Baffour, Francis

Abstract Objective. Four-dimensional CT (4DCT) enables visualization of dynamic wrist joint pathology but may be compromised by motion artifacts. Deep learning (DL)-assisted motion correction has the potential to enhance wrist 4DCT quality, but model development is hindered by scarce training data. To address this, we developed a model-based motion simulation framework that generated realistic 4DCT data with paired static ground truth images to demonstrate wrist motion correction using a physics-informed DL model trained with simulated data. Approach. Wrist motion was simulated by synchronizing rotational and translational movements of carpal bones and connective tissues. Elastic deformation guided by analytically-derived motion vector fields was applied to static wrist scans at neutral positions to create artifact-free images at multiple angular positions. Virtual motion-corrupted 4DCT images were produced via forward projection and reconstruction with synchronized gantry and wrist motion. Experimental data from 4DCT cadaver scans were collected to validate simulation quality. Low-intensity region score (LIRS), positivity, and entropy were used to assess simulated motion artifacts. A physics-informed motion correction network was adapted exclusively using simulated training data and subsequently deployed on simulated, real cadaveric, and in vivo 4DCT scans. LIRS and structural similarity index (SSIM) were used to evaluate motion correction quality. Wilcoxon signed-rank tests were conducted ( α = 0.05). Results. The simulation method created realistic motion artifacts compared to real scan reference ( p > 0.05). Motion artifacts were effectively mitigated across testing cases demonstrating generalizability. In simulated scans, LIRS improved from 0.55 ± 0.12–0.75 ± 0.04 and SSIM from 0.87 ± 0.08–0.95 ± 0.03 at bone regions (each p < 0.01). In experimental cadaveric scans, LIRS improved from 0.05 ± 0.01–0.31 ± 0.17 in marker regions and from 0.58 ± 0.19–0.77 ± 0.14 in bone regions (each p < 0.01). Significance. Our simulation method facilitates training DL-assisted motion correction algorithms by providing high-quality training data, effectively supporting 4DCT image quality enhancement.

Whole-body cross-sectional imaging has largely replaced skeletal survey as the standard for evaluating hematologic malignancies and bone marrow disorders, but the practical choice between whole-body low-dose CT (WBCT) and whole-body MRI (WBMRI) remains incompletely resolved. This clinical review provides a practical, scenario-based comparison of WBCT and WBMRI across diagnosis, staging, treatment response, and surveillance. We emphasize real-world practical considerations, including scanner access, expertise, patient tolerance, radiation considerations, and cost. In multiple myeloma, with available comparative evidence, we include a focused research synthesis of 3 studies (152 patients) demonstrating high pooled CT-MRI concordance of 0.895 (95% CI: 0.834-0.935) with no detectable heterogeneity ( I 2 =0%), supporting either modality as a reasonable first-line depending on the clinical question. Across all included disease categories, the broader pooled concordance estimate was 0.797 (95% CI: 0.667-0.885) with substantial heterogeneity reflecting variability in clinical context, reference standard, and protocol. WBMRI dominates in non-neoplastic marrow disorders where marrow characterization is essential. In lymphoma, FDG-PET/CT remains the standard for adult disease, with WBMRI most indicated in pediatrics and adolescents. Emerging CT techniques, including dual-energy CT with virtual noncalcium images and photon-counting detector CT, are extending CT into the marrow imaging space and narrowing the historical gap with MRI. Modality selection should be guided by the specific clinical scenario, available resources, and patient factors rather than by global judgments of modality superiority.

Abstract Photon-counting detector CT (PCD-CT) directly detects individual photons and measures their energies, enabling the acquisition of multi-energy data from a single x-ray source with higher spatial resolution, thereby allowing visualization of smaller arteries and veins and other important imaging features not seen at conventional CT. It also substantially reduces calcium and stent blooming artifacts. Appropriate patient selection and task-based optimization of acquisition, reconstruction, and interpretation are critical to realize these benefits. Vascular imaging examinations for which early evidence shows that PCD-CT demonstrates higher diagnostic performance compared to conventional CT include coronary CT angiography (CTA) for evaluation of partially calcified plaques or stents, peripheral runoff CTA, detection of cerebrospinal fluid-venous fistulas, and head CTA for evaluation of small intracranial vessels and aneurysms. Current limitations include excessive image noise with the sharpest reconstruction kernels and challenges when adapting conventional CT protocols (eg, requiring sharper kernels, thinner slices, higher matrices, tailored scan modes) to achieve time-efficient image reconstruction and hanging protocols. New solutions and directions will include deep-learning-based image noise reduction, improved spectral separation, strategic triage of specific patient populations to PCD-CT systems, and subspecialty clinical practice recommendations for this new technology.

Background: Distal radius fractures involving the physis are among the most common upper extremity injuries in children and adolescents. Unlike transitional fractures of the distal tibia, known as Tillaux and triplane fractures, transitional fractures of the distal radius have not been well characterized. This study aims to evaluate Salter-Harris III and IV fractures of the distal radius in the pediatric transitional age population to determine if a characteristic fracture pattern exists analogous to the distal tibia. We hypothesized that pediatric transitional fractures of the distal radius would follow a pattern that would ultimately dictate treatment and predict outcomes. Methods: A retrospective chart review of pediatric patients with transitional fractures of the distal radius at a single institution was performed. Salter-Harris III and IV fractures of the distal radius with CT imaging were included. Two independent reviewers determined the metaphyseal fracture plane and the major intra-articular epiphyseal fracture fragments. Descriptive statistical analysis was performed. Results: Thirty patients who met inclusion criteria made the study cohort. There were 5 Salter-Harris III fractures and 25 Salter-Harris IV fractures. Mean age at the time of injury was 15±1.5 years. The metaphyseal fracture demonstrated a coronal fracture plane in all cases, and 20% had a sagittal plane component. The major epiphyseal fracture fragments were identified as dorsal ulnar corner in 70%, radial column in 43%, volar rim in 30%, and dorsal wall in 17%. Patients were treated with open reduction and internal fixation (N=12, 40%), closed reduction and percutaneous pinning (N=4, 13%), or cast immobilization (N=14, 47%). Most patients (N=24, 80%) did not demonstrate a growth disturbance after treatment. Angular deformity, however, was significantly higher in patients with a primary dorsal ulnar corner epiphyseal fragment (N=4, 19% vs. N=0%, P =0.03). Conclusion: Transitional fractures of the distal radius occurred on average at age 15. The injuries demonstrated a consistent pattern, with a coronal fracture plane in the metaphysis and a dorsal ulnar corner fragment in most epiphyses. The dorsal physis may be the strongest portion of the distal radius at the time of injury, though mechanism of injury may impact patterns as well. Level of Evidence: Level III.

Abstract Photon-counting detector CT (PCD-CT) represents a significant advancement in medical imaging, particularly for musculoskeletal (MSK) applications. Its primary innovation lies in enhanced spatial resolution, which facilitates improved detection of small anatomical structures such as trabecular bone, osteophytes, and subchondral cysts. PCD-CT enables high-quality imaging with reduced radiation doses, making it especially beneficial for populations requiring frequent imaging, such as paediatric patients and individuals with multiple myeloma. Additionally, PCD-CT supports advanced applications like bone quality assessment, which correlates well with gold-standard tests, and can aid in diagnosing osteoporosis and assessing fracture risk. Techniques such as spectral shaping and virtual monoenergetic imaging further optimize the technology, minimizing artefacts and enhancing material decomposition. These capabilities extend to conditions like gout and haematologic malignancies, offering improved detection and assessment. The integration of artificial intelligence could enhance PCD-CT’s performance by reducing image noise and improving quantitative assessments. Ultimately, PCD-CT’s superior resolution, reduced dose protocols, and multi-energy imaging capabilities will likely have a transformative impact on MSK imaging, improving diagnostic accuracy, patient care, and clinical outcomes.

Abstract Quantitative computed tomography (CT) enables the measurement of biophysical processes characterized by morphology, composition, flow, and/or motion to aid in clinical diagnosis and intervention. Since its initial application for determining bone mineral density for skeletal fragility assessment, quantitative CT has continued to evolve alongside CT’s technological advancements. A key challenge facing quantitative CT is the lack of standardization pertinent to image acquisition, reconstruction, and image analysis. With the introduction of spectral CT involving dual-energy approaches and photon-counting detectors (PCD), we are now able to obtain detailed information regarding mass densities of endogenous and exogeneous materials. Furthermore, energy-resolved CT yields spectral image types (eg, virtual monoenergetic image) that are, in principle, independent of tube potential and patient size. This paves the way for workflow standardization and helps improve the consistency and reproducibility of CT-derived measurements. In this article, we review clinical applications of quantitative CT, discuss key challenges associated with quantitative CT and its adoption into routine practice, and outline the unique benefits ushered by new CT technologies such as PCD-CT towards improving quantitative imaging.

The term monoclonal gammopathy of clinical significance (MGCS) refers to a group of symptomatic monoclonal gammopathies that do not meet the diagnostic criteria for malignant plasma cell disorders, such as multiple myeloma or Waldenström macroglobulinemia. These symptoms are attributable to the paraneoplastic effects of monoclonal immunoglobulins that occur through diverse mechanisms. The presence of symptoms distinguishes MGCS from monoclonal gammopathy of undetermined significance, which lacks significant symptomatic presentation. The presentations of MGCS are manifold, adding to the diagnostic challenge. Clinical suspicion is key for accurate and timely diagnosis. Radiologic imaging can provide pivotal information to guide the diagnosis. In this review, we discuss MGCS from a radiology perspective and highlight pertinent imaging features associated with the disorders.

OBJECTIVE The purpose of this study was to determine the effect of osteoporosis medications on opportunistic CT-based Hounsfield units (HU). METHODS Spine and nonspine surgery patients were retrospectively identified who had been treated with romosozumab for 3 to 12 months, teriparatide for 3 to 12 months, teriparatide for > 12 months, denosumab for > 12 months, or alendronate for > 12 months. HU were measured in the L1–4 vertebral bodies. One-way ANOVA was used to compare the mean change in HU among the five treatment regimens. RESULTS In total, 318 patients (70% women) were included, with a mean age of 69 years and mean BMI of 27 kg/m 2 . There was a significant difference in mean HU improvement (p < 0.001) following treatment with romosozumab for 3 to 12 months (n = 32), teriparatide for 3 to 12 months (n = 30), teriparatide for > 12 months (n = 44), denosumab for > 12 months (n = 123), and alendronate for > 12 months (n = 100). Treatment with romosozumab for a mean of 10.5 months significantly increased the mean HU by 26%, from a baseline of 85 to 107 (p = 0.012). Patients treated with teriparatide for > 12 months (mean 23 months) experienced a mean HU improvement of 25%, from 106 to 132 (p = 0.039). Compared with the mean baseline HU, there was no significant difference after treatment with teriparatide for 3 to 12 months (110 to 119, p = 0.48), denosumab for > 12 months (105 to 107, p = 0.68), or alendronate for > 12 months (111 to 113, p = 0.80). CONCLUSIONS Patients treated with romosozumab for a mean of 10.5 months and teriparatide for a mean of 23 months experienced improved spinal bone mineral density as estimated by CT-based opportunistic HU. Given the shorter duration of effective treatment, romosozumab may be the preferred medication for optimization of osteoporotic patients in preparation for elective spine fusion surgery.