Abstract Purpose Proximal reflux of liquid embolic agents remains a primary safety concern during endovascular embolization, yet the quantitative relationships governing reflux mechanics are poorly characterized. An analytical model was developed to determine the relative contributions of catheter geometry, agent viscosity, polymerization kinetics, and injection technique to reflux behavior of ethylene–vinyl alcohol copolymer (EVOH). Methods An annular Poiseuille flow model was constructed for a 1 mm vessel with coaxial microcatheters (1.3–2.8 French; catheter-to-vessel diameter ratio D* = 0.43–0.92). Carreau rheology was applied to EVOH-18 and EVOH-34; blood and iodinated contrast were modeled as Newtonian. Extensions incorporated vessel compliance, first-order EVOH polymerization kinetics, and intermittent injection parameterized by duty cycle δ. Results The annular geometry function φ(D*) spanned three orders of magnitude across the catheter range (0.179 to 0.0006), surpassing the maximum 2.4-fold inter-agent viscosity difference. At injection shear rates, EVOH-18 thinned to near-contrast viscosity (6.4 vs 6.1 mPa·s). EVOH polymerization reduced reflux up to 68% at low D* but was negligible at D* > 0.9. Under intermittent injection (δ = 0.20), effective reflux lengths fell up to tenfold, and the protective advantage of EVOH-34 over contrast increased from 1.35-fold to 4.1-fold. Conclusions Catheter-to-vessel geometry dominates reflux by orders of magnitude over viscosity; catheter selection is the primary modifiable safety determinant. EVOH polymerization provides geometrically selective secondary protection maximized by intermittent injection. The duty cycle δ is proposed as a standardizable parameter for reporting injection protocols.

Supplemental Table 1. Single-cell material properties.

Objective To evaluate the adequacy of Rapid Onsite Evaluation (ROSE) in relation to diagnostic yield of CT-guided percutaneous lung core needle biopsies (CNB) at a tertiary care cancer center. Methods A total of 943 CT-guided percutaneous CNB performed in the year 2022 were retrospectively reviewed. ROSE of specimens provided immediate feedback regarding the sample adequacy. The biopsies were divided into 3 groups based on ROSE results: 1) adequate on first pass; 2) adequate after repeat sampling and 3) inadequate. Patient, lesion, and procedure characteristics were analyzed in relation to ROSE adequacy using a multinomial logistic regression model. Results Median lesion size was 1.8 cm (IQR: 1.2-2.8). The first-pass adequacy rate was 64.8% (611/943), increasing to 82.4% (777/943) after seven passes, with a clear plateau after three passes; 17.9% (169/943) samplings were persistently inadequate. Complete histopathologic processing resulted in an overall diagnostic yield of 89.7% (846/943). Critically, 59.2% of biopsies deemed inadequate by ROSE ultimately yielded a diagnostic result after complete pathologic processing. ROSE demonstrated a sensitivity of 88.2%, specificity of 71.1%, positive predictive value of 96.4%, and negative predictive value of 40.8%. Larger lesion size and absence of perilesional hemorrhage were associated with higher odds of first-pass adequacy on multivariable analysis. Conclusion Lesion size and perilesional hemorrhage are independent predictors of ROSE- adequacy for lung CNB. The low negative predictive value (40.8%) and the finding that 59.2% of ROSE-inadequate biopsies ultimately yielded a diagnostic result highlight that ROSE inadequacy should not be interpreted as synonymous with biopsy failure.

To evaluate the preliminary feasibility of using generative artificial intelligence (GenAI) to determine optimal entry angles for CT-guided liver needle biopsies in a controlled retrospective setting. This retrospective IRB-approved pilot study analyzed 30 de-identified axial CT images from consecutive liver biopsies performed by 16 interventional radiologists at a single academic center. GenAI operated in 2D on the selected images without specific training, using standardized prompts and overlaid radial grid to generate theoretical trajectory recommendations. Two conditions were evaluated: one with lesions marked and structures to avoid explicitly delineated, and one with lesions marked without annotations. Theoretical trajectory safety assessments were performed by two independent reviewers using consensus methodology. GenAI trajectories were compared retrospectively with clinician-selected paths using intention-to-treat analysis for safety and per-protocol analysis for length. In condition one, median iterations were 2 (IQR, 1–3.8), with 27/30 (90

PURPOSE:One recurring challenge in cell therapy for solid tumors is poor tumor infiltration of adoptively transferred T cells. We previously showed that a subablative dose of tumor-targeted radiation generates a chemokine gradient that promotes infiltration, proliferation, and a memory phenotype of chimeric antigen receptor (CAR) T cells in solid tumors. However, radiation is cytotoxic to infiltrating CAR T cells, limiting its repeated use. EXPERIMENTAL DESIGN:We hypothesized that irreversible electroporation could generate a chemokine gradient that promotes CAR T-cell infiltration into solid tumors and that selective irreversible electroporation (sIRE) tuned for selective cancer cell lysis (thus sparing infiltrating CAR T cells) can be used in a repeated fashion. Using experimental screening and simulation models, we optimized sIRE parameters to kill cancer cells while sparing T cells. RESULTS:Using 3D tumor mimics and mouse models of malignant pleural mesothelioma, we confirmed the therapeutic benefit of repeated sIRE. Chemokine secretion by cancer cells injured by sIRE promoted migration and tumor infiltration of systemically administered CAR T cells and facilitated sustained immunity in a tumor-rechallenge model. CONCLUSIONS:By leveraging a dual-purpose translational strategy-through direct cancer cell-targeted cytotoxicity and augmented CAR T-cell infiltration-sIRE can reduce cancer burden while preserving and enhancing CAR T-cell function.

To propose a cumulative cold dose (CCD) model integrating spatial, temporal, and biological dosimetry for cryoablation protocol optimization. Systematic searches identified studies reporting freeze duration effects, cell-type-specific lethal thresholds, lethal isotherm ratio, or protocol-stratified outcomes. CCD was defined as the total time tissue is held at or below its cell-type-specific lethal threshold across all freeze cycles, targeting ≥ 80

Supplemental Figure 4. Intratumoral T cell viability after sIRE or IRE in an immunocompetent syngeneic flank tumor model.

Purpose To develop a lung-specific deformable image registration algorithm optimized for lung thermal ablation and evaluate whether three-dimensional (3D) margin assessment predicts time to local recurrence. Materials and Methods This institutional review board-approved, single-institution retrospective study evaluated patients who underwent lung thermal ablation with available pre- and postprocedural CT scans suitable for deformable registration. Images were preprocessed with segmentation of tumor, ablation zone, and lung. A four-stage deformable image registration framework was applied: (a) affine registration, (b) deformable image registration to the cropped lung, (c) lung mask-guided deformable image registration, and (d) local deformable image registration focused on the neighborhood adjacent to the ablation zone. Registrations were performed using free-form B-spline transformations with cost function masking of the ablation zone. Registration accuracy was assessed using target registration error (TRE). The 3D ablation margins were quantified using a distance-transform-based analysis of the spatial relationship between the tumor surface and ablation zone boundary. Associations between margin size and time to local recurrence were evaluated using competing-risks regression, and time-dependent receiver operating characteristic analysis was performed. Results A total of 69 patients (median age, 59 years [IQR, 50-69 years]; 38 female) with 108 ablated lung tumors were included. Mean TRE ± SD was 0.4 mm ± 0.3 and mean ablation margin was 1.6 mm ± 2.1. Larger margins were associated with longer time to local recurrence (subdistribution hazard ratio, 0.5 per millimeter increase [95% CI: 0.4, 0.6]; P < .001) and remained independently associated on multivariate analysis. Using a 2-mm margin threshold, the 2-year local recurrence rate was 3% (95% CI: 1, 8). The area under the receiver operating characteristic curve for predicting 2-year local recurrence was 0.86. Conclusion The four-step lung-optimized deformable image registration framework enabled accurate automated 3D tumor ablation margin quantification, and margin size was associated with time to local recurrence. Keywords: Ablation Techniques, Interventional-Oncology, Percutaneous, Thorax, Lung, Computer Applications-3D, Computational Studies, CT © RSNA, 2026.

Supplemental Table 3. Pulse parameters used for conventional IRE and sIRE.

Supplemental Figure 7. sIRE promotes infiltration of CAR T cells with minimal killing of preexisting intratumoral T cells.

We quantified volume and shape variability in lung microwave ablation (LMWA) zones, comparing them with expected ablation zones, exploring the correlation with tissue contraction. After Institutional Review Board approval, we retrospectively included patients who underwent LMWA between January 2015 and January 2019. Exclusion criteria were ablations with multiple burns/probes, overlapping ablation zones, or indistinguishable background lung parenchyma. Ablation zones were oriented along an applicator-centric coordinate system. We used Pyradiomics to generate volumes and the Euler characteristic transform for three-dimensional shape space analysis. Wilcoxon paired signed-rank tests compared the expected versus the actual ablation zone. Tissue contraction was quantified using paired anatomical landmarks before and after computed tomography scans. We included 111 ablations in 72 patients (31 male, 41 female; median age 59). Median ablation power was 65 watts (range 20‒65), median ablation time 5 min (range 1‒10). Total energy correlated with volume and width (p = 0.007, p = 0.003, respectively). Ablation volume did not differ from vendor predictions (p = 0.452), whereas length (p < 0.001) and maximum width (p < 0.001) were greater than predicted. Ablation shapes were more elongated (p < 0.001), less spherical (p < 0.001), asymmetric (wider in back than in front, p = 0.007), and diverged from expected ellipsoids. There was no correlation between tissue contraction and volume, power, or time. The provided vendor model offers a reasonable estimate of mean ablation volume, but wide variability in volume and shape necessitates a more bespoke method of ablation zone prediction. Tissue contraction did not correlate with ablation zone variability. High variability in actual ablation volume, shape, length, width, and position along the needle and divergence from ellipsoids necessitates the development of improved ablation zone prediction models.

PURPOSE:To evaluate the safety and effectiveness of coil-only middle meningeal artery embolization (MMAE) for the treatment of subacute to chronic subdural hematoma (SDH) in patients with cancer. MATERIALS AND METHODS:A single-center retrospective analysis was performed of 30 patients with cancer with SDH, 12 of whom had bilateral hematomas, who underwent MMAE of the affected side(s) using coils alone between 2022 and 2025. Clinical and radiographic outcomes were evaluated, including hematoma resolution, change in SDH thickness, need for reoperation, and overall survival. RESULTS:Median SDH thickness declined from 12 mm (interquartile range [IQR], 9 mm) before embolization to 3.6 mm (IQR, 8.8 mm) on final imaging (Wilcoxon signed-rank z = 4.59, P < .001). A ≥50% reduction was observed in 56% of SDHs, and complete radiographic resolution was observed in 37%. One patient (3%) required surgical evacuation after MMAE. Seventeen patients (59%) died due to cancer progression during follow-up. Median survival was significantly longer among patients with reduced hematoma thickness at initial follow-up imaging (148 vs 29 days, log-rank P = .0002). CONCLUSIONS:Coil-only MMAE may be a safe and effective treatment option for SDH in patients with cancer. Reduction in hematoma thickness was associated with longer survival in this high-risk population.

Background Real-time methods are needed for intraprocedural detection of residual tumors and incomplete thermal ablation (TA) to allow immediate retreatment and tumor eradication. Purpose To validate a TA workflow for detecting and immediately ablating residual viable colorectal liver metastases (CLMs). Materials and Methods This prospective single-center trial enrolled participants who underwent PET/CT-guided microwave CLM ablation from November 2019 to February 2023. The minimal ablation margin (MM) was calculated in all directions. Biopsies were obtained from the ablation zone (AZ) center and margin, with rapid tissue assessment for viable tumor (VT) cells using imprint cytology and fluorescent viability staining. Immediate reablation was performed if any of the following criteria were met: MM less than 5 mm at contrast-enhanced CT, residual PET-avid tumor, and/or VT cells at rapid tissue assessment. Gray-model statistics quantified the MM and VT impact on local tumor progression subdistribution hazard amid the competing risk of death. Results Seventy-seven participants (median age, 56 years [IQR, 47-64.5 years]; 39 male participants) underwent ablation in 104 CLMs. Overall, 15 of 104 (14%) CLMs underwent immediate reablation per the criteria (12 of 15, VT; seven of 15, MM <5 mm; and four of 15, residual fluorodeoxyglucose avidity). After reablation, all 12 initially VT-positive AZs underwent repeat biopsies with negative findings. Five of seven MMs less than 5 mm in AZs increased to greater than 5 mm after reablation. All four CLMs that underwent reablation due to PET/CT findings had AZs positive for VT, and one had MM less than 5 mm. MM greater than 5 mm protected against local tumor progression (LTP) (subdistribution hazard ratio, 0.12; 95% CI: 0.05, 0.30; P < .001). There was no LTP for MMs greater than 10 mm. The cumulative LTP incidence at 1, 2, and 3 years for participants with biopsy-proven completely ablated CLMs with MM greater than 5 mm was 7%, 12%, and 12%, respectively. Conclusion MM remained a critical technical factor affecting tumor control; the proposed multimodal comprehensive AZ assessment enabled immediate onsite reablation of 14% of CLMs with initially insufficient ablation treatment and improved local tumor control after thermal ablation. ClinicalTrials.gov identifier: NCT04143516 © RSNA, 2026 Supplemental material is available for this article. See also the editorial by Georgiades in this issue.

Supplemental Figure 1. Mesothelioma and T cell viability at 24 hours post-IRE in vitro. Mesothelioma cell lines.

Supplemental Table 2. Cell viability material properties.