Fire suppression makes wildfires more severe and accentuates impacts of climate change and fuel accumulation.

Fire suppression is the primary management response to wildfires in many areas globally. By removing less-extreme wildfires, this approach ensures that remaining wildfires burn under more extreme conditions. Here, we term this the "suppression bias" and use a simulation model to highlight how this bias fundamentally impacts wildfire activity, independent of fuel accumulation and climate change. We illustrate how attempting to suppress all wildfires necessarily means that fires will burn with more severe and less diverse ecological impacts, with burned area increasing at faster rates than expected from fuel accumulation or climate change. Over a human lifespan, the modeled impacts of the suppression bias exceed those from fuel accumulation or climate change alone, suggesting that suppression may exert a significant and underappreciated influence on patterns of fire globally. Managing wildfires to safely burn under low and moderate conditions is thus a critical tool to address the growing wildfire crisis.

Latitudinal patterns in stabilizing density dependence of forest communities.

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.

Identifying potential imaging markers for diffusion property changes in a mouse model of amyotrophic lateral sclerosis: Application of the continuous time random walk model to ultrahigh b-value diffusion-weighted MR images of spinal cord tissue.

Diffusion MRI (dMRI) explores tissue microstructures by analyzing diffusion-weighted signal decay measured at different b-values. While relatively low b-values are used for most dMRI models, high b-value diffusion-weighted imaging (DWI) techniques have gained interest given that the non-Gaussian water diffusion behavior observed at high b-values can yield potentially valuable information. In this study, we investigated anomalous diffusion behaviors associated with degeneration of spinal cord tissue using a continuous time random walk (CTRW) model for DWI data acquired across an extensive range of ultrahigh b-values. The diffusion data were acquired in situ from the lumbar level of spinal cords of wild-type and age-matched transgenic SOD1G93A mice, a well-established animal model of amyotrophic lateral sclerosis (ALS) featuring progressive degeneration of axonal tracts in this tissue. Based on the diffusion decay behaviors at low and ultrahigh b-values, we applied the CTRW model using various combinations of b-values and compared diffusion metrics calculated from the CTRW model between the experimental groups. We found that diffusion-weighted signal decay curves measured with ultrahigh b-values (up to 858,022 s/mm2 in this study) were well represented by the CTRW model. The anomalous diffusion coefficient obtained from lumbar spinal cords was significantly higher in SOD1G93A mice compared with control mice (14.7 × 10-5 ± 5.54 × 10-5  vs. 7.87 × 10-5 ± 2.48 × 10-5  mm2 /s, p = 0.01). We believe this is the first study to illustrate the efficacy of the CTRW model for analyzing anomalous diffusion regimes at ultrahigh b-values. The CTRW modeling of ultrahigh b-value dMRI can potentially present a novel approach for noninvasively evaluating alterations in spinal cord tissue associated with ALS pathology.

Neck scar perception after neck dissection in HPV-associated oropharyngeal squamous cell carcinoma.

IMPORTANCE: While there has been an increased understanding of the impact of visible neck scars in some patients with certain diseases, this has not yet been explored in the HPV+ OPSCC population. OBJECTIVE: To understand patients' perception of their scar and the impact on their quality of life (QOL) at least 6 months after neck dissection (ND) for HPV+ oropharyngeal squamous cell carcinoma (OPSCC). DESIGN, SETTING, AND PARTICIPANTS: In this retrospective case-control study, patients who underwent primary transoral robotic surgery (TORS) and ND for HPV+ OPSCC between 2016 and 2021 at a single tertiary care center were identified. Data analysis was performed in January 2022. MAIN OUTCOMES AND MEASURES: Dermatology Life Quality Index was modified (mDLQI) to assess patients' perceptions of their scars. The primary outcome was the mean mDLQI survey score with higher scores corresponding to worse perceptions. Three questions adapted from the Self-Consciousness Scale (SCS) were also included to assess awareness of appearance. All questions were scaled on a 0-3 Likert Scale. Tweedie generalized linear model was used to understand the relationship between mDLQI score and patient- and procedure-specific factors (including the three SCS survey questions). An additional exploratory logistic regression was performed to understand the risk factors for clinically significant mDLQI score change. RESULTS: A total of 67 patients (response rate 57 %) completed the survey with a mean mDLQI survey score of 0.84 (max 30). Although there was a statistically significant negative association between private insurance and mDLQI survey score (95 % Confidence Interval [CI]: -2.72 - -0.38), and a positive association between the SCS score and mDLQI survey score (95 % CI: 0.23-0.81) (p < 0.05), these variables were not found to be risk factors for a clinically significant difference in mDLQI on multivariable analysis. CONCLUSION: The majority of patients felt their neck scars did not interfere with their daily lives. Patient perceptions of neck scars were consistent despite differing patient characteristics and treatment regimens.

Mycorrhizal feedbacks influence global forest structure and diversity.

One mechanism proposed to explain high species diversity in tropical systems is strong negative conspecific density dependence (CDD), which reduces recruitment of juveniles in proximity to conspecific adult plants. Although evidence shows that plant-specific soil pathogens can drive negative CDD, trees also form key mutualisms with mycorrhizal fungi, which may counteract these effects. Across 43 large-scale forest plots worldwide, we tested whether ectomycorrhizal tree species exhibit weaker negative CDD than arbuscular mycorrhizal tree species. We further tested for conmycorrhizal density dependence (CMDD) to test for benefit from shared mutualists. We found that the strength of CDD varies systematically with mycorrhizal type, with ectomycorrhizal tree species exhibiting higher sapling densities with increasing adult densities than arbuscular mycorrhizal tree species. Moreover, we found evidence of positive CMDD for tree species of both mycorrhizal types. Collectively, these findings indicate that mycorrhizal interactions likely play a foundational role in global forest diversity patterns and structure.

World-Class Innovation, but at What Cost? A Brief Examination of the American Healthcare System.

The American healthcare system, often counted among the world's best, offers expedient access to a highly subspecialized network of physicians who work at the forefront of developing and utilizing novel, cutting-edge procedures, and medications. Patients typically have access to large numbers of qualified physicians in every metropolitan area and thus are afforded the luxury of individual choice in hospital, physician, and experience. Unfortunately, the costs of maintaining such a system are quite profound, and the higher investments do not pay dividends in health outcomes. Here, we elaborate on the greatest achievement and worst flaw in the American healthcare system.

Chemical Shift MRI Monitoring of Chemoembolization Delivery for Hepatocellular Carcinoma: Multicenter Feasibility of Initial Clinical Translation.

Purpose To demonstrate the feasibility of using chemical shift fat-water MRI methods to visualize and measure intrahepatic delivery of ethiodized oil to liver tumors following conventional transarterial chemoembolization (cTACE). Materials and Methods Twenty-eight participants (mean age, 66 years ± 8 [SD]; 22 men) with hepatocellular carcinoma (HCC) treated with cTACE were evaluated with follow-up chemical shift MRI in this Health Insurance Portability and Accountability Act-compliant prospective, institutional review board-approved study. Uptake of ethiodized oil was evaluated at 1-month follow-up chemical shift MRI. Measurements of tumor size (MRI and CT), attenuation and enhancement (CT), fat content percentage, and tumor:normal ratio (MRI) were compared by lesion for responders versus nonresponders, as assessed with modified Response Evaluation Criteria in Solid Tumors and European Association for the Study of the Liver (EASL) criteria. Adverse events and overall survival by the Kaplan-Meier method were secondary end points. Results Focal tumor ethiodized oil retention was 46% (12 of 26 tumors) at 24 hours and 47% (18 of 38 tumors) at 1 month after cTACE. Tumor volume at CT did not differ between EASL-defined responders and nonresponders (P = .06). Tumor ethiodized oil volume measured with chemical shift MRI was statistically significantly higher for EASL-defined nonresponders (P = .02). Doxorubicin dosing (P = .53), presence of focal fat (P = .83), and a combined end point of focal fat and low doxorubicin dosing (P = .97) did not stratify overall survival after cTACE. Conclusion Chemical shift MRI allowed for assessment of tumor delivery of ethiodized oil out to 1 month after cTACE in participants with HCC and demonstrated tumor ethiodized oil volume as a potential tool for stratification of tumor response by EASL criteria. Keywords: MRI, Chemical Shift Imaging, CT, Hepatic Chemoembolization, Ethiodized Oil Clinicaltrials.gov registration no.: NCT02173119 Supplemental material is available for this article. © RSNA, 2023.

Reduced fire severity offers near-term buffer to climate-driven declines in conifer resilience across the western United States.

Increasing fire severity and warmer, drier postfire conditions are making forests in the western United States (West) vulnerable to ecological transformation. Yet, the relative importance of and interactions between these drivers of forest change remain unresolved, particularly over upcoming decades. Here, we assess how the interactive impacts of changing climate and wildfire activity influenced conifer regeneration after 334 wildfires, using a dataset of postfire conifer regeneration from 10,230 field plots. Our findings highlight declining regeneration capacity across the West over the past four decades for the eight dominant conifer species studied. Postfire regeneration is sensitive to high-severity fire, which limits seed availability, and postfire climate, which influences seedling establishment. In the near-term, projected differences in recruitment probability between low- and high-severity fire scenarios were larger than projected climate change impacts for most species, suggesting that reductions in fire severity, and resultant impacts on seed availability, could partially offset expected climate-driven declines in postfire regeneration. Across 40 to 42% of the study area, we project postfire conifer regeneration to be likely following low-severity but not high-severity fire under future climate scenarios (2031 to 2050). However, increasingly warm, dry climate conditions are projected to eventually outweigh the influence of fire severity and seed availability. The percent of the study area considered unlikely to experience conifer regeneration, regardless of fire severity, increased from 5% in 1981 to 2000 to 26 to 31% by mid-century, highlighting a limited time window over which management actions that reduce fire severity may effectively support postfire conifer regeneration.

Perioperative Topical Antisepsis and Surgical Site Infection in Patients Undergoing Upper Aerodigestive Tract Reconstruction.

Importance: Surgical site infections (SSIs) after vascularized reconstruction of the upper aerodigestive tract (UADT) are associated with considerable morbidity. The association between perioperative prophylaxis practices, particularly topical antisepsis, and SSIs remains uncertain. Objective: To assess the association between perioperative topical antisepsis and SSIs in patients undergoing vascularized reconstruction of the UADT. Design, Setting, and Participants: This cohort study included patients from 12 academic tertiary care centers over an 11-month period, from July 1, 2020, to June 1, 2021. Patients undergoing open surgical procedures requiring a communication between the UADT and cervical skin with a planned regional pedicled flap, free flap, or both were included. Patients with an active infection at the time of surgical procedure were excluded. Main Outcomes and Measures: The primary outcome measure was an SSI within 30 days of surgery. The association of demographic characteristics, perioperative antibiotic prophylaxis, surgical technique, and postoperative care with SSIs was assessed using univariable and multivariable analyses. The relative risk ratio and 95% CIs for developing SSI were calculated for each of the variables based on predetermined categories. Variables for which the relative risk 95% CI did not include the value of zero effect (relative risk = 1.00) were included in the multivariable model. Results: A total of 554 patients (median age, 64 years; range, 21-95 years; 367 men [66.2%]) were included. Cancer ablation was the most frequent reason for surgery (n = 480 [86.6%]). Overall, the SSI rate was 20.9% (n = 116), with most infections involving the head and neck surgical site only (91 [78.4%]). The median time to SSI diagnosis was 11 days (range, 1-28 days). Topical antisepsis mucosal preparation was performed preoperatively in 35.2% (195) and postoperatively in 52.2% (289) of cases. Ampicillin and sulbactam was the most common systemic antibiotic prophylaxis agent used (n = 367 [66.2%]), with 24 hours being the most common duration (n = 363 [65.5%]). On multivariable analysis, preoperative topical antisepsis mucosal preparation (odds ratio [OR], 0.49; 95% CI, 0.30-0.77) and systemic prophylaxis with piperacillin and tazobactam (OR, 0.42; 95% CI, 0.21-0.84) were associated with a decreased risk of a postoperative SSI. The use of an osseous vascularized flap was associated with an increased risk of postoperative SSI (OR, 1.76; 95% CI, 1.13-2.75). Conclusions and Relevance: Findings of this study suggest that preoperative topical antisepsis mucosal preparation was independently associated with a decreased risk of SSIs in a 12-center multi-institutional cohort. Further investigation of the association between individual perioperative practices and the incidence of postoperative SSIs is necessary to develop evidence-based protocols to reduce SSIs after UADT reconstruction.

Demographic composition, not demographic diversity, predicts biomass and turnover across temperate and tropical forests.

The growth and survival of individual trees determine the physical structure of a forest with important consequences for forest function. However, given the diversity of tree species and forest biomes, quantifying the multitude of demographic strategies within and across forests and the way that they translate into forest structure and function remains a significant challenge. Here, we quantify the demographic rates of 1961 tree species from temperate and tropical forests and evaluate how demographic diversity (DD) and demographic composition (DC) differ across forests, and how these differences in demography relate to species richness, aboveground biomass (AGB), and carbon residence time. We find wide variation in DD and DC across forest plots, patterns that are not explained by species richness or climate variables alone. There is no evidence that DD has an effect on either AGB or carbon residence time. Rather, the DC of forests, specifically the relative abundance of large statured species, predicted both biomass and carbon residence time. Our results demonstrate the distinct DCs of globally distributed forests, reflecting biogeography, recent history, and current plot conditions. Linking the DC of forests to resilience or vulnerability to climate change, will improve the precision and accuracy of predictions of future forest composition, structure, and function.

Immediate postoperative non-invasive positive pressure ventilation following midface microvascular free flap reconstruction.

BACKGROUND: There is a rare need for postoperative non-invasive positive pressure ventilation (NIPPV) following microvascular reconstruction of the head and neck. In midface reconstruction, the free flap vascular pedicle is especially vulnerable to the compressive forces of positive pressure delivery. CASE: A 60 year old female with Amyotrophic Lateral Sclerosis (ALS) presented with squamous cell carcinoma of the anterior maxilla, for which she underwent infrastructure maxillectomy and fibula free flap reconstruction. To avoid tracheotomy, the patient was extubated postoperatively and transitioned to NIPPV immediately utilizing a full-face positive pressure mask with a soft and flexible sealing layer. The patient was successfully transitioned to NIPPV immediately after extubation. The free flap exhibited no signs of vascular compromise postoperatively, and healed very well. CONCLUSION: Postoperative non-invasive positive pressure ventilation can be successfully applied following complex microvascular midface reconstruction to avoid tracheotomy in select patients without vascular compromise of the free flap.

Submental Island Flap After Prior Contralateral Neck Dissection: A Case Series and Technical Considerations.

OBJECTIVES: The submental island flap is a dependable workhorse in head and neck reconstruction. However, the viability of this flap has not been established for oral cavity reconstruction when a contralateral neck dissection has already been performed in an earlier surgical setting. The aim of this study is to highlight technical considerations and outcomes of this approach with a small case series. METHODS: Three cases of oral cavity reconstruction with a submental island flap elevated in the context of a prior contralateral neck dissection are presented. RESULTS: In all cases, a doppler was used to identify the maintenance of the submental perforator in the neck opposite the previous neck dissection. In 2 cases, level IA was included within the dissection field of the previous neck dissection. Additionally, the old neck scar was included within the skin paddle of the submental island flap in 2 cases. In all cases, excellent healing of the flap was observed without partial or complete loss. CONCLUSIONS: The submental island flap appears to be a reliable reconstruction when a previous contralateral neck dissection has been performed, even when level IA was included in the prior dissection.

An equity-based narrative review of barriers to timely postoperative radiation therapy for patients with head and neck squamous cell carcinoma.

OBJECTIVES: The majority of patients with head and neck squamous cell carcinoma (HNSCC) do not commence postoperative radiation treatment (PORT) within the recommended 6 weeks. We explore how delayed PORT affects survival outcomes, what factors are associated with delayed PORT initiation, and what interventions exist to reduce delays in PORT initiation. METHODS: We conducted a PubMed search to identify articles discussing timely PORT for HNSCC. We performed a narrative review to assess survival outcomes of delayed PORT as well as social determinants of health (SDOH) and clinical factors associated with delayed PORT, using the PROGRESS-Plus health equity framework to guide our analysis. We reviewed interventions designed to reduce delays in PORT. RESULTS: Delayed PORT is associated with reduced overall survival. Delays in PORT disproportionately burden patients of racial/ethnic minority backgrounds, Medicaid or no insurance, low socioeconomic status, limited access to care, more comorbidities, presentation at advanced stages, and those who experience postoperative complications. Delays in PORT initiation tend to occur during transitions in head and neck cancer care. Delays in PORT may be reduced by interventions that identify patients who are most likely to experience delayed PORT, support patients according to their specific needs and barriers to care, and streamline care and referral processes. CONCLUSIONS: Both SDOH and clinical factors are associated with delays in timely PORT. Structural change is needed to reduce health disparities and promote equitable access to care for all. When planning care, providers must consider not only biological factors but also SDOH to maximize care outcomes.

Yttrium-90 Radioembolization in the VX2 Rabbit Model: Radiation Safety and Factors Influencing Delivery Efficiency.

The purpose of this study was to define the optimal infusion parameters and operator radiation exposure for yttrium-90 (90Y) radioembolization in the VX2 rabbit model of liver cancer. Forty-one rabbits with VX2 were treated with glass microspheres with vial sizes of 1, 3, and 5 GBq. The mean administered activity was 51.5 MBq (95% CI, 39.1-63.9). Delivery efficiency improved with 1 GBq versus with 3 GBq (residual 11.0% vs 46.4%, respectively; P = .0013) and improved with 1 GBq versus with 5 GBq (residual 11.0% vs 33.8%, respectively; P = .0060). The mean operator extremity exposure was 41.7 µSv/infusion. The optimal minimum infusion volume and rate was 49 mL and 21 mL/min, respectively. Fecal elimination occurred with microsphere uptake in the gallbladder at 1 and 2 weeks. 90Y radioembolization can be safely and efficiently performed in the VX2 rabbit model. Methodological considerations as a "how-to" for the setup of a preclinical 90Y laboratory are included to support future translational research.

Use of X-Ray Fluorescence Microscopy for Studies on Research Models of Hepatocellular Carcinoma.

Introduction: TheraSphere® microspheres containing yttrium 90Y are among many radioembolization agents used clinically to reduce liver tumor burden, and their effects on cancer volume reduction are well-established. At the same time, concerns about off target tissue injury often limit their use. Deeper investigation into tissue distribution and long-term impact of these microspheres could inform us about additional ways to use them in practice. Methods: Healthy rat liver and rabbit liver tumor samples from animals treated with TheraSpheres were sectioned and their elemental maps were generated by X-ray fluorescence microscopy (XFM) at the Advanced Photon Source (APS) synchrotron at Argonne National Laboratory (ANL). Results: Elemental imaging allowed us to identify the presence and distribution of TheraSpheres in animal tissues without the need for additional sample manipulation or staining. Ionizing radiation produced by 90Y radioactive contaminants present in these microspheres makes processing TheraSphere treated samples complex. Accumulation of microspheres in macrophages was observed. Conclusions: This is the first study that used XFM to evaluate the location of microspheres and radionuclides in animal liver and tumor samples introduced through radioembolization. XFM has shown promise in expanding our understanding of radioembolization and could be used for investigation of human patient samples in the future.

Duramycin radiosensitization of MCA-RH 7777 hepatoma cells through the elevation of reactive oxygen species.

OBJECTIVE: The objective of this study is to explore the radiosensitization effects of duramycin against the liver cancer hepatoma cells and relationship to reactive oxygen species (ROS) generation. MATERIALS AND METHODS: MCA-RH 7777 cells were treated with various combinations of duramycin concentrations and radiation doses. After the treatment, cell viabilities were determined by a cell proliferation assay; intracellular ROS levels were detected with the flow cytometric method. RESULTS: MCA-RH 7777 cell viability was found significantly reduced after combining duramycin and radiation exposure (comparing to that of either treatment alone). Increased intracellular ROS levels were observed in cells treated with combinations of duramycin and radiation. CONCLUSION: Duramycin increased the intracellular ROS generation and also increased the radiosensitivity of MCA-RH 7777 cells.

Arbuscular mycorrhizal trees influence the latitudinal beta-diversity gradient of tree communities in forests worldwide.

Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to total beta-diversity and its components (turnover and nestedness) of all trees. We find AM rather than EcM trees predominantly contribute to decreasing total beta-diversity and turnover and increasing nestedness with increasing latitude, probably because wide distributions of EcM trees do not generate strong compositional differences among localities. Environmental variables, especially temperature and precipitation, are strongly correlated with beta-diversity patterns for both AM trees and all trees rather than EcM trees. Results support our hypotheses that latitudinal beta-diversity patterns and environmental effects on these patterns are highly dependent on mycorrhizal types. Our findings highlight the importance of AM-dominated forests for conserving global forest biodiversity.

Transoral Excision of Parapharyngeal Space Tumors.

Transoral excision of parapharyngeal space (PPS) tumors has increased in popularity along with the increased use of robotic and endoscopic surgical technology. Here, the authors highlight the indications, techniques, outcomes, and complications of transoral approaches to PPS tumors, with a special emphasis on salivary tumors of the PPS and the transoral robotic surgery approach.

Alpine treeline ecotones are potential refugia for a montane pine species threatened by bark beetle outbreaks.

Warming-induced mountain pine beetle (Dendroctonus ponderosae; MPB) outbreaks have caused extensive mortality of whitebark pine (Pinus albicaulis; WBP) throughout the species' range. In the highest mountains where WBP occur, they cross alpine treeline ecotones (ATEs) where growth forms transition from trees to shrub-like krummholz, some of which survived recent MPB outbreaks. This observation motivated the hypothesis that ATEs are refugia for WBP because krummholz growth forms escape MPB attack and have the potential to produce viable seed. To test this hypothesis, we surveyed WBP mortality along transects from the ATE edge (locally highest krummholz WBP) downslope into the forest and, to distinguish if survival mechanisms are unique to ATEs, across other forest ecotones (OFEs) from the edge of WBP occurrence into the forest. We replicated this design at 10 randomly selected sites in the U.S. Northern Rocky Mountains. We also surveyed reproduction in a subset of ATE sites. Mortality was nearly absent in upper ATEs (mean ± SE percent dead across all sites of 0.03% ± 0.03% 0-100 m from the edge and 14.1% ± 1.7% 100-500 m from the edge) but was above 20% along OFEs (21.4 ± 5.2% 0-100 m and 32.4 ± 2.7% 100-500 m from the edge). We observed lower reproduction in upper ATEs (16 ± 9.9 cones/ha and 12.9 ± 5.3 viable seeds/cone 0-100 m from the edge) compared to forests below (317.1 ± 64.4 cones/ha and 32.5 ± 2.5 viable seeds/cone 100-500 m from the edge). Uniquely high WBP survival supports the hypothesis that ATEs serve as refugia because krummholz growth forms escape MPB attack. However, low reproduction suggests ATE refugia function over longer time periods. Beyond our WBP system, we propose that plant populations in marginal environments are candidate refugia if distinct phenotypes result in reduced disturbance impacts.

Development and Validation of Sorafenib-eluting Microspheres to Enhance Therapeutic Efficacy of Transcatheter Arterial Chemoembolization in a Rat Model of Hepatocellular Carcinoma.

Purpose: To validate the therapeutic efficacy of sorafenib-eluting embolic microspheres (SOR-EMs) used in combination with transarterial chemoembolization (TACE) for treatment of hepatocellular carcinoma (HCC) in a preclinical animal model. Materials and Methods: SOR-EMs were prepared with poly(d,l-lactide-co-glycolide), iron oxide nanoparticles, and sorafenib. The morphology of the prepared SOR-EMs was confirmed by using optical microscopy. Drug release from the SOR-EMs was quantified in vitro by using high-performance liquid chromatography. In an orthotopic rat model of HCC, embolic doxorubicin-Lipiodol (ethiodized oil) emulsion (DLE) and SOR-EMs were sequentially injected into the hepatic artery of the rats: The rats in group 1 were injected with DLE; group 2 was injected with DLE plus unloaded embolic microspheres (DLE + EM); group 3, with DLE plus SOR-EMs (DLE + SOR-EM); and group 4, with saline solution. The SOR-EM and tumor size changes in each group (of six rats each) over time were measured by using MRI. Tissues were assessed by using immunohistochemistry, with hematoxylin-eosin and terminal deoxynucleotidyl transferase-mediated dUTP (2'-deoxyuridine 5'-triphosphate) nick-end labeling staining used for dead cells and CD34 staining used for new microvessel formation. Results: The SOR-EMs were a mean size of 6.6 µm ± 2.3 (standard deviation) and showed 53.7% ± 8.3 sorafenib loading efficiency with T2-weighted MRI capability. In the HCC rat model, the intra-arterially injected SOR-EMs were successfully monitored by using MRI. The DLE + SOR-EM-treated rats showed a superior tumor growth-inhibitory effect compared with the rats treated with DLE only (P < .05). Immunohistochemical assessment of tissue specimens showed that compared with the other treatment groups, the DLE + SOR-EM treatment group had the lowest number of microvessels, as quantified by using the percentage of CD34-positive stained area (P < .01 for all comparisons). Conclusion: In a preclinical rat HCC model, SOR-EMs used in combination with DLE TACE were effective in treating HCC.Keywords: Chemoembolization, Experimental Investigations, Laboratory Tests, Liver, Technology Assessment Supplemental material is available for this article. © RSNA, 2021See also the commentary by Yamada and Gayed in this issue.