Iodinated Contrast Research Articles

The molecular mechanism of contrast-induced nephropathy (CIN) and its link to in vitro studies on iodinated contrast media (CM)

The molecular mechanism of contrast-induced nephropathy (CIN) and its link to in vitro studies on iodinated contrast media (CM)

Development and Clinical Evaluation of a Contrast Optimizer for Contrast-Enhanced CT Imaging of the Liver

Objective Patient characteristics, iodine injection, and scanning parameters can impact the quality and consistency of contrast enhancement of hepatic parenchyma in CT imaging. Improving the consistency and adequacy of contrast enhancement can enhance diagnostic accuracy and reduce clinical practice variability, with added positive implications for safety and cost-effectiveness in the use of contrast medium. We developed a clinical tool that uses patient attributes (height, weight, sex, age) to predict hepatic enhancement and suggest alternative injection/scanning parameters to optimize the procedure. Methods The tool was based on a previously validated neural network prediction model that suggested adjustments for patients with predicted insufficient enhancement. We conducted a prospective clinical study in which we tested this tool in 24 patients aiming for a target portal-venous parenchyma CT number of 110 HU ± 10 HU. Results Out of the 24 patients, 15 received adjustments to their iodine contrast injection parameters, resulting in median reductions of 8.8% in volume and 9.1% in injection rate. The scan delays were reduced by an average of 42.6%. We compared the results with the patients' previous scans and found that the tool improved consistency and reduced the number of underenhanced patients. The median enhancement remained relatively unchanged, but the number of underenhanced patients was reduced by half, and all previously overenhanced patients received enhancement reductions. Conclusions Our study showed that the proposed patient-informed clinical framework can predict optimal contrast enhancement and suggest empiric injection/scanning parameters to achieve consistent and sufficient contrast enhancement of hepatic parenchyma. The described GUI-based tool can prospectively inform clinical decision-making predicting optimal patient's hepatic parenchyma contrast enhancement. This reduces instances of nondiagnostic/insufficient enhancement in patients.

Predictors for Irreversibility of Contrast-Induced Acute Kidney Injury in Patients with Obesity After Contrast-Enhanced Computed Tomography Coronary Angiography.

Although contrast-induced (CI) acute kidney injury (AKI) is a common complication in high-risk individuals requiring evaluation with contrast-enhanced angiography, the possible predictors of CI-AKI in patients with obesity are not fully understood. The aim of this study was to elucidate plausible factors associated with the irreversibility of CI-AKI in individuals with obesity undergoing contrast-enhanced computed tomography coronary angiography. A total of 96 adult patients with obesity and the KDIGO criteria of CI-AKI (increase of serum levels of creatinine≥25% or≥500µmol/L at 48h after procedure) were retrospectively screened from the cohort of 1833 patients who underwent iodine contrast medium (ICM)-enhanced computed tomography coronary angiography, and were included in the study. The patients were divided into two cohorts: 96 adult patients with obesity and recovery of CI-AKI in 7days after initiating of the event, and 57 individuals with irreversibility of CI-AKI. Serum concentrations of conventional biochemistry and urine biomarkers [i.e., hemoglobin, creatinine, high-sensitivity C-reactive protein, urinary albumin/creatinine ratio (UACR)] as well as natriuretic peptide, adropin, apelin, irisin, tumor necrosis factor-alpha (TNF-alpha), were determined at baseline. The levels of creatinine were measured at baseline, at the event, and in 7days after the event. We identified 12 variables, which were associated with irreversibility of CI-AKI: age>75years [odds ratio (OR)=1.22. P=0.001], male gender (OR=1.03, P=0.042), stable coronary artery disease (OR=1.06, P=0.048), chronic kidney disease (CKD) 1-3 grade (OR=1.60, P=0.001), heart failure with preserved ejection fraction (HFpEF) (OR=1.07, P=0.046), baseline estimated GFR<80mL/min/1.73 m2 (OR=1.10, P=0.040), UACR>17.5mg/g Cr (OR=1.05, P=0.048), TNF-alpha>3.11pg/mL (OR=1.12, P=0.001), and adropin<2.43ng/mL (OR=1.18, P=0.001). After adjustment for CKD and UACR>17.5mg/g Cr, only HFpEF (OR=1.06, P=0.042) and adropin<2.43ng/mL (OR=1.11, P=0.001) remained independent predictors of CI-AKI irreversibility. Yet, adropin<2.43ng/mL at baseline exerted sufficiently better predictive ability than both HFpEF and preexisting CKD 1-3 grade. In a multivariate prediction model adjusted for CKD and urinary albumin/creatinine ratio>17.5mg/g Cr, low levels of adropin (<2.43ng/mL) in individuals with non-morbid obesity together with the presence of HFpEF were independent predictors of CI-AKI irreversibility after ICM-enhanced computed tomography coronary angiography.

Comparative Safety Profiles and Usage Patterns of Iodinated Contrast Media in Medical Imaging

Comparative Safety Profiles and Usage Patterns of Iodinated Contrast Media in Medical Imaging

Introduction to iodinated contrasts: Properties, intravenous administration and distribution throughout the body

Iodinated contrast media enable greater attenuation of vascular and visceral structures in radiological studies and are widely used due to their high degree of safety, easy administration, acceptable level of tolerance, wide distribution and rapid excretion, qualities determined by their composition.Automated power injectors are used to administer contrast media. Once injected, contrast is distributed throughout the body, remaining in the intravascular space during its first passage before reaching the organs and spreading into the extracellular interstitial space, followed by a recirculation phenomenon.In CT studies, the level of contrast enhancement obtained is determined by multiple factors including patient-related factors, contrast medium characteristics, method of administration, equipment and technique. Different methods are available for determining the scan timing depending on the aim of the exploration.

Magnetic vagus nerve stimulation ameliorates contrast-induced acute kidney injury by circulating plasma exosomal miR-365-3p

BackgroundContrast-induced acute kidney injury (CI-AKI) is manifested by a rapid decline in renal function occurring within 48–72 h in patients exposed to iodinated contrast media (CM). Although intravenous hydration is currently the effective method confirmed to prevent CI-AKI, it has several drawbacks. Some investigations have demonstrated the nephroprotective effects of vagus nerve stimulation (VNS) against kidney ischemia-reperfusion injury, but no direct research has investigated the use of VNS for treating CI-AKI. Additionally, most current VNS treatment applies invasive electrical stimulator implantation, which is largely limited by the complications. Our recent publications introduce the magnetic vagus nerve stimulation (mVNS) system pioneered and successfully used for the treatment of myocardial infarction. However, it remains uncertain whether mVNS can mitigate CI-AKI and its specific underlying mechanisms. Therefore, we herein evaluate the potential therapeutic effects of mVNS on CM-induced nephropathy in rats and explore the underlying mechanisms.ResultsmVNS treatment was found to significantly improve the damaged renal function, including the reduction of elevated serum creatinine (Scr), blood urea nitrogen (BUN), and urinary N-acetyl-β-D-glucosaminidase (NAG) with increased urine output. Pathologically, mVNS treatment alleviated the renal tissue structure injury, and suppressed kidney injury molecule-1 (KIM-1) expression and apoptosis in renal tubular epithelial cells. Mechanistically, increased circulating plasma exosomal miR-365-3p after mVNS treatment enhanced the autophagy and reduced CM-induced apoptosis in renal tubular epithelial cells by targeting Ras homolog enriched in brain (Rheb).ConclusionsIn summary, we demonstrated that mVNS can improve CI-AKI through enhanced autophagy and apoptosis inhibition, which depended on plasma exosomal miR-365-3p. Our findings highlight the therapeutic potential of mVNS for CI-AKI in clinical practice. However, further research is needed to determine the optimal stimulation parameters to achieve the best therapeutic effects.Graphical abstract

Feasibility of ultra-low volume contrast pulmonary arterial injection protocol for CTA in TAVI candidates with severe renal failure

Abstract Introduction Computer tomography angiography (CTA) has an important role in patient screening before TAVI. The high volumes of iodinated contrast media (CM) injected during the examination represents the main limitation of CTA with a dose-dependent association with contrast-induced nephropathy. Purpose Show the feasibility of an ultra-low-dose CM pulmonary arterial injection protocol for CTA in TAVI candidates in high risk patients with severe renal failure. Methods In our retrospective study seventy-seven (77) patients with CKD on stage 3b or worse (eGFR ≤ 45/min/1.73 m2) underwent pre-procedural CTA for TAVI-planning with a pulmonary arterial administration of CM. All CTA examinations were performed using a Dual Source 256-slice CT system. All enhanced CT acquisitions were performed using our dedicated biphasic injection protocol composed of two connected phases of contrast medium injection using different amount of CM (8, 10, 15 and 20 ml) according to BMI (&amp;lt;22 kg/m2; 22-24 kg/m2; 24-28 kg/m2; &amp;gt;28 kg/m2). The CM was administered directly into the pulmonary artery in all patients. For each examination was measured Intraluminal attenuation at thoraco-abdominal aorta and along the ilio-femoral vessels using the ROI (mean SD in HU) as objective image parameters (Picture 1). Serum creatinine and the eGFR were recorded pre-TAVI CT scan and after the procedures as reference of CM to renal function. Results CTA was successfully performed in all patients. Mean creatinine was 2.25 ± 0,76 mg/dL and mean GFR was 26.5± 8.1 mL/min/m2. Mean vessel attenuation was 352±164 HU at the aortic annulus, 238.1 ± 141,3 HU in the aortic arch and 266±168 in the iliac arteries (Picture 2). The mean image noise was 28.2 ± 7 HU in the aortic annulus, 24.4 ± 10,9 in the right external iliac artery, and 25. ± 12,8 HU in the left external iliac artery. After CTA examination, a total of 74 patients (96%) underwent TAVI. Mean CM dose administered during TAVI procedure was 150,6 ± 85,8. Three patients (3.9%) were abolished for TAVI. Postprocedural settings complications were recorded. A total of 31 patients (41%) had grade 1 paravalvular regurgitation, 10 patients (14%) grade 2. No cases of valve embolization or anulus rupture occured. No major vascular complications occured. No significant differences between creatine and eGFR pre and post procedures (p&amp;lt;0,001). Conclusions The use of an ultra-low-dose CM pulmonary arterial injection protocol for CTA in TAVI candidates does not affect the renal function and procedural success rate is high and the clinical outcomes after TAVI is satisfactory according to the litterature.

Imaging for upper tract urothelial carcinoma: update of the evidence and a glimpse into the future.

Upper tract urothelial carcinoma (UTUC) is a rare malignancy posing significant diagnostic and management challenges. This review provides an overview of the evidence supporting various imaging modalities and offers insights into future innovations in UTUC imaging. With the growing use of advancements in computed tomography (CT) technologies for both staging and follow-up of UTUC patients, continuous innovations aim to enhance performance and minimize the risk of excessive exposure to ionizing radiation and iodinated contrast medium. In patients unable to undergo CT, magnetic resonance imaging serves as an alternative imaging modality, though its sensitivity is lower than CT. Positron emission tomography, particularly with innovative radiotracers and theranostics, has the potential to significantly advance precision medicine in UTUC. Endoscopic imaging techniques including advanced modalities seem to be promising in improved visualization and diagnostic accuracy, however, evidence remains scarce. Radiomics and radiogenomics present emerging tools for noninvasive tumor characterization and prognosis. The landscape of imaging for UTUC is rapidly evolving, with significant advancements across various modalities promising improved diagnostic accuracy, patient outcomes, and safety.

Iodine Assessment of Carbon Dioxide Angiography in Iliac Branched Repair.

The objective of this study was to investigate whether the use of carbon dioxide (CO2) angiography decreases the intraoperative use of iodine contrast medium (ICM), thereby decreasing the risk of developing postoperative renal damage in patients undergoing iliac branch device (IBD) implantation. Patients undergoing IBD implantation at a single tertiary center between May 2013 and August 2019 were screened for inclusion in the study. A cohort of patients in whom an intraoperative imaging protocol using predominantly CO2 was compared with a control group in whom ICM was used (CO2 and ICM groups). Fusion imaging was used in both groups. Retrospective review of the medical charts and all imaging was performed. Variables were expressed as median with interquartile range (IQR) or absolute number and percentage. Wilcoxon-Mann-Whitney and χ2 tests were used to compare continuous and categorical variables, respectively. P values of <0 .05 were considered statistically significant. Twenty-three patients were included in the CO2 group and 21 in the ICM group without significant differences in patient characteristics between the groups. Intraoperative iodine exposure was lower in the CO2 group than in the ICM group (8.2 g [IQR, 7.1-10.9 g) vs 15.8 g (IQR 7.6-21 g); P = 0.015, respectively). There were no differences in technical success, clinical success, fluoroscopy time, and dose-area product in the 2 groups. There were no adverse events that could be related to the intraoperative use of CO2. There was no difference in postoperative survival nor renal function assessment between the groups despite the higher number of accessory renal arteries embolized in the CO2 group (P = 0.221). Reduction of intraoperative ICM exposure during IBD implantation is feasible through the predominant use of CO2 automated angiography. This can be done safely without affecting the technical success or radiation exposure. The immediate postoperative renal damage was low when a modern intraoperative imaging protocol with ICM was used and was not significantly reduced by the use of CO2. Further and larger studies are needed to investigate the long-term effects. This study aimed to investigate how to minimize intraoperative risk during iliac branched repair exploring the intraoperative use of automated carbon dioxide angiography in order to decrease the use of contrast media protecting renal function and thereby potentially impacting long-term survival.

Deep-learning reconstruction enhances image quality of Adamkiewicz Artery in low-keV dual-energy CT.

Low-keV virtual monoenergetic images (VMIs) of dual-energy computed tomography (CT) enhances iodine contrast for detecting small arteries like the Adamkiewicz artery (AKA), but image noise can be problematic. Deep-learning image reconstruction (DLIR) effectively reduces noise without sacrificing image quality. To evaluate whether DLIR on low-keV VMIs of dual-energy CT scans improves the visualization of the AKA. We enrolled 29 patients who underwent CT angiography before aortic repair. VMIs obtained at 70 and 40 keV were reconstructed using hybrid iterative reconstruction (HIR), and 40 keV VMIs were reconstructed using DLIR. The image noise of the spinal cord, the maximum CT values of the anterior spinal artery (ASA), and the contrast-to-noise ratio (CNR) of the ASA were compared. The overall image quality and the delineation of the AKA were evaluated on a 4-point score (1 = poor, 4 = excellent). The mean image noise of the spinal cord was significantly lower on 40-keV DLIR than on 40-keV HIR scans; they were significantly higher than on 70-keV HIR images. The CNR of the ASA was highest on the 40-keV DLIR images among the three reconstruction images. The mean image quality scores for 40-keV DLIR and 70-keV HIR scans were comparable, and higher than of 40-keV HIR images. The mean delineation scores for 40-keV HIR and 40-keV DLIR scans were significantly higher than for 70-keV HIR images. Visualization of the AKA was significantly better on low-keV VMIs subjected to DLIR than conventional HIR images.

Substituting with alternativeiodinated contrast medium to prevent recurrent adverse drug reactions associated with its use: a meta-analysis.

To systematically review and meta-analyze the recurrent rate of iodinated contrast medium (ICM)-associated adverse drug reactions (ADRs) and the preventive effect of using alternative ICM lacking a common carbamoyl side chain. A systematic literature search was conducted in the MEDLINE and EMBASE databases to identify studies that investigated the recurrence rate of ICM-associated ADRs or hypersensitivity reactions (HSRs). Studies that included patients who subsequently underwent contrast-enhanced computed tomography scans after their index reactions were included, while studies with overlapping cohorts were excluded. The first search was conducted on November 10, 2023. The pooled recurrence rate of ICM-associated ADR was determined using the DerSimonian-Laird random-effects model. Subgroup analyses were also conducted based on the substitution of ICM, with particular consideration given to the N-(2,3-dihydroxypropyl) carbamoyl side chain. A total of ten original articles were included in the analysis, collectively spanning from June 2001 to March 2021. The pooled recurrence rate of ICM-associated ADR was not significantly different from that of ICM-associated HSR (16.6% [95% CI, 7.8-31.9%] vs. 15.5% [95% CI, 10.8-21.8%], p = 0.87). In the subgroup analyses, the pooled odds ratio for ICM-associated recurrent ADR when using a different ICM compared with using the same ICM was 0.31 (95% CI, 0.21-0.45), which means a 69% reduction. Moreover, the pooled odds ratio for ICM-associated recurrent ADR when substituting ICMs with different side chains compared with substituting with common side chains was 0.65 (95% CI, 0.52-0.82), which means an additional 35% reduction. Substituting with an alternative ICM led to a 69% reduction in recurrent ADRs, with an additional 35% reduction observed when using ICM lacking a common carbamoyl side chain. Question No standardized guidelines exist for replacing previously used iodinated contrast medium (ICM) to prevent recurrent adverse reactions. Findings Using alternative contrast medium with a different carbamoyl side chain prevents adverse drug reactions effectively. Clinical relevance This study advocates using alternative ICM without a common carbamoyl side chain to prevent recurrent adverse drug reactions in patients with a history of such events.

Validation of an UPLC-PDA Method for the Simultaneous Quantification of Phenol and Iomeprol in a Sterile Parenteral Preparation Used for Coeliac Plexus Block, and Its Application to a Pharmaceutical Stability Study.

Objectives: A commonly applied analgesic therapy for patients with severe abdominal pain due to cancer-related pain in the upper abdomen, is coeliac plexus neurolysis (CPN). Herein, a combination product of phenol and an iodine contrast agent are injected simultaneously. The chemical stability of such a combination product is unknown, and no chromatographic method is yet available that describes the simultaneous quantification of phenol and iomeprol. The aim of this study was to develop and validate a stability-indicating UPLC method for the simultaneous quantification of both phenol and iomeprol and to determine the chemical stability of a sterile 100 mg/mL phenol in 350 mg I/mL iomeprol solution for injection during shelf life. Methods: The product was compounded and sterilized in a GMP certified facility. The pharmaceutical analysis was validated by determination of the accuracy, precision, specificity, selectivity, carry-over and linearity. Pharmaceutical product stability was determined before and after sterilization, and during shelf life of 36 months at 25°C ± 2°C. Results: The accuracy for phenol and iomeprol was 97.1% to 99.3% and 100.0% to 100.2%, respectively. The RSD for repeatability and reproducibility for phenol were 0.65% and 1.17%, and for iomeprol 0.61% and 1.49%, respectively. All other tested parameters met the predefined validation criteria. All concentrations at all tested time points remained within ±2% of the initial concentrations for phenol and ±4% for iomeprol. No additional peaks were visible on the chromatograms. Conclusion: A stability-indicating method for the simultaneous quantification of phenol and iomeprol in a parental pharmaceutical preparation was developed and validated. This method was used to demonstrate the chemical stability of a newly developed sterile solution of 100 mg/mL phenol and 350 mg I/mL iomeprol. Chemical product stability was demonstrated during shelf life of up to 36 months.

Image Quality and Lesion Detectability of Low-Concentration Iodine Contrast and Low Radiation Hepatic Multiphase CT Using a Deep-Learning-Based Contrast-Boosting Model in Chronic Liver Disease Patients.

This study investigated the image quality and detectability of double low-dose hepatic multiphase CT (DLDCT, which targeted about 30% reductions of both the radiation and iodine concentration) using a vendor-agnostic deep-learning-based contrast-boosting model (DL-CB) compared to those of standard-dose CT (SDCT) using hybrid iterative reconstruction. The CT images of 73 patients with chronic liver disease who underwent DLDCT between June 2023 and October 2023 and had SDCT were analyzed. Qualitative analysis of the overall image quality, artificial sensation, and liver contour sharpness on the arterial and portal phase, along with the hepatic artery clarity was conducted by two radiologists using a 5-point scale. For quantitative analysis, the image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured. The lesion conspicuity was analyzed using generalized estimating equation analysis. Lesion detection was evaluated using the jackknife free-response receiver operating characteristic figures-of-merit. Compared with SDCT, a significantly lower effective dose (16.4 ± 7.2 mSv vs. 10.4 ± 6.0 mSv, 36.6% reduction) and iodine amount (350 mg iodine/mL vs. 270 mg iodine/mL, 22.9% reduction) were utilized in DLDCT. The mean overall arterial and portal phase image quality scores of DLDCT were significantly higher than SDCT (arterial phase, 4.77 ± 0.45 vs. 4.93 ± 0.24, AUCVGA 0.572 [95% CI, 0.507-0.638]; portal phase, 4.83 ± 0.38 vs. 4.92 ± 0.26, AUCVGA 0.535 [95% CI, 0.469-0.601]). Furthermore, DLDCT showed significantly superior quantitative results for the lesion contrast-to-noise ratio (7.55 ± 4.55 vs. 3.70 ± 2.64, p < 0.001) and lesion detectability (0.97 vs. 0.86, p = 0.003). In patients with chronic liver disease, DLDCT using DL-CB can provide acceptable image quality without impairing the detection and evaluation of hepatic focal lesions compared to SDCT.

Computed tomography image quality in patients with primary hepatocellular carcinoma: intraindividual comparison of contrast agent concentrations.

This study aimed to assess the impact of the different concentrations of iodine contrast agents used on the quality of computed tomography (CT) images obtained intraindividually in hepatocellular carcinoma patients. In this retrospective study, data from a cohort of 29 patients diagnosed with primary hepatocellular carcinoma who had undergone two preoperative CT-enhanced examinations within a 3-month timeframe were analyzed. Each patient was randomly assigned to receive either a low-concentration contrast agent (300 mg I/mL iohexol) or a high-concentration contrast agent (350 mg I/mL iohexol) for the first scan and the alternative contrast agent for the second scan. CT images of different liver regions of each patient were compared between low-and high-concentration scans using their before-and-after control design. Subjective image quality scores for portal vein images were also assessed. The findings of this study indicate that patients in the high-concentration group presented significantly elevated CT values across various anatomical regions, including the liver parenchyma, abdominal aorta, and hepatic portal vein, compared to those in the low-concentration group (p < 0.05). Moreover, the high-concentration group demonstrated superior subjective image ratings (p < 0.05). Nevertheless, there was no statistically significant difference in the CT values observed in liver cancer parenchyma scans at different phases between the two groups (p > 0.05). In summary, using a high-concentration iodine contrast agent is efficient in enhancing the visual clarity of the liver parenchyma, the aorta, and the portal vein in individuals diagnosed with primary hepatocellular carcinoma.

Acute iodinate contrast medium reaction: look at the CT images!

Acute iodinate contrast medium reaction: look at the CT images!

Puffed-Cheek CT Improved Evaluation of Buccal Mucosal Neoplasm in Contest to Conventional CT Scan

Background: Oral cancer is a frequent cancer in our country, most people are affected by this cancer are older age. Accurate evaluation of this cancer difficult due to close proximity of bones and soft tissue. So for improve diagnostic accuracy Puffed cheek maneuver should be used with traditional Multidetector Computed Tomography (MDCT).Objective: To determine the improved diagnostic accuracy of Puffed cheek Computed Tomography (PCCT) in evaluation of buccal mucosa tumors in contest to non puffed cheek Computed Tomography.Materials and Methods: This descriptive cross sectional study was carried out in Radiology and Imaging department of Khwaja Yunus Ali Medical College and Hospital from 2022(January) to 2023(July). Cases were referred from different department. After meeting the inclusion criteria patients were subjected for CT scan. Imaging was performed from paranasal sinus and neck region with axial sections from pituitary fossa to arch of aorta, after injection of intravenous iodinated contrast media, multiplanar sagittal, coronal reformation images were obtained. Puffed cheek manoeuvre was performed to separate gingival and oral buccal mucosa in all the cases for improved detailed evaluation. The CT result were then compared with non puffed cheek scans results. Results: Among 30 patients 7 cases were missed by conventional CT scan, thirteen patients showed a mass in the oral cavity that were inseparable from 2 mucosal surfaces. Puffed-cheek images clearly showed the mass and surface of tumor involvement. Other 10 patients in conventional CT showed mass in the margins of tongue, oral cavity but extension and infiltration of surrounding structures by the lesion could not be well delineated, puffed-cheek images clearly showed the specific location, extension, adjacent muscles and other structures infiltration. Conclusion: Puffed cheek CT gives better performance to diagnosis the small buccal mucosal tumors, any irregularity, thickening, more detailing of mucosal surface of oral cavity than conventional CT scan, so can helps in choosing the management &amp; surgical approach also. KYAMC Journal Volume: 15, No: 01, April 2024: 29-32.

Deep-learning-based attenuation map generation in kidney single photon emission computed tomography

BackgroundAccurate attenuation correction (AC) is vital in nuclear medicine, particularly for quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) imaging. This study aimed to establish a CT-free quantification technology in kidney SPECT imaging using deep learning to generate synthetic attenuation maps (μ-maps) from SPECT data, thereby reducing radiation exposure and eliminating the need for CT scans.ResultsA dataset of 1000 Tc-99m DTPA SPECT/CT scans was analyzed for training (n = 800), validation (n = 100), and testing (n = 100) using a modified 3D U-Net for deep learning. The study investigated the use of primary emission and scattering SPECT data, normalization methods, loss function optimization, and up-sampling techniques for optimal μ-map generation. The problem of checkerboard artifacts, unique to μ-map generation from SPECT signals, and the effects of iodine contrast media were evaluated. The addition of scattering SPECT to primary emission SPECT imaging, logarithmic maximum normalization, the combination of absolute difference loss (L1) and three times the absolute gradient difference loss (3 × LGDL), and the nearest-neighbor interpolation significantly enhanced AI performance in μ-map generation (p < 0.00001). Checkerboard artifacts were effectively eliminated using the nearest-neighbor interpolation technique. The developed AI algorithm produced μ-maps neutral to the presence of iodine contrast and showed negligible contrast effects on quantitative SPECT measurement, such as glomerular filtration rate (GFR). The potential reduction in radiation exposure by transitioning to AI-based CT-free SPECT imaging ranges from 45.3 to 78.8%.ConclusionThe study successfully developed and optimized a deep learning algorithm for generating synthetic μ-maps in kidney SPECT images, demonstrating the potential to transition from conventional SPECT/CT to CT-free SPECT imaging for GFR measurement. This advancement represents a significant step towards enhancing patient safety and efficiency in nuclear medicine.

Catalytic hydrodehalogenation of iodinated contrast agents in drinking water: A kinetic study

The occurrence of iodinated contrast media (ICM) in water bodies represents a significant threat for public health due to their strong biochemical stability and recalcitrance to conventional water treatment systems. In this work, the feasibility of catalytic hydrodehalogenation (HDH) for the degradation of a representative group of ICMs (iohexol (IHX), iopromide (IPR), iopamidol (IPM) and diatrizoic acid (DIA)) is investigated. Complete degradation and deiodination of the isolated ICMs (1.6·10−2 mmol L−1) was achieved in less than 30 min in the presence of 0.25 g L−1 of different precious metal catalysts (Pd/Al2O3, Rh/Al2O3 and Pt/Al2O3) under ambient conditions, closing iodine balance by >95 %. Based on the identified reaction intermediates and final products, reaction mechanisms were accordingly proposed. A sequential reaction pathway was proposed for DIA removal, while reaction mechanisms encompassing both sequential and concerted reaction steps were proposed for the non-ionic ICMs (IHX, IPR, and IPM). Subsequent kinetic models, which successfully described experimental data, were developed from the elucidated reaction mechanisms, considering all species involved in the reaction. The versatility of the process was finally demonstrated in the treatment of real aqueous matrices (surface water and tap water) spiked with the ICMs mixture, except in the case of Pt/Al2O3 which suffered deactivation due to surface poisoning by halides. For this catalyst, kinetic constants ranged from 0.31 to 0.22 min−1 in deionized water, and from 0.04 to 0.08 min−1 in surface water as the reaction matrix. Among the tested catalysts, Pd/Al2O3 showed the highest activity and stability for the removal of ICMs.

Injection of carbon dioxide instead of iodinated contrast to display the common bile duct during endoscopic retrograde cholangiopancreatography.

Common bile duct (CBD) stones are usually caused by biliary tract infection, biliary stricture, duodenal peripapillary diverticulum, Oddis sphincter dysfunction, and so on. Treatment is preferably with endoscopic retrograde cholangiopancreatography (ERCP), where an iodine-containing contrast agent is injected into the CBD to display the stone under fluoroscopy and then to confirm complete removal of the stone(s). We described a 65-year-old woman with CBD stones who had undergone cardiac pacemaker implantation and was allergic to iodinated contrast media. We performed ERCP + lithotomy + stent implantation under local anesthesia, with injection of carbon dioxide instead of iodinated contrast into the CBD, and successfully visualized the stones under fluoroscopy and then confirmed complete removal of them. The patient was generally in good condition without complications. Thus, we have demonstrated in this case report that carbon dioxide can be used as a safe, economical, and effective alternative to iodinated contrast agent during ERCP.

3D Printing Materials Mimicking Human Tissues after Uptake of Iodinated Contrast Agents for Anthropomorphic Radiology Phantoms.

(1) Background: 3D printable materials with accurately defined iodine content enable the development and production of radiological phantoms that simulate human tissues, including lesions after contrast administration in medical imaging with X-rays. These phantoms provide accurate, stable and reproducible models with defined iodine concentrations, and 3D printing allows maximum flexibility and minimal development and production time, allowing the simulation of anatomically correct anthropomorphic replication of lesions and the production of calibration and QA standards in a typical medical research facility. (2) Methods: Standard printing resins were doped with an iodine contrast agent and printed using a consumer 3D printer, both (resins and printer) available from major online marketplaces, to produce printed specimens with iodine contents ranging from 0 to 3.0% by weight, equivalent to 0 to 3.85% elemental iodine per volume, covering the typical levels found in patients. The printed samples were scanned in a micro-CT scanner to measure the properties of the materials in the range of the iodine concentrations used. (3) Results: Both mass density and attenuation show a linear dependence on iodine concentration (R2 = 1.00), allowing highly accurate, stable, and predictable results. (4) Conclusions: Standard 3D printing resins can be doped with liquids, avoiding the problem of sedimentation, resulting in perfectly homogeneous prints with accurate dopant content. Iodine contrast agents are perfectly suited to dope resins with appropriate iodine concentrations to radiologically mimic tissues after iodine uptake. In combination with computer-aided design, this can be used to produce printed objects with precisely defined iodine concentrations in the range of up to a few percent of elemental iodine, with high precision and anthropomorphic shapes. Applications include radiographic phantoms for detectability studies and calibration standards in projective X-ray imaging modalities, such as contrast-enhanced dual energy mammography (abbreviated CEDEM, CEDM, TICEM, or CESM depending on the equipment manufacturer), and 3-dimensional modalities like CT, including spectral and dual energy CT (DECT), and breast tomosynthesis.