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International consensus supports the development of standardized protocols for measured glomerular filtration rate (mGFR) to facilitate the integration of mGFR testing in both clinical and research settings. To this end, the European Kidney Function Consortium convened an international group of experts with relevant experience in mGFR. The working group performed an extensive literature search to inform the development of recommendations for mGFR determination using 1-compartment plasma clearance models and iohexol as the exogenous filtration marker. Iohexol was selected as it is non-radio labeled, inexpensive, and safe, can be assayed at a central laboratory, and the other commonly used non-radio-labeled tracers have been (inulin) or are soon to be (iothalamate) discontinued. A plasma clearance model was selected over urine clearance as it requires no urine collection. A 1 compartment was preferred to 2 compartments as it requires fewer samples. The recommendations are based on published evidence complemented by expert opinion. The consensus paper covers practical advice for patients and health professionals, preparation, administration, and safety aspects of iohexol, laboratory analysis, blood sample collection and sampling times using both multiple and single-sample protocols, description of the mGFR mathematical calculations, as well as implementation strategies. Supplementary materials include patient and provider information sheets, standard operating procedures, a study protocol template, and support for mGFR calculation., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Objective: Contrast media (CM) is a commonly applied drug in medical examination and surgery. However, contrast-induced acute kidney injury (CIAKI) poses a severe threat to human life and health. Notably, the CUT-like homeobox 1 (CUX1) gene shows protective effects in a variety of cells. Therefore, the objective of this study was to provide a new target for the treatment of CIAKI through exploring the role and possible molecular mechanism of CUX1 in CIAKI., Method: Blood samples were collected from 20 patients with CIAKI and healthy volunteers. Human kidney 2 (HK-2) cells were incubated with 200 mg/mL iohexol for 6 h to establish a contrast-induced injury model of HK-2 cells. Subsequently, qRT-PCR was used to detect the relative mRNA expression of CUX1; CCK-8 and flow cytometry to assess the proliferation and apoptosis of HK-2 cells; the levels of IL(interleukin)-1β, tumor necrosis factor alpha (TNF-α) and malondialdehyde (MDA) in cells and lactate dehydrogenase (LDH) activity in cell culture supernatant were detect; and western blot to observe the expression levels of CUX1 and the PI3K/AKT signaling pathway related proteins [phosphorylated phosphoinositide 3-kinase (p-PI3K), PI3K, phosphorylated Akt (p-AKT), AKT]., Results: CUX1 expression was significantly downregulated in blood samples of patients with CIAKI and contrast-induced HK-2 cells. Contrast media (CM; iohexol) treatment significantly reduced the proliferation of HK-2 cells, promoted apoptosis, stimulated inflammation and oxidative stress that caused cell damage. CUX1 overexpression alleviated cell damage by significantly improving the proliferation level of HK-2 cells induced by CM, inhibiting cell apoptosis, and reducing the level of LDH in culture supernatant and the expression of IL-1β, TNF-α and MDA in cells. CM treatment significantly inhibited the activity of PI3K/AKT signaling pathway activity. Nevertheless, up-regulating CUX1 could activate the PI3K/AKT signaling pathway activity in HK-2 cells induced by CM., Conclusion: CUX1 promotes cell proliferation, inhibits apoptosis, and reduces inflammation and oxidative stress in CM-induced HK-2 cells to alleviate CM-induced damage. The mechanism of CUX1 may be correlated with activation of the PI3K/AKT signaling pathway., (© 2024. The Author(s).)

Polyoxotungstate nanoclusters have recently emerged as promising contrast agents for computed tomography (CT). In order to evaluate their clinical potential, in this study, we evaluated the in vitro CT imaging properties, potential toxic effects in vivo, and tissue distribution of monolacunary Wells-Dawson polyoxometalate, α 2 -K 10 P 2 W 17 O 61 . O (mono-WD POM). Mono-WD POM showed superior X-ray attenuation compared to other tungsten-containing nanoclusters (its parent WD-POM and Keggin POM) and the standard iodine-based contrast agent (iohexol). The calculated X-ray attenuation linear slope for mono-WD POM was significantly higher compared to parent WD-POM, Keggin POM, and iohexol (5.97 ± 0.14 vs. 4.84 ± 0.05, 4.55 ± 0.16, and 4.30 ± 0.09, respectively). Acute oral (maximum-administered dose (MAD) = 960 mg/kg) and intravenous administration (1/10, 1/5, and 1/3 MAD) of mono-WD POM did not induce unexpected changes in rats' general habits or mortality. Results of blood gas analysis, CO-oximetry status, and the levels of electrolytes, glucose, lactate, creatinine, and BUN demonstrated a dose-dependent tendency 14 days after intravenous administration of mono-WD POM. The most significant differences compared to the control were observed for 1/3 MAD, being approximately seventy times higher than the typically used dose (0.015 mmol W/kg) of tungsten-based contrast agents. The highest tungsten deposition was found in the kidney (1/3 MAD-0.67 ± 0.12; 1/5 MAD-0.59 ± 0.07; 1/10 MAD-0.54 ± 0.05), which corresponded to detected morphological irregularities, electrolyte imbalance, and increased BUN levels.2 O (mono-WD POM). Mono-WD POM showed superior X-ray attenuation compared to other tungsten-containing nanoclusters (its parent WD-POM and Keggin POM) and the standard iodine-based contrast agent (iohexol). The calculated X-ray attenuation linear slope for mono-WD POM was significantly higher compared to parent WD-POM, Keggin POM, and iohexol (5.97 ± 0.14 vs. 4.84 ± 0.05, 4.55 ± 0.16, and 4.30 ± 0.09, respectively). Acute oral (maximum-administered dose (MAD) = 960 mg/kg) and intravenous administration (1/10, 1/5, and 1/3 MAD) of mono-WD POM did not induce unexpected changes in rats' general habits or mortality. Results of blood gas analysis, CO-oximetry status, and the levels of electrolytes, glucose, lactate, creatinine, and BUN demonstrated a dose-dependent tendency 14 days after intravenous administration of mono-WD POM. The most significant differences compared to the control were observed for 1/3 MAD, being approximately seventy times higher than the typically used dose (0.015 mmol W/kg) of tungsten-based contrast agents. The highest tungsten deposition was found in the kidney (1/3 MAD-0.67 ± 0.12; 1/5 MAD-0.59 ± 0.07; 1/10 MAD-0.54 ± 0.05), which corresponded to detected morphological irregularities, electrolyte imbalance, and increased BUN levels., Competing Interests: The authors declare no conflicts of interest.

Background: The feasibility of oral dark contrast media is under exploration in abdominal computed tomography (CT) applications. One of the experimental contrast media in this class is dark borosilicate contrast media (DBCM), which has a CT attenuation lower than that of intra-abdominal fat., Purpose: To evaluate the performances of DBCM using single- and multi-energy CT imaging on a clinical photon-counting-detector CT (PCD-CT)., Methods: Five vials, three with iodinated contrast agent (5, 10, and 20 mg/mL; Omnipaque 350) and two with DBCM (6% and 12%; Nextrast, Inc.), and one solid-water rod (neutral contrast agent) were inserted into two multi-energy CT phantoms, and scanned on a clinical PCD-CT system (NAEOTOM Alpha) at 90, 120, 140, Sn100, and Sn140 kV (Sn: tin filter) in multi-energy mode. CARE keV IQ level was 180 (CTDIvol: 3.0 and 12.0 mGy for the small and large phantoms, respectively). Low-energy threshold images were reconstructed with a quantitative kernel (Qr40, iterative reconstruction strength 2) and slice thickness/increment of 2.0/2.0 mm. Virtual monoenergetic images (VMIs) were reconstructed from 40 to 140 keV at 10 keV increments. On all images, average CT numbers for each vial/rod were measured using circular region-of-interests and averaged over eight slices. The contrast-to-noise ratio (CNR) of iodine (5 mg/mL) against DBCM was calculated and plotted against tube potential and VMI energy level, and compared to the CNR of iodine against water. Similar analyses were performed on iodine maps and VNC images derived from the multi-energy scan at 120 kV., Results: With increasing kV or VMI keV, the negative HU of DBCM decreased only slightly, whereas the positive HU of iodine decreased across all contrast concentrations and phantom sizes. CT numbers for DBCM decreased from -178.5 ± 9.6 to -194.4 ± 6.3 HU (small phantom) and from -181.7 ± 15.7 to -192.1 ± 11.9 HU (large phantom) for DBCM-12% from 90 to Sn140 kV; on VMIs, the CT numbers for DBCM decreased minimally from -147.1 ± 15.7 to -185.1 ± 9.2 HU (small phantom) and -158.8 ± 28.6 to -188.9 ± 14.7 HU (large phantom) from 40 to 70 keV, but remained stable from 80 to 140 keV. The highest iodine CNR against DBCM in low-energy threshold images was seen at 90 or Sn140 kV for the small phantom, whereas all CNR values from low-energy threshold images for the large phantom were comparable. The CNR values of iodine against DBCM computed on VMIs were highest at 40 or 70 keV depending on iodine and DBCM concentrations. The CNR values of iodine against DBCM were consistently higher than iodine to water (up to 460% higher dependent on energy level). Further, the CNR of iodine compared to DBCM is less affected by VMI energy level than the identical comparison between iodine and water: CNR values at 140 keV were reduced by 46.6% (small phantom) or 42.6% (large phantom) compared to 40 keV; CNR values for iodine compared to water were reduced by 86.3% and 83.8% for similar phantom sizes, respectively. Compared to 70 keV VMI, the iodine CNR against DBCM was 13%-79% lower on iodine maps and VNC., Conclusions: When evaluated at different tube potentials and VMI energy levels using a clinical PCD-CT system, DBCM showed consistently higher CNR compared to iodine versus water (a neutral contrast)., (© 2023 American Association of Physicists in Medicine.)

Materials and Methods: Phase I: Eleven radiological technologists were asked to fill a CM injector 3 times with 50% diluted CM (iopromide 300 mg I/mL). The dilution was injected (12 mL/s) through a Coriolis flowmeter, with CM concentration and total volume calculated. Interoperator, intraoperator, and intraprocedural variations were calculated as coefficients of variability. Contrast media dose reporting accuracy was determined. Phase II: The study was repeated after implementation of a standardized dilution protocol with 5 representative operators., Results: Phase I: The average injected concentration among 11 operators was 68% ± 16% CM (n = 33; range, 43%-98%), as compared with the target of 50% CM. The interoperator variability was 16%, the intraoperator variability was 6% ± 3%, and the intraprocedural variability was 23% ± 19% (range, 5%-67%). This led to overdelivery of CM compared with intended patient dose by 36% on average. Phase II: After standardization, injections averaged 55% ± 4% CM (n = 15; range, 49%-62%), with interoperator variability of 8%, intraoperator variability of 5% ± 1%, and intraprocedural variability of 1.6% ± 0.5% (range, 0.4%-3.7%)., Conclusions: Manual CM dilution can lead to substantial interoperator and intraoperator, as well as intraprocedural variability in injected concentration. This can result in underreporting of administered CM doses to patients. It is recommended that clinics assess their current standard of care regarding CM injections for endovascular interventions and evaluate potential corrective actions if appropriate., Competing Interests: Conflicts of interest and sources of funding: J.E.W. reports institutional grants by Bard, Bayer, Boston, Brainlab, GE, Philips, Siemens outside of the submitted work. He reports funding via speakers bureau by Bayer, Siemens, outside of the submitted work. S.W.d.B. reports an institutional grant by Brainlab, outside of the submitted work. B.M.F.H. reports funding via speakers bureau by Bayer, outside the submitted work. M.C.M. reports no funding or personal fees. M.C.M. is a part-time employee of Bayer AG. There are no relationships with industry that would constitute a conflict of interest within the scope of this particular work., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background and Purpose: Several studies in the literature have attempted to subjectively assess the degree of visualization of different neurovascular structures using different contrast agents and concentrations. Given the recent contrast shortages, we aim to objectively compare the radiopacity achieved with four angiographic contrast agents used in clinical practice., Methods: Isovue 370, Visipaque 320, Omnipaque 300, and Isovue 300 were each drawn up at 25%, 50%, 75%, and 100% concentrations and compared against normal saline and air syringes. CT scans were obtained, and regions of interest were analyzed for radiopacity using Hounsfield unit (HU) measurements. An aneurysm model with different contrast concentrations was also scanned and dimensions compared. Two-tailed t-tests and Cohen's d coefficients were applied to assess for differences in mean HU measurements., Results: Isovue 370 and Isovue 300 had the highest and lowest mean HU, respectively (p < .001). Visipaque 320 at 25% concentration had the lowest mean HU at -.76. Statistically similar agents (p < .05) were Visipaque 320 and Omnipaque 300 at a 100% concentration (p = .30), and Omnipaque 300 and Isovue 300 at a 25% concentration (p = .73). Aneurysm dimensions among Isovue 370, Visipaque 320, and Omnipaque 300 were all similar, whereas with Isovue 300, the dimensions were significantly smaller (p < .05)., Conclusion: Isovue 370 provides the highest HU radiopacity and the most accurate aneurysm measurements. Angiographic measurements obtained with Isovue 300 may underestimate the actual aneurysmal dimensions. Visipaque 320 and Omnipaque 300 at 100% concentration have similar mean HUs and are beneficial for patients with chronic kidney or cardiac disease., (© 2023 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

We studied the encapsulation of iohexol (Ihex), a nonionic contrast agent used for X-ray computational tomography, into lipid vesicles using the multiple emulsification-solvent evaporation method to formulate a nanosized contrast agent. This lipid vesicle preparation method consists of three steps: (1) primary emulsification for producing water-in-oil (W/O) emulsions containing fine water droplets that will be converted to the internal water phase of the lipid vesicles, (2) secondary emulsification for formulating multiple water-in-oil-in-water (W/O/W) emulsions encapsulating the fine water droplets containing Ihex, and (3) solvent evaporation to remove the oil phase solvent (n-hexane) and to form lipid bilayers surrounding the fine inner droplets, resulting in the formation of lipid vesicles encapsulating Ihex. As the diameter and Ihex concentration of the primary W/O emulsion droplets decreased, a higher Ihex encapsulation yield was obtained for the final lipid vesicles. The entrapment yield of Ihex in the final lipid vesicles varied significantly with the emulsifier (Pluronic® F-68) concentration in the external water phase of W/O/W emulsion, and the highest yield (65%) was obtained when the emulsifier concentration was 0.1 wt%. We also investigated the powderization of lipid vesicles encapsulating Ihex via lyophilization. The powderized vesicles were dispersed in water after rehydration and maintained their controlled diameters. The entrapment yield of Ihex in powderized lipid vesicles was maintained for over 1 month at 25 ˚C, while significant leakage of Ihex was observed in the lipid vesicles suspended in the aqueous phase., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Takashi Kuroiwa has patent licensed to Konica Minolta Inc. and University of Tsukuba. Takashi Kuroiwa has patent licensed to University of Tsukuba. Sosaku Ichikawa has patent licensed to Konica Minolta Inc. and University of Tsukuba. Sosaku Ichikawa has patent licensed to University of Tsukuba., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The present study investigated the biodegradation of three iodinated X-ray contrast media (ICM), namely, iopamidol, iohexol, and iopromide, in simultaneous nitrification-denitrification (SND) system maintained in a sequencing batch reactor (SBR). The results showed that variable aeration patterns (anoxic-aerobic-anoxic) and micro-aerobic condition were most effective in the biotransformation of ICM while achieving organic carbon and nitrogen removal. The highest removal efficiencies of iopamidol, iohexol, and iopromide were 48.24%, 47.75%, and 57.46%, respectively, in micro-aerobic condition. Iopamidol was highly resistant to biodegradation and possessed the lowest K bio value, followed by iohexol and iopromide, regardless of operating conditions. The removal of iopamidol and iopromide was affected by the inhibition of nitrifiers. The transformation products after hydroxylation, dehydrogenation, and deiodination of ICM were detected in the treated effluent. Due to the addition of ICM, the abundance of denitrifier genera Rhodobacter and Unclassified Comamonadaceae increased, and the abundance of class TM7-3 decreased. The presence of ICM affected the microbial dynamics, and the diversity of microbes in SND resulted in improving the biodegradability of the compounds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

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/m 3 -day, nitrogen loading rate (NLR)- 0.08 KgNH 4 -N/m 3 -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/m 3 -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 KgNH 4 -N/m 3 -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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Microcontaminants in the water environment have received increasing attention due to their adverse effects on human health and wildlife. However, iodinated X-ray contrast media (ICM), a type of microcontaminants, have not yet been systematically documented in source and tap water. This study investigated ICM in water samples via a sampling activity from 25 drinking water sources and their corresponding 30 household taps in south-central Jiangsu Province, China. The total concentrations of ICM ranged from 14.2 to 138.5 ng/L in source water and 3.7 to 101.3 ng/L in tap water, respectively. The calculated average water treatment efficiency to remove ICM is 38.3% with large variation under different processes (ranging from 7.3% to 75.7%), which implied that ICM could not be effectively removed using current treatment technologies. By integrating other ICM into the predominant compound iohexol with relative potency factors, the health risks of total ICM through water consumption were assessed using the Monte Carlo simulation. The results concluded that the risk of ingesting ICM through tap water was not a major health concern for adults, teens, or children in the study area. Nevertheless, due to the lack of long-term toxicity data relevant for humans for ICM, this risk may be underestimated, which requires further research., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Contrast-enhanced computed tomography (CECT) is increasingly used to screen for abdominal pathology in dogs, and the contrast dose used is commonly calculated as a linear function of total body weight (TBW). Body fat is not metabolically active and contributes little to dispersing or diluting contrast medium (CM) in the blood. This prospective, analytic, cross-section design pilot study aimed to establish the feasibility of intravenous CM dosed according to lean body weight (LBW) for abdominal CECT in dogs compared to TBW. We hypothesized that when dosing intravenous CM according to LBW, studies will remain at diagnostic quality, there will be a reduced interindividual contrast enhancement (CE) variability, and there will be less change to heart rate and blood pressure in dogs compared to when administering CM calculated on TBW. Twelve dogs had two CECT studies with contrast doses according to TBW and LBW at least 8 weeks apart. Interindividual organ and vessel CE variability, diagnostic quality of the studies, and changes in physiological status were compared between protocols. The LBW-based protocol provided less variability in the CE of most organs and vessels (except the aorta). When dosed according to LBW, liver enhancement was positively associated with grams of iodine per kg TBW during the portal venous phase (P = 0.046). There was no significant difference in physiological parameters after CM administration between dosing protocols. Our conclusion is that a CM dose based on LBW for abdominal CECT lowers interindividual CE variability and is effective at maintaining studies of diagnostic quality., (© 2022 The Authors. Veterinary Radiology & Ultrasound published by Wiley Periodicals LLC on behalf of American College of Veterinary Radiology.)

Small-angle X-ray scattering (SAXS) has become an indispensable tool in structural biology, complementing atomic-resolution techniques. It is sensitive to the electron-density difference between solubilized biomacromolecules and the buffer, and provides information on molecular masses, particle dimensions and interactions, low-resolution conformations and pair distance-distribution functions. When SAXS data are recorded at multiple contrasts, i.e. at different solvent electron densities, it is possible to probe, in addition to their overall shape, the internal electron-density profile of biomacromolecular assemblies. Unfortunately, contrast-variation SAXS has been limited by the range of solvent electron densities attainable using conventional co-solutes (for example sugars, glycerol and salt) and by the fact that some biological systems are destabilized in their presence. Here, SAXS contrast data from an oligomeric protein and a protein-RNA complex are presented in the presence of iohexol and Gd-HPDO3A, two electron-rich molecules that are used in biomedical imaging and that belong to the families of iodinated and lanthanide-based complexes, respectively. Moderate concentrations of both molecules allowed solvent electron densities matching those of proteins to be attained. While iohexol yielded higher solvent electron densities (per mole), it interacted specifically with the oligomeric protein and precipitated the protein-RNA complex. Gd-HPDO3A, while less efficient (per mole), did not disrupt the structural integrity of either system, and atomic models could be compared with the SAXS data. Due to their elevated solubility and electron density, their chemical inertness, as well as the possibility of altering their physico-chemical properties, lanthanide-based complexes represent a class of molecules with promising potential for contrast-variation SAXS experiments on diverse biomacromolecular systems., (open access.)

BACKGROUND. Data are limited regarding utility of positive oral contrast material for peritoneal tumor detection on CT. OBJECTIVE. The purpose of this article is to compare positive versus neutral oral contrast material for detection of malignant deposits in nonsolid intraabdominal organs on CT. METHODS. This retrospective study included 265 patients (133 men, 132 women; median age, 61 years) who underwent an abdominopelvic CT examination in which the report did not suggest presence of malignant deposits and a subsequent CT examination within 6 months in which the report indicated at least one unequivocal malignant deposit. Examinations used positive (iohexol; n = 100) or neutral (water; n = 165) oral agents. A radiologist reviewed images to assess whether the deposits were visible (despite clinical reports indicating no deposits) on unblinded comparison with the follow-up examinations; identified deposits were assigned to one of seven intraabdominal compartments. The radiologist also assessed adequacy of bowel filling with oral contrast material. Two additional radiologists independently reviewed examinations in blinded fashion for malignant deposits. NPV was assessed of clinical CT reports and blinded retrospective readings for detection of malignant deposits visible on unblinded comparison with follow-up examinations. RESULTS. Unblinded review identified malignant deposits in 58.1% (154/265) of examinations. In per-patient analysis of clinical reports, NPV for malignant deposits was higher for examinations with adequate bowel filling with positive oral contrast material (65.8% [25/38]) than for examinations with inadequate bowel filling with positive oral contrast material (45.2% [28/62], p = .07) or with neutral oral contrast material regardless of bowel filling adequacy (35.2% [58/165], p = .002). In per-compartment analysis of blinded interpretations, NPV was higher for examinations with adequate and inadequate bowel filling with positive oral contrast material than for examinations with neutral oral contrast regardless of bowel filling adequacy (reader 1: 94.7% [234/247] and 92.5% [382/413] vs 88.3% [947/1072], both p = .045; reader 2: 93.1% [228/245] and 91.6% [361/394] vs 85.9% [939/1093], both p = .01). CONCLUSION. CT has suboptimal NPV for malignant deposits in intraabdominal nonsolid organs. Compared with neutral material, positive oral contrast material improves detection, particularly with adequate bowel filling. CLINICAL IMPACT. Optimization of bowel preparation for oncologic CT may help avoid potentially severe clinical consequences of missed malignant deposits.

A recent coronavirus disease 2019-related shutdown of the main production facility of iohexol in China has led to massive shortages of iodinated contrast material across the globe. This shortage has also jeopardized neuroimaging. In this article, we describe remedies to reduce iodinated contrast material use for stroke imaging, which is its primary use in neuroimaging, that we have implemented in our hospital network., (© 2022 by American Journal of Neuroradiology.)

Background: A negative oral contrast agent (OCA) has been long sought for, to better delineate the bowel and visualise surrounding structures. Lumentin® 44 (L44) is a new OCA formulated to fill the entire small bowel. The aim of this study was to compare L44 with positive and neutral conventional OCA in abdominal computed tomography (CT)., Methods: Forty-five oncologic patients were randomised to receive either L44 or one of the two comparators (MoviPrep® or diluted Omnipaque®). Abdominal CT examinations with intravenous contrast agent were acquired according to standard protocols. The studies were read independently by two senior radiologists., Results: The mean intraluminal Hounsfield units (HU)-values of regions-of-interest (ROIs) for each subsegment of small bowel and treatment group were -404.0 HU for L44, 166.1 HU for Omnipaque®, and 16.7 HU for MoviPrep® (L44 versus Omnipaque, p < 0.001: L44 versus MoviPrep p < 0.001; Omnipaque versus MoviPrep, p = 0.003). Adverse events, only mild, using L44 were numerically fewer than for using conventional oral contrast agents. Visualisation of abdominal structures beyond the small bowel was similar to the comparators., Conclusions: L44 is a negative OCA with luminal radiodensity at approximately -400 HU creating a unique small bowel appearance on CT scans. The high bowel wall-to-lumen contrast may enable improved visualisation in a range of pathologic conditions. L44 showed a good safety profile and was well accepted by patients studied., Trial Registration: EudraCT (2017-002368-42) and in ClinicalTrials.gov (NCT03326518)., (© 2022. The Author(s) under exclusive licence to European Society of Radiology.)

Background: Our goal was to compare the metabolic curves of plasma clearance of iohexol (Cl IOH ) at standard dose (5 ml) and contrast-level dose (50 ml)., Methods: The concentration of iohexol was measured at fasting state and at nine different time periods after a single bolus of iohexol injection. The interval between the injection of the two doses was longer than 24 hrs. Using a multi-point method and a dual-sample method, Cl IOH-M and Cl IOH-D were calculated, and the correlation and consistency of Cl IOH between the two doses were compared., Results: The metabolic curves of iohexol at the 5 ml and 50 ml injection were substantially identical. The correlation of Cl IOH-M between the two doses was 0.930, the mean deviation was 1.3 ± 6.9 ml/min/1.73 m 2 . Taking Cl IOH-5ml-M as the standard, the Cl IOH-50ml-D at 2 h and 4 h had a correlation coefficient of 0.975, a mean deviation of 0.1 ± 5.3 ml/min/1.73 m 2 , and the concordances were 100% corresponding to P 30 , 88.9% corresponding to P 10 , and 77.8% corresponding to P 5 ., Conclusion: When a regular dose of iohexol is used for enhanced CT, Cl IOH can be used for the measurement of GFR, and a proper time for blood collection can be 2 h and 4 h., (Copyright © 2021. Published by Elsevier B.V.)

Dynamic contrast CT with Patlak plot analysis can be used to determine the glomerular filtration rate (GFR). However, several studies have shown different GFR values and they are most likely less than the values by the standard techniques. The purpose of this prospective, experimental, and method comparison study was to evaluate the GFR using a CT technique (CT-GFR) in 12 healthy dogs compared to serum iohexol clearance (SIC-GFR). All dogs were anesthetized and placed in the right lateral recumbency position and the caudal part was lifted inside the CT gantry. A single-slice dynamic CT of the aorta and both kidneys was scanned sequentially every 2 s for 2 min after a bolus injection (3 mL/s) of iohexol (300 mg/kg). Time attenuation curves (TAC) were constructed and the GFR per volume of kidney was calculated using the Patlak plot analysis method based on 30-120 s time intervals, and results were compared to global GFR from SIC that was determined with eight blood samples for up to 240 min. The CT-GFR value (1.85 ± 0.48 mL/min/kg) was significantly less than the SIC-GFR value (3.40 ± 0.80 mL/min/kg; P < .05). The CT-GFR was correlated with SIC-GFR by the coefficient of correlation (r) at 0.61 (P = .046). In conclusion, the CT-GFR underestimated SIC-GFR and should be used carefully. We suggest that the GFR should be calculated using the equation derived from linear regression between CT-GFR and the standard GFR method. With its own particular parameters, each institute should have its own prediction equation., (© 2021 American College of Veterinary Radiology.)

Objective: We aimed to determine whether dual-energy computed tomography (CT) is useful for evaluating deep neck abscesses., Methods: This study included 22 consecutive patients who were clinically suspected of having a deep neck abscess and underwent dual-energy CT. Conventional 120-kVp images, 70- and 40-keV virtual monochromatic images (VMIs), and iodine maps were inspected to calculate the contrast ratio of the abscess rim (AR) to the abscess center (AC) or to the adjacent muscle (M). The diagnostic certainty of abscesses was assessed on these images., Results: Twenty (91%) of 22 patients had a definitive diagnosis. The contrast ratio for AR/AC and AR/M was significantly higher on 40-keV VMIs and iodine maps than on 120-kVp images and 70-keV VMIs (P < 0.05). On both 40-keV VMIs and iodine maps, the diagnostic certainty of abscess improved in 3 (15%) cases compared with 120-kVp images and 70-keV VMIs., Conclusions: Dual-energy CT-based 40-keV VMIs and iodine maps are useful for evaluating deep neck abscesses and may improve diagnostic certainty., Competing Interests: The authors declare no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Contrast-enhanced computed tomography (CT) is increasingly being used as a standard diagnostic test for dogs with suspected abdominal pathology. The iodinated contrast dose is commonly calculated based on linear increases in total body weight. However, body fat is not metabolically active and contributes little to dispersing or diluting the contrast medium in the blood. The aim of this retrospective single-center analytic study was to investigate the possible correlation between abdominal organ and vessel enhancement, and abdominal fat percentage in dogs. We hypothesized that, when dosing intravenous iodinated contrast according to total body weight, there would be a positive association between the degree of contrast enhancement of selected organs and vessels with increasing abdominal fat percentage. Vascular and parenchymal attenuation data were collected from 62 multiphasic abdominal CECT scans performed on dogs over a 5-year period at U-Vet Werribee Animal Hospital between February 2014 and February 2019. Findings based on a linear regression model showed a positive association of aorta (P = .005), liver (P = .045), and portal vein (P = .001) enhancement to abdominal fat percentage during the portal venous phase. Authors recommend that other body size parameters, such as lean body weight, should be considered when calculating iodine dose for abdominal contrast-enhanced CT in dogs., (© 2021 American College of Veterinary Radiology.)

Purpose: To assess whether a fixed contrast media (CM) injection duration improves the magnitude and inter-patient variability in hepatic enhancement over a fixed injection rate., Methods: Outpatients who underwent portovenous phase abdominal CT (fixed duration, February-November 2018; fixed rate, January-July 2020) with 1.22 mL/kg iohexol 350 were included. Subjects with liver, kidney or heart disease were excluded. The number of subjects and injection protocols were as follows: fixed duration arm, 56 women, 60 men, 35 s injection duration; fixed rate arm, 66 women, 62 men, 3 mL/s injection rate. Liver attenuation measurements were obtained from regions of interest on pre- and post-contrast images. Mean hepatic enhancement (MHE) and MHE normalized to iodine dose (MHE/I) were compared (unpaired t-tests and F-tests)., Results: There was no statistically significant difference in age, weight, body mass index or CM dosing (p > 0.05). Enhancement indices were significantly lower in the fixed rate group as compared to the fixed duration group, as follows: MHE, 50.0 ± 12 vs. 54.8 ± 11 HU (p = 0.001); and MHE/I, 1.53 ± 0.43 vs. 1.66 ± 0.51 HU/g, (p = 0.04). However, there was no significant difference in the variances of MHE (p = 0.51) and MHE/I (p = 0.08)., Conclusion: A fixed CM injection duration yields a greater magnitude in hepatic enhancement indices than a fixed injection rate. Inter-patient variability in hepatic enhancement indices do not significantly differ between the two injection protocols.

Background: Iohexol is a typical iodinated radiocontrast medium and widely used in clinical angiography. Hypersensitivity reactions induced by iohexol are common side effects known to increase the risk for patients. Iodine is the main functional group of iohexol, and it can induce delayed anaphylaxis. However, iohexol also induces immediate-type allergies, but the underlying mechanism is still not clear. MRGPRX2 is a key receptor present on mast cells, which mediates pseudo-allergic reactions induced by various drugs., Methods: We aimed to verify the relationship between iohexol-induced anaphylactic reactions and MRGPRX2. MRGPRX2-mediated pseudo-allergic reactions induced by iohexol were investigated in vivo and in vitro using a mouse model of local and systemic anaphylaxis and mast cell degranulation assays, respectively., Results: Iohexol caused pseudo-allergic reactions in wild-type (WT) mice by activating mast cells to release histamine and cytokines. However, it did not induce a similar phenomenon in Kit W-sh/W-sh (MUT) mice. Iohexol stimulated intracellular calcium ion (Ca 2+ ) influx in MRGPRX2-HEK293, MrgprB2-HEK293, and LAD2 cells but not in NC-HEK293 cells. After knockdown of MRGPRX2 expression in LAD2 cells, the degree of iohexol-induced degranulation was reduced. In addition, after structural modification of iohexol by removal of iodine, a reduction in iohexol-induced effects, such as local and systemic anaphylaxis in mice and degranulation of LAD2 cells, could be observed. Iohexol was shown to induce immediate-type pseudo-allergic reactions via MRGPRX2, which was dependent on the presence of iodine., Conclusions: Conclusively, inhibition of MRGPRX2-mediated mast cell degranulation and cytokine release is important to prevent iohexol-induced immediate-type pseudo-allergic reactions., (Copyright © 2021 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Objectives: Previous large studies of contrast-induced or post-contrast acute kidney injury (CI-AKI/PC-AKI) have been observational, and mostly retrospective, often with patients undergoing non-enhanced CT as controls. This carries risk of inclusion bias that makes the true incidence of PC-AKI hard to interpret. Our aim was to determine the incidence of PC-AKI in a large, randomly selected cohort, comparing the serum creatinine (Scr) changes after contrast medium exposure with the normal intraindividual fluctuation in Scr., Methods: In this prospective study of 1009 participants (age 50-65 years, 48% females) in the Swedish CArdioPulmonary bioImage Study (SCAPIS), with estimated glomerular filtration rate (eGFR) ≥ 50 mL/min, all received standard dose intravenous iohexol at coronary CT angiography (CCTA). Two separate pre-CCTA Scr samples and a follow-up sample 2-4 days post-CCTA were obtained. Change in Scr was statistically analyzed and stratification was used in the search of possible risk factors., Results: Median increase of Scr post-CCTA was 0-2 μmol/L. PC-AKI was observed in 12/1009 individuals (1.2%) according to the old ESUR criteria (> 25% or > 44 μmol/L Scr increase) and 2 individuals (0.2%) when using the updated ESUR criteria (≥ 50% or ≥ 27 μmol/L Scr increase). Possible risk factors (e.g., diabetes, age, eGFR, NSAID use) did not show increased risk of developing PC-AKI. The mean effect of contrast media on Scr did not exceed the intraindividual Scr fluctuation., Conclusions: Iohexol administration to a randomly selected cohort with mildly reduced eGFR is safe, and PC-AKI is very rare, occurring in only 0.2% when applying the updated ESUR criteria., Key Points: • Iohexol administration to a randomly selected cohort, 50-65 years old with mildly reduced eGFR, is safe and PC-AKI is very rare. • Applying the updated ESUR PC-AKI criteria resulted in fewer cases, 0.2% compared to 1.2% using the old ESUR criteria in this cohort with predominantly mild reduction of renal function. • The mean effect of CM on Scr did not exceed the intraindividual background fluctuation of Scr, regardless of potential risk factors, such as diabetes or NSAID use in our cohort of 1009 individuals.

Carbonized iodine-doped particles (CIPs) were developed to overcome the disadvantages of computed tomography (CT) contrast agents, such as high osmolality and the radiodensity dilution of monomolecular contrast agents and low solubility and high toxicity of polymeric contrast agents. The CIPs were synthesized via a hydrothermal synthesis for 8 h using ATIPA (5-amino-2,4,6-triiodoisophthalic acid), glycerol, and tromethamine in the presence of D.W. (deionized water)-insoluble ATIPA converted into CIPs through a hydrothermal synthesis, showing high solubility and low osmotic pressure. The in vitro contrast effect determined for the resulting CIPs demonstrated a 57.6% enhancement compared to iohexol, and the osmotic pressure of the resulting CIPs was lower than that of iohexol. In addition, the CIPs demonstrated no dilution-induced contrast decrease in plasma and, therefore, demonstrated high contrast strength in vivo . Cytotoxicity tests, hemolysis assays, and histological analyses were conducted to verify the biocompatibility of the CIP product; however, no toxicity was observed. Furthermore, the CIP demonstrated a much higher contrast effect than iohexol at low concentrations. These results indicate that the CIP we have produced may be used as an effective blood pool agent for CT imaging.

Objective: To evaluate a contrast medium that could be used for radiographic and ultrasonographic assessment of the small intestine in dogs., Animals: 8 healthy adult Beagles., Procedures: Carboxymethylcellulose (CMC; 0.5% solution) was combined with iohexol (300 mg of iodine/mL) to yield modified contrast medium (MCM). Dogs were orally administered the first of 3 MCMs (10 mL/kg [9.5 mL of CMC/kg plus 0.5 mL of iohexol/kg]). Radiographic and ultrasonographic assessment of the small intestine followed 10 minutes after administration and every 10 minutes thereafter, until MCM was seen within the ascending colon. Minimally, 1 week elapsed between dosing of subsequent MCMs (10 mL/kg [9 mL of CMC/kg plus 1 mL of iohexol/kg and 8.5 mL of CMC/kg plus 1.5 mL of iohexol/kg]) and repeated radiography and ultrasonography., Results: Radiographic contrast enhancement of the small intestine was best with MCM that combined 8.5 mL of CMC/kg and 1.5 mL of iohexol/kg. Mean small intestinal transit time for all MCMs was 86 minutes. All MCMs did not interfere with ultrasonographic assessment of the small intestine and may have improved visualization of the far-field small intestinal walls., Conclusions and Clinical Relevance: An MCM that combined 8.5 mL of 0.5% CMC/kg and 1.5 mL of iohexol/kg could be an alternative to barium or iohexol alone for contrast small intestinal radiography in dogs, especially when abdominal ultrasonography is to follow contrast radiography.

Objective: To determine the correlation between patient attributes and contrast enhancement in liver parenchyma and demonstrate the potential for patient-informed prediction and optimization of contrast enhancement in liver imaging., Methods: The study included 418 chest/abdomen/pelvis computed tomography scans, with 75% to 25% training-testing split. Two regression models were built to predict liver parenchyma contrast enhancement over time: first model (model A) utilized patient attributes (height, weight, sex, age, bolus volume, injection rate, scan times, body mass index, lean body mass) and bolus-tracking data. A second model (model B) only used the patient attributes. Pearson coefficient was used to assess predictive accuracy., Results: Weight- and height-related features were found to be statistically significant predictors (P < 0.05), weight being the strongest. Of the 2 models, model A (r = 0.75) showed greater accuracy than model B (r = 0.42)., Conclusions: Patient attributes can be used to build prediction model for liver parenchyma contrast enhancement. The model can have utility in optimization and improved consistency in contrast-enhanced liver imaging.

Background: Iliac vein stenosis is a frequent pathologic process in advanced chronic venous disease. Intravascular ultrasound (IVUS) has emerged as the "gold standard" to diagnose iliac vein stenosis and to guide stent treatment. A pre-IVUS test is often obtained. Routine venography is deficient in several respects to fill this role; absence of an internal scale is a critical deficiency. Computed tomography venography (CTV) may be superior; its measurement capabilities can be used to precisely identify stenotic iliac vein caliber. Furthermore, the calibers of common iliac vein (CIV) and external iliac vein (EIV) can be individually assessed, yielding two data points instead of single-point assessment used in venography and current CTV protocols. We compared the diagnostic accuracy of the two-segment caliber method of CTV (arm vein injection of contrast material) with IVUS., Methods: In patients who underwent computed tomography assessment of iliac vein segments before IVUS examination during a 5-year period, 91 limbs were analyzed. This is a single-center, retrospective analysis of prospectively collected data. CTV images of CIV and EIV segments were compared individually and in combination with IVUS planimetry images. A caliber diameter of <16 mm for CIV and <14 mm for EIV was considered stenotic with either imaging technique. Bland-Altman plots and receiver operating characteristic curves were used., Results: On IVUS evaluation, 84% of CIVs and 78% of EIVs were stenotic and 16% and 22% were of normal caliber. These provided IVUS positive and negative controls for CTV comparison. On CTV, at least one of the two segments (CIV or EIV) was stenotic in 90% of the limbs, about 10% to 15% higher than single-segment involvement. Mean CTV caliber difference from IVUS was +2.5% for CIV and +7.3% for EIV. On Bland-Altman plot, single-segment diagnostic sensitivity of CTV was 83% and 73% for CIV and EIV, respectively, compared with IVUS. The sensitivity increased to 97% with a positive predictive value and accuracy of 93% and 91%, respectively, when a stenotic caliber in at least one of the two segments was considered diagnostic of iliac vein stenosis. Receiver operating characteristic analysis confirmed increased accuracy of the two-segment method over single-segment assessment with an area under the curve of 0.89 (P < .001)., Conclusions: Caliber diameter of <16 mm for CIV or <14 mm for EIV on routine CTV imaging appears to correlate with IVUS caliber stenosis with good diagnostic metrics of low false positives and false negatives., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Carboplatin dose is calculated based on kidney function, commonly estimated with imperfect creatinine-based formulae. Iohexol is used to measure glomerular filtration rate (GFR) and allows calculation of a more appropriate carboplatin dose. To address potential concerns that iohexol administered during a course of chemotherapy impacts that therapy, we performed in vitro and in vivo pharmacokinetic drug-drug interaction evaluations of iohexol., Methods: Carboplatin was administered IV to female mice at 60 mg/kg with or without iohexol at 300 mg/kg. Plasma ultrafiltrate, kidney and bone marrow platinum was quantitated by atomic absorption spectrophotometry. Paclitaxel microsomal and gemcitabine cytosolic metabolism as well as metabolism of CYP and UGT probes was assessed with and without iohexol at 300 µg/mL by LC-MS/MS., Results: In vivo carboplatin exposure was not significantly affected by iohexol co-administration (platinum AUC combination vs alone: plasma ultrafiltrate 1,791 vs 1920 µg/mL min; kidney 8367 vs 9757 µg/g min; bone marrow 12.7 vs 12.7 µg/mg-protein min). Paclitaxel microsomal metabolism was not impacted (combination vs alone: 6-α-OH-paclitaxel 38.3 versus 39.4 ng/mL/60 min; 3-p-OH-paclitaxel 26.2 versus 27.7 ng/mL/60 min). Gemcitabine human cytosolic elimination was not impacted (AUC combination vs gemcitabine alone: dFdU 24.1 versus 23.7 µg/mL/30 min). Iohexol displayed no relevant inhibition of the CYP and UGT enzymes in human liver microsomes., Conclusions: Iohexol is unlikely to affect the clinical pharmacokinetics of carboplatin, paclitaxel, gemcitabine, or other agents used in combination with carboplatin treatment. Measuring GFR with iohexol to better dose carboplatin is unlikely to alter the safety or efficacy of chemotherapy through pharmacokinetic drug-drug interactions.

Backgrounds: Contrast-induced acute kidney injury (CIAKI) is the third most common cause of hospital-acquired AKI. It has been demonstrated that microRNA-30c (miR-30c) was upregulated in the CIAKI. However, the underlying mechanism remain unclear., Methods: The CIAKI was induced in miniature pig. The expression profile of miR-30c in the kidney was evaluated by qPCR. The pathways regulated by miR-30c was identified by qPCR and western blot on renal tubular epithelial cells isolated from miniature pig. Finally, the potential therapeutic application of targeting miR-30c was assessed in the pig model of CIAKI., Results: The miR-30c was up-regulated in miniature pig with CIAKI. The miR-30c suppressed cell apoptosis, expression of NLRP3, the secretion of IL-1β and caspase-1 p10 on renal cells stimulated by iohexol in vitro. In the pig model, miR-30c inhibited the CIAKI development., Conclusion: Our data demonstrated that the miR-30c induced by CIAKI could suppress cell apoptosis and kidney injury via targeting NLRP3. Therefore, targeting miR-30c might be a novel therapeutic candidate for CIAKI treatment and prevention., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Backgrounds: Due to the unexpected side effects of the iodinated contrast agents, novel contrast agents for X-ray computed tomography (CT) imaging are urgently needed. Nanoparticles made by heavy metal elements are often employed, such as gold and bismuth. These nanoparticles have the advantages of long in vivo circulation time and tumor targeted ability. However, due to the long residence time in vivo, these nanoparticles may bring unexpected toxicity and, the preparation methods of these nanoparticles are complicated and time-consuming., Methods: In this investigation, a small molecular bismuth chelate using diethylenetriaminepentaacetic acid (DPTA) as the chelating agent was proposed to be an ideal CT contrast agent., Results: The preparation method is easy and cost-effective. Moreover, the bismuth agent show better CT imaging for kidney than iohexol in the aspect of improved CT values. Up to 500 µM, the bismuth agent show negligible toxicity to L02 cells and negligible hemolysis. And, the bismuth agent did not induce detectable morphology changes to the main organs of the mice after intravenously repeated administration at a high dose of 250 mg/kg. The pharmacokinetics of the bismuth agent follows the first-order elimination kinetics and, it has a short half-life time of 0.602 h. The rapid clearance from the body promised its excellent biocompatibility., Conclusions: This bismuth agent may serve as a potential candidate for developing novel contrast agent for CT imaging in clinical applications.

A 43-year-old male patient on maintenance hemodialysis had an enhanced computed tomography scan examination with iohexol for the first time 10 min before regular hemodialysis therapy. At the start of hemodialysis, no symptoms were observed, and the platelet count was 148,000/μl. Approximately 1 h after starting hemodialysis, dyspnea and chest discomfort appeared. Since oxygen saturation of the peripheral artery decreased to 87%, oxygen administration was immediately started while continuing hemodialysis therapy. Furthermore, gingival hemorrhage was observed, and the platelet count decreased to 5000/μl. We were carefully monitoring his conditions while continuing hemodialysis and oxygen administration, but no further deterioration was observed. Thereafter, these symptoms and severe thrombocytopenia gradually improved without additional treatment. At the end of hemodialysis, these symptoms completely disappeared. As well, the platelet count recovered to 35,000/μl at the end of hemodialysis and increased to 92,000/μl the next morning. From the clinical course, we diagnosed with contrast medium-induced thrombocytopenia. Acute thrombocytopenia is a rare complication induced by the contrast medium. Until now, 16 cases on contrast medium-induced thrombocytopenia have been reported. Our case spontaneously recovered from severe thrombocytopenia relatively earlier than previous reports. Our patient started hemodialysis therapy 10 min after an enhanced computed tomography examination. Early removal of contrast medium by hemodialysis might be associated with early improvement. We should acknowledge that contrast media have potential to induce severe thrombocytopenia, even in patients on maintenance hemodialysis.

Rationale & Objective: Glomerular filtration rate (GFR) estimation based on creatinine or cystatin C level is currently the standard method for assessing GFR in epidemiologic research and clinical trials despite several important and well-known limitations. Plasma iohexol clearance has been proposed as an inexpensive method for measuring GFR that could replace estimated GFR in many research projects. However, lack of standardization for iohexol assays and the use of different protocols such as single- and multiple-sample methods could potentially hamper comparisons across studies. We compared iohexol assays and GFR measurement protocols in 3 population-based European cohorts., Study Design: Cross-sectional investigation., Setting & Participants: Participants in the Age, Gene/Environment Susceptibility-Kidney Study (AGES-Kidney; n=805), the Berlin Initiative Study (BIS, n=570), and the Renal Iohexol Clearance Survey Follow-up Study (RENIS-FU; n=1,324)., Tests Compared: High-performance liquid chromatography analyses of iohexol. Plasma iohexol clearance calculated using single- versus multiple-sample protocols., Outcomes: Measures of agreement between methods., Results: Frozen samples from the 3 studies were obtained and iohexol concentrations were remeasured in the laboratory at the University Hospital of North Norway. Lin's concordance correlation coefficient ρ was>0.96 and C b (accuracy) was>0.99 for remeasured versus original serum iohexol concentrations in all 3 cohorts, and Passing-Bablok regression did not find differences between measurements, except for a slope of 1.025 (95% CI, 1.006-1.046) for the log-transformed AGES-Kidney measurements. The multiple-sample iohexol clearance measurements in AGES-Kidney and BIS were compared with single-sample GFRs derived from the same iohexol measurements. Mean bias for multiple-sample relative to single-sample GFRs in AGES-Kidney and BIS were-0.25 and-0.15mL/min, and 99% and 97% of absolute differences were within 10% of the multiple-sample result, respectively., Limitations: Lack of comparison with an independent gold-standard method., Conclusions: Agreement between the iohexol assays and clearance protocols in the 3 investigated cohorts was substantial. Our findings indicate that plasma iohexol clearance measurements can be compared across these studies., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Rationale and Objectives: To compare the magnitude and interpatient variability in normalized mean hepatic enhancement (MHE) indices when dosing contrast media (CM) according to total body weight (TBW) and lean body weight (LBW)., Materials and Methods: This ethics-approved stratified randomized controlled study allocated 280 outpatients for abdominal Computed Tomography (CT) between February-November 2018 to TBW- or LBW-dosing using computer-generated tables. CTs were acquired in portal venous phase after fixed 35-second injection of Iohexol 350. Patients with missing precontrast image, incorrect dose, or chronic kidney, liver or heart disease were excluded. The number of included patients and CM doses were: TBW arm, 51 women and 60 men, 1.22 mL/kg; LBW arm, 59 women, 1.66 mL/kg LBW, and 59 men, 1.52 mL/kg LBW. Liver attenuations were obtained from regions of interest. Values and standard deviations in MHE indices normalized to iodine dose (MHE/I) and iodine dose per kg TBW (aMHE = MHE/[I/TBW]) were compared (unpaired t tests and F-tests)., Results: Cohorts were similar in age, sex, TBW, and LBW. TBW groups received more CM than LBW groups: men, 106.5 ± 20 versus 98.4 ± 11 mL, p = 0.007; women, 93.7 ± 20 versus 77.5 ± 11 mL, p < 0.0001. TBW and LBW groups showed no significant difference in MHE/I (women, 1.75 ± 0.5 versus 1.86 ± 0.6 HU/g, p = 0.31; men, 1.53 ± 0.4 versus 1.52 ± 0.4 HU/g, p = 0.90) or aMHE (women, 0.03 ± 0.01 versus 0.03 ± 0.01 HU/g/kg, p = 0.25; men, 0.02 ± 0.01 versus 0.02 ± 0.01 HU/g/kg, p = 0.52). Variances in MHE/I and aMHE were not significantly different for all groups (p > 0.05)., Conclusion: TBW- and LBW-based CM dosing yield a similar magnitude and interpatient variability in normalized MHE indices at routine abdominal CT., (Copyright © 2019 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Objective: To investigate the application value of multiple injections of contrast agent in head and neck CT arteriovenous angiography in children., Methods: A total of 100 children aged 6 to 7 years who needed head and neck CT arteriovenous angiography were prospectively selected. They were randomly divided into a control group and a research group, with 50 children in each group. The same scanning parameters and reconstruction methods were used. The right median cubital vein was injected intravenously with the contrast agent Omnipaque (350 mg I/ml). For children in the control group, a bolus of undiluted contrast agent (dose was 2 ml/kg, upper limit was 50 ml) was injected 1 time. The arterial phase and vein phase of the head and neck vessels were scanned. For children in the research group, a contrast agent bolus diluted with saline to a concentration of 20% was first injected (dose was 1 ml/kg, upper limit was 25 ml), and then an undiluted contrast agent bolus (dose was 1 ml/kg, upper limit was 25 ml) was injected. Thresholds were used to trigger the scanning of the head and neck arterial phases. The CT image quality of the head and neck arteries and veins, radiation dose and contrast agent dose were compared between the 2 groups., Results: Subjective evaluation of CT image quality of arteries: there were 47 cases of 4 points and 3 cases of 3 points in the control group and 34 cases of 4 points and 16 cases of 3 points in the research group. Subjective evaluation of CT image quality of veins: there were 47 cases of 4 points and 3 cases of 3 points in the control group and 5 cases of 4 points, 42 cases of 3 points and 3 cases of 2 points in the research group. The CT value of brain arterial vessel enhancement was higher in the control group than the research group, and the difference was statistically significant (P < .05). The CT value of vein enhancement was higher in the control group than the research group, and the difference was statistically significant (P < .05). The X-ray dose in the research group was 51% lower than that in the control group; the contrast agent dose in the research group was 44% lower than that in the control group., Conclusion: For the head and neck enhanced CT examination of children, the method of first bolus injection of 20% diluted contrast agent and later bolus injection of undiluted contrast agent can clearly demonstrate the head and neck arteries and veins one time, reducing the X-ray dose and contrast agent dose, which has clinical practical value in the enhanced CT examination of children with head and neck disease.

To evaluate the influence of low-concentration contrast agents and low-tube-voltage computed tomography on chest enhancement examinations, we conducted a multicenter prospective study. A total of 216 inpatients enrolled from 12 different hospitals were randomly divided into four groups: A: voltage, 120 kVp; iohexol, 350 mgI/mL; B: voltage, 100 kVp, iohexol, 350 mgI/mL; C: voltage, 120 kVp, iodixanol, 270 mgI/mL; and D: voltage, 100 kVp, iodixanol, 270 mgI/mL. Subjective image quality was assessed by two radiologists and compared by weighted kappa test. The objective image scores, scanning radiation doses, and pathological coincidence rates were analyzed. There were no significant differences in gender, age, height, weight, and body mass index between the four groups (p > 0.05). The consistency of the radiologists' ratings were good, with kappa value ranging from 0.736 (95% confidence interval: 0.54-0.933) to 0.809 (95% confidence interval: 0.65-0.968), and there was no difference in subjective image score between the four groups. The computed tomography value of group D had no difference with group A. The volume computed tomography dose index, dose length product, and effective dose of group D (6.93 ± 3.03, 241.55 ± 104.75, and 3.38 ± 1.47, respectively) were all significantly lower than those of group A (10.30 ± 4.37, 359.70 ± 152.65, and 5.04 ± 2.14, respectively). There was no significant difference in the imaging diagnosis accuracy rate between the four groups (p > 0.05). The results indicated that low-concentration contrast agents (270 mgI/mL) and low-tube-voltage (100 kVp) computed tomography can not only decrease radiation dose but also guarantee the image quality and meet the needs of imaging diagnosis in chest enhancement examinations, which make it possible for its generalization and application.

Background: Contrast-induced nephropathy (CIN) is a frequent cause of hospital-acquired acute kidney injury. Previous animal models developed to explore the pathogenesis of CIN were based primarily on surgery or indomethacin treatment. Thus, we sought to explore a novel CIN rat model comparable to the human CIN., Methods and Results: Both serum creatinine and tubular injury score were used to assess the successful establishment of the present model. In our study, dehydration duration and the iohexol dosage were found to be the two most important factors to develop a rat CIN model. And, dehydration for 3 days plus furosemide (10 mL/kg) injection before iohexol (15 mL/kg) administration was demonstrated the optimal strategy. Renal injury induced by 15 mL/kg iohexol was almost twice more severe than 10 mL/kg. Moreover, significant renal function decrease, morphological damage and mitochondrial dysfunction occurred as early as 6 h after iohexol injection, not 24 h as previous studies reported. Unexpectedly, we firstly discovered that dehydration after iohexol administration did not increase the extent of renal damage, indicating that hydration after contrast media exposure may be ineffective., Conclusions: A novel CIN rat model based on dehydration and iohexol exposure was established and validated to assist in understanding and preventing CIN., (Copyright © 2019 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Efficient abatement of an iodinated X-ray contrast media iohexol by an emerging sulfite autoxidation advanced oxidation process is demonstrated, which is based on transition metal ion-catalyzed autoxidation of sulfite to form active oxidizing species. The efficacy of the combination of sulfite and transition metal ions (Ag(I), Mn(II), Co(II), Fe(II), Cu(II), Fe(III), or Ce(III)) was tested for iohexol abatement. Co(II) and Cu(II) are proven to show more pronounced catalytic activity than other metals at pH 8.0. According to the quenching studies, sulfate radical (SO 4 ) is identified to be the primary species for oxidation of iohexol. Increasing dosages of metal ion or sulfite and higher pH values are favorable for iohexol abatement. Inhibition of iohexol abatement is observed in the absence of dissolved oxygen, which is vital for the production of SO •- ) is identified to be the primary species for oxidation of iohexol. Increasing dosages of metal ion or sulfite and higher pH values are favorable for iohexol abatement. Inhibition of iohexol abatement is observed in the absence of dissolved oxygen, which is vital for the production of SO 5 •- and subsequent formation of SO 4 •- . Overall, activation of sulfite to produce reactive radicals with extremely low Co(II) or Cu(II) concentrations (in the range of μg L -1 ) in circumneutral conditions is confirmed, which offers a potential SO 4 •- -based advanced oxidation process in treatment of aquatic organic contaminants.

Background: The number of contrast media-related procedures is ever increasing due to the widespread availability of theoretically safe, low osmolar iodinated contrast material. Although intravenously administered contrast is known to precipitate myasthenic crisis, oral contrast aspiration as a causative factor is not yet documented as such. A 48-year-old Sinhalese man diagnosed as having myasthenia gravis, was evaluated for progressive dysphagia with an upper gastrointestinal contrast study. Iodinated contrast material (iohexol) was used as the contrast medium and there was direct evidence of contrast aspiration during the study. Several minutes after the procedure, severe respiratory distress with evidence of myasthenic crisis requiring intubation and intensive care admission was noted. Treatment with intravenous immunoglobulin, high-dose steroids, and broad-spectrum intravenously administered antibiotics led to an uneventful recovery, although the latter part of the clinical course was complicated with total left lung collapse. Myasthenic crisis can be precipitated by various factors and a successful recovery requires mechanical respiratory support with immunomodulatory and steroid therapy. This is the first reported case that describes the development of myasthenic crisis following iohexol-associated aspiration pneumonitis.

Objectives: The aim of this study was to evaluate the performance of the radiomics method in classifying lung cancer histological subtypes based on multiphasic contrast-enhanced computed tomography (CT) images., Methods: A total of 229 patients with pathologically confirmed lung cancer were retrospectively recruited. All recruited patients underwent nonenhanced and dual-phase chest contrast-enhanced CT; 1160 quantitative radiomics features were calculated to build a radiomics classification model. The performance of the classification models was evaluated by the receiver operating characteristic curve., Results: The areas under the curve of radiomics models in classifying adenocarcinoma and squamous cell carcinoma, adenocarcinoma and small cell lung cancer, and squamous cell carcinoma and small cell lung cancer were 0.801, 0.857, and 0.657 (nonenhanced); 0.834, 0.855, and 0.619 (arterial phase); and 0.864, 0.864, and 0.664 (venous phase), respectively. Moreover, the application of contrast-enhanced CT may affect the selection of radiomics features., Conclusions: Our study indicates that radiomics may be a promising tool for noninvasive predicting histological subtypes of lung cancer based on the multiphasic contrast-enhanced CT images.

Rational & Objective: The risks of iodinated contrast material administered to pediatric patients are not well defined. The purpose of this study was to examine the rates of postcontrast acute kidney injury (AKI), dialysis therapy, and death following administration of intravenous contrast material to pediatric patients., Study Design: Retrospective cohort study., Setting & Participants: Pediatric (aged <18 years) patients who underwent either contrast-enhanced (contrast group) or unenhanced (noncontrast group) computed tomography (CT) at our institution from December 2001 to January 2016., Exposure: Intravenous iodinated contrast material., Outcomes: Postcontrast AKI based on serum creatinine-defined KDIGO criteria, dialysis therapy, and death., Analytical Approach: Risks for AKI, dialysis therapy, and death were compared between contrast and noncontrast group patients using a propensity score analysis incorporating clinical covariates related to contrast exposure., Results: 2,201 pediatric patients (1,773 contrast and 428 noncontrast) were identified. Rates of AKI and dialysis therapy in the contrast group were 3.3% (59/1,773) and 0.1% (2/1,773), respectively. Following propensity score adjustment, no differences in risk for AKI (stage 1 AKI: OR, 0.75 [95% CI, 0.32-1.78], P=0.5; stage 2: OR, 2.00 [95% CI, 0.18-21.9], P=0.6; stage 3: OR, 0.50 [95% CI, 0.05-5.48], P=0.6), dialysis therapy (OR, 1.00 [95% CI, 0.06-15.9], P=0.9), or death (OR, 1.50 [95% CI, 0.53-4.22], P=0.4) were observed between the contrast and noncontrast groups. All patients with post-CT stage 3 AKI diagnosed also had contrast-independent potential causes of AKI., Limitations: The study's small sample size and low rates of postcontrast AKI, dialysis therapy, and death limited the ability to detect an effect of contrast administration on these outcomes. Unmeasured residual confounders may limit the validity of our results. Few patients had decreased kidney function at the time of CT., Conclusions: Rates of postcontrast AKI, dialysis therapy, and death following contrast-enhanced CT were very low in this pediatric cohort. Although not detectably different, an effect of contrast on these outcomes could not be ruled out., (Copyright © 2018 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Iodinated contrast media may contribute to acute kidney injury. However, several recent works suggest that this toxicity is minimal in the clinical setting. Recently, urinary G1 cell-cycle arrest proteins tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin like growth factor binding protein 7 (IGFBP-7) were identified as highly sensitive and specific biomarkers for early detection of kidney aggression. The impact of contrast administration on those biomarkers has not been specifically evaluated but could provide clues about the toxicity of contrast media. This study aimed at measuring changes in TIMP-2 and IGFBP-7 urinary concentrations before and after a contrast-enhanced computed tomography in critically ill patients., Methods: 77 patients were included in a prospective observational cohort study. Urinary [TIMP -2]·[IGFBP-7] was measured before, 6 and 24 h after contrast infusion. Urine output and serum creatinine were followed 3 days., Results: Median [TIMP-2]·[IGFBP-7] was 0.06 [interquartile range 0.04;0.26], 0.07 [0.03;0.34] and 0.10 [0.04;0.37] (ng/mL) 2 /1000 respectively before, 6 and 24 h after contrast infusion. Individual changes from baseline were - 0.01 [- 0.11;0.11] and 0.00 [- 0.10;0.09] (ng/ml) 2 /1000 at 6 and 24 h. These changes were not higher among the patients increasing their Kidney Disease Improving Global Outcome (KDIGO) classification within 3 days after contrast infusion (n = 14 [18%] based on creatinine criterion only, n = 42 [55%] based on creatinine and urine output)., Conclusions: Changes in [TIMP-2]·[IGFBP-7] urinary concentration after contrast-enhanced computed tomography were insignificant, suggesting minimal kidney aggression by modern iodinated contrast media.

The application of iodinated contrast medium has become a risk factor for metformin-associated lactic acidosis (MALA), which leads to the accumulation of metformin in vivo is one of the principal reasons for MALA. However, the molecular mechanism of the adverse event is not yet clear. In this study, iohexol injection was used as a model drug. The contrast agent acute kidney injury rat model, in vivo rat pharmacokinetic study, kidney slices and HK-2 cells were performed to elucidate the pharmacokinetic molecular mechanism of accumulation of metformin caused by contrast-induced nephropathy (CIN). Plasma exposure of metformin was increased significantly in the CIN group compared with that in the normal and control groups. The AUC of metformin was from 2791 ± 382 μg min mL -1 to 4784 ± 767 μg min mL -1 . The cumulative urinary excretion of metformin was also reduced in the CIN group. The uptake of metformin decreased in kidney slices in the CIN group. Compared with the normal and control groups, the blood lactate concentration was increased after intravenous administration of metformin in the CIN group followed a similar trend to the plasma concentrations of metformin. After treatment with contrast medium, the expression of OCT2 was reduced in rat kidney and HK-2 cells. These findings highlight that OCT2 deficiency was associated with increased lactate levels during metformin treatment caused by CIN., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Objectives: The computed tomography angiography (CTA) spot sign is a validated predictor of haematoma expansion (HE) in spontaneous intracerebral haemorrhage (SICH). We investigated whether defining the iodine concentration (IC) inside the spot sign and the haematoma on Gemstone spectral imaging (GSI) would improve its sensitivity and specificity for predicting HE., Methods: From 2014 to 2016, we prospectively enrolled 65 SICH patients who underwent single-phase spectral CTA within 6 h. Logistic regression was performed to assess the risk factors for HE. The predictive performance of individual spot sign characteristics was examined via receiver operating characteristic (ROC) analysis., Results: The spot sign was detected in 46.1% (30/65) of patients. ROC analysis indicated that IC inside the spot sign had the greatest area under the ROC curve for HE (0.858; 95% confidence interval, 0.727-0.989; p = 0.003). Multivariate analysis found that spot sign with higher IC (i.e. IC > 7.82 100 μg/ml) was an independent predictor of HE (odds ratio = 34.27; 95% confidence interval, 5.608-209.41; p < 0.001) with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 0.81, 0.75, 0.90 and 0.60, respectively; while the spot sign showed sensitivity, specificity, PPV and NPV of 0.81, 0.79, 0.73 and 0.86. Logistic regression analysis indicated that the IC in haematomas was independently associated with HE (odds ratio = 1.525; 95% confidence interval, 1.041-2.235; p = 0.030)., Conclusions: ICs in haematoma and in spot sign were all independently associated with HE. IC analysis in spectral imaging may help to identify SICH patients for targeted haemostatic therapy., Key Points: • Iodine concentration in spot sign and haematoma can predict haematoma expansion • Spectral imaging could measure the IC inside the spot sign and haematoma • IC in spot sign improved the positive predictive value (PPV) cf. CTA.

Objective: Sensitivity of CT of the abdomen for detection of acute bowel ischemia (ABI) can be as low as 60%. In this study, we assessed the diagnostic performance of iodine-map and monoenergetic (40-keV) images in patients with suspected ABI., Materials and Methods: This retrospective study included 60 consecutive patients with suspected ABI who underwent a standardized imaging protocol dual-source dual-energy CT (DECT) over a 26-month period. Clinical and operative outcomes were recorded as the reference standard. Two abdominal radiologists who were unaware of clinical and surgical information independently assessed conventional CT images for ABI. After a time interval designed to reduce recall, readers reassessed conventional images with supplementary iodine-map and 40-keV postprocessed images. Quantitative ROI analysis was also performed., Results: ABI was observed in 11 patients. For reader A, sensitivity was 63.6% (95% CI, 30.8-89.1%) when interpreting conventional images alone. Sensitivity for detection of ABI increased to 81.8% (95% CI, 48.2-97.7%) and 100% (95% CI, 71.5-100%) when iodine-map and 40-keV images were assessed, respectively. For reader B, no change in sensitivity was seen with either technique, but the number of false-positives were reduced with supplementary iodine-map and 40-keV postprocessed images. Interobserver agreement was fair with conventional images (κ = 0.29) but improved to moderate (κ = 0.45) and substantial (κ = 0.63) with iodine-map and 40-keV images, respectively. Quantitative assessment found significant differences in iodine uptake (1.01 ± 0.55 mg/mL vs 3.04 ± 1.19 mg/mL) and mean attenuation (75.2 ± 38.4 HU vs 163.5 ± 48.9 HU) between nonischemic and ischemic segments, respectively., Conclusion: Iodine-map and 40-keV monoenergetic images increase conspicuity of ABI, resulting in improved diagnostic accuracy compared with review of conventional CT images alone.

Background: Current guidelines regarding plasma-sampling techniques for glomerular filtration rate (GFR) determination are inconsistent. Single-sample methods are commonly believed not to be precise enough to meet clinical demands. The present study compared the agreement between single- and dual- plasma sampling methods with a three-point plasma clearance of iohexol., Methods: A total of 46 healthy volunteers and 124 chronic kidney disease (CKD) patients with varying degrees of renal dysfunction received 5 ml iohexol (300 mgI/ml) i.v. and plasma samples were drawn at 2-, 3- and 4-h post-injection. Plasma-iodine concentrations were detected by high-performance liquid chromatography (HPLC)., Results: Bias was similar among single-plasma sampling methods (SPSM) and dual-plasma sampling methods (DPSM). The best correlation was obtained from the 2- and 4-h DPSM (concordance correlation coefficient [CCC]: 0.9988) with none of the estimates differed by more than 30% from the reference GFR and only one (0.06%) estimate differed by more than 10% (P 30 , 100%; P 10 , 99.4%). SPSM using samples around 3- or 4-h demonstrated acceptable accuracy at a GFR level of ≥60 ml/min/1.73m 2 (P 30  = 100% and P 10  > 75% for both measurements)., Conclusion: 4-h SPSM is advantageous in clinical practice in subjects with GFR ≥ 60 ml/min/1.73m 2 . For patients with an expected GFR < 60 ml/min/1.73m 2 , a prolonged sampling time is more reliable.

Radiocontrast dyes are used for a wide range of diagnostic procedures for enhancing the image of anatomical structures, pain targets, and vascular uptake. While some of these dyes show toxicity to primary cells, their effect on stem cells, particularly mesenchymal stem cells (MSCs), is unknown. This study investigates the cytotoxic effects of two clinically used radiocontrast dyes, iohexol and iopamidol, on bone marrow and human umbilical cord MSCs. Exposure to these dyes significantly affected morphology of MSCs from both sources, as treated cells appeared transparent and no longer fibroblastoid. Cell viability decreased as determined by trypan blue and Annexin-V/PI staining, in a dose dependent manner with simultaneous loss of CD90 and CD105 concurrent with spontaneous differentiation in MSCs treated with iohexol and iopamidol. In addition, significantly higher cell death was observed in MSCs exposed to iopamidol than iohexol. At a concentration of 1:1, iohexol and iopamidol induced apoptosis in 19% and 92% (<.01) of MSCs, respectively. Global transcriptome analysis of treated MSCs revealed 139 and 384 differentially expressed genes in iohexol vs control and iopamidol vs control at p ≤ .01 and 1.5-fold, respectively. This suggested that iopamidol had more significant effect on the transcription of MSCs. Based on these results a molecular mechanism of radiocontast dye induced cell death via intrinsic apoptosis pathway mediated by p53 was proposed. Since iopamidol was significantly more toxic than iohexol in human MSCs, a more careful examination of safety of radiocontrast dyes for clinical use is warranted., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: The objective of our study was to evaluate the diagnostic performance of CT in the identification of anastomotic leaks., Materials and Methods: This was a study of patients who underwent bowel surgery and a subsequent postoperative CT examination performed specifically for investigating for an anastomotic leak. The study group included patients with surgically confirmed anastomotic leaks (n = 59), and the control group included patients without anastomotic leaks (n = 48) confirmed by either repeat surgery or uneventful clinical follow-up for at least 6 months. Two radiologists and two radiology residents independently reviewed each CT examination for specific CT findings from a set of predetermined imaging predictors. The sensitivity and specificity for each imaging predictor were calculated for each reader, and the interobserver agreement was calculated using the Cohen kappa coefficient. Diagnostic performance was assessed using ROC curve analysis., Results: The most sensitive imaging predictor was intraabdominal free fluid (95.3%). Leakage of intraluminal contrast agent was also a highly specific imaging predictor (96.6%). Substantial interobserver agreement was shown for intraabdominal free gas (κ = 0.76) and leakage of intraluminal contrast agent (κ = 0.76). Overall diagnostic performance in correctly identifying surgically confirmed leaks, as assessed by the area under the ROC curve, ranged from 0.76 to 0.86. Diagnostic performance was higher for all readers when intraluminal contrast agent was used and reached the anastomosis, with the exception of one reader, whose diagnostic performance remained unchanged., Conclusion: Diagnostic performance of CT was highest when an intraluminal contrast agent was used. Meticulous and careful use of an intraluminal contrast agent is therefore important in this patient population.