Reproducibility of arterial spin labeling cerebral blood flow image processing: A report of the ISMRM open science initiative for perfusion imaging (OSIPI) and the ASL MRI challenge.

PURPOSE: Arterial spin labeling (ASL) is a widely used contrast-free MRI method for assessing cerebral blood flow (CBF). Despite the generally adopted ASL acquisition guidelines, there is still wide variability in ASL analysis. We explored this variability through the ISMRM-OSIPI ASL-MRI Challenge, aiming to establish best practices for more reproducible ASL analysis. METHODS: Eight teams analyzed the challenge data, which included a high-resolution T1-weighted anatomical image and 10 pseudo-continuous ASL datasets simulated using a digital reference object to generate ground-truth CBF values in normal and pathological states. We compared the accuracy of CBF quantification from each team's analysis to the ground truth across all voxels and within predefined brain regions. Reproducibility of CBF across analysis pipelines was assessed using the intra-class correlation coefficient (ICC), limits of agreement (LOA), and replicability of generating similar CBF estimates from different processing approaches. RESULTS: Absolute errors in CBF estimates compared to ground-truth synthetic data ranged from 18.36 to 48.12 mL/100 g/min. Realistic motion incorporated into three datasets produced the largest absolute error and variability between teams, with the least agreement (ICC and LOA) with ground-truth results. Fifty percent of the submissions were replicated, and one produced three times larger CBF errors (46.59 mL/100 g/min) compared to submitted results. CONCLUSIONS: Variability in CBF measurements, influenced by differences in image processing, especially to compensate for motion, highlights the significance of standardizing ASL analysis workflows. We provide a recommendation for ASL processing based on top-performing approaches as a step toward ASL standardization.

The Role of FAS Receptor Methylation in Osteosarcoma Metastasis.

Osteosarcoma is the most frequent primary malignant bone tumor with an annual incidence of about 400 cases in the United States. Osteosarcoma primarily metastasizes to the lungs, where FAS ligand (FASL) is constitutively expressed. The interaction of FASL and its cell surface receptor, FAS, triggers apoptosis in normal cells; however, this function is altered in cancer cells. DNA methylation has previously been explored as a mechanism for altering FAS expression, but no variability was identified in the CpG island (CGI) overlapping the promoter. Analysis of an expanded region, including CGI shores and shelves, revealed high variability in the methylation of certain CpG sites that correlated significantly with FAS mRNA expression in a negative manner. Bisulfite sequencing revealed additional CpG sites, which were highly methylated in the metastatic LM7 cell line but unmethylated in its parental non-metastatic SaOS-2 cell line. Treatment with the demethylating agent, 5-azacytidine, resulted in a loss of methylation in CpG sites located within the FAS promoter and restored FAS protein expression in LM7 cells, resulting in reduced migration. Orthotopic implantation of 5-azacytidine treated LM7 cells into severe combined immunodeficient mice led to decreased lung metastases. These results suggest that DNA methylation of CGI shore sites may regulate FAS expression and constitute a potential target for osteosarcoma therapy, utilizing demethylating agents currently approved for the treatment of other cancers.

Complications Are Infrequent After Humeral Shaft Fractures Due to Low-Energy Gunshot Injuries.

OBJECTIVE: To describe humerus shaft fractures after low-energy gunshot wound (GSW) and compare with blunt injuries. We hypothesized that nerve injury, infection, and fracture union would be similar. DESIGN: Retrospective. SETTING: Urban Level 1 trauma center. PATIENTS/PARTICIPANTS: Four hundred three patients were treated for a humeral shaft fracture over 18 years. Sixty-two patients sustained injury due to GSW. INTERVENTION: Primary open reduction and internal fixation was pursued in 59%, including 32% after GSW. MAIN OUTCOME MEASUREMENTS: Rates of nerve injury, infection, and fracture union. RESULTS: Patients with GSW were younger with a mean age of 30 years, more likely male (90%), with isolated injuries (84%), and less likely to have simple fractures (84%). Both groups experienced high rates of union (98% of GSW fractures vs. 99% of closed high-energy fractures). Deep infection occurred in 1 patient (1.6%) after GSW. Rates of deep infection in the closed and open blunt trauma fracture groups were similarly low at 1% and 4.5%, respectively. Nerve injury on presentation after GSW was more common than after low-energy and high-energy closed fractures (47% vs. 13% and 27%), but similar to blunt open fracture (52%). Despite higher rates of nerve injury, nerve recovery occurred at similarly high rates after both GSW and blunt injuries (78% vs. 86%). CONCLUSIONS: Nerve injuries are more common after GSW, but most recover without intervention. Infection is uncommon after GSW, and secondary unplanned operations are rare. Initial nonoperative care of most GSW humerus fractures, even with radial nerve injury at the time of presentation, seems appropriate. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Laparoscopic Lumen-guided cholecystectomy in face of the difficult gallbladder.

BACKGROUND: Where the critical view of safety cannot be established during cholecystectomy, certain salvage techniques are indicated to reduce the likelihood of bile duct injury. The present study describes a salvage technique termed the "laparoscopic lumen-guided cholecystectomy" (LLC) and reports its peri-operative outcomes. METHOD: A summary of the technique is as follows: (1) Hartmann's pouch is incised and stones are evacuated; (2) the cystic anatomy is inspected from the inside of the gallbladder; (3) the lumen is used to guide retrograde dissection towards the cystic pedicle; (4) cystic duct control is achieved if deemed safe. LLC cases performed between June 2020 and January 2022 in a single health board were included. The operative details and peri-operative outcomes of the technique are reported and compared to cases of similar difficulty where the LLC was not attempted. RESULTS: LLC was performed in 4.6% (27/587) of cases. In all 27 cases, LLC was performed for a "frozen" cholecystohepatic triangle. Hartmann's pouch was completely excised in all cases (27/27) and cystic duct control was achieved in 85.2% of cases (23/27). No cases of bile leak or ductal injury were reported. Rates of bile leak, post-operative complications and ERCP were lower following LLC compared to the group where LLC was not attempted (p < 0.01). CONCLUSION: LLC is a safe salvage technique and should be considered in cases where the critical view of safety cannot be established. The technique achieves cystic duct control in the majority of cases and favourable outcomes in the face of a difficult cholecystectomy.

ASL-BIDS, the brain imaging data structure extension for arterial spin labeling.

Arterial spin labeling (ASL) is a non-invasive MRI technique that allows for quantitative measurement of cerebral perfusion. Incomplete or inaccurate reporting of acquisition parameters complicates quantification, analysis, and sharing of ASL data, particularly for studies across multiple sites, platforms, and ASL methods. There is a strong need for standardization of ASL data storage, including acquisition metadata. Recently, ASL-BIDS, the BIDS extension for ASL, was developed and released in BIDS 1.5.0. This manuscript provides an overview of the development and design choices of this first ASL-BIDS extension, which is mainly aimed at clinical ASL applications. Discussed are the structure of the ASL data, focussing on storage order of the ASL time series and implementation of calibration approaches, unit scaling, ASL-related BIDS fields, and storage of the labeling plane information. Additionally, an overview of ASL-BIDS compatible conversion and ASL analysis software and ASL example datasets in BIDS format is provided. We anticipate that large-scale adoption of ASL-BIDS will improve the reproducibility of ASL research.

Integrated DNA Copy Number and Expression Profiling Identifies IGF1R as a Prognostic Biomarker in Pediatric Osteosarcoma.

Osteosarcoma is a primary malignant bone tumor arising from bone-forming mesenchymal cells in children and adolescents. Despite efforts to understand the biology of the disease and identify novel therapeutics, the survival of osteosarcoma patients remains dismal. We have concurrently profiled the copy number and gene expression of 226 osteosarcoma samples as part of the Strategic Partnering to Evaluate Cancer Signatures (SPECS) initiative. Our results demonstrate the heterogeneous landscape of osteosarcoma in younger populations by showing the presence of genome-wide copy number abnormalities occurring both recurrently among samples and in a high frequency. Insulin growth factor receptor 1 (IGF1R) is a receptor tyrosine kinase which binds IGF1 and IGF2 to activate downstream pathways involved in cell apoptosis and proliferation. We identify prevalent amplification of IGF1R corresponding with increased gene expression in patients with poor survival outcomes. Our results substantiate previously tenuously associated copy number abnormalities identified in smaller datasets (13q34+, 20p13+, 4q35-, 20q13.33-), and indicate the significance of high fibroblast growth factor receptor 2 (FGFR2) expression in distinguishing patients with poor prognosis. FGFR2 is involved in cellular proliferation processes such as division, growth and angiogenesis. In summary, our findings demonstrate the prognostic significance of several genes associated with osteosarcoma pathogenesis.

Actin nano-architecture of phagocytic podosomes.

Podosomes are actin-enriched adhesion structures important for multiple cellular processes, including migration, bone remodeling, and phagocytosis. Here, we characterize the structure and organization of phagocytic podosomes using interferometric photoactivated localization microscopy, a super-resolution microscopy technique capable of 15-20 nm resolution, together with structured illumination microscopy and localization-based super-resolution microscopy. Phagocytic podosomes are observed during frustrated phagocytosis, a model in which cells attempt to engulf micropatterned IgG antibodies. For circular patterns, this results in regular arrays of podosomes with well-defined geometry. Using persistent homology, we develop a pipeline for semi-automatic identification and measurement of podosome features. These studies reveal an hourglass shape of the podosome actin core, a protruding knob at the bottom of the core, and two actin networks extending from the core. Additionally, the distributions of paxillin, talin, myosin II, α-actinin, cortactin, and microtubules relative to actin are characterized.

A reproducible dynamic phantom for sequence testing in hyperpolarised 13C-magnetic resonance.

OBJECTIVE: To develop a phantom system which can be integrated with an automated injection system, eliminating the experimental variability that arises with manual injection; for the purposes of pulse sequence testing and metric derivation in hyperpolarised 13C-MR. METHODS: The custom dynamic phantom was machined from Ultem and filled with a nicotinamide adenine dinucleotide and lactate dehydrogenase mixture dissolved in phosphate buffered saline. Hyperpolarised [1-13C]-pyruvate was then injected into the phantom (n = 8) via an automated syringe pump and the conversion of pyruvate to lactate monitored through a 13C imaging sequence. RESULTS: The phantom showed low coefficient of variation for the lactate to pyruvate peak signal heights (11.6%) and dynamic area-under curve ratios (11.0%). The variance for the lactate dehydrogenase enzyme rate constant (kP) was also seen to be low at 15.6%. CONCLUSION: The dynamic phantom demonstrates high reproducibility for quantification of 13C-hyperpolarised MR-derived metrics. Establishing such a phantom is needed to facilitate development of hyperpolarsed 13C-MR pulse sequenced; and moreover, to enable multisite hyperpolarised 13C-MR clinical trials where assessment of metric variability across sites is critical. ADVANCES IN KNOWLEDGE: The dynamic phantom developed during the course of this study will be a useful tool in testing new pulse sequences and standardisation in future hyperpolarised work.

Bladder incarceration within a displaced pelvic ring nonunion.

Pelvic ring injuries can be challenging to manage and may have a range of associated injuries. When bladder injuries occur in combination with pelvic ring fractures, a multidisciplinary approach may be required to plan the best course of treatment. Acute entrapment or injury to the urinary bladder after a pelvic fracture is well reported. Here, we present an interesting case of chronic bladder incarceration within a lateral compression pelvic ring injury nonunion after failed nonoperative management of the initial pelvis fracture. Treatment of the nonunion was complicated by an incidental diagnosis of lymphoma.

A Cyclotron Decommissioning Radiological Assessment Exercise Performed by Student Mentees Underrepresented in the Radiation Safety Profession.

Cyclotrons used in nuclear medicine imaging accelerate protons, deuterons, and helium ions to bombard a target, which produces nuclear reactions that generate positron-emitting radionuclides. Secondary neutrons are nonuniformly emitted in these reactions and induce heterogeneous activation of the cyclotron components and concrete vault enclosure. This poses radioactive waste management complications when decommissioning a cyclotron facility, since the objective is to ensure that exposures are within regulatory limits and as low as reasonably achievable (ALARA). The McGovern Medical School in The University of Texas Health Science Center in Houston housed a Scanditronix MC40 cyclotron that produced short-lived radioisotopes for Positron Emission Tomography (PET) imaging from 1984 to 2001 until Tropical Storm Allison rendered it inoperable. The purpose of this study was to provide underrepresented Science, Technology, Engineering and Mathematics (STEM) students an ALARA experience with a practical problem encountered in the radiation safety profession. Gamma dose rate measurements were performed with both a Mirion InSpector 1000 spectrometer and Fluke 451P survey meter in the vault at locations identified as hotspots based on preliminary scoping surveys with the Ludlum model 44-9 detector. However, gamma spectra were measured with the spectrometer exclusively at hotspots along the west wall. Results indicated the maximum gamma dose rate of 129 ± 31 nSv h was about 2 times background near the central beam transport line of the now inoperable cyclotron. Furthermore, gamma emission peaks were identified in the spectra from trace amounts of Co and Eu in the vault's concrete walls.

Periprosthetic Intertrochanteric Fracture between Hip Resurfacing and Retrograde Nail.

Periprosthetic femur fractures present a growing worldwide challenge for orthopaedic surgeons. Fractures around a hip resurfacing implant create unique management problems. When considering fixation, there can be limited options for ideal stabilization and some require creative constructs. We present an interesting case of a periprosthetic intertrochanteric femur fracture between a hip resurfacing implant and retrograde intramedullary nail.

Fifteen-Year Institutional Retrospective Case Series of Decompressive Craniectomy for Malignant Middle Cerebral Artery Infarction.

OBJECTIVE: In the present study, we updated our previously reported case series of patients who had undergone decompressive craniectomy for malignant middle cerebral artery infarction (mMCAI) (2005-2020). To the best of our knowledge, the present case series constitutes the largest reported series from a UK neurosurgical unit of decompressive craniectomy for mMCAI. METHODS: We extracted data regarding the clinical discriminators, surgical timescales, and functional outcomes of patients. RESULTS: A total of 67 patients had undergone decompressive craniectomy. The 30-day mortality was 17.9% (n = 12). Of the 67 patients, 31 were male (46.3%) and 36 were female (53.7%). Their mean age was 45 years (range, 16-64 years). The mean age of the survivors was 43 years (range, 16-62 years) compared with 50 years (range, 38-64 years) for those who had died. The median ictal and preoperative Glasgow coma scale score was 14 (range, 7-15) and 8 (range, 3-15), respectively. The corresponding motor scores were 6 and 5. The mean interval from ictus to neurosurgical unit admission was 18.25 hours (range, 0.5-66 hours) and from admission to decompressive craniotomy was 7.30 hours (range, 0.5-46 hours). Of the 67 patients, 63% had undergone "early" craniectomy (<48 hours from mMCAI evolution), with 89% of these patients having undergone craniectomy <24 hours after neurosurgical unit admission. The mean maximum anteroposterior craniectomy diameter was 13.01 cm (range, 10.29-15.56 cm), and mean surface area was 94.38 cm2 (range, 74.75-132.32 cm2). Overall, 46% of patients had had a modified Rankin scale score of <3 (range, 0-6) from discharge to 12 months postoperatively. The median neurosurgical unit length of stay was 15 days (range, 6 hours to 365 days). CONCLUSIONS: The findings from the present update have confirmed that local practice has remained consistent with current evidence. However, patient selection might be optimized if diffusion-weighted magnetic resonance imaging and computed tomography perfusion were used at the original middle cerebral artery infarct admission.

Endoplasmic reticulum-associated degradation regulates mitochondrial dynamics in brown adipocytes.

The endoplasmic reticulum (ER) engages mitochondria at specialized ER domains known as mitochondria-associated membranes (MAMs). Here, we used three-dimensional high-resolution imaging to investigate the formation of pleomorphic "megamitochondria" with altered MAMs in brown adipocytes lacking the Sel1L-Hrd1 protein complex of ER-associated protein degradation (ERAD). Mice with ERAD deficiency in brown adipocytes were cold sensitive and exhibited mitochondrial dysfunction. ERAD deficiency affected ER-mitochondria contacts and mitochondrial dynamics, at least in part, by regulating the turnover of the MAM protein, sigma receptor 1 (SigmaR1). Thus, our study provides molecular insights into ER-mitochondrial cross-talk and expands our understanding of the physiological importance of Sel1L-Hrd1 ERAD.

Spatiotemporally Super-Resolved Volumetric Traction Force Microscopy.

Quantification of mechanical forces is a major challenge across biomedical sciences. Yet such measurements are essential to understanding the role of biomechanics in cell regulation and function. Traction force microscopy remains the most broadly applied force probing technology but typically restricts itself to single-plane two-dimensional quantifications with limited spatiotemporal resolution. Here, we introduce an enhanced force measurement technique combining 3D super-resolution fluorescence structural illumination microscopy and traction force microscopy (3D-SIM-TFM) offering increased spatiotemporal resolution, opening-up unprecedented insights into physiological three-dimensional force production in living cells.

Cytoskeletal Control of Antigen-Dependent T Cell Activation.

Cytoskeletal actin dynamics is essential for T cell activation. Here, we show evidence that the binding kinetics of the antigen engaging the T cell receptor influences the nanoscale actin organization and mechanics of the immune synapse. Using an engineered T cell system expressing a specific T cell receptor and stimulated by a range of antigens, we found that the peak force experienced by the T cell receptor during activation was independent of the unbinding kinetics of the stimulating antigen. Conversely, quantification of the actin retrograde flow velocity at the synapse revealed a striking dependence on the antigen unbinding kinetics. These findings suggest that the dynamics of the actin cytoskeleton actively adjusted to normalize the force experienced by the T cell receptor in an antigen-specific manner. Consequently, tuning actin dynamics in response to antigen kinetics may thus be a mechanism that allows T cells to adjust the lengthscale and timescale of T cell receptor signaling.

Characterization of neurite dystrophy after trauma by high speed structured illumination microscopy and lattice light sheet microscopy.

BACKGROUND: Unbiased screening studies have repeatedly identified actin-related proteins as one of the families of proteins most influenced by neurotrauma. Nevertheless, the status quo model of cytoskeletal reorganization after neurotrauma excludes actin and incorporates only changes in microtubules and intermediate filaments. Actin is excluded in part because it is difficult to image with conventional techniques. However, recent innovations in fluorescent microscopy provide an opportunity to image the actin cytoskeleton at super-resolution resolution in living cells. This study applied these innovations to an in vitro model of neurotrauma. NEW METHOD: New methods are introduced for traumatizing neurons before imaging them with high speed structured illumination microscopy or lattice light sheet microscopy. Also, methods for analyzing structured illumination microscopy images to quantify post-traumatic neurite dystrophy are presented. RESULTS: Human induced pluripotent stem cell-derived neurons exhibited actin organization typical of immature neurons. Neurite dystrophy increased after trauma but was not influenced by jasplakinolide treatment. The F-actin content of dystrophies varied greatly from one dystrophy to another. COMPARISON WITH EXISTING METHODS: In contrast to fixation dependent methods, these methods capture the evolution of the actin cytoskeleton over time in a living cell. In contrast to prior methods based on counting dystrophies, this quantification scheme parameterizes the severity of a given dystrophy as it evolves from a local swelling to an almost-perfect spheroid that threatens to transect the neurite. CONCLUSIONS: These methods can be used to investigate genetic factors and therapeutic interventions that modulate the course of neurite dystrophy after trauma.

Measurement equivalence of child feeding and eating measures across gender, ethnicity, and household food security.

BACKGROUND: Although there have been extensive studies that make group comparisons on child eating and feeding practices, few studies have examined measurement equivalence to ensure that measures used to make such group comparisons are equivalent across important group characteristics related to childhood obesity. METHODS: Using a sample of 243 caregivers with children between the ages of 4 to 6 years, we conducted a measurement equivalence analysis across gender, ethnicity (Latino versus non-Latino White), and household food security. The subscales of the Child Feeding Questionnaire (CFQ) and the Child Eating Behaviour Questionnaire (CEBQ) were examined separately using a one factor multi-group confirmatory factor analysis. RESULTS: For the CFQ, Concern about Child Weight and Parental Responsibility subscales were consistent across all groups examined. In contrast, Pressure to Eat, Restriction, and Perceived Parent Weight subscales varied or fit poorly across the groups. For the CEBQ, Emotional Overeating, Enjoyment of Food, and Satiety Responsiveness performed consistently across the groups. On the other hand, Food Fussiness, Desire to Drink, Slowness in Eating, and Emotional Undereating subscales varied or fit poorly across the groups. CONCLUSIONS: Findings from this study suggest both of these measures need continued psychometric work, and group comparisons using some subscales should be interpreted cautiously. Some subscales such as Food Responsiveness and Parental Restriction may be assessing behaviors that occur in food secure households and are less applicable to food insecure environments.