials and Methods

One hundred and four patients with 168 HCCs and 55 benign FHLs who underwent Gd-EOB-DTPA-enhanced MRI with 10m-FA30, 20m-FA10, and 20m-FA30 were enrolled. Patients were divided into two groups according to the Child-Pugh classification: group A with chronic hepatitis or Child-Pugh A cirrhosis and group B with Child-Pugh B or C cirrhosis. Lesion-to-liver CNR for HCCs was compared between 10m-FA30 and 20m-FA10 or 20m-FA30 for each group. The presence of FHLs was evaluated using a four-point scale by two independent reviewers, and the detection sensitivity was analyzed.

Results

In group A, the CNR for HCCs (n = 86) on 10m-FA30 (165.8 ± 99.7) was significantly higher than that on 20m-FA10 (113.4 ± 71.4) and lower than that of 20m-FA30 (210.2 ± 129.3). However, there was no significant difference in the sensitivity of FHL detection between 10m-FA30 (mean 95.0% for two reviewers) and 20m-FA10 (94.7%) or 20m-FA30 (94.7%). In group B, the CNR (54.0 ± 36.4) for HCCs (n = 57) and the sensitivity (94.2%) of FHL detection for 10m-FA30 were significantly higher than those for 20m-FA10 (41.8 ± 36.4 and 80.8%, respectively) and were not different from those for 20m-FA30 (62.7 ± 44.4 and 93.3%, respectively).

Conclusion

The diagnostic performance of 10m-FA30 was similar to or higher than 20m-FA10 or 20m-FA30 in both groups A and B. This finding indicates that 10m-FA30 could replace 20-min delayed HPI regardless of patient liver function and reduce the delay time by 10 minutes.

Iodinated X-ray contrast agents: Photoinduced transformation and monitoring in surface water

Conventional wastewater treatment methods have shown to be unsuitable for a complete elimination of iodinated X-ray contrast agents (ICMs), which have thus been found in wastewater treatment plant (WWTP) effluent and in surface water. Once in the surface water, they could be transformed through different processes and form several transformation products that may need to be monitored as well. To this end, we studied the abatement and transformation of ICMs by combining laboratory experiments with in field analyses. We irradiated different aqueous solutions of the selected pollutants in the presence of TiO₂ as photocatalyst, aimed to promote ICMs degradation and to generate photoinduced transformation products (TPs) similar to those occurring in the environment and effluent wastewater. This experimental strategy has been applied to the study of three ICMs, namely iopromide, iopamidol and diatrizoate. A total of twenty-four, ten, and ten TPs were detected from iopamidol, diatrizoate and iopromide, respectively. The analyses were performed using a liquid chromatography-LTQ-FT-Orbitrap mass spectrometer. The mineralization process and acute toxicity evolution were assessed as well over time and revealed a lack of mineralization for all ICMs and the formation of harmful byproducts. After characterizing these transformation products, WWTP effluent and surface water taken from several branches of the Chicago River were analyzed for ICMs and their TPs. HRMS with MS/MS fragmentation was used as a confirmatory step for proper identification of compounds in water and wastewater samples. All three of ICM were detected in the effluent and surface water samples, while no significant amount of TPs were detected.

Lipoproteins and lipoprotein mimetics for imaging and drug delivery

Lipoproteins are a set of natural nanoparticles whose main role is the transport of fats within the body. While much work has been done to develop synthetic nanocarriers to deliver drugs or contrast media, natural nanoparticles such as lipoproteins represent appealing alternatives. Lipoproteins are biocompatible, biodegradable, non-immunogenic and are naturally targeted to some disease sites. Lipoproteins can be modified to act as contrast agents in many ways, such as by insertion of gold cores to provide contrast for computed tomography. They can be loaded with drugs, nucleic acids, photosensitizers or boron to act as therapeutics. Attachment of ligands can re-route lipoproteins to new targets. These attributes render lipoproteins attractive and versatile delivery vehicles. In this review we will provide background on lipoproteins, then survey their roles as contrast agents, in drug and nucleic acid delivery, as well as in photodynamic therapy and boron neutron capture therapy.

Elimination of radiocontrast agent diatrizoic acid by photo-Fenton process and enhanced treatment by coupling with electro-Fenton process

The removal of radiocontrast agent diatrizoic acid (DIA) from water was performed using photo-Fenton (PF) process. First, the effect of H2O2 dosage on mineralization efficiency was determined using ultraviolet (UV) irradiation. The system reached a maximum mineralization degree of 60 % total organic carbon (TOC) removal at 4 h with 20 mM initial H2O2 concentration while further concentration values led to a decrease in TOC abatement efficiency. Then, the effect of different concentrations of Fenton's reagents was studied for homogeneous Fenton process. Obtained results revealed that 0.25 mM Fe(3+) and 20 mM H2O2 were the best conditions, achieving 80 % TOC removal efficiency at 4 h treatment. Furthermore, heterogeneous PF treatment was developed using iron-activated carbon as catalyst. It was demonstrated that this catalyst is a promising option, reaching 67 % of TOC removal within 4 h treatment without formation of iron leachate in the medium. In addition, two strategies of enhancement for process efficiency are proposed: coupling of PF with electro-Fenton (EF) process in two ways: photoelectro-Fenton (PEF) or PF followed by EF (PF-EF) treatments, achieving in both cases the complete mineralization of DIA solution within only 2 h. Finally, the Microtox tests revealed the formation of more toxic compounds than the initial DIA during PF process, while, it was possible to reach total mineralization by both proposed alternatives (PEF or PF-EF) and thus to remove the toxicity of DIA solution.

Metabolism and pharmacokinetics of MnDPDP in man

Purpose: To study the metabolism and pharmacokinetics of mangafodipir trisodium injection, 0.01 mmol/ml (Teslascan), in healthy male volunteers.

Material and Methods: Eight volunteers received mangafodipir trisodium as an infusion over 20 min, and 5 received it as an injection (≤ min). Both groups received 5 and 10 μmol/kg b.w. with a wash-out period of 3 weeks between doses. Metabolites were measured in plasma, total manganese and zinc were measured in plasma and urine and total manganese was measured in faeces.

Results: The parent compound MnDPDP (manganese dipyridoxyl diphosphate) and 5 metabolites; MnDPMP (manganese dipyridoxyl monophosphate), MnPLED (manganese dipyridoxyl ethylenediamine) and the corresponding zinc compounds ZnDPDP, ZnDPMP and ZnPLED, were detected in plasma. ZnPLED was the only detectable metabolite 8 h after dosing. The apparent volume of distribution of manganese exceeded the interstitial body fluids. The volume of distribution of the ligand indicated distribution to the extracellular fluid only, with the plasma clearance close to the glomerular filtration rate. The manganese was incompletely excreted during the 4 days after treatment with the major part in faeces and less than 20% of the dose in the urine.

Conclusion: Dephosphorylation and simultaneous transmetallation with zinc are the main metabolic pathways of MnDPDP in man.

NMR relaxation studies with MnDPDP

Purpose: Our studies were designed to compare the efficacy of mangafodipir triso-dium (MnDPDP, Teslascan) as a tissue-specific MR agent with that of manganese chloride (MnCl2), to compare the efficacy of different doses and rates of administration of MnDPDP, and to collect the data needed for predicting optimum pulse sequences.

Material and Methods: The dose response for the relaxation rates R1 and R2 at 0.47 T, and the manganese (Mn) concentrations in rat liver and in the liver, pancreas, heart and adrenals of pigs was determined for both MnDPDP and MnCl2 administered i.v. Computer simulations were carried out to model the effects of different tissue Mn concentrations and TR on signal intensities and contrast-to-noise ratios.

Results: In rat liver and pig organs both compounds produced a positive dose-response in R1 and tissue Mn concentration, and only small or no response in R2. The Mn concentration in rat liver was positively correlated with R1, regardless of the form in which Mn was given, or the rate of administration. Optimal imaging parameters are therefore expected to be different pre- and post-MnDPDP administration.

Conclusion: The added cardiovascular safety of MnDPDP compared with MnCl2 does not result in loss of efficacy in increasing R1 at the intended clinical dose of 5 μmol/kg MnDPDP. The changes in R2 were too small to affect T2-weighted images. The data give the basis for choosing the appropriate pulse sequences for MnDPDP-en-hanced MR imaging.

Physicochemical characterisation of mangafodipir trisodium

Purpose: To determine the structure and various physicochemical properties of man-gafodipir (MnDPDP) trisodium, the active ingredient of Teslascan, a new organ-specific contrast medium for MR imaging.

Material and Methods: The structure of MnDPDP trisodium crystals was determined by X-ray crystallography. The possible existence of polymorphism in MnDPDP trisodium was evaluated by powder X-ray diffraction, optical microscopy, thermal analysis and IR spectroscopy. In addition, various spectroscopic techniques and physicochemical measurements were used for characterisation of MnDPDP trisodium.

Results: The crystallographic data obtained for MnDPDP trisodium show that the general core structure of the MnDPDP anion is similar to that seen in related substances. The metal coordination geometry is a distorted octahedron defined by 2 phenolate oxygens, 2 carboxylate oxygens and 2 amine nitrogens. The unit cell contains 2 MnDPDP anions, 6 sodium ions and 50 water molecules. The various spectroscopic data are consistent with the structure determined by X-ray crystallography. The product (Teslascan) has low viscosity, is isotonic with blood and has a physiological pH.

Conclusion: MnDPDP trisodium is a crystalline, hygroscopic solid which is readily soluble in water. No evidence of polymorphism was seen in the samples studied.

Lanthanides: Applications in Cancer Diagnosis and Therapy

Lanthanide complexes are of increasing importance in cancer diagnosis and therapy, owing to the versatile chemical and magnetic properties of the lanthanide-ion 4f electronic configuration. Following the first implementation of gadolinium(III)-based contrast agents in magnetic resonance imaging in the 1980s, lanthanide-based small molecules and nanomaterials have been investigated as cytotoxic agents and inhibitors, in photodynamic therapy, radiation therapy, drug/gene delivery, biosensing, and bioimaging. As the potential utility of lanthanides in these areas continues to increase, this timely review of current applications will be useful to medicinal chemists and other investigators interested in the latest developments and trends in this emerging field.

Ubiquitous Detection of Artificial Sweeteners and Iodinated X-ray Contrast Media in Aquatic Environmental and Wastewater Treatment Plant Samples from Vietnam, The Philippines, and Myanmar

Water samples from Vietnam, The Philippines, and Myanmar were analyzed for artificial sweeteners (ASs) and iodinated X-ray contrast media (ICMs). High concentrations (low micrograms per liter) of ASs, including aspartame, saccharin, and sucralose, were found in wastewater treatment plant (WWTP) influents from Vietnam. Three ICMs, iohexol, iopamidol, and iopromide were detected in Vietnamese WWTP influents and effluents, suggesting that these ICMs are frequently used in Vietnam. ASs and ICMs were found in river water from downtown Hanoi at concentrations comparable to or lower than the concentrations in WWTP influents. The ASs and ICMs concentrations in WWTP influents and adjacent surface water significantly correlated (r (2) = 0.99, p < 0.001), suggesting that household wastewater is discharged directly into rivers in Vietnam. Acesulfame was frequently detected in northern Vietnamese groundwater, but the concentrations varied spatially by one order of magnitude even though the sampling points were very close together. This implies that poorly performing domestic septic tanks sporadically leak household wastewater into groundwater. High acesulfame, cyclamate, saccharin, and sucralose concentrations were found in surface water from Manila, The Philippines. The sucralose concentrations were one order of magnitude higher in the Manila samples than in the Vietnamese samples, indicating that more sucralose is used in The Philippines than in Vietnam. Acesulfame and cyclamate were found in surface water from Pathein (rural) and Yangon (urban) in Myanmar, but no ICMs were found in the samples. The ASs concentrations were two-three orders of magnitude lower in the samples from Myanmar than in the samples from Vietnam and The Philippines, suggesting that different amounts of ASs are used in these countries. We believe this is the first report of persistent ASs and ICMs having ubiquitous distributions in economically emerging South Asian countries.

The contribution of pharmaceutically active compounds from healthcare facilities to a receiving sewage treatment plant in Canada

Concentrations and percent loadings of pharmaceutically active compounds (PhACs) and other emerging contaminants released from healthcare facilities (2 hospitals and a long-term care facility) to a sewage treatment plant (STP) in a large urban sewershed were evaluated. An additional hospital outside the sewershed was also monitored. Fourteen of the 24 steroids/hormones and 88 of the 117 PhACs and emerging contaminants were detected at least once. Commonly used substances, including cotinine, caffeine and its metabolite 1,7-dimethylxanthine, ibuprofen and naproxen (analgesics), venlafaxine (antidepressant), and N,N-diethyl-meta-toluamide (insect repellant), were detected in all samples at all sites. Concentrations detected in the large specialty hospital outside the sewershed were similar to those within the sewershed. Cytotoxic drugs (tamoxifen and cyclophosphamide) and x-ray contrast media (iopamidol and diatrizoic acid) were infrequently detected in hospital effluents. Analysis for antibiotics indicated that azithromycin, clarithromycin, ciprofloxacin, erythromycin, ofloxacin, and sulfamethoxazole were consistently detected in hospital wastewaters, as was triclosan (antibacterial agent). Fifteen compounds individually contributed greater than 1% to the total PhAC and emerging contaminant load to the STP from the 2 hospitals in the sewershed, and 9 compounds in the STP effluent exceeded ecotoxicological criteria. The present survey demonstrates that point source discharges from healthcare facilities in this sewershed make a small contribution to the overall PhAC and emerging contaminant loading compared with the total concentrations entering the receiving STP.

Trans-Stent B-Mode Ultrasound and Passive Cavitation Imaging

Angioplasty and stenting of a stenosed artery enable acute restoration of blood flow. However, restenosis or a lack of re-endothelization can subsequently occur depending on the stent type. Cavitation-mediated drug delivery is a potential therapy for these conditions, but requires that particular types of cavitation be induced by ultrasound insonation. Because of the heterogeneity of tissue and stochastic nature of cavitation, feedback mechanisms are needed to determine whether the sustained bubble activity is induced. The objective of this study was to determine the feasibility of passive cavitation imaging through a metal stent in a flow phantom and an animal model. In this study, an endovascular stent was deployed in a flow phantom and in porcine femoral arteries. Fluorophore-labeled echogenic liposomes, a theragnostic ultrasound contrast agent, were injected proximal to the stent. Cavitation images were obtained by passively recording and beamforming the acoustic emissions from echogenic liposomes insonified with a low-frequency (500 kHz) transducer. In vitro experiments revealed that the signal-to-noise ratio for detecting stable cavitation activity through the stent was greater than 8 dB. The stent did not significantly reduce the signal-to-noise ratio. Trans-stent cavitation activity was also detected in vivo via passive cavitation imaging when echogenic liposomes were insonified by the 500-kHz transducer. When stable cavitation was detected, delivery of the fluorophore into the arterial wall was observed. Increased echogenicity within the stent was also observed when echogenic liposomes were administered. Thus, both B-mode ultrasound imaging and cavitation imaging are feasible in the presence of an endovascular stent in vivo. Demonstration of this capability supports future studies to monitor restenosis with contrast-enhanced ultrasound and pursue image-guided ultrasound-mediated drug delivery to inhibit restenosis.