American Journal of Roentgenology最新文献

BACKGROUND. The low clinically approved doses of gadolinium-based contrast agents (GBCAs) do not generate sufficient enhancement on CT for diagnostic purposes. Photon-counting detector (PCD) CT offers improved spectral resolution and could potentially enable visualization of hepatocyte-specific GBCAs, given their associated high gadolinium concentrations within hepatocytes. OBJECTIVE. The purpose of this study was to investigate the potential of gadoxetate disodium in combination with PCD CT and low-energy virtual monoenergetic imaging (VMI) reconstructions to achieve an increase in attenuation in a phantom. METHODS. A series of solutions was prepared of diluted gadoxetate disodium (concentrations of 0.250-2.5 μmol/mL, corresponding with doses of 25-200 μmol/kg). These solutions, along with deionized water, were evaluated in an anthropomorphic abdominal phantom using a clinical PCD CT scanner; VMI reconstructions at 40, 50, 60, and 70 keV and virtual noncontrast (VNC) imaging reconstructions were generated. Attenuation measurements were obtained; a linear regression model combined these values with previously reported in vivo data to estimate hepatic enhancement and CNR across doses. RESULTS. Attenuation increased with increasing concentration at a given energy level and with decreasing energy level for a given concentration; VNC images had the lowest attenuation. The maximum attenuation reached in the abdominal phantom was 45.2 HU for a concentration of 2.5 μmol/mL at 40 keV. A concentration of 0.25 μmol/mL had attenuation at 40 keV of 13.0 HU. The model yielded estimated in vivo hepatic enhancement at 40 keV of 4.9 HU for a dose of 25 μmol/kg, 19.9 HU for 100 μmol/kg, and 30.8 HU for 200 μmol/kg; corresponding CNRs were 0.13, 0.52, and 0.81, respectively. CONCLUSION. The combination of gadoxetate disodium and PCD CT could theoretically allow appreciable hepatic enhancement at a 200-μmol/kg dose; such effect was not observed for the clinically approved 25-μmol/kg dose. CLINICAL IMPACT. PCD CT achieved attenuation increases for gadoxetate disodium at considerably lower doses than previously documented for CT of GBCAs, albeit at approximately eight times greater than clinical doses, which were thus too high for clinical use. Additional research exploiting PCD CT technology could seek to reduce further doses required for sufficient visualization into a clinically feasible range, to potentially allow CT using a liver-specific agent.

BACKGROUND - Breast MRI is a sensitive tool for detecting small cancers. However, differentiating benign and malignant lesions remains challenging, particularly for foci. Studies evaluating other lesion types have identified ultrafast MRI (UFMRI) parameters associated with malignancy. OBJECTIVE - The purpose of this study was to determine if kinetic features of UFMRI can differentiate malignant and nonmalignant foci. METHODS - In this single-center retrospective study, consecutive UFMRI examinations performed from July 2019 to April 2023 with subsequent MRI-guided biopsy of a focus were selected. Patient characteristics and lesion features were collected from the EMR, imaging reports, and imaging review. Focus and background parenchymal enhancement (BPE) time to enhancement (TTE), and the difference between them was calculated. Associations with malignancy were assessed with univariable and multivariable logistic regression. RESULTS - A total of 124 patients (mean age, 53 years old; range, 29-78 years old) underwent biopsy of 124 foci. Sixty-four (51.6%) were postmenopausal, 71 (57.3%) had a personal history of breast cancer, 81 (65.3%) had a family history of breast cancer, and 33/94 (35.3%) had genetic mutations. Most examinations were performed for extent of disease evaluation (47.6%; 59/124), followed by screening (41.9%; 52/124). Patients predominantly had heterogeneous fibroglandular tissue (58.1%; 72/124) and mild BPE (57.3%; 71/124). Of 124 lesions, 21 (16.9%) were malignant, 16 were invasive, and five were ductal carcinoma in situ. Odds of malignancy increased 5% with each 1-second increase in the difference of lesion TTE and BPE TTE (95% CI: 2-9%, p = .006). Older age and lower BPE were associated with increased likelihood of malignancy (p = .005 and p = .02, respectively). Odds of malignancy for patients with minimal or mild BPE were 11.69 times the odds of those with moderate or marked BPE (95% CI: 1.51-90.67). No other demographic or lesion characteristics were predictive of malignancy. CONCLUSION - Earlier visualization of a focus relative to BPE on UFMRI was associated with increased likelihood of malignancy; morphologic features showed no association with malignancy. CLINICAL IMPACT - The difference of TTE of a focus compared with that of BPE may be a useful parameter for assessing malignancy, which could help reduce unnecessary biopsies.

IV contrast media improve the diagnostic power of radiology examinations. These media include gadolinium-based contrast media and iron oxide nanoparticles for MRI, iodinated contrast material for CT, microbubbles for ultrasound, and radiopharmaceuticals for nuclear medicine. As do all medications, contrast media carry risks, which may be heightened in the conditions of pregnancy and lactation. Radiologists must understand the potential risks from contrast media exposure to the pregnant patient, fetus, and nursing infant, as well as understand these administrations' impact on the clinical utility of examinations. This article reviews the available literature on these media, along with key regulatory bodies' and professional societies' current recommendations for their use, in the settings of pregnancy and lactation. This knowledge should help radiologists make well-reasoned risk-benefit analyses regarding contrast media administration and allow informed consent discussions with pregnant and nursing patients for whom contrast media administration is being considered. This information and analysis can also assist facilities in designing policies and standard operating procedures of possible clinical benefit to the pregnant patient, fetus, or nursing infant, balancing contrast media exposure considerations against augmented diagnostic capabilities.

Ascites can develop in the setting of a variety of pathologies. The approach to treatment depends on accurate determination of the underlying cause, for which fluid analysis plays a central role. In particular, the serum-ascites-albumin gradient serves as a primary diagnostic test for differentiating among causes, with certain additional fluid tests performed based on clinical suspicion. Treatment options range from nonspecific fluid removal, including large-volume paracentesis and tunneled peritoneal catheters, to targeted therapies (e.g., diuretics, transjugular intrahepatic portosystemic shunt, and lymphangiography). Societal guidelines exist for the approach to cirrhotic ascites, but the management of other less common causes remains less well defined. The goal of this AJR Expert Panel Narrative Review is to provide guidance for the diagnosis and management of ascites, based on available evidence and the authors' clinical experience.

Background: Lung-RADS has shown variable interreader agreement in the literature, in part related to a broad range of factors that may influence the consistency of its implementation. Objective: To assess the interreader agreement of Lung-RADS and to investigate factors influencing the system's variability. Evidence Acquisition: EMBASE, PubMed, and Cochrane databases were searched for original research studies published through June 18, 2024 reporting the interreader agreement of Lung-RADS on chest CT. Random-effect models were used to calculate pooled kappa coefficients for Lung-RADS categorization and pooled intraclass correlation coefficients (ICCs) for nodule size measurements. Potential sources of heterogeneity were explored using metaregression analyses. Evidence Synthesis: The analysis included 11 studies (1470 patients) for Lung-RADS categorization and five studies (617 patients) for nodule size measurement. Interreader agreement for Lung-RADS categorization was substantial (κ=0.72 [95% CI, 0.57-0.82]), and for nodule size measurement was almost perfect (ICC=0.97 [95% CI, 0.90-0.99]). Interreader agreement for Lung-RADS categorization was significantly associated with the method of nodule measurement (p=.005), with pooled kappa coefficients for studies using computer-aided detection (CAD)-based semiautomated volume measurements, using CAD-based semiautomated diameter measurements, and using manual diameter measurements of 0.95, 0.91, and 0.66, respectively. Interreader agreement for Lung-RADS categorization was also significantly associated with studies' nodule type distribution (p<.001), with pooled kappa coefficients for studies evaluating 100% solid nodules, 30-99% solid nodules, and <30% solid nodules of 0.85, 0.76, and 0.55, respectively. Interreader agreement for nodule size measurement was significantly associated with radiation dose (p<.001), with pooled ICCs for studies that used standard-dose CT, used low-dose CT, and used ultralow-dose CT of 0.97, 0.96, and 0.59, respectively. Interreader agreement for nodule size measurement was also significantly associated with the Lung-RADS version used (p=.02), with pooled ICCs for studies using Lung-RADS 1.1 and using Lung-RADS 1.0 of 0.99 and 0.93, respectively. Conclusion: While supporting the overall reliability of Lung-RADS, the findings indicate roles for CAD assistance as well as training and standardized approaches for nodule type characterization to further promote reproducible application. Clinical Impact: Consistent nodule assessments will be critical for Lung-RADS to optimally impact patient management and outcomes.

The American Lung Association's State of Lung Cancer Report showed a dramatic increase in national lung cancer screening rates from 4.5% in 2023 to 16.0% in 2024. This apparent improvement stems from a methodologic change-switching from the American College of Radiology lung cancer screening registry to the Behavioral Risk Factor Surveillance System. This Viewpoint examines this transition, discusses research and policy implications, and highlights the importance of understanding methodologic changes when interpreting screening statistics.