Glass Microspheres Research Articles

Abstract No. 243 Treatment Timing and Overall Survival of Liver-Dominant Metastatic Colorectal Cancer Patients Treated with Glass Transarterial Radioembolization: Analyses from the EPOCH Trial

The EPOCH trial investigated the potential benefit of adding transarterial radioembolization (TARE) with yttrium-90 glass microspheres to second-line chemotherapy in patients with liver-dominant metastatic colorectal cancer (mCRC). Post-hoc analyses evaluated the effect of TARE treatment day post calibration on clinical and safety outcomes.

Abstract No. 197 Predictors of complete pathologic necrosis in hepatocellular carcinoma treated with yttrium-90 radiation segmentectomy prior to liver transplantation: an explant analysis of 75 tumors

To analyze yttrium-90 glass microsphere radiation segmentectomy treatment parameters predictive of complete pathological necrosis (CPN) in patients with hepatocellular carcinoma (HCC) prior to liver transplantation.

Strategy for preventing explosive spalling and enhancing material efficiency of lightweight ultra high-performance concrete

The highly dense structure which causes the risk of explosive spalling is one of the major limitations of using ultra high-performance concrete (UHPC). This study developed a lightweight UHPC (L-UHPC) and proposed a strategy to improve its material efficiency and lower the risk of explosive spalling. High-strength hollow glass microspheres and fine lightweight aggregates were jointly used in the UHPC system to achieve light weight and ultra high strength. The L-UHPC was cured at different curing regimes to maximize its material efficiency and prevent its spalling after exposure to high temperature. The experimental results showed that the combination of lightweight materials and dry heat curing was effective in reducing the density (<1800 kg/m3) and enhancing the compressive strength (>150 MPa) of the L-UHPC. By means of minimizing the amount of internal free water, the heat curing approach contributed to avoiding the thermal spalling of the L-UHPC exposed to fire conditions. Microstructural results indicated that the elevated temperature curing promoted the pozzolanic reaction and increased the microhardness of the paste matrix by increasing silicate polymerization of the C-S-H structure. The created voids of the collapsed glass microspheres might accommodate some internal vapor pressure and mitigate the degradation caused by the high temperature exposure. The synergetic effect of the porous materials and the dry heat curing lowered the thermal conductivity and significantly improved the material efficiency of the L-UHPC.

Form-stable phase change composites with high thermal conductivity and electrical insulation

The commercialization of phase change materials (PCMs) based on paraffin is obstructed by the drawbacks of leakage and low thermal conductivity. Herein, we developed form-stable phase change composites via trapping paraffin into triblock copolymer. The hybrid filler, namely boron nitride and Ag-coated hollow glass microspheres (Ag@HGMs), was introduced to enhance the thermal conductivity of the composites. The latent heat values of composites could be easily tailored in a range of 157.6–192.4 J g−1 by changing the loading of filler. Interestingly, the addition of boron nitride and Ag@HGMs hybrid filler has little impact on electrical insulation property, and displays a synergistic effect on the heat transfer improvement within the composites. The sample BN/Ag@HGMs-4 exhibits excellent latent heat, electrical insulation performance, thermal recycling properties and stability, and the thermal conductivity reaches up to 1.54 W m−1 K−1, which has great potential application in thermal management and heat energy collection system.

Simultaneous Effects of Carboxyl Group-Containing Hyperbranched Polymers on Glass Fiber-Reinforced Polyamide 6/Hollow Glass Microsphere Syntactic Foams.

The hollow glass microsphere (HGM) containing polymer materials, which are named as syntactic foams, have been applied as lightweight materials in various fields. In this study, carboxyl group-containing hyperbranched polymer (HBP) was added to a glass fiber (GF)-reinforced syntactic foam (RSF) composite for the simultaneous enhancement of mechanical and rheological properties. HBP was mixed in various concentrations (0.5–2.0 phr) with RSF, which contains 23 wt% of HGM and 5 wt% of GF, and the rheological, thermal, and mechanical properties were characterized systematically. As a result of the lubricating effect of the HBP molecule, which comes from its dendritic architecture, the viscosity, storage modulus, loss modulus, and the shear stress of the composite decreased as the HBP content increased. At the same time, because of the hydrogen bonding among the polymer, filler, and HBP, the compatibility between filler and the polymer matrix was enhanced. As a result, by adding a small amount (0.5–2.0 phr) of HBP to the RSF composite, the tensile strength and flexural modulus were increased by 24.3 and 9.7%, respectively, and the specific gravity of the composite was decreased from 0.948 to 0.917. With these simultaneous effects on the polymer composite, HBP could be potentially utilized further in the field of lightweight materials.

Development and characterization of surface functionalized hierarchical carbon fiber reinforced hybrid polypropylene composites

Light-weight hybrid composites of relevant industrial applications were prepared using surface functionalized hierarchical carbon fibers ( f-CF), silane treated hollow glass microspheres (HGM), and a blend of polypropylene (PP) and maleic anhydride-grafted-styrene ethylene butylene styrene as the base polymer matrix. The f-CF were prepared by coating amine functionalized carbon nanotubes onto silane treated CF using an ultrasonic assisted electrophoretic deposition technique to improve fiber-matrix interfacial adhesion. For hybrid composition of 20 wt.% f-CF and 10 wt.% HGM, the tensile strength and modulus improved by ∼141 and ∼536% over neat PP while flexural strength and modulus increased by ∼118% and ∼583% respectively. Impact strength of 11.06 kJ/m2 was obtained and uniform dispersion and distribution of f-CF and HGMs was observed in Scanning electron microscope (SEM) images. Desirable reduction in density and melt viscosity along with improvement in composite stiffness were observed due to addition of HGM filler. Compared to PP, the crystallization temperature increased by ∼12°C while a maximum decrease of ∼5°C in melting temperature was obtained for the hybrid composites. Crystallinity of the hybrid composites decreased with an evident β crystal formation brought in by the nucleation.

A tri-layer floating photocatalyst/adsorbent for the removal of organic compounds from wastewater: Layer-by-layer deposition of silicalite-1 and titania on hollow glass microspheres

Removal of organic compounds from wastewater is necessary to ensure that aquatic organisms are not adversely affected. In the past, it had been shown that zeolite-based systems provide good opportunities for wastewater treatment; however, most of the zeolite systems reported thus far face the disadvantages of sinking in water and saturated adsorption site. Therefore, in the current study, we attempted to develop zeolite-based composite systems with good floatability, adsorption capacity, and photocatalytic activity. In addition, our aim was to ensure that these composites could be easily separated from the treated water. Thus, a tri-layer floating photocatalyst/adsorbent was prepared via the layer-by-layer deposition of silicalite-1, a pure silica MFI-type zeolite (PSZ), and TiO 2 on hollow glass microspheres (HGMs). A thin layer of silicalite-1 was crystallized on the dense walls of HGMs to fabricate floating adsorbents (PSZ-HGMs). Subsequently, a layer of TiO 2 was deposited on PSZ-HGM surfaces using the sol–gel method to develop photocatalytic composites (TiO 2 /PSZ-HGMs). A good PSZ coverage and attachment were achieved on HGM surfaces by adding HGMs to an alkali solution containing tetrapropylammonium hydroxide and tetraethyl orthosilicate, followed by hydrothermal synthesis at 180 °C for 40 h. Subsequent deposition of TiO 2 was effective in homogeneously covering the PSZ surface without clogging the zeolite pores. The wastewater treatment capacity of the synthesized materials was verified using methylene blue (MB). It was found that TiO 2 /PSZ-HGMs, which exhibited both photocatalytic and adsorption activities, acted synergistically with UV-C irradiation to drastically degrade MB concentration by ∼ 98% within 2 h. Therefore, these materials may be considered to have high potential in wastewater-treatment processes. • Newly designed tri-layer floating TiO 2 /pure silica MFI-type zeolite/hollow glass microsphere (TiO 2 /PSZ/HGMs) was developed. • The effects of HGM size distribution, precursor composition, and synthesis time on PSZ layer formation on HGM were examined. • Anatase/rutile-TiO 2 were homogeneously embedded onto PSZ/HGMs without clogging the zeolite pores by using the sol–gel method. • Optimized TiO 2 /PSZ/HGMs could remove 98% of methylene blue under UV-C irradiation for 2 h.

Expanded vermiculite and polyvinyl acetate composite as gap filler for wooden objects conservation

• Gap fillers are composites used to fill the gaps caused by deterioration processes in wooden objects. • A gap filler composite of expanded vermiculite and polyvinyl acetate was studied for the conservation of wooden objects. • Vermiculite is an inert micaceous mineral. It can also act as a pH buffer. • The mechanical properties, shrinkage and expansion with varying relative humidity of the gap filler indicated the potential use of expanded vermiculite for the conservation of wooden objects stored indoors. Gap fillers are composites used to fill the gaps caused by deterioration processes in wooden objects. The materials commonly used in gap fillers are acrylic, vinyl, cellulosic, and epoxy resins mixed with fillers such as sawdust, glass microspheres, and paper. In this work, a gap filler composite of expanded vermiculite and polyvinyl acetate was studied for the conservation of wooden objects. Expanded vermiculite is a stable material that meets some criteria for gap filler composites. This study evaluated the properties of the proposed gap filler by comparing it to a model gap filler containing sawdust as a filler. The particle size distribution of the filler materials was measured, and the pH, modulus of elasticity, yield point, and expansion and contraction behavior as a function of the relative humidity of the air were measured. The proposed composite showed comparable properties to those of the sawdust and polyvinyl acetate composite; in some tests, the properties were better than those of the model. These data suggest potential use of expanded vermiculite as a filler in gap filler for the conservation of wooden objects.

Manufacture Hollow Glass Microsphere (HGS) in University Laboratory Scale (Phase 1)

Hollow Glass Microsphere (HGS) can be used as an additive of drilling fluid to decrease the density and hydrostatic pressure without changing the chemistry characteristic to make underbalanced drilling condition. HGS is relatively easier to be mixed with the fluid without complicated equipment, can prevent formation damage, and can improve oil and gas production. There are various HGS commercial products that have been developed in the industry for various purposes with a density range 0.125-1.1 gr/cm3, grain size range 2-120 μm, and compressive strength up to 200 MPa. HGS has been successfully used in underbalanced drilling operation in several oil and gas fields in Indonesia. HGS costs less than UBD and the application shows good results with the improvement of oil and gas production. However, the cost of commercial HGS products in the market is very expensive. Petroleum Engineering Study Program Institut Teknologi Bandung (ITB) performed the HGS research in three phases. The first phase reported in this paper was to manufacture HGS in the university laboratory scale. HGS was manufactured based on various chemical compositions and temperature and time variation of the burning process. Scanning Electron Microscope (SEM), Energy Dispersive Spectrometry (EDS), and X-Ray Diffraction (XRD) analysis were performed to identify and characterize the raw chemical material and manufactured HGS. HGS was successfully manufactured with the following characteristics: low density (<0.8 gr/cm3) and low grain size (20-40 μm). These characteristics show that HGS can compete with commercial industry HGS products that have been successfully used in the underbalanced drilling operation. The second phase is to scale-up manufacture HGS from university laboratory scale to industrial scale. The third phase is to test the manufactured HGS with drilling fluid according to the American Petroleum Institute (API) Spec. 13A and API Spec. 13B-1.

Influence of Heat Treatment on Microstructure and Performance of Degradable Mg Matrix Composites Reinforced with Hollow Glass Microsphere

Recently degradable Mg matrix composites as a promising candidate for degradable downhole tools application have aroused extensive interest. In the present work, the effects of heat treatment (solution treatment and artificial aging) on the microstructure, mechanical properties and degradation behaviors of the newly developed hollow glass microsphere reinforced Mg-Al15-Zn6-Cu1.5 composites were investigated. The results show that the solution treatment causes the β-Mg17Al12 phase and Mg32(Al,Zn)49 phase to dissolve into the α-Mg matrix and the coarse eutectic τ-Al2CuMg phase to translate into blocky morphology. Aging treatment causes the β phase to precipitate at the grain boundaries or the edge of the residual second phases in lamellar and blocky morphology. After solution treatment, the ductility of the composites was significantly increased, while the following aging treatment could significantly increase the ultimate compressive strength (UCS), hardness and degradation rate. The composites solution treated at 420 °C for 20 h and aged at 200 °C for 24 h shows the higher degradation rate of 6.5 mg·cm-2·h-1 in 3 wt.% KCl at ambient temperature, with UCS of 471 MPa, Brinell hardness of 115 HB and fracture strain of 8.7 %, this outstanding comprehensive performance is more suitable for degradable downhole tools application.

Preparation and characterization of cobalt-60 glass microspheres for radioactive particle tracking applications

The current work describes development and optimization of a process for preparation of cobalt-60 glass microspheres. These microspheres have potential for applications in radioactive particle tracking (RPT) studies in multiphase flow systems. In the first step of preparation, soda lime glass containing 5–10 wt% cobalt oxide was produced through melt-quench method. Subsequently, cobalt glass microspheres (CMSs) were prepared by microwave heating of tiny glass grains in presence of graphite. In the final step, radioactive cobalt-60 microspheres (RMSs) were produced by neutron irradiation of the CMSs in a nuclear reactor. The CMSs were characterized for surface morphology, elemental composition, homogeneity, crystalinity using SEM, EDX and XRD, respectively. The thermal behaviour of the microspheres was characterized by TG and DSC analysis. The size distribution of CMSs analyzed by SEM was found to be in the range 500–2000 μm. The preparation step was optimized to produce adequate activity in a single microsphere, so that they can be utilized for RPT applications.

Optimizing 90Y Particle Density Improves Outcomes After Radioembolization.

To determine how particle density affects dose distribution and outcomes after lobar radioembolization. Matched pairs of patients, treated with glass versus resin microspheres, were selected by propensity score matching (114 patients), in this single-institution retrospective study. For each patient, tumor and liver particle density (particles/cm3) and dose (Gy) were determined. Tumor-to-normal ratio was measured on both 99mTc-MAA SPECT/CT and post-90Y bremsstrahlung SPECT/CT. Microdosimetry simulations were used to calculate first percentile dose, which is the dose in the cold spots between microspheres. Local progression-free survival (LPFS) and overall survival were analyzed. As more particles were delivered, doses on 90Y SPECT/CT became more uniform throughout the treatment volume: tumor and liver doses became more similar (p = 0.04), and microscopic cold spots between particles disappeared. For hypervascular tumors (tumor-to-normal ratio ≥ 2.6 on MAA scan), delivering fewer particles (< 6000 particles/cm3 treatment volume) was associated with better LPFS (p = 0.03). For less vascular tumors (tumor-to-normal ratio < 2.6), delivering more particles (≥ 6000 particles/cm3) was associated with better LPFS (p = 0.02). In matched pairs of patients, using the optimal particle density resulted in improved overall survival (11.5 vs. 6.8months, p = 0.047), compared to using suboptimal particle density. Microdosimetry resulted in better predictions of LPFS (p = 0.03), and overall survival (p = 0.02), compared to conventional dosimetry. The number of particles delivered can be chosen to maximize the tumor dose and minimize the liver dose, based on tumor vascularity. Optimizing the particle density resulted in improved LPFS and overall survival.

Mitigating thermal runaway propagation of NCM 811 prismatic batteries via hollow glass microspheres plates

The propagation of thermal runaway in Lithium-ion battery modules can escalate fire hazards and damage in energy storage systems. More effective strategies are needed to ensure the safe application of high-energy lithium-ion batteries and alleviate the thermal runaway propagation. This work explores the use of ultra-light plates based on hollow glass microspheres (HGM) as firewalls in the large-format battery module. A systematic experimental study is conducted using the prismatic battery with LiNi0.8Co0.1Mn0.1O2 (NCM 811) cathode and HGM firewalls with different thicknesses. Performance tests suggest that the composite plate with 60 wt% HGM, 25 wt% curing agent, and 15 wt% flame retardant is most effective in mitigating thermal runaway propagation. Without firewalls, the thermal runaway propagation rate increases from 0.43 cell/min to 0.85 cell/min as the SOC level increases from 25% to 100%. Inserting HGM plates can effectively slow down thermal runaway propagation, where the 3-mm HGM plates can successfully block the thermal runaway. A simplified heat transfer model is also proposed to explain the performance of the firewall in inhibiting thermal runaway and help to optimize the safety design for battery modules. This work provides important insights into the thermal runaway risks and safety measures of large battery systems.

Analysis and numerical investigations on the temperature-dependent creep behavior of polypropylene matrix composite used for coating of offshore pipeline

In this paper, the effect of temperature on the creep-recovery behavior of a polypropylene matrix syntactic foam material under low stresses is analyzed. Previous dynamic mechanical analyses have shown that the mechanical response of the composite material is strongly time dependent with the polymeric nature of its matrix despite a high volume fraction of hollow glass microspheres. The permanent deformations are more pronounced at the higher temperatures. With the low level of the applied stress, the results lead to the assumption that the microcracks can be generated in the matrix of the composite material. Under the effect of temperature gradients in the offshore environment, the response of the material could evolve from a linear viscoelastic behavior to a behavior of which one part could be associated with the viscoelasticity of the matrix and a second with its viscoplasticity. We propose to use hooke, spectral triangular, and Zapas-Crissmann models to predict the overall creep response of a polypropylene matrix syntactic foam at the different temperatures. The results showed that the creep deformation at the higher temperatures conforms well to the global model including a power law that takes into account the permanent deformations of the polypropylene matrix composite of syntactic foam material type.

Hepatocellular carcinoma radiation segmentectomy treatment intensification prior to liver transplantation increases rates of complete pathologic necrosis: an explant analysis of 75 tumors.

To verify the correlation between yttrium-90 glass microsphere radiation segmentectomy treatment intensification of hepatocellular carcinoma (HCC) and complete pathologic necrosis (CPN) at liver transplantation. A retrospective, single center, analysis of patients with HCC who received radiation segmentectomy prior to liver transplantation from 2016 to 2021 was performed. The tumor treatment intensification cohort (n = 38) was prescribed radiation segmentectomy as per response recommendations identified in a previously published baseline cohort study (n = 37). Treatment intensification and baseline cohort treatment parameters were compared for rates of CPN. Both cohorts were then combined for an overall analysis of treatment parameter correlation with CPN. Sixty-three patients with a combined 75 tumors were analyzed. Specific activity, dose, and treatment activity were significantly higher in the treatment intensification cohort (all p < 0.01), while particles per cubic centimeter of treated liver were not. CPN was achieved in 76% (n = 29) of tumors in the treatment intensification cohort compared to 49% (n = 18) in the baseline cohort (p = 0.013). The combined cohort CPN rate was 63% (n = 47). ROC analysis showed that specific activity ≥ 327Bq (AUC 0.75, p < 0.001), dose ≥ 446Gy (AUC 0.69, p = 0.005), and treatment activity ≥ 2.55 Gbq (AUC 0.71, p = 0.002) were predictive of CPN. Multivariate logistic regression demonstrated that a specific activity ≥ 327Bq was the sole independent predictor of CPN (p = 0.013). Radiation segmentectomy treatment intensification for patients with HCC prior to liver transplantation increases rates of CPN. While dose strongly correlated with pathologic response, specific activity was the most significant independent radiation segmentectomy treatment parameter associated with CPN.

Thermo-optical control of L-band lasing in Er-doped tellurite glass microsphere with blue laser diode.

Miniature lasers based on rare-earth ion-doped tellurite microsphere resonators with whispering gallery modes (WGMs) are promising devices for basic research and applications. However, the excitation of WGMs using an external pump is not a simple task requiring passive or active control. We propose and demonstrate the implementation of thermo-optical control of the L-band laser generation in an Er-doped in-band pumped tellurite glass microsphere using a cheap low-power blue laser diode and a constant-wavelength telecom laser as a pump. The proposed scheme ensures simplification and cost reduction of microlasers.

Study on a new method of controlling casing shear deformation based on hollow glass microspheres cement sheath

Casing shear deformation caused by fault slip is a serious problem that restricts shale gas development. As yet, there is no effective method for controlling casing shear deformation. In this study, a cement sheath with hollow glass microspheres was used to prevent and mitigate casing deformation caused by a fault slip. An equivalent outer-diameter model was established. This model analyzes the mechanism by which casing shear deformation is controlled by a cement sheath with hollow glass microspheres under the condition of fault slip. The hollow glass microspheres in the cement sheath were broken owing to the strong shear forces of the fault slip. The internal volume of the hollow glass microspheres was released, which reduced the distance of the fault slip across the casing. The casing deformation was prevented or slowed down. A 3D assembly numerical model was established to evaluate the control effect of the hollow glass microspheres on casing shear deformation. Furthermore, the influences of slip distance, casing thickness, mechanical parameters of formation, mechanical parameters of the cement sheath, and crustal stress difference were analyzed. The mathematical calculation results showed that casing deformation increased with an increase in the fault slip distance, an increase in the stratum elastic modulus, and a decrease in the in situ stress difference. Therefore, the mass content of the hollow glass microspheres in the cement sheath also needs to be increased to ensure that the casing does not deform. The numerical analysis results showed that the change in casing thickness, Poisson’s ratio of formation, and mechanical parameters of the cement sheath had little effect on the mass content of hollow glass microspheres. Finally, the model was used to analyze the test wells in the Weirong Block, Sichuan, China. The calculation results showed that under the same condition of casing deformation of 8.23 mm in adjacent wells, casing shear deformation could be avoided by using a cement sheath with 11.9% hollow glass microspheres in the test well. This study provides a theoretical basis and reference for controlling the casing shear deformation caused by fault slip in shale gas wells.

Development of high strength & lightweight cementitious composites using hollow glass microsphere in a low water-to-cement matrix

It has been a challenge for structural concrete to satisfy both high strength and lightweight, since general lightweight properties have been achieved through the use of lightweight aggregates with inherently weak strength. In this study, a cement composite with high strength and lightweight was developed using very low-specific gravity material of hollow particles. A combination of a polycarboxylate-ether superplasticizer, filler materials, and a low water-to-cement ratio was selected to increase the viscosity of the cement matrix for minimizing floating of the hollow particles. As a result, the developed cementitious composites substantially outperformed the material performance of previously reported lightweight concretes. Compressive strength of 69 MPa and 97 MPa at 28 days were achieved with the density less than 1.5 g/cm3 from ambient and heat-treated curing, respectively. From a reaction perspective, the used hollow particles did not actively participate in the cement-based hydration reaction, which indicated that their role is limited to being very light inert fillers in the designed cementitious matrix.

Eco-friendly poly(dopamine)-modified glass microspheres as a novel self-floating adsorbent for enhanced adsorption of tetracycline

Hollow glass microspheres (HGM), as a promising hollow spherical ultra-light material, have the advantages of uniform particle size, regular shape, high mechanical strength and stable physical and chemical properties. It has been widely utilized in many fields but its application in water treatment is yet to be developed. Herein, a novel self-floating composite adsorbent was obtained by forming a poly(dopamine) (PDA) biomass coating on the surface of HGM and introducing sulfonic acid groups. The hollow composite material (HGM@PDA-SO3H) was utilized in the adsorptive elimination of tetracycline (TC) from aqueous solutions. In addition to great adsorption performance, HGM@PDA-SO3H also exhibited satisfactory self-floating solid-liquid separation capability. Langmuir, pseudo second-order and Elovich models correlate isotherms and kinetic data relatively well, respectively. The theoretical saturated TC adsorption amount of HGM@PDA-SO3H evaluated by Langmuir model reached 333.70 mg g−1. Thermodynamic analysis confirmed the spontaneous exothermic property of the adsorption process. There was no serious decline in the adsorption of TC by the material after 5 adsorption cycles, and the adsorbent saturated with contaminants could be easily regenerated via solution desorption, reflecting its satisfactory renewability and stability. Based on the results of batch experiments and characterization analysis, it could be concluded that the corresponding adsorption mechanisms mainly involve electrostatic attraction, hydrogen bonding and π-π stacking interactions. This research aimed to decorate HGM with biomaterials and apply it in the adsorptive purification of TC-contaminated water, which brought some insights and inspiration for the environmental application of HGM, and proved its potential applicability.

Gastrointestinal Tract Injury by Yttrium-90 Appears Largely Restricted to Resin Microspheres But Can Occur Years After Embolization.

Radioembolization therapy utilizes yttrium-90 (Y90) impregnated resin (SIR-Spheres) or glass (TheraSpheres) microspheres to selectively target hepatic lesions via transarterial radioembolization. Occasional cases of gastrointestinal tract injury, secondary to nontargeted delivery of microspheres, have been reported, but large descriptive pathology series are lacking. We identified 20 cases of histologically confirmed mucosal injury associated with Y90 from 17 patients and assessed the corresponding clinical and pathologic sequelae. The mucosal biopsies were obtained from 1 to 88 months following Y90 therapy (median: 5 mo). Most cases were gastric (17, 85%), while the remaining were duodenal. Endoscopic ulceration was seen in the majority of cases (16, 80%), and mucosal erythema in the remaining 4. Histologically, a majority (19, 95%) of cases showed rounded, dark blue to purple microspheres measuring 4 to 30 µm, consistent with resin microspheres. A single case with glass microspheres demonstrated 26 µm translucent beads. Histologic evidence of ulceration was appreciated in 14 (70%) cases, and the microspheres were clearly intravascular in 6 (30%). A foreign body giant cell reaction to the microspheres was uncommon (3 cases, 15%). We additionally performed a retrospective review of all gastrointestinal tissue obtained postprocedure from 784 sequential patients treated with Y90 microspheres. Three patients (0.4%) demonstrated the presence of resin microspheres upon histologic examination. No cases involving glass-based Y90 were identified ( P =0.0078), despite the majority of patients having received glass radioembolization (630, 80%). This increased risk of secondary sphere dissemination is likely related to the increased number of particles required per activity for resin versus glass microspheres. We conclude that Y90 microspheres may be encountered in the gastrointestinal tract years after initial liver-targeted therapy and, when present, are often associated with mucosal ulceration. This finding is less likely to be encountered in patients who received Y90 radioembolization utilizing glass microspheres.