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IntroductionExperimental stroke studies suggest an influence of the time of day of stroke onset on infarct progression. Whether this holds true after human stroke is unknown, but would have implications for the design of randomised controlled trials, especially those on neuroprotection.MethodsWe pooled data from 583 patients with anterior large-vessel occlusion stroke from three prospectively recruited cohorts. Ischaemic core and penumbra volumes were determined with CT perfusion using automated thresholds. Core growth was calculated as the ratio of core volume and onset-to-imaging time. To determine circadian rhythmicity, we applied multivariable linear and sinusoidal regression analysis adjusting for potential baseline confounders.ResultsPatients with symptom onset at night showed larger ischaemic core volumes on admission compared with patients with onset during the day (median, 40.2 mL vs 33.8 mL), also in adjusted analyses (p=0.008). Sinusoidal analysis indicated a peak of core volumes with onset at 11pm. Core growth was faster at night compared with day onset (adjusted p=0.01), especially for shorter onset-to-imaging times. In contrast, penumbra volumes did not change across the 24-hour cycle.DiscussionThese results suggest that human infarct progression varies across the 24-hour cycle with potential implications for the design and interpretation of neuroprotection trials.

Objectives To investigate the cost-effectiveness of supplemental short-protocol brain MRI after negative non-contrast CT for the detection of minor strokes in emergency patients with mild and unspecific neurological symptoms. Methods The economic evaluation was centered around a prospective single-center diagnostic accuracy study validating the use of short-protocol brain MRI in the emergency setting. A decision-analytic Markov model distinguished the strategies “no additional imaging” and “additional short-protocol MRI” for evaluation. Minor stroke was assumed to be missed in the initial evaluation in 40% of patients without short-protocol MRI. Specialized post-stroke care with immediate secondary prophylaxis was assumed for patients with detected minor stroke. Utilities and quality-of-life measures were estimated as quality-adjusted life years (QALYs). Input parameters were obtained from the literature. The Markov model simulated a follow-up period of up to 30 years. Willingness to pay was set to $100,000 per QALY. Cost-effectiveness was calculated and deterministic and probabilistic sensitivity analysis was performed. Results Additional short-protocol MRI was the dominant strategy with overall costs of $26,304 (CT only: $27,109). Cumulative calculated effectiveness in the CT-only group was 14.25 QALYs (short-protocol MRI group: 14.31 QALYs). In the deterministic sensitivity analysis, additional short-protocol MRI remained the dominant strategy in all investigated ranges. Probabilistic sensitivity analysis results from the base case analysis were confirmed, and additional short-protocol MRI resulted in lower costs and higher effectiveness. Conclusion Additional short-protocol MRI in emergency patients with mild and unspecific neurological symptoms enables timely secondary prophylaxis through detection of minor strokes, resulting in lower costs and higher cumulative QALYs. Key Points • Short-protocol brain MRI after negative head CT in selected emergency patients with mild and unspecific neurological symptoms allows for timely detection of minor strokes. • This strategy supports clinical decision-making with regard to immediate initiation of secondary prophylactic treatment, potentially preventing subsequent major strokes with associated high costs and reduced QALY. • According to the Markov model, additional short-protocol MRI remained the dominant strategy over wide variations of input parameters, even when assuming disproportionally high costs of the supplemental MRI scan.

Background: Fractures of the distal radius are common, particularly among young men and elderly women, often leading to painful wrist arthritis, especially if the joint surface has been affected. Traditional treatments of the wrist, such as full or partial wrist fusion, limit movement, and common wrist prostheses have high complication rates. Regenerative medicine and 3D bioprinting offer the potential for personalized joint replacements. Methods: This study evaluates using the contralateral radius as a template for creating customized distal radius prostheses. Bilateral CT scans of healthy wrists were analyzed to assess the shape and symmetry of the distal radius using a landmark-free morphometric method. Instead of comparing defined landmarks, the entire surface of the radius is analyzed employing dense point- and deformation-based morphometry to detect subtle morphological differences, providing an unbiased and more accurate comparison of the overall deformations in the distal radii. Results: results show strong intraindividual symmetry in joint surfaces. Interindividual comparisons revealed significant morphological variations, particularly gender-specific differences. Conclusions: These findings support the use of the contralateral radius as a template for the replaced side. At the same time, the interindividual results endorse the approach of pursuing personalized prostheses as the optimal replacement for distal joint surfaces. The increasing improvement of 3D-printed prostheses promises new methods for better outcomes in distal radius arthrosis after intraarticular fractures. Further research into clinical applications and biocompatible 3D printing materials is recommended.

ObjectiveTo evaluate the impact of a postoperative baseline (PB) MRI on diagnostic confidence and performance in detecting local recurrence (LR) of soft-tissue sarcoma (STS) of the limb.Materials and methodsA total of 72 patients (8 with LR, 64 without LR) with primary STS of the limb were included. Routine follow-up MRI (1.5 T) at 6 and approximately 36 months (meanLR: 39.7 months; meanno LR: 34.9 months) after multimodal therapy or at time of LR were assessed by three independent readers using a 5-point Likert scale. Furthermore, the following imaging parameters were evaluated: presence of a mass, signal characteristics at T2- and T1-weighted imaging, contrast enhancement (CE), and in some of the cases signal intensity on the apparent diffusion coefficient (ADC). U-test, McNemar test, and ROC-analysis were applied. Interobserver reliability was calculated using Fleiss kappa statistics. A p value of 0.05 was considered statistically significant.ResultsThe presence of a PB MRI significantly improved diagnostic confidence in detecting LR of STS (p < 0.001) and slightly increased specificity (mean specificity without PE 74.1% and with presence of PB MRI 81.2%); however, not to a significant level. The presence of a mass showed highest diagnostic performance and highest interreader agreement (AUC [%]; κ: 73.1–83.6; 0.34) followed by T2-hyperintensity (50.8–66.7; 0.08), CE (52.4–62.5; 0.13), and T1-hypointensity (54.7–77.3; 0.23). ADC showed an AUC of 65.6–96.6% and a κ of 0.55.ConclusionThe presence of a PB MRI increases diagnostic confidence in detecting LR of STS of the limb.

Background/Objectives: Magnetic resonance imaging (MRI) is the preferred diagnostic means to visualize spinal pathologies, and offers the possibility of precise structural tissue analysis. However, knowledge about MRI-based measurements of physiological cross-sectional musculoskeletal dimensions and associated tissue-specific average structural brightness in the lumbar spine of healthy young women and men is scarce. The current study was planned to investigate characteristic intersexual differences and to provide MRI-related musculoskeletal baseline values before the onset of biological aging. Methods: At a single medical center, lumbar MRI scans of 40 women and 40 men aged 20–40 years who presented with moderate nonspecific low back pain were retrospectively evaluated for sex-specific differences in cross-sectional sizes of the fifth lumbar vertebrae, psoas and posterior paravertebral muscles, and respective sex- and age-dependent average brightness alterations on T2-weighted axial sections in the L5-level. Results: In women (mean age 33.5 years ± 5.0 (standard deviation)), the investigated musculoskeletal cross-sectional area sizes were significantly smaller (p < 0.001) compared to those in men (mean age 33.0 years ± 5.7). Respective average musculoskeletal brightness values were higher in women compared to those in men, and most pronounced in posterior paravertebral muscles (p < 0.001). By correlating brightness results to those of subcutaneous fat tissue, all intersexual differences, including those between fifth lumbar vertebrae and psoas muscles, turned out to be statistically significant. This phenomenon was least pronounced in psoas muscles. Conclusions: Lumbar musculoskeletal parameters showed significantly larger dimensions of investigated anatomical structures in men compared to those in women aged 20–40 years, and an earlier onset and faster progress of bone loss and muscle degradation in women.

Objectives Stroke triage using CT perfusion (CTP) or MRI gained importance after successful application in recent trials on late-window thrombectomy but is often unavailable and time-consuming. We tested the clinical value of software-based analysis of cerebral attenuation on Single-phase CT angiography source images (CTASI) as CTP surrogate in stroke patients. Methods Software-based automated segmentation and Hounsfield unit (HU) measurements for all regions of the Alberta Stroke Program Early CT Score (ASPECTS) on CTASI were performed in patients with large vessel occlusion stroke who underwent thrombectomy. To normalize values, we calculated relative HU (rHU) as ratio of affected to unaffected hemisphere. Ischemic regions, regional ischemic core and final infarction were determined on simultaneously acquired CTP and follow-up imaging as ground truth. Receiver operating characteristics analysis was performed to calculate the area-under-the-curve (AUC). Resulting cut-off values were used for comparison with visual analysis and to calculate an 11-point automated CTASI ASPECTS. Results Seventy-nine patients were included. rHU values enabled significant classification of ischemic involvement on CTP in all ten regions of the ASPECTS (each p<0.001, except M4-cortex p = 0.002). Classification of ischemic core and prediction of final infarction had best results in subcortical regions but produced lower AUC values with significant classification for all regions except M1, M3 and M5. Relative total hemispheric attenuation provided strong linear correlation with CTP total ischemic volume. Automated classification of regional ischemia on CTASI was significantly more accurate in most regions and provided better agreement with CTP cerebral blood flow ASPECTS than visual assessment. Conclusions Automated attenuation measurements on CTASI provide excellent performance in detecting acute ischemia as identified on CTP with improved accuracy compared to visual analysis. However, value for the approximation of ischemic core and morphologic outcome in large vessel occlusion stroke after thrombectomy was regionally dependent and limited. This technique has the potential to facilitate stroke imaging as sensitive surrogate for CTP-based ischemia.

Computed tomography (CT) and magnetic resonance imaging (MRI) are commonly used to assess femoral and tibial torsion. While CT offers high spatial resolution, it involves ionizing radiation. MRI avoids radiation but requires multiple sequences and extended acquisition time. We retrospectively evaluated whether a three-dimensional isotropic MRI localizer (FastView) could serve as a reliable and faster alternative. In this retrospective single-center study, 60 lower limbs from 30 patients, aged 27.1 ± 11.5 years (mean ± standard deviation), 19 females and 11 males, were assessed using both FastView and a dedicated MRI protocol. FastView (5 × 5 × 5 mm 3 voxels) imaged the entire lower limb in 17.4 s compared to nearly 7 min for the dedicated protocol. Torsion angles were measured independently by two readers. Agreement between methods was evaluated using intraclass correlation coefficients (ICCs), Bland–Altman plots, and Pearson R ². No significant differences in torsion values were found (all p  > 0.305). Femoral (ICC: 0.91–0.96) and tibial (ICC: 0.91–0.94) torsion showed excellent inter-modality agreement. Inter-reader reliability was also high (ICC: 0.95–0.99). Correlation values confirmed strong agreement ( R ²: 0.891–0.963). FastView demonstrated accuracy comparable to the dedicated protocol, offering a fast, efficient, and radiation-free option for routine torsion assessment. Relevance statement FastView MRI localizer offers a fast and resource-efficient method for assessing lower limb torsion, potentially replacing standard multisequence protocols in routine clinical practice. Key Points FastView MRI enables lower limb torsion measurements with full-limb coverage in under 20 s. Torsion angles from FastView and dedicated MRI showed no significant differences. Femoral and tibial ICCs between 0.91 and 0.96 confirm excellent inter-protocol agreement. Inter-reader agreement was consistently high across both protocols. FastView may replace multisequence MRI protocols in routine clinical torsion assessment. Graphical Abstract

Objective: In suspected acute ischemic stroke, it is now reasonable to expand the conventional “stroke protocol” (non-contrast computed tomography (NCCT), arterial CT angiography (CTA), and optionally CT perfusion (CTP)) to early and late venous head scans yielding a multiphase CTA (MP-CTA) to increase diagnostic confidence. Diagnostic reference levels (DRLs) have been defined for neither MP-CTA nor CTP. We therefore present dosimetry data, while also considering image quality, for a large, unselected patient cohort. Methods: A retrospective single-center study of 1790 patients undergoing the extended stroke protocol with three scanners (2× dual-source, DSCT; 1× single-source, SSCT) between 07/21 and 12/23 was conducted. For each sequence, we analyzed the radiation dose (volumetric CT dose index (CTDIvol); dose length product; effective dose); objective image quality using manually placed regions of interest (contrast-to-noise ratio (CNR)); and subjective image quality (4-point scale: 1 = non-diagnostic, 4 = excellent). The DRL was defined as the 75% percentile of the CTDIvol distribution. The Kruskal-Wallis test was used initially to test for overall equality of median values in each data group. Single post-test comparisons were performed with Dunn’s test, with an overall statistical significance level of 0.05. Results: Dosimetry values were significantly higher for SSCT (p < 0.001, each). Local DRLs ranged between 37.3 and 49.1 mGy for NCCT, 3.6–5.5 mGy for arterial CTA, 1.2–2.5 mGy each for early/late venous CTA, and 141.1–220.5 mGy for CTP. Protocol adjustment (DSCT-1: CTP) yielded a 28.2% dose reduction. The highest/lowest CNRs (arterial/early venous CTA, respectively) were recorded for SSCT/DSCT-2 (p < 0.001). Subjective image quality was rated excellent except for slightly increased MP-CTA noise at DSCT-2 (median = 3). Conclusions: Our data imply that additive MP-CTA scans only yield a minor increase in radiation exposure, particularly when using DSCT. CTP should be limited to selected patients.

Background: Hamate-lunate impingement or osteoarthritis can be a cause of ulnar-sided wrist pain. In the literature, the lunate has commonly been classified according to the configuration of its distal articular surface into type 1 and type 2, as described by Viegas. A type 1 lunate possesses only a distal articular surface for the capitate, while a type 2 lunate shows an additional medial facet articulating directly with the hamate. Type 2 lunates have been identified as a risk factor for ulnar-sided wrist pain and the development of osteoarthritis in the midcarpal wrist. However, this does not sufficiently explain all arthritic changes between the hamate and lunate. Methods: In this prospective anatomical-radiological cadaver study, 60 wrists were examined. The midcarpal articulation was documented using conventional X-ray, CT arthrography, and anatomical dissection. The study specifically analyzed the positioning of the lunate relative to the hamate apex and its association with the development of hamate-lunate osteoarthritis. For this purpose, the classification by Viegas was refined. Based on posterior-anterior (p.a.) X-ray examinations of the wrist lunates were divided into type 1a, type 1b, and type 2. The type 1a lunate articulates only with the capitate in the midcarpal joint. The type 1b lunate also articulates only with the capitate; however, medially, the apex of the hamate protrudes beyond a Differentiation Line (D-line), which extends from the radial border of the trapezium or the ulnar border of the lunotriquetral (LT) space, without forming a facet with the lunate. A type 2 lunate articulates distally with the capitate and has an additional medial facet with the hamate. Results: Osteoarthritis between the hamate and lunate was observed in both Viegas type 1 and type 2 lunates. According to our refined lunate classification, both in situ and radiologically, type 1b and type 2 lunates showed a substantially higher prevalence and severity of hamate-lunate osteoarthritis compared to type 1a lunates. However, there was no significant difference in the prevalence of hamate-lunate osteoarthritis between type 1b and type 2 lunates. Conclusions: Assessing lunate type and signs of osteoarthritis is essential when evaluating patients with ulnar-sided wrist pain. Our study demonstrates that osteoarthritis in Viegas type 1 lunate is influenced by the position of the hamate apex relative to the D-line. The refined lunate classification, based on correlated radiological and anatomical studies of the wrist, provides a straightforward method for identifying a potential cause of ulnar-sided wrist pain on p.a. X-rays. This classification can help guide further diagnostic and therapeutic decisions, such as wrist arthroscopy with possible resection of the hamate apex.

Purpose This retrospective single-center study aimed to investigate incidence and risk factors influencing tibial periprosthetic fractures (TPF) in Oxford unicompartmental knee arthroplasty (UKA), with a specific focus on tibial component positioning and sizing. Methods A total of 2063 patients with medial UKA using the Oxford® mobile partial knee implant were analyzed between July 2014 and September 2022. Various preoperative and postoperative radiographic parameters determining pre- and postoperative alignment and implant positioning, incidence and characteristics of periprosthetic fractures, and patient demographics were assessed. Statistical analyses, including Mann–Whitney U test and logistic regression, were conducted to identify significant associations and predictors of tibial fractures. Results Of the 1853 cases that were finally included in the study, 19 (1%) patients experienced TPF. The fracture group presented with a significantly shorter relative mediolateral and posteroanterior distance between the keel and cortex [mediolateral: 23.3% (23.2–24.8%) versus 27.1% (25.7–28.3%), p  < 0.001; posteroanterior: 8.4% (6.3–10.3%) versus 10.0% (9.8–10.1%), p  = 0.004]. Additionally, an increased posterior tibial slope in pre- and postoperative radiographs [preoperative: 10.4° (8.6–11.1°) versus 7.7° (5.4–10.0°), p  < 0.001; postoperative 9.1° ± 3.1° versus 7.5° (5.9–9.0°), p  = 0.030] was observed in the fracture group. Furthermore, the use of smaller-sized implants (AA) was associated with higher fracture rates ( p  < 0.001). Anatomical variants, such as a medial overhanging tibial plateau, were not observed. Conclusions In UKA, type Oxford TPF are linked to shorter mediolateral and posteroanterior keel-cortex distances, increased pre- and postoperative PTS, and small implant sizes (AA). Fracture lines often extend from the distal keel to the medial tibial cortex. These findings emphasize the importance of precise implant positioning and sizing to minimize fracture risk. Level of evidence Retrospective single-center study, III.