Investigative Radiology最新文献

Abstract: Photon-counting detectors (PCDs) have emerged as one of the most influential technical developments for medical imaging in recent memory. Surpassing conventional systems with energy-integrating detector technology in many aspects, PCD-CT scanners provide superior spatial resolution and dose efficiency for all radiological subspecialities. Demanding detailed display of trabecular microarchitecture and extensive anatomical coverage frequently within the same scan, musculoskeletal (MSK) imaging in particular can be a beneficiary of PCD-CT's remarkable performance. Since PCD-CT provides users with a plethora of customization options for both image acquisition and reconstruction, however, MSK radiologists need to be familiar with the scanner to unlock its full potential. From filter-based spectral shaping for artifact reduction over full field-of-view ultra-high-resolution scans to postprocessing of single- or dual-source multienergy data, almost every imaging task can be met with an optimized approach in PCD-CT. The objectives of this review were to give an overview of the most promising applications of PCD-CT in MSK imaging to date, to state current limitations, and to highlight directions for future research and developments.

Objectives: Gadopiclenol is a q = 2 pyclen gadolinium-based contrast agent (GBCA) recently approved by the Food and Drug Administration, European Medicines Agency, and other European countries. The aim of this report is to demonstrate its stability in multiple stressed in vitro conditions and in vivo, in rat kidney, while maintaining its higher relaxivity compared with conventional GBCAs on the market.

Materials and methods: Both gadopiclenol and its chemical precursor Pi828-Gd were characterized and compared with q = 1 gadolinium (Gd) complexes. The number of water molecules coordinated to the Gd (the hydration number, q) was determined by luminescence. 17 O NMR (Nuclear Magnetic Resonance) measurements gave access to the water residence time τ M . These parameters were used for the fitting of the nuclear magnetic relaxation dispersion profiles in water. Proton relaxivities of the complexes were determined in different media at 60 MHz (1.4 T), at different pH and temperature. The kinetic inertness was investigated in human serum, acidic media, under zinc competition in the presence of phosphate, and under ligand competition. The in vivo stability was evaluated in rat kidneys 12 months after repeated injections.

Results: The presence of 2 inner-sphere water molecules per Gd complex was confirmed for both pyclen derivatives. The high relaxivity of the complexes in water is maintained under physiological conditions, even under stressed conditions (ionic media, extreme pH, and temperature), which guarantees their efficiency in a large range of in vivo situations. Gd release from the q = 2 complexes was investigated in different potentially destabilizing conditions. Either no Gd release or a slower one than with "q = 1" stable macrocyclic GBCA (acidic conditions) was observed. Their kinetic inertness was demonstrated in physiological conditions, and the Gd release was below the lower limit of quantification of 0.1 μM after 12 days at 37°C in human serum. It was also demonstrated that gadopiclenol is stable in vivo in rat kidney 12 months after repeated injections.

Conclusions: Thanks to its optimized structural design, gadopiclenol is a highly stable and effective macrocyclic q = 2 GBCA.

Abstract: The aging process induces a variety of changes in the brain detectable by magnetic resonance imaging (MRI). These changes include alterations in brain volume, fluid-attenuated inversion recovery (FLAIR) white matter hyperintense lesions, and variations in tissue properties such as relaxivity, myelin, iron content, neurite density, and other microstructures. Each MRI technique offers unique insights into the structural and compositional changes occurring in the brain due to normal aging or neurodegenerative diseases. Age-related brain volume changes encompass a decrease in gray matter and an increase in ventricular volume, associated with cognitive decline. White matter hyperintensities, detected by FLAIR, are common and linked to cognitive impairments and increased risk of stroke and dementia. Tissue relaxometry reveals age-related changes in relaxivity, aiding the distinction between normal aging and pathological conditions. Myelin content, measurable by MRI, changes with age and is associated with cognitive and motor function alterations. Iron accumulation, detected by susceptibility-sensitive MRI, increases in certain brain regions with age, potentially contributing to neurodegenerative processes. Diffusion MRI provides detailed insights into microstructural changes such as neurite density and orientation. Neurofluid imaging, using techniques like gadolinium-based contrast agents and diffusion MRI, reveals age-related changes in cerebrospinal and interstitial fluid dynamics, crucial for brain health and waste clearance. This review offers a comprehensive overview of age-related brain changes revealed by various MRI techniques. Understanding these changes helps differentiate between normal aging and pathological conditions, aiding the development of interventions to mitigate age-related cognitive decline and other symptoms. Recent advances in machine learning and artificial intelligence have enabled novel methods for estimating brain age, offering also potential biomarkers for neurological and psychiatric disorders.

Abstract: Invasive open surgery used to be compulsory to access tumor mass to perform excision or resection. Development of minimally invasive laparoscopic procedures followed, as well as catheter-based approaches, such as stenting, endovascular surgery, chemoembolization, brachytherapy, which minimize side effects and reduce the risks to patients. Completely noninvasive procedures bring further benefits in terms of reducing risk, procedure time, recovery time, potential of infection, or other side effects. Focusing ultrasound waves from the outside of the body specifically at the disease site has proven to be a safe noninvasive approach to localized ablative hyperthermia, mechanical ablation, and targeted drug delivery. Focused ultrasound as a medical intervention was proposed decades ago, but it only became feasible to plan, guide, monitor, and control the treatment procedures with advanced radiological imaging capabilities. The purpose of this review is to describe the imaging capabilities and approaches to perform these tasks, with the emphasis on magnetic resonance imaging and ultrasound. Some procedures already are in clinical practice, with more at the clinical trial stage. Imaging is fully integrated in the workflow and includes the following: (1) planning, with definition of the target regions and adjacent organs at risk; (2) real-time treatment monitoring via thermometry imaging, cavitation feedback, and motion control, to assure targeting and safety to adjacent normal tissues; and (3) evaluation of treatment efficacy, via assessment of ablation and physiological parameters, such as blood supply. This review also focuses on sonosensitive microparticles and nanoparticles, such as microbubbles injected in the bloodstream. They enable ultrasound energy deposition down to the microvascular level, induce vascular inflammation and shutdown, accelerate clot dissolution, and perform targeted drug delivery interventions, including focal gene delivery. Especially exciting is the ability to perform noninvasive drug delivery via opening of the blood-brain barrier at the desired areas within the brain. Overall, focused ultrasound under image guidance is rapidly developing, to become a choice noninvasive interventional radiology tool to treat disease and cure patients.

Objective: This systematic review and meta-analysis investigated the added value of DWI compared with the structured assessment of BI-RADS criteria using the Kaiser score.

Materials and methods: Articles published in English until May 2024 were included. Two independent reviewers extracted data on the characteristics of studies evaluating the added value of DWI to distinguish benign from malignant breast lesions compared with structured assessment of the BI-RADS criteria. Using bivariate random-effects models, the sensitivity and specificity were calculated. I2 statistics, Deek's funnel plot asymmetry test for publication bias, and meta-regression were applied for the data analysis.

Results: Five studies comprising 1005 malignant and 846 benign lesions were eligible for data synthesis. The pooled sensitivity and specificity estimates of structured BI-RADS assessment were 95.7% (95% confidence interval [CI], 92.6%-97.5%) and 68.7% (95% CI, 60.9%-75.6%), respectively. Adding DWI to the structured BI-RADS assessment achieved a pooled sensitivity of 94.4% (95% CI, 90.5%-96.7%) and a pooled specificity of 74.9% (95% CI, 68.8%-80.2%). Adding DWI to the structured BI-RADS assessment significantly changed neither the sensitivity ( P = 0.52) nor the specificity ( P = 0.20).

Conclusions: This systematic review and meta-analysis revealed only a limited, statistically nonsignificant added value of DWI compared with the structured assessment of BI-RADS criteria using the Kaiser score.

Abstract: Although conventional 2-dimensional magnetic resonance (MR) sequences have traditionally comprised the foundational imaging strategy for visualization of musculoskeletal anatomy and pathology, the emergence of isotropic volumetric 3-dimensional sequences offers to advance musculoskeletal evaluation with comparatively similar image quality and diagnostic performance, shorter acquisition times, and the added advantages of improved spatial resolution and multiplanar reformation capability. The purpose of this review article is to summarize the available 3-dimensional MR sequences and their role in the management of patients with musculoskeletal disorders, including sports imaging, rheumatologic conditions, peripheral nerve imaging, bone and soft tissue tumor imaging, and whole-body MR imaging.

Objectives: This study aimed to evaluate the influence of reader training and experience on the detection of (small) myocardial infarctions (MIs) and the assessment of ischemic scar transmurality using dark-blood late gadolinium enhancement (LGE) and bright-blood LGE magnetic resonance imaging. It was hypothesized that dark-blood LGE simplifies the detection of (small) MIs for less experienced readers, compared with bright-blood LGE imaging.

Materials and methods: One hundred patients referred for cardiac magnetic resonance imaging for suspected ischemic scar were retrospectively included. Dark-blood LGE was performed first, followed by bright-blood LGE. Nine clinicians, grouped into three levels based on their training and experience, assessed the LGE images for the presence of MI and ischemic scar transmurality. Their assessment was subsequently compared with a European Association of Cardiovascular Imaging level 3 consultant. Reader confidence was evaluated with a 4-point Likert scale. Multilevel logistic regression was used to compare the 2 LGE methods and assess differences in myocardial infarction detection and transmurality among the 3 experience levels. Wilcoxon signed rank tests were performed to compare the reader confidence between the 2 LGE methods, whereas Friedman omnibus tests were conducted to assess differences in reader confidence among the 3 experience levels.

Results: Dark-blood LGE resulted in increased correct detection of MIs compared with bright-blood LGE for both level 1 (87.3% vs 82.7%, odds ratio [OR]: 1.55 [95% confidence interval (CI): 0.94-2.54], P = 0.083) and level 2 readers (89.7% vs 83.0%, OR: 2.05 [95% CI: 1.20-3.51], P = 0.009). There was no significant difference observed between dark-blood LGE and bright-blood LGE for level 3 readers (88.7% vs 87.0%, OR: 1.20 [95% CI: 0.70-2.06], P = 0.495). Level 2 readers significantly detected more small MIs correctly when using dark-blood LGE compared with bright-blood LGE (66.7% vs 50.8%, OR: 2.40 [95% CI: 1.03-5.60], P = 0.042). All experience levels showed significantly increased confidence in presence of ischemic scar and transmurality with dark-blood LGE.

Conclusions: Readily available dark-blood LGE can assist less experienced readers in correctly detecting and assessing (small) MIs compared with conventional bright-blood LGE. Regardless of experience level, dark-blood LGE improves reader confidence in assessing the presence and transmurality of MIs.

Background: Gadolinium-based contrast agents (GBCAs) increase the sensitivity and clinical utility of magnetic resonance imaging (MRI) examinations and are used extensively worldwide. While concerns remain regarding the potential toxicity of retained gadolinium (Gd) based on "elevated" serum or urinary Gd concentrations, current Gd reference intervals were established in GBCA-naive patients with normal renal function. Therefore, the aim of this study was to determine the serum and urine Gd clearance in patients with normal renal function after being administered intravenous gadobutrol for a contrast-enhanced MRI examination.

Methods: Patients with normal renal function (estimated glomerular filtration rate ≥60 mL/min) with no prior GBCA exposure in the past 6 months were enrolled and had blood and urine collected before and ~1, 3, 7, 14, 28, 56, and 84 days after their gadobutrol-enhanced MRI examination to measure Gd at each time point. Serum and urine Gd were quantified using a clinically validated inductively coupled plasma mass spectrometry-based assay with a limit of quantitation of 0.1 ng/mL (μg/L).

Results: Thirty-one patients who underwent a gadobutrol-enhanced MRI were enrolled, and 24 completed all collection time points. The pharmacokinetic data suggested a multicompartment (5 phase) model of elimination where 95% of patient's serum Gd fell below the unexposed reference interval (<0.5 ng/mL) at ~56 days and 95% of urine Gd would fall below the unexposed reference interval (<0.8 μg/g creatinine) at ~132 days. Based on review of the electronic medical record, none of the patients self-reported any Gd-related toxicity.

Conclusions: Current reference intervals for serum and urinary gadolinium clearance are not applicable for patients in the 5 months following intravenous gadobutrol exposure.