Imaging methods capable of detecting inflammation, such as MR imaging and ultrasound, are of paramount importance in rheumatic disease management, not only for diagnostic purposes but also for monitoring disease activity and treatment response. However, more advanced stages of arthritis, characterized by findings of cumulative structural damage, have traditionally been accomplished by radiographs and computed tomography. The purpose of this review is to provide an overview of imaging of some of the most prevalent inflammatory rheumatic diseases affecting the lower limb (osteoarthritis, rheumatoid arthritis, and gout) and up-to-date recommendations regarding imaging diagnostic workup.

Interstitial lung disease (ILD) complicates connective tissue disease (CTD) with variable incidence and is a leading cause of death in these patients. To improve CTD-ILD outcomes, early recognition and management of ILD is critical. Blood-based and radiologic biomarkers that assist in the diagnosis CTD-ILD have long been studied. Recent studies, including -omic investigations, have also begun to identify biomarkers that may help prognosticate such patients. This review provides an overview of clinically relevant biomarkers in patients with CTD-ILD, highlighting recent advances to assist in the diagnosis and prognostication of CTD-ILD.

The majority of connective tissue diseases (CTDs) are multisystem disorders that are often heterogeneous in their presentation and do not have a single laboratory, histologic, or radiologic feature that is defined as the gold standard to support a specific diagnosis. Given this challenging situation, the diagnosis of CTD is a process that requires the synthesis of multidisciplinary data which may include patient clinical symptoms, serologic evaluation, laboratory testing, and imaging. Pulmonary manifestations of connective tissue disease include interstitial lung disease as well as multicompartmental manifestations. These CT imaging patterns and features of specific diseases will be discussed in this article.

OBJECTIVE: To evaluate the role of visual and quantitative chest CT parameters in assessing treatment response in patients with severe asthma.
METHODS: Korean participants enrolled in a prospective multicenter study, named the Precision Medicine Intervention in Severe Asthma study, from May 2020 to August 2021, underwent baseline and follow-up chest CT scans (inspiration/expiration) 10-12 months apart, before and after biologic treatment. Two radiologists scored bronchiectasis severity and mucus plugging extent. Quantitative parameters were obtained from each CT scan as follows: normal lung area (normal), air trapping without emphysema (AT without emph), air trapping with emphysema (AT with emph), and airway (total branch count, Pi10). Clinical parameters, including pulmonary function tests (forced expiratory volume in 1 s [FEV1] and FEV1/forced vital capacity [FVC]), sputum and blood eosinophil count, were assessed at initial and follow-up stages. Changes in CT parameters were correlated with changes in clinical parameters using Pearson or Spearman correlation.
RESULTS: Thirty-four participants (female:male, 20:14; median age, 50.5 years) diagnosed with severe asthma from three centers were included. Changes in the bronchiectasis and mucus plugging extent scores were negatively correlated with changes in FEV1 and FEV1/FVC (ρ = from -0.544 to -0.368, all P < 0.05). Changes in quantitative CT parameters were correlated with changes in FEV1 (normal, r = 0.373 [P = 0.030], AT without emph, r = -0.351 [P = 0.042]), FEV1/FVC (normal, r = 0.390 [P = 0.022], AT without emph, r = -0.370 [P = 0.031]). Changes in total branch count were positively correlated with changes in FEV1 (r = 0.349 [P = 0.043]). There was no correlation between changes in Pi10 and the clinical parameters (P > 0.05).
CONCLUSIONS: Visual and quantitative CT parameters of normal, AT without emph, and total branch count may be effective for evaluating treatment response in patients with severe asthma.

Since the emergence of the first photon-counting computed tomography (PCCT) system in late 2021, its advantages and a wide range of applications in all fields of radiology have been demonstrated. Compared to standard energy-integrating detector-CT, PCCT allows for superior geometric dose efficiency in every examination. While this aspect by itself is groundbreaking, the advantages do not stop there. PCCT facilitates an unprecedented combination of ultra-high-resolution imaging without dose penalty or field-of-view restrictions, detector-based elimination of electronic noise, and ubiquitous multi-energy spectral information. Considering the high demands of orthopedic imaging for the visualization of minuscule details while simultaneously covering large portions of skeletal and soft tissue anatomy, no subspecialty may benefit more from this novel detector technology than musculoskeletal radiology. Deeply rooted in experimental and clinical research, this review article aims to provide an introduction to the cosmos of PCCT, explain its technical basics, and highlight the most promising applications for patient care, while also mentioning current limitations that need to be overcome.

OBJECTIVE: To develop and validate a preoperative risk score incorporating carbohydrate antigen (CA) 19-9, CT, and fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT variables to predict recurrence-free survival (RFS) after upfront surgery in patients with resectable pancreatic ductal adenocarcinoma (PDAC).
METHODS: Patients with resectable PDAC who underwent upfront surgery between 2014 and 2017 (development set) or between 2018 and 2019 (test set) were retrospectively evaluated. In the development set, a risk-scoring system was developed using the multivariable Cox proportional hazards model, including variables associated with RFS. In the test set, the performance of the risk score was evaluated using the Harrell C-index and compared with that of the postoperative pathological tumor stage.
RESULTS: A total of 529 patients, including 335 (198 male; mean age ± standard deviation, 64 ± 9 years) and 194 (103 male; mean age, 66 ± 9 years) patients in the development and test sets, respectively, were evaluated. The risk score included five variables predicting RFS: tumor size (hazard ratio [HR], 1.29 per 1 cm increment; P < 0.001), maximal standardized uptake values of tumor ≥ 5.2 (HR, 1.29; P = 0.06), suspicious regional lymph nodes (HR, 1.43; P = 0.02), possible distant metastasis on 18F-FDG PET/CT (HR, 2.32; P = 0.03), and CA 19-9 (HR, 1.02 per 100 U/mL increment; P = 0.002). In the test set, the risk score showed good performance in predicting RFS (C-index, 0.61), similar to that of the pathologic tumor stage (C-index, 0.64; P = 0.17).
CONCLUSIONS: The proposed risk score based on preoperative CA 19-9, CT, and 18F-FDG PET/CT variables may have clinical utility in selecting high-risk patients with resectable PDAC.

OBJECTIVE: This study aimed to evaluate the diagnostic efficacy and safety of low-contrast-dose, dual-source dual-energy CT before transcatheter aortic valve replacement (TAVR) in patients with compromised renal function.
METHODS: A total of 54 consecutive patients (female:male, 26:38; 81.9 ± 7.3 years) with reduced renal function underwent pre-TAVR dual-energy CT with a 30-mL contrast agent between June 2022 and March 2023. Monochromatic (40- and 50-keV) and conventional (120-kVp) images were reconstructed and analyzed. The subjective quality score, vascular attenuation, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were compared among the imaging techniques using the Friedman test and post-hoc analysis. Interobserver reliability for aortic annular measurement was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. The procedural outcomes and incidence of post-contrast acute kidney injury (AKI) were assessed.
RESULTS: Monochromatic images achieved diagnostic quality in all patients. The 50-keV images achieved superior vascular attenuation and CNR (P < 0.001 in all) while maintaining a similar SNR compared to conventional CT. For aortic annular measurement, the 50-keV images showed higher interobserver reliability compared to conventional CT: ICC, 0.98 vs. 0.90 for area and 0.97 vs. 0.95 for perimeter; 95% limits of agreement width, 0.63 cm² vs. 0.92 cm² for area and 5.78 mm vs. 8.50 mm for perimeter. The size of the implanted device matched CT-measured values in all patients, achieving a procedural success rate of 92.6%. No patient experienced a serum creatinine increase of ≥ 1.5 times baseline in the 48-72 hours following CT. However, one patient had a procedural delay due to gradual renal function deterioration.
CONCLUSIONS: Low-contrast-dose imaging with 50-keV reconstruction enables precise pre-TAVR evaluation with improved image quality and minimal risk of post-contrast AKI. This approach may be an effective and safe option for pre-TAVR evaluation in patients with compromised renal function.

Systemic lupus erythematosus (SLE) is a complex autoimmune disease where the body loses tolerance to its own antigens, particularly nuclear antigens. Abnormal responses from T and B cells lead to the production of autoantibodies and the formation of immune complexes in tissues, triggering complement activation, inflammation, and irreversible organ damage. SLE can affect any part of the body, resulting in diverse clinical symptoms. One rare manifestation of SLE is lupus mesenteric vasculitis (LMV), which presents with vague symptoms, abnormal laboratory findings, and specific imaging features. LMV, although uncommon, can progress to severe complications such as bowel perforation, haemorrhage, and even mortality. Here, we report a case of LMV with the involvement of multiple organ systems (including mucocutaneous, musculoskeletal, serosal cavities, and haematological systems), presenting initially with life-threatening intractable gastrointestinal bleeding, and complicated by severe pulmonary infection. By sharing this case, we aim to enhance clinicians\' confidence in managing critical SLE cases and raise awareness about disease surveillance.

This study investigated recurrence rates and treatment efficacy based on tomographic findings during a long-term follow-up after primary spontaneous pneumothorax (PSP) treatment. We retrospectively analyzed patients with PSP treated at our hospital between 2003 and 2020. Patients were categorized into 2 groups based on computed tomography (CT) findings: group 1 (no bulla/bleb) and group 2 (bullae-bleb <3 cm). Data on demographics, recurrence, treatment methods, and outcomes were also collected and compared. A total of 251 PSP cases were evaluated, predominantly male (93.6%) with a mean age of 29.23 ± 1.14 years. Most cases (57%) occurred on the right side. Recurrence rates were highest within the first year (77.8%), with the first and second recurrences occurring at rates of 26% and 27.3%, respectively. In group 1 (n = 117), conservative treatment was applied in 15 cases, tube thoracostomy in 81, autologous blood pleurodesis (ABP) in 19, and surgery in 12. Recurrence rates were 46.6%, 21%, 5.3%, and 8.3%, respectively. In group 2 (n = 134), the recurrence rates were 50%, 32.7%, 20%, and 3.1%, respectively (P < .001). No mortality was observed for any patient. The treatment groups included conservative (n = 19), thoracostomy (n = 179), ABP (n = 34), and surgical (n = 44) groups. Recurrence rates were 47.3%, 27.4%, 11.8% (group 1: 5.3%, group 2: 20%, P = .035), and 4.5% (0% vs 6.3%), respectively. ABP effectively reduced recurrence in group 1 PSP patients without bullae or blebs on CT, potentially avoiding surgery. Video-assisted thoracoscopic surgery should be preferred in group 2 cases with bullae or blebs to minimize recurrence. These results underscore the importance of tailoring treatment strategies based on CT findings to optimize PSP management outcomes.

The aim of this study is to delineate the distinctive high-resolution computed tomography features of pulmonary cryptococcosis in non-HIV-infected patients. This retrospective analysis encompasses high-resolution computed tomography scans from 58 patients with histologically confirmed pulmonary cryptococcosis, focusing on the diagnostic challenges and the factors that lead to misdiagnosis. Analysis of computed tomography scans from these patients indicated that nodular or mass-like presentations were evident in 32 cases (55.2%), consolidation presentations in 7 cases (12.1%), and mixed presentations in 19 cases (32.8%). Lesions were predominantly located in the lower lobes of the lungs (40 cases, 69.0%) and in peripheral zones (55 cases, 94.8%). Notable radiographic signs included the presence of the burr sign in 55 cases (94.8%), lobulation sign in 53 cases (91.4%), halo sign in 53 cases (91.4%), and air bronchogram in 46 cases (79.0%). Moreover, 24 cases (41.4%) exhibited necrosis or cavitation, mediastinal lymphadenopathy was noted in 6 cases (10.3%), and pleural effusion was present in 5 cases (8.6%). Lesions were devoid of calcification. Pulmonary cryptococcosis ought to be contemplated in the differential diagnosis when computed tomography imaging exhibits patterns including, but not limited to, lower lobe and peripheral distribution, a broad base abutting the pleura, clustered growth with a propensity for fusion, air bronchogram within lesions, and peripheral halo sign.