Positive Contrast Research Articles

NIMG-73. FALSE POSITIVE INTRA-OPERATIVE MAGNETIC RESONANCE IMAGING DURING HIGH GRADE GLIOMA RESECTION

Abstract Intraoperative magnetic resonance imaging (iMRI) allows assessment of extent of resection during surgery for high-grade glioma (HGG). In most cases, contrast-enhancing areas noted on iMRI indicate residual tumor. However, false positives may occur, leading to inappropriate additional resection and patient morbidity. The rate and pattern of false positive findings in iMRI have not been fully described. We analyzed surgical and imaging findings in patients undergoing iMRI during resection of HGG to determine factors linked with potential false positive contrast enhancement. A single-center analysis retrospectively assessed consecutive patients undergoing resection of newly diagnosed high-grade glioma using iMRI guidance. Preoperative, intraoperative and postoperative imaging, as well as pathologic findings were assessed. One hundred seventy-four consecutive patients who underwent surgery from 2016-2023 were included. All patients had preoperative MRI showing contrast-enhancing tumor and all underwent one iMRI during surgery to assess extent of resection. 124/174 cases (71.3%) demonstrated contrast enhancement on iMRI that prompted inspection and additional resection using updated neuronavigation. Enhancement corresponding to residual tumor was identified with or without additional removal in 120/124 cases (96.8%). No residual tumor was found in 4/124 cases (3.2%, false positives). All false positive cases were the result of contrast accumulation in hematomas (2), hemostatic agents (1) or dependent portions of the resection cavity (1). Both hematomas were located in the walls of the resection cavity and confirmed as hematoma, rather than tumor, by separate pathology analysis. False positives were not associated with patient positioning, tumor sub-type, anatomic location of tumor or extent of resection. Gross total resection (GTR) was confirmed in 163/174 (93.7%) cases on postoperative imaging. False-positive iMRI during HGG surgery can mimic residual tumor. This occurs at a low rate due to contrast pooling in the cavity or accumulation within hemostatic agents or hematomas along the cavity wall. Meticulous hemostasis when preparing the patient for iMRI may help prevent false positives and prevent unnecessary additional resection.

Engineering Protein-Nanoparticle Hybrids as Targeted Contrast Agents.

Iron oxide nanoparticles (IONPs) have shown great promise in biomedical applications, particularly as MRI contrast agents due to their magnetic properties and biocompatibility. Although several IONPs have been approved by regulatory agencies as MRI contrast agents, their primary application as negative contrast agents limits their usage. Additionally, there is an emerging need for the development of molecular contrast agents that can specifically target biomarkers, enabling more accurate and sensitive diagnostics. To address these challenges, we exploited the engineerability of proteins to stabilize IONPs with tailored magnetic properties, creating protein-stabilized iron oxide nanoparticles (Prot-IONPs) and leveraged the chemical diversity of proteins to functionalize Prot-IONPs with targeting moieties. As a proof-of-concept, we used alendronate (Ald) to target atherosclerotic plaques in the aorta. Simple protein functionalization allowed targeting while maintaining the stability and relaxation properties of the Prot-IONPs. Prot-IONPs-Ald successfully enabled positive contrast imaging of atherosclerotic plaques in vivo in an atherosclerotic mouse model (ApoE-/- mice on a high-fat diet). This study demonstrates the potential of engineering protein-nanoparticle hybrids as versatile platforms for developing targeted in vivo MRI contrast agents.

A New Approach Toward Extreme Thermal Stability of Femtosecond Laser Induced Modifications in Glasses

AbstractImprinting thermally stable transformations by femtosecond laser in glass would benefit the development of optical sensors dedicated to harsh environments including combustors, nuclear reactors, aircraft engines, or metal/ceramic manufacturing processes. While glass brings undeniable assets over refractory crystalline materials like shaping ability (e.g., optical fiber form), one key challenge is to prevent the erasure of induced transformations at high temperatures and for long periods. In this article, the role of glass composition and viscosity to achieve modifications stable at high temperatures is first reviewed, providing a comprehensive roadmap for engineers in optics and photonics. While silica appears to be the candidate of choice, it is revealed that binary aluminosilicates can compete and sometimes surpass it. The hypothesis is formulated and investigated that a hybrid glass‐crystalline nano‐structuring can imprint ultra‐stable modifications inside glass. Laser‐induced modifications in Al2O3‐SiO2 and ZrO2‐Al2O3‐SiO2 glasses reveal a partial crystallization, shaped into a lamellar structure and orientable with laser light polarization. These birefringent structures can withstand temperatures up to 1300 °C for 30 minutes. Even after erasure, a positive index contrast persists, up to 1650 °C for binary 60Al2O3‐40SiO2 (mol%). This is the first observation of this kind of persisting index contrast, paving the way to ultra‐stable glass‐based optical waveguiding.

Oral CT Contrast Agents: What's New and Why, From the AJR Special Series on Contrast Media.

Current CT oral contrast agents improve the conspicuity of and confidence in bowel and peritoneal findings in many clinical scenarios, particularly for outpatient and oncologic abdominopelvic imaging. Yet, existing positive and neutral oral contrast agents may diminish the detectability of certain radiologic findings, frequently in the same scans in which the oral contrast agent improves the detectability of other findings. With ongoing improvements in CT technology, particularly multienergy CT, opportunities are opening for new types of oral contrast agents to further improve anatomic delineation and disease detection using CT. The CT signal of new dark oral contrast agents and of new high-Z oral contrast agents promises to combine the strengths of both positive and neutral oral CT contrast agents by providing distinct CT appearances in comparison with bodily tissues, iodinated IV contrast agents, and other classes of new CT contrast agents. High-Z oral contrast agents will unlock previously inaccessible capabilities of multienergy CT, particularly photon-counting detector CT, for differentiating simultaneously administered IV and oral contrast agents; this technique will allow generation of rich 3D, intuitive, perfectly coregistered, high-resolution image sets with individual contrast agent "colors" that provide compelling clarity for intertwined intraabdominal anatomy and disease processes.

Enhancing organ and vascular contrast in preclinical ultra-low field MRI using superparamagnetic iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) are characterized by their exceptional susceptibility and relaxivity at ultra-low field (ULF) regimes, make them a promising contrast agent (CA) for ULF MRI. Despite their distinct advantages, the translation of these properties into clinically valuable image contrast in ULF MRI remains underexplored. In this study, we investigate the use of SPIONs to generate in vivo MRI contrast at 6.5 mT within the organs and vascular system of rodents. This investigation includes comprehensive SPION characterization and phantom imaging experiments to validate the utility of SPIONs to produce positive image contrast and to facilitate phase-sensitive imaging at ULF. Optimized balanced steady-state free precession (bSSFP) and spoiled gradient echo (SPGR) MRI sequences are used to generate in vivo contrast by leveraging the distinctive properties of SPIONs at ULF. Imaging studies in rodents reveal positive organ contrast attainable in magnitude images, and MRI phase maps can be used to visualize the vascular system. This work demonstrates the effectiveness of SPIONs in enhancing preclinical organ and vascular imaging at ULF; it bridges the gap between the study of the distinctive physical properties of SPIONs and the demonstration of in vivo image contrast.

Positive Contrast Scope Insensitivity

Abstract When consumers compare a worse product to a better product, negative contrast can make the worse product less attractive, and positive contrast can make the better product more attractive. We show that positive contrast is relatively scope insensitive: the size of the difference between products affects negative contrast but not positive contrast. Even when the difference between products is small enough to make negative contrast negligible, positive contrast remains strong. This means that when consumers compare a product to a slightly worse product, contrast makes the better product more attractive without making the worse product any less attractive. The asymmetry occurs because consumers are less likely to consider the size of the difference between products when evaluating the better product than when evaluating the worse product, such that nudging consumers to consider the size of the difference eliminates the asymmetry.

Variable-density velocity-selective magnetization preparation for non-contrast-enhanced peripheral MR angiography.

Velocity-selective (VS) magnetization preparation has shown great promise for non-contrast-enhanced (NCE) magnetic resonance angiography (MRA) with the ability to generate positive angiographic contrast directly using a single 3D acquisition. However, existing VS-MRA methods have an issue of aliased saturation around a certain velocity, known as velocity field-of-view (vFOV), which can cause undesired signal loss in arteries. This study aimed to develop a new version of the VS preparation pulse sequence that overcomes the aliased saturation problem in conventional VS preparation. Utilizing the fact that an excitation profile is the Fourier transform of excitation k-space sampling, we sampled the k-space in a non-uniform fashion by scaling gradient pulses accordingly to have aliased excitation diffused over velocity. The variable density sampling function was numerically optimized to maximize the average of the velocity passband signal while minimizing its variance. The optimized variable density VS magnetization was validated through Bloch simulations and applied to peripheral NCE MRA in healthy subjects. The in-vivo experiments showed that the proposed variable density VS-MRA significantly lowered arterial signal loss observed in conventional VS-MRA, as evidenced by a higher arterial signal-to-noise ratio (58.50 ± 14.29 vs. 55.54 ± 12.32; p < 0.05) and improved artery-to-background contrast-to-noise ratio (22.75 ± 7.57 vs. 20.60 ± 6.51; p < 0.05).

Prosedur Pemeriksaan Dacryocystografi Pada Kasus Dacryosistitis Kronis Di Instalasi Radiologi RSUP. Dr.Wahidin Sudirohusodo Makassar

Dacryocystography examination is the examination of the radiologist to show the nasolacrimal duct by using a positive contrast medium. The purpose of this examination is to describe the system of tear duct blockage and the level of blockage. This research method is descriptive with aproachcase study conducted in RSUP. Dr. WahidinSudirohusodo Makassar on Juni 2019. The inspection technique is done by using the projection Antero Posterior (AP), which contrast material is inserted throught the tear duct in the lacrimal punctum which empties into the concha nasalis inferior. From the result of the examination has been done, it can be concluded that the contrast as much as 1 cc inserted throught the superior lacrimal punctum, contrast restrained and spilled out. Contrast as much as 1 cc inserted throught the inferior lacrimal punctum, the contrast seems to fill out the inferior palpebra area. From the research, lacrimal duct obstruction impression superior and inferior.

Gadolinium-doped carbon dots with long-wavelength emission for dual-modal imaging

Subject of study. This study is focused on luminescent carbon dots derived from o-phenylenediamine and gadolinium chloride or nitrate hexahydrate. Aim of study. The study aims to fabricate long-wavelength photoluminescent gadolinium-doped carbon dots that could function as contrast agents for magnetic resonance imaging. Additionally, the study investigates the impact of the precursor type used on the chemical composition and optical transitions of the resulting nanoparticles. Method. Carbon dots were synthesized using a one-step solvothermal method, and their composition and optical properties were analyzed using spectroscopy methods. Magnetic resonance imaging was conducted using a clinical magnetic resonance imaging scanner with a field strength of 1.5 T. Main results. In this study, two types of carbon dots were synthesized from o-phenylenediamine and gadolinium chloride or nitrate hexahydrate using the solvothermal method. Metal doping, at a concentration sufficient for further investigations, is achieved only when gadolinium chloride is used. Additionally, the presence of gadolinium chloride during the synthesis leads to the formation of luminescent centers within the carbon dots with emission at 600–720 nm and a photoluminescence quantum yield of 6.3%. In contrast, gadolinium nitrate increases the nitrogen content within the o-phenylenediamine-based carbon dots while inhibiting metal doping. The luminescent band with an emission maximum at 550 nm and a photoluminescence quantum yield of 7.4% originates from the o-phenylenediamine derivatives formed within such carbon dots. The study results also show that the gadolinium-doped carbon dots alter the relaxation times during magnetic resonance scanning, and the calculated relaxivity (r1 and r2) values are 6.4 and 38.6L⋅mmol−1⋅s−1, respectively. Thus, the synthesized carbon dots function as positive contrast agents during magnetic resonance scanning. Practical significance. Carbon dots with long-wavelength emission are promising nanoprobes for luminescence imaging. With gadolinium doping, these nanoparticles can also be used as contrast agents during magnetic resonance imaging. Consequently, carbon dots based on o-phenylenediamine and gadolinium chloride hexahydrate can be further utilized as dual-mode nanoprobes for bioimaging.

Chitosan-modified manganese oxide-conjugated methotrexate nanoparticles delivering 5-aminolevulinic acid as a dual-modal T1-T2* MRI contrast agent in U87MG cell detection.

Glioblastoma multiforme is a highly aggressive form of brain cancer, and early diagnosis plays a pivotal role in improving patient survival rates. In this regard, molecular magnetic resonance imaging has emerged as a promising imaging modality due to its exceptional sensitivity to minute tissue changes and the ability to penetrate deep into the brain. This study aimed to assess the efficacy of a novel contrast agent in detecting gliomas during MRI scans. The contrast agent utilized modified chitosan coating on manganese oxide nanoparticles. The modification included adding methotrexate and 5-aminolevulinic acid (MnO2/CS@5-ALA-MTX) to target cells with overexpressed folate receptors and breaking down excess hydrogen peroxide in tumor tissue, resulting in enhanced signal intensity in T1-weighted MR images but diminished signal intensity in T2*-weighted MR images. The nanosystem was characterized and evaluated in MR imaging, safety, and ability to target cells both in vivo and in vitro. MTX-free nanoparticles (MnO2/CS@5-ALA NPs) had no obvious cytotoxicity on cell lines U87MG and NIH3T3 after 24/48 h at a concentration of up to 160 µgr/mL (cell viability more than 80%). In this system, methotrexate enables tumor targeting and the MnO2/5-ALA improves T1-T2*-weighted MRI. In addition, MRI scans of mice with M109 carcinoma indicated significant tumor uptake and NP capacity to improve the positive contrast effect. This developed MnO2/CS@5-ALA-MTX nanoparticle system may exhibit great potential in the accurate diagnosis of folate receptor over-expressing cancers such as glioblastoma.

Naturally biocompatible melanin based iron-complex nanoparticles for pH-responsive magnetic resonance imaging

The sensitivity and diagnostic accuracy of magnetic resonance imaging mainly depend on the relaxation capacity of contrast agents (CAs) and their accumulated amount at the pathological region. Due to the better biocompatibility and high-spin capacity, Fe-complexes have been studied widely as an alternative to replace popular Gd-based CAs associated with potential biotoxicity. Compared with a variety of Fe complex-based CAs, such as small molecular, macrocyclic, multinuclear complexes, the form of nanoparticle exhibits outstanding longitudinal relaxation, but the clinical transformation was still limited by the inconspicuous difference of contrast between tumor and normal tissue. The enhanced effect of contrast is a positive relation as relaxation of CAs and their concentration in desired region. To specifically improve the amount of CAs accumulated in the tumor, pH-responsive polymer poly(2-ethyl-2-oxazoline) (PEOz) was modified on melanin, a ubiquitous natural pigment providing much active sites for chelating with Fe(III). The Fe(III)-Mel-PEOz we prepared could raise the tumor cell endocytosis efficiency via switching surface charge from anion to cation with the stimuli of the decreasing pH of tumor microenvironment. The change of pH has negligible effect on the r 1 of Fe(III)-Mel-PEOz, which is always maintained at around 1.0 mM−1s−1 at 0.5 T. Moreover, Fe(III)-Mel-PEOz exhibited low cytotoxicity, and satisfactory enhancement of positive contrast effect in vivo. The excellent biocompatibility and stable relaxation demonstrate the high potential of Fe(III)-Mel-PEOz in the diagnosis of tumor.

Anatomy of Liver and Radiographic Study on Hepatic Duct in a South African Ostrich Struthio camelus australis

The South African Ostrich Struthio camelus australis, an acarinate flightless ratite bird, native to the African continent has been introduced in many countries including India in the recent past for meat as well as egg purpose. Although this largest extant bird is gaining popularity globally, the functional anatomy of this majestic giant has received relatively less attention. The liver, the largest gland in the body of an Ostrich (weighing approximately 1.5-2 Kg) is also the heaviest among all the birds. The Ostrich lacks gall bladder and thus, the bile needs to be produced continuously as in the case of certain mammals like horses and elephants. The present study aimed to investigate the gross morphological and radiographic characteristics of the liver of the Ostrich. The liver was divisible into two primary lobes: an undivided right lobe and a divided left lobe. The later consisted of dorso-cranial, intermediate, and ventro-caudal lobes. Notably, the ventro-caudal lobe was observed as the largest, while the intermediate lobe was the smallest. The right lobe, larger than the left, was connected to later by a thick isthmus at its cranial extremity. Using barium sulphate injection and positive contrast radiography, the intrahepatic course of the hepatic duct was visualized, revealing two distinct divisions and tributaries thereof for draining bile from the right and left lobes, respectively. A radiographic study of the intrahepatic course of the hepatic duct revealed a single right intralobar duct and two left intralobar ducts. The distinct isthmus was drained by the branch of the left intralobar duct.

Super High Contrast USPIO-Enhanced Cerebrovascular Angiography Using Ultrashort Time-to-Echo MRI.

Ferumoxytol (Ferahame, AMAG Pharmaceuticals, Waltham, MA) is increasingly used off-label as an MR contrast agent due to its relaxivity and safety profiles. However, its potent T2∗ relaxivity limits achievable T1-weighted positive contrast and leads to artifacts in standard MRI protocols. Optimization of protocols for ferumoxytol deployment is necessary to realize its potential. We present first-in-human clinical results of the Quantitative Ultrashort Time-to-Echo Contrast Enhanced (QUTE-CE) MRA technique using the superparamagnetic iron oxide nanoparticle agent ferumoxytol for vascular imaging of the head/brain in 15 subjects at 3.0T. The QUTE-CE MRA method was implemented on a 3T scanner using a stack-of-spirals 3D Ultrashort Time-to-Echo sequence. Time-of-flight MRA and standard TE T1-weighted (T1w) images were also collected. For comparison, gadolinium-enhanced blood pool phase images were obtained retrospectively from clinical practice. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and intraluminal signal heterogeneity (ISH) were assessed and compared across approaches with Welch's two-sided t-test. Fifteen volunteers (54 ± 17 years old, 9 women) participated. QUTE-CE MRA provided high-contrast snapshots of the arterial and venous networks with lower intraluminal heterogeneity. QUTE-CE demonstrated significantly higher SNR (1707 ± 226), blood-tissue CNR (1447 ± 189), and lower ISH (0.091 ± 0.031) compared to ferumoxytol T1-weighted (551 ± 171; 319 ± 144; 0.186 ± 0.066, respectively) and time-of-flight (343 ± 104; 269 ± 82; 0.190 ± 0.016, respectively), with p < 0.001 in each comparison. The high CNR increased the depth of vessel visualization. Vessel lumina were captured with lower heterogeneity. Quantitative Ultrashort Time-to-Echo Contrast-Enhanced MR angiography provides approximately 5-fold superior contrast with fewer artifacts compared to other contrast-enhanced vascular imaging techniques using ferumoxytol or gadolinium, and to noncontrast time-of-flight MR angiography, for clinical vascular imaging. This trial is registered with NCT03266848.

Esophageal stenosis as a result of a right aortic arch in 2 cats

A 3-month-old and a 4-year-old cat were presented in the clinic due to regurgitation. The kitten had displayed the symptoms since it had been fed solid foods and was smaller than the litter mates. The 4-year-old cat showed sudden-onset symptoms for 5 days prior to presentation and had a good general condition. Positive contrast thoracic radiographs of both cats in lateral recumbency showed an esophageal dilatation cranial to the heart base and raised a suspicion of foreign material with soft tissue density in this area. In the 4-year-old cat, findings of ventrodorsal thoracic radiographs were compatible with a dextroposition of the aorta and a slightly marked focal left curve of the trachea. The echocardiographic examination of the kitten pictured a right sided aorta, hence a vascular ring anomaly with a dextroposition from the aorta was suspected. Aberrant blood flow as it is seen in a persistent ductus arteriosus was not apparent in the echocardiography. As a result of the sudden development of the clinical signs in the older cat without displaying any former history of regurgitation, an esophagoscopy was performed to exclude an intraluminal esophageal cause for the stricture as well as to extract the foreign material. In this cat, computed tomography imaging also displayed an aberrant left subclavian artery. Both cats recovered well after surgical correction.The diagnosis of a ring anomaly in the kitten via echocardiography is a rare situation. As is the diagnosis of a high-grade esophageal stricture due to a vascular ring anomaly at the age of 4 without a former history of regurgitation.Recovery was excellent in the younger cat. There were no signs of regurgitation 6 months after surgery. The adult cat was in good general condition without clinical symptoms according to the owners when presented for stitch removal. Unfortunately, the adult cat was lost to follow up.

Enhanced contrast imaging with polyamide 6/Fe(OH)3 nanofibrous scaffolds: A focus on high T1 relaxivity

Nanofibers serve as widely employed tissue engineering scaffolds in diverse biomedical applications. When implanted in vivo, it is crucial for tissue engineering scaffolds to be visualizable, enabling the monitoring of their shape, position, and performance. This capability facilitates the effective assessment of implant deformations, displacements, degradations, and functionalities. However, in many biomedical imaging techniques such as magnetic resonance imaging (MRI), the contrast of tissue engineering scaffolds is often inadequate. MRI is particularly notable for its effectiveness in imaging soft tissues. Previous endeavors to enhance the contrast of tissue engineering scaffolds in MRI have involved the use of negative contrast agents (CAs). Nonetheless, negative CAs can result in artifacts, thus favoring the preference for positive CAs due to their ability to generate clearer boundaries. In this study, we successfully prepared composite polyamide 6 nanofibrous scaffolds with ultrafine dispersion Fe(OH)3 nanoparticles using electrospinning and in-situ growth techniques. The relaxation properties of the magnetic nanofibrous scaffolds confirmed the successful production of scaffolds suitable for positive imaging. In vitro cell seeding experiments demonstrated the efficient proliferation and adhesion of endothelial cells and fibroblasts. In vivo studies further revealed the biocompatibility and functionality of the scaffolds. These findings indicate that the prepared PA6/Fe(OH)3 composite nanofibrous scaffolds can enable straightforward, safe, and efficient in vivo positive contrast MRI monitoring, thereby playing a pivotal role in the integration of diagnosis and treatment within tissue engineering scaffolds.

An initial test of the contrast avoidance model in bipolar spectrum disorders

The Contrast Avoidance Model suggests that individuals sensitive to negative emotional shifts use prior increases in negative affect to prevent further escalation in response to adverse situations, while the heightened negative affect amplifies positive emotional contrasts when encountering unexpected positive events. Individuals with bipolar spectrum disorders (BSDs), characterized by shifts between (hypo)manic and depressive episodes, may undergo more salient emotional contrasts. Drawing from the Contrast Avoidance Model, the shifts from depression to (hypo)mania can be conceptualized as positive emotional contrasts, potentially heightening the perceived pleasure during (hypo)manic episodes. On the other hand, the shifts from (hypo)manic to depressive episodes can be viewed as negative emotional contrasts, contributing to the challenges associated with depressive states. Despite the intriguing potential of this interplay, the link between the Contrast Avoidance Model and BSDs has never been empirically tested. Our study addressed this gap by examining group differences in contrast avoidance traits between individuals with BSDs, unipolar depression, and healthy controls in a large cohort study (N = 536). Results indicated that individuals with BSDs exhibited significantly higher scores in the total, and Discomfort with Negative Emotional Shifts and Avoidance of Negative Emotional Contrasts/Enhancement of Positive Emotional Contrasts factors, as well as separate item scores on the Contrast Avoidance Questionnaire-General Emotion (CAQ-GE), compared to those with unipolar depression and healthy controls. Although marginal, the BD II subtype demonstrated a stronger inclination to avoid negative emotional contrasts compared to BD I. These findings suggest that contrast avoidance may be a psychological mechanism implicated in BSDs.

Assessment of the visibility of unprotected road users in pedestrian crossing

The article presents selected results of research on improving pedestrian traffic safety. Based on annually-updated accident statistics made available by the police, as well as the new pedestrian traffic regulations in force, detailed work was undertaken to assess the level of visibility of pedestrians by drivers in pedestrian crossing areas. The research was carried out by analyzing several characteristic cases of pedestrian crossings occurring in Poland, in which there was only dedicated lighting for crossings, only street lighting, and a variant of coexistence of both of the above lighting solutions. Illuminance measurements were made in the horizontal and vertical planes of pedestrian crossings, and the results were confronted with the relevant guidelines. The next step involved a complementary measurement of the luminance distribution of the vertical plane containing the pedestrian and a portion of the sub- and super-horizontal background. Visibility pedestrians was considered in positive and negative contrast variants, and was then related to the obtained results of the illumination distribution. The analysis of the results of the study indicated the possibility of limited visibility of pedestrians at the crossings despite the satisfactory results obtained from measurements of the illuminance distribution within the crossings.

Comprehensive literature review of oral and intravenous contrast-enhanced PET/CT: a step forward?

The integration of diagnostic CT scans into PET/CT facilitates a comprehensive single examination, presenting potential advantages for patients seeking a thorough one-shot check-up. The introduction of iodinated contrast media during PET scanning raises theoretical concerns about potential interference with uptake quantification, due to the modification of tissue density on CT. Nevertheless, this impact appears generally insignificant for clinical use, compared to the intrinsic variability of standardized uptake values. On the other hand, with the growing indications of PET, especially 18F-FDG PET, contrast enhancement increases the diagnostic performances of the exam, and provides additional information. This improvement in performance achieved through contrast-enhanced PET/CT must be carefully evaluated considering the associated risks and side-effects stemming from the administration of iodinated contrast media. Within this article, we present a comprehensive literature review of contrast enhanced PET/CT, examining the potential impact of iodinated contrast media on quantification, additional side-effects and the pivotal clinically demonstrated benefits of an all-encompassing examination for patients. In conclusion, the clinical benefits of iodinated contrast media are mainly validated by the large diffusion in PET protocols. Contrary to positive oral contrast, which does not appear to offer any major advantage in patient management, intravenous iodine contrast media provides clinical benefits without significant artifact on images or quantification. However, studies on the benefit-risk balance for patients are still lacking.

Perceptions and digitalisation of outbreak management in UK health services: A cross-sectional survey.

Global challenges arise from infectious diseases which represent significant challenges to the provision of healthcare, requiring efficient management procedures to limit transmission. Evaluating current outbreak management processes within UK healthcare services is essential for identifying strengths, weaknesses, and potential improvements. This study aimed to assess infection prevention and control (IPC) practitioners' access to outbreak management (OM) data. Secondary objectives involved determining IPC practitioners' perceptions of outbreak management processes and the state of digitalisation of OM in the UK. National cross-sectional survey data were collected to evaluate current outbreak management approaches. To supplement this, information requests were sent to the 10 largest teaching and research NHS hospital trusts in England. The survey received 55 responses with 53 considered for analysis. Out of 10 NHS trusts, nine provided completed FOI responses, while one was unable to provide data. The study offers unique insights into prevailing outbreak management practices within UK health services. Although positive perceptions surround key outbreak management stages, concerns arise, including varying confidence levels in surveillance processes' robustness, efficacy of management interventions, and communication effectiveness. The study highlights challenges with OM processes in the UK, including issues like poor surveillance and delayed outbreak detection. Positive practitioner perceptions contrast with concerns over data collection, follow-up, and limited digitalisation, relying on basic tools like Excel and Word, hindering retrospective learning.

Rational Design of Magnetic Nanoparticles as T1-T2 Dual-Mode MRI Contrast Agents.

Magnetic nanoparticles (MNPs), either paramagnetic or superparamagnetic depending on their composition and size, have been thoroughly studied as magnetic resonance imaging (MRI) contrast agents using in vitro and in vivo biomedical preclinical studies, while some are clinically used. Their magnetic properties responsible in some cases for high magnetization values, together with large surface area-to-volume ratios and the possibility of surface functionalization, have been used in MRI-based diagnostic and theranostics applications. MNPs are usually used as positive (T1) or negative (T2) MRI contrast agents, causing brightening or darkening of selected regions in MRI images, respectively. This review focusses on recent developments and optimization of MNPs containing Gd, Mn, Fe and other lanthanide ions which may function as dual-mode T1-T2 MRI contrast agents (DMCAs). They induce positive or negative contrast in the same MRI scanner upon changing its operational mode between T1-weighted and T2-weighted pulse sequences. The type of contrast they induce depends critically on their r2/r1 relaxivity ratio, which for DMCAs should be in the 2-10 range of values. After briefly discussing the basic principles of paramagnetic relaxation in MNPs, in this review, the basic strategies for the rational design of DMCAs are presented and typical examples are discussed, including in vivo preclinical applications: (1) the use of NPs with a single type of contrast material, Gd- or Mn-based NPs or superparamagnetic NPs with appropriate size and magnetization to provide T2 and T1 contrast; and (2) inclusion of both types of T1 and T2 contrast materials in the same nanoplatform by changing their relative positions.