X-ray imageable, drug-loaded hydrogel that forms at body temperature for image-guided, needle-based locoregional drug delivery.

Liver cancer ranks as the fifth leading cause of cancer-related death globally. Direct intratumoral injections of anti-cancer therapeutics may improve therapeutic efficacy and mitigate adverse effects compared to intravenous injections. Some challenges of intratumoral injections are that the liquid drug formulation may not remain localized and have unpredictable volumetric distribution. Thus, drug delivery varies widely, highly-dependent upon technique. An X-ray imageable poloxamer 407 (POL)-based drug delivery gel was developed and characterized, enabling real-time feedback. Utilizing three needle devices, POL or a control iodinated contrast solution were injected into an ex vivo bovine liver. The 3D distribution was assessed with cone beam computed tomography (CBCT). The 3D distribution of POL gels demonstrated localized spherical morphologies regardless of the injection rate. In addition, the gel 3D conformal distribution could be intentionally altered, depending on the injection technique. When doxorubicin (DOX) was loaded into the POL and injected, DOX distribution on optical imaging matched iodine distribution on CBCT suggesting spatial alignment of DOX and iodine localization in tissue. The controllability and localized deposition of this formulation may ultimately reduce the dependence on operator technique, reduce systemic side effects, and facilitate reproducibility across treatments, through more predictable standardized delivery.

A Prospective Study of the Diagnostic Performance of Photon-Counting CT Compared With MRI in the Characterization of Renal Masses.

OBJECTIVES: The aim of this study was to assess the interreader reliability and per-RCC sensitivity of high-resolution photon-counting computed tomography (PCCT) in the detection and characterization of renal masses in comparison to MRI. MATERIALS AND METHODS: This prospective study included 24 adult patients (mean age, 52 ± 14 years; 14 females) who underwent PCCT (using an investigational whole-body CT scanner) and abdominal MRI within a 3-month time interval and underwent surgical resection (partial or radical nephrectomy) with histopathology (n = 70 lesions). Of the 24 patients, 17 had a germline mutation and the remainder were sporadic cases. Two radiologists (R1 and R2) assessed the PCCT and corresponding MRI studies with a 3-week washout period between reviews. Readers recorded the number of lesions in each patient and graded each targeted lesion's characteristic features, dimensions, and location. Data were analyzed using a 2-sample t test, Fisher exact test, and weighted kappa. RESULTS: In patients with von Hippel-Lindau mutation, R1 identified a similar number of lesions suspicious for neoplasm on both modalities (51 vs 50, P = 0.94), whereas R2 identified more suspicious lesions on PCCT scans as compared with MRI studies (80 vs 56, P = 0.12). R1 and R2 characterized more lesions as predominantly solid in MRIs (R1: 58/70 in MRI vs 52/70 in PCCT, P < 0.001; R2: 60/70 in MRI vs 55/70 in PCCT, P < 0.001). R1 and R2 performed similarly in detecting neoplastic lesions on PCCT and MRI studies (R1: 94% vs 90%, P = 0.5; R2: 73% vs 79%, P = 0.13). CONCLUSIONS: The interreader reliability and per-RCC sensitivity of PCCT scans acquired on an investigational whole-body PCCT were comparable to MRI scans in detecting and characterizing renal masses. CLINICAL RELEVANCE STATEMENT: PCCT scans have comparable performance to MRI studies while allowing for improved characterization of the internal composition of lesions due to material decomposition analysis. Future generations of this imaging modality may reveal additional advantages of PCCT over MRI.

Development of a separability index for task specific characterization of spectral computed tomography.

PURPOSE: In this work, we define a signal detection based metrology to characterize the separability of two different multi-dimensional signals in spectral CT acquisitions. METHOD: Signal response was modelled as a random process with a deterministic signal and stochastic noise component. A linear Hotelling observer was used to estimate a scalar test statistic distribution that predicts the likelihood of an intensity value belonging to a signal. Two distributions were estimated for two materials of interest and used to derive two metrics separability: a separability index (s') and the area under the curve of the test statistic distributions. Experimental and simulated data of photon-counting CT scanners were used to evaluate each metric. Experimentally, vials of iodine and gadolinium (2, 4, 8 mg/mL) were scanned at multiple tube voltages, tube currents and energy thresholds. Additionally, a simulated dataset with low tube current (10-150 mAs) and material concentrations (0.25-4 mg/mL) was generated. RESULTS: Experimental data showed that conditions favorable for low noise and expression of k-edge signal produced the highest separability. Material concentration had the greatest impact on separability. The simulated data showed that under more difficult separation conditions, difference in material concentration still had the greatest impact on separability. CONCLUSION: The results demonstrate the utility of a task specific metrology to measure the overlap in signal between different materials in spectral CT. Using experimental and simulated data, the separability index was shown to describe the relationship between image formation factors and the signal responses of material.

Smart goggles augmented reality CT-US fusion compared to conventional fusion navigation for percutaneous needle insertion.

PURPOSE: Targeting accuracy determines outcomes for percutaneous needle interventions. Augmented reality (AR) in IR may improve procedural guidance and facilitate access to complex locations. This study aimed to evaluate percutaneous needle placement accuracy using a goggle-based AR system compared to an ultrasound (US)-based fusion navigation system. METHODS: Six interventional radiologists performed 24 independent needle placements in an anthropomorphic phantom (CIRS 057A) in four needle guidance cohorts (n = 6 each): (1) US-based fusion, (2) goggle-based AR with stereoscopically projected anatomy (AR-overlay), (3) goggle AR without the projection (AR-plain), and (4) CT-guided freehand. US-based fusion included US/CT registration with electromagnetic (EM) needle, transducer, and patient tracking. For AR-overlay, US, EM-tracked needle, stereoscopic anatomical structures and targets were superimposed over the phantom. Needle placement accuracy (distance from needle tip to target center), placement time (from skin puncture to final position), and procedure time (time to completion) were measured. RESULTS: Mean needle placement accuracy using US-based fusion, AR-overlay, AR-plain, and freehand was 4.5 ± 1.7 mm, 7.0 ± 4.7 mm, 4.7 ± 1.7 mm, and 9.2 ± 5.8 mm, respectively. AR-plain demonstrated comparable accuracy to US-based fusion (p = 0.7) and AR-overlay (p = 0.06). Excluding two outliers, AR-overlay accuracy became 5.9 ± 2.6 mm. US-based fusion had the highest mean placement time (44.3 ± 27.7 s) compared to all navigation cohorts (p < 0.001). Longest procedure times were recorded with AR-overlay (34 ± 10.2 min) compared to AR-plain (22.7 ± 8.6 min, p = 0.09), US-based fusion (19.5 ± 5.6 min, p = 0.02), and freehand (14.8 ± 1.6 min, p = 0.002). CONCLUSION: Goggle-based AR showed no difference in needle placement accuracy compared to the commercially available US-based fusion navigation platform. Differences in accuracy and procedure times were apparent with different display modes (with/without stereoscopic projections). The AR-based projection of the US and needle trajectory over the body may be a helpful tool to enhance visuospatial orientation. Thus, this study refines the potential role of AR for needle placements, which may serve as a catalyst for informed implementation of AR techniques in IR.

Image-Guided Transbronchial Pulmonary Cryoablation with a Flexible Cryoprobe in Swine: Performance and Radiology-Pathology Correlation.

PURPOSE: To evaluate the performance of a prototype flexible transbronchial cryoprobe compared with that of percutaneous transthoracic cryoablation and to define cone-beam computed tomography (CT) imaging and pathology cryolesion features in an in vivo swine model. MATERIALS AND METHODS: Transbronchial cryoablation was performed with a prototype flexible cryoprobe (3 central and 3 peripheral lung ablations in 3 swine) and compared with transthoracic cryoablation performed with a commercially available rigid cryoprobe (2 peripheral lung ablations in 1 swine). Procedural time and cryoablation success rates for endobronchial navigation and cryoneedle deployment were measured. Intraoperative cone-beam CT imaging features of cryolesions were characterized and correlated with gross pathology and hematoxylin and eosin-stained sections of the explanted cryolesions. RESULTS: The flexible cryoprobe was successfully navigated and delivered to each target through a steerable guiding sheath (6/6). At 4 minutes after ablation, 5 of 6 transbronchial and 2 of 2 transthoracic cryolesions were visible on cone-beam CT. The volumes on cone-beam CT images were 55.5 cm3 (SE ± 8.0) for central transbronchial ablations (n = 2), 72.5 cm3 (SE ± 8.1) for peripheral transbronchial ablations (n = 3), and 79.5 cm3 (SE ±11.6) for peripheral transthoracic ablations (n = 2). Pneumothorax developed in 1 animal after transbronchial ablation and during ablation in the transthoracic cryoablation. Images of cryoablation zones on cone-beam CT correlated well with the matched gross pathology and histopathology sections of the cryolesions. CONCLUSIONS: Transbronchial cryoablation with a flexible cryoprobe, delivered through a steerable guiding sheath, is feasible. Transbronchial cryoablation zones are imageable with cone-beam CT, with gross pathology and histopathology similar to those of transthoracic cryoablation.

X-ray imageable, drug-loaded hydrogel that forms at body temperature for image-guided, needle- based locoregional drug delivery.

Liver cancer ranks as the fifth leading cause of cancer-related death globally. Direct intratumoral injections of anti-cancer therapeutics may improve therapeutic efficacy and mitigate adverse effects compared to intravenous injections. Some challenges of intratumoral injections are that the liquid drug formulation may not remain localized and have unpredictable volumetric distribution. Thus, drug delivery varies widely, highly-dependent upon technique. An x-ray imageable poloxamer 407 (POL)-based drug delivery gel was developed and characterized, enabling real-time feedback. Utilizing three needle devices, POL or a control iodinated contrast solution were injected into an ex vivo bovine liver. The 3D distribution was assessed with cone beam computed tomography (CBCT). The 3D distribution of POL gels demonstrated localized spherical morphologies regardless of the injection rate. In addition, the gel 3D conformal distribution could be intentionally altered, depending on the injection technique. When doxorubicin (DOX) was loaded into the POL and injected, DOX distribution on optical imaging matched iodine distribution on CBCT suggesting spatial alignment of DOX and iodine localization in tissue. The controllability and localized deposition of this formulation may ultimately reduce the dependence on operator technique, reduce systemic side effects, and facilitate reproducibility across treatments, through more predictable standardized delivery.

Immune Effects of Cryoablation in Woodchuck Hepatocellular Carcinoma.

Objectives: Local and systemic immune responses evoked by locoregional therapies such as cryoablation are incompletely understood. The aim of this study was to characterize cryoablation-related immune response and the capacity of immune drugs to augment immunity upon cryoablation for the treatment of hepatocellular carcinoma (HCC) using a woodchuck hepatocellular carcinoma model. Materials and Methods: Twelve woodchucks chronically infected with woodchuck hepatitis virus and with hepatocellular carcinoma underwent imaging with contrast-enhanced CT. Partial cryoablation of tumors in three woodchucks was performed. Fourteen days after cryoablation, liver tissues were harvested and stained with H&E and TUNEL, and immune infiltrates were quantified. Peripheral blood mononuclear cells (PBMC) were collected from ablated and nonablated woodchucks, labeled with carboxyfluorescein succinimidyl ester (CFSE) and cultured with immune-modulating drugs, including a small PD-L1 antagonist molecule (BMS-202) and three TLR7/8 agonists (DSR 6434, GS-9620, gardiquimod). After incubation, cell replication and immune cell populations were analyzed by flow cytometry. Results: Local immune response in tumors was characterized by an increased number of CD3+ T lymphocytes and natural killer cells in the cryolesion margin compared to other tumor regions. T regulatory cells were found in higher numbers in distant tumors within the liver compared to untreated or control tumors. Cryoablation also augmented the systemic immune response as demonstrated by higher numbers of PBMC responses upon immune drug stimulation in the cryoablation group. Conclusions: Partial cryoablation augmented immune effects in both treated and remote untreated tumor microenvironments, as well as systemically, in woodchucks with HCC. Characterization of these mechanisms may enhance development of novel drug-device combinations for treatment of HCC.

Virtual monoenergetic imaging in photon-counting CT of the head and neck.

PURPOSE: Advantages of virtual monoenergetic images (VMI) have been reported for dual energy CT of the head and neck, and more recently VMIs derived from photon-counting (PCCT) angiography of the head and neck. We report image quality metrics of VMI in a PCCT angiography dataset, expanding the anatomical regions evaluated and extending observer-based qualitative methods further than previously reported. METHODS: In a prospective study, asymptomatic subjects underwent contrast enhanced PCCT of the head and neck using an investigational scanner. Image sets of low, high, and full spectrum (Threshold-1) energies; linear mix of low and high energies (Mix); and 23 VMIs (40-150 keV, 5 keV increments) were generated. In 8 anatomical locations, SNR and radiologists' preferences for VMI energy levels were measured using a forced-choice rank method (4 observers) and ratings of image quality using visual grading characteristic (VGC) analysis (2 observers) comparing VMI to Mix and Threshold-1 images. RESULTS: Fifteen subjects were included (7 men, 8 women, mean 57 years, range 46-75). Among all VMIs, SNRs varied by anatomic location. The highest SNRs were observed in VMIs. Radiologists preferred 50-60 keV VMIs for vascular structures and 75-85 keV for all other structures. Cumulative ratings of image quality averaged across all locations were higher for VMIs with areas under the curve of VMI vs Mix and VMI vs Threshold-1 of 0.67 and 0.68 for the first reader and 0.72 and 0.76 for the second, respectively. CONCLUSION: Preferred keV level and quality ratings of VMI compared to mixed and Threshold-1 images varied by anatomical location.

Impact of the confluence of cardiac motion and high spatial resolution on performance of ECG-gated imaging with an investigational photon-counting CT system: A phantom study.

PURPOSE: Photon-counting CT (PCCT) has higher spatial resolution that conventional EID CT which improves imaging of stationary coronary plaques and stents.. In this work, we evaluated the relationship between higher spatial resolution and motion acquisition on an investigational PCCT system. METHODS: An investigational photon-counting CT scanner (Siemens CounT) with ECG gating was used to image a coronary tree phantom with models of healthy, stenotic, and stented arteries using a motion simulator. Images were acquired with matched clinical parameters at rest and 60 beats per minute. An additional set of high dose stationary images were averaged to generate a motion-free, reduced noise reference. Scans were completed at standard (0.5 mm2) and high-resolution (0.25 mm2). Motion images were reconstructed at multiple phases. Regions of interest were drawn around vessels and segmented. Percentage difference from the reference standard was evaluated for vessel diameter and circularity. Mutual information between the reference and stationary and motion datasets was used as a measure of volumetric similarity. RESULTS: The stenotic vessel showed the most variation from the reference when compared to healthy or stented vessels. Compared to standard resolution, high-resolution images had lower bias for diameter (-0.012 ± 0.19% vs -0.052 ± 0.14%) and lower variability for circularity (-0.13 ± 0.138% vs -0.12 ± 0.144%). Both differences were found to be statistically significant. High-resolution images had a slightly lower mutual information (1.28) than standard resolution (1.31). CONCLUSION: The higher spatial resolution enabled by photon-counting CT can be harnessed for cardiac imaging as the benefits of high spatial resolution acquisitions remain relevant in the presence of motion.

Morphometric characterization and temporal temperature measurements during hepatic microwave ablation in swine.

PURPOSE: Heat-induced destruction of cancer cells via microwave ablation (MWA) is emerging as a viable treatment of primary and metastatic liver cancer. Prediction of the impacted zone where cell death occurs, especially in the presence of vasculature, is challenging but may be achieved via biophysical modeling. To advance and characterize thermal MWA for focal cancer treatment, an in vivo method and experimental dataset were created for assessment of biophysical models designed to dynamically predict ablation zone parameters, given the delivery device, power, location, and proximity to vessels. MATERIALS AND METHODS: MWA zone size, shape, and temperature were characterized and monitored in the absence of perfusion in ex vivo liver and a tissue-mimicking thermochromic phantom (TMTCP) at two power settings. Temperature was monitored over time using implanted thermocouples with their locations defined by CT. TMTCPs were used to identify the location of the ablation zone relative to the probe. In 6 swine, contrast-enhanced CTs were additionally acquired to visualize vasculature and absence of perfusion along with corresponding post-mortem gross pathology. RESULTS: Bench studies demonstrated average ablation zone sizes of 4.13±1.56cm2 and 8.51±3.92cm2, solidity of 0.96±0.06 and 0.99±0.01, ablations centered 3.75cm and 3.5cm proximal to the probe tip, and temperatures of 50 ºC at 14.5±13.4s and 2.5±2.1s for 40W and 90W ablations, respectively. In vivo imaging showed average volumes of 9.8±4.8cm3 and 33.2±28.4cm3 and 3D solidity of 0.87±0.02 and 0.75±0.15, and gross pathology showed a hemorrhagic halo area of 3.1±1.2cm2 and 9.1±3.0cm2 for 40W and 90W ablations, respectfully. Temperatures reached 50ºC at 19.5±9.2s and 13.0±8.3s for 40W and 90W ablations, respectively. CONCLUSION: MWA results are challenging to predict and are more variable than manufacturer-provided and bench predictions due to vascular stasis, heat-induced tissue changes, and probe operating conditions. Accurate prediction of MWA zones and temperature in vivo requires comprehensive thermal validation sets.

Imaging and Pathologic Evaluation of Cryoablation of Woodchuck (Marmota monax) Hepatocellular Carcinoma.

We characterized cryoablation as a mode of clinical intervention in adult woodchucks with hepatocellular carcinoma (HCC). Woodchucks (n = 4) were infected with woodchuck hepatitis virus at birth and developed LI-RADS-5 hypervascular HCC. At 21 mo of age, they underwent ultrasound (US), contrast-enhanced CT (CECT) imaging, and US-guided subtotal cryoablation (IcePearl 2.1 CX, Galil, BTG) of their largest tumor (Mean HCC volume of 49 ± 9 cm³). Cryoablation was performed using two 10-min freeze cycles, each followed by an 8-min thaw cycle. The first woodchuck developed significant hemorrhage after the procedure and was euthanized. In the other 3 woodchucks, the probe track was cauterized and all 3 completed the study. Fourteen days after ablation, CECT was performed, and woodchucks were euthanized. Explanted tumors were sectioned using subject-specific, 3D-printed cutting molds. Initial tumor volume, the size of the cryoablation ice ball, gross pathology and hematoxylin and eosin-stained tissue sections were evaluated. On US, the edges of the solid ice balls were echogenic with dense acoustic shadowing and average dimensions of 3.1 ± 0.5 × 2.1 ± 0.4 cm and cross-sectional area of 4.7 ± 1.0 cm². On day 14 after cryoablation, CECT of the 3 woodchucks showed devascularized hypo-attenuating cryolesions with dimensions of 2.8 ± 0.3 × 2.6 ± 0.4 × 2.93 ± 0.7 cm and a cross sectional area of 5.8 ± 1.2 cm². Histopathologic evaluation showed hemorrhagic necrosis with a central amorphous region of coagulative necrosis surrounded by a rim of karyorrhectic debris. A rim of approximately 2.5 mm of coagulative necrosis and fibrous connective tissue clearly demarcated the cryolesion from adjacent HCC. Partial cryoablation of tumors produced coagulative necrosis with well-defined ablation margins at 14 d. Cauterization appeared to prevent hemorrhage after cryoablation of hypervascular tumors. Our findings indicate that woodchucks with HCC may provide a predictive preclinical model for investigating ablative modalities and developing new combination therapies.

Effect of exposure to ionizing radiation on competitive proliferation and differentiation of hESC.

PURPOSE: We studied the effects of computed tomography (CT) scan irradiation on proliferation and differentiation of human embryonic stem cells (hESCs). It was reported that hESC is extremely radiosensitive; exposure of hESC in cultures to 1 Gy of ionizing radiation (IR) results in massive apoptosis of the damaged cells and, thus, they are eliminated from the cultures. However, after recovery the surviving cells proliferate and differentiate normally. We hypothesized that IR-exposed hESC may still have growth rate disadvantage when they proliferate or differentiate in the presence of non-irradiated hESC, as has been shown for mouse hematopoietic stem cells in vivo. MATERIALS AND METHODS: To study such competitive proliferation and differentiation, we obtained cells of H9 hESC line that stably express green fluorescent protein (H9GFP). Irradiated with 50 mGy or 500 mGy H9GFP and non-irradiated H9 cells (or vice versa) were mixed and allowed to grow under pluripotency maintaining conditions or under conditions of directed differentiation into neuronal lineage for several passages. The ratio of H9GFP to H9 cells was measured after every passage or approximately every week. RESULTS: We observed competition of H9 and H9GFP cells; we found that the ratio of H9GFP to H9 cells increased with time in both proliferation and differentiation conditions regardless of irradiation, i.e. the H9GFP cells in general grew faster than H9 cells in the mixtures. However, we did not observe any consistent changes in the relative growth rate of irradiated versus non-irradiated hESC. CONCLUSIONS: We conclude that population of pluripotent hESC is very resilient; while damaged cells are eliminated from colonies, the surviving cells retain their pluripotency, ability to differentiate, and compete with non-irradiated isogenic cells. These findings are consistent with the results of our previous studies, and with the concept that early in pregnancy omnipotent cells injured by IR can be replaced by non-damaged cells with no impact on embryo development.

Patient-specific needle guidance templates drilled intraprocedurally for image guided intervention: feasibility study in swine.

PURPOSE: Thermal ablation of large tumors may benefit from simultaneous placement of multiple needles, but accurate placement becomes challenging as the number of needles increases. The aim of this work was to evaluate use of personalized needle guidance grid templates based on intraprocedural CT and fabricated at the point of care to implement ablation treatment plans with multiple needles in vivo. METHODS: A plastic frame was designed to hold two parallel plastic guide plates in a rigid relationship, fixed over the abdomen by a mounting arm. Steel ball targets (1.5 mm) were implanted under ultrasound in the livers of two domestic swine under general anesthesia. Following breath-hold CT of the subject and frame, the targets and frame were identified using customized 3D Slicer-based planning software. Multiple needle trajectories targeting the balls were planned, including complex off-plane trajectories. A machining program for drilling the hole pattern corresponding to the planned needle trajectories was generated. The pattern was drilled in the two plates with a numerical-controlled milling machine in the suite. The plates were attached to the frame and needles passed through the paired holes to the calculated depth. Placement accuracy was defined as needle tip-to-target distance on post-placement CT. RESULTS: The planning process and manufacturing required approximately 6 and 15 min, respectively. Needles were rapidly inserted (n = 11) to the target points without complications or traversing nontarget anatomy. The mean needle tip-to-target distance error was 3.4 ± 2.2, range 0-7 mm. CONCLUSION: Rapid and accurate needle placement was feasible using a subject-specific, custom-drilled, needle guidance grid template fabricated intraprocedurally. Targeting accuracy and performance were similar to more complex and expensive tracking systems which may enable accurate intraprocedural implementation of treatment plans in the liver or other organs. This may be of value in complex ablation cases or in areas where more advanced guidance systems are not available.

In vitro characterization of immune modulating drug-eluting immunobeads towards transarterial embolization in cancer.

Hepatocellular carcinoma (HCC) is an aggressive liver cancer with limited effective treatment options. In this study, we selected TLR agonists imiquimod (IMQ), gardiquimod (GARD), GS-9620 and DSR 6434, and a small molecule checkpoint inhibitor, BMS-202, for characterization of drug loading and release from radiopaque embolic beads (DC Bead LUMI) for potential use in image-guided transarterial embolization (TACE) of HCC. The maximum drug loading capacity and amount of drug released over time were determined by high performance liquid chromatography and compared with the commonly used anthracycline, doxorubicin hydrochloride (Dox). Maximum drug loading was 204.54 ± 3.87, 65.28 ± 3.09, 65.95 ± 6.96, 65.97 ± 1.54, and 148.05 ± 2.24 mg of drug per milliliter of DC Bead LUMI for Dox, GARD, DSR 6434, IMQ, and BMS-202, respectively. Fast loading and subsequent rapid release in saline were observed for IMQ, GARD, and DSR 6434. These drugs could also be partially removed from the beads by repeated washing with de-ionized water suggesting weak interaction with the beads. Aggregation of IMQ was observed in water and saline. GS-9620 partially decomposed in the solubilizing solution, so loading and release were not characterized. Compared to TLR agonists, slower loading and release were observed for Dox and BMS-202. Potential factors influencing drug loading into and release from DC Bead LUMI including steric hinderance, hydrophobicity, drug pKa, and the electrostatic nature of the beads are discussed. The maximum loading capacity of BMS-202 and Dox in DC Bead LUMI exceeded the maximum theoretical loading capacity of the beads expected from ionic interaction alone suggesting additional drug-bead or drug-drug interactions may play a role. Slightly more release was observed for BMS-202 at early time points followed by a slower release compared to Dox. Further study of these drug-bead combinations is warranted in search of new tools for locoregional delivery of immune-modulating agents for treatment of HCC via drug-eluting bead chemoembolization.

In-line miniature 3D-printed pressure-cycled ventilator maintains respiratory homeostasis in swine with induced acute pulmonary injury.

The COVID-19 pandemic demonstrated the need for inexpensive, easy-to-use, rapidly mass-produced resuscitation devices that could be quickly distributed in areas of critical need. In-line miniature ventilators based on principles of fluidics ventilate patients by automatically oscillating between forced inspiration and assisted expiration as airway pressure changes, requiring only a continuous supply of pressurized oxygen. Here, we designed three miniature ventilator models to operate in specific pressure ranges along a continuum of clinical lung injury (mild, moderate, and severe injury). Three-dimensional (3D)-printed prototype devices evaluated in a lung simulator generated airway pressures, tidal volumes, and minute ventilation within the targeted range for the state of lung disease each was designed to support. In testing in domestic swine before and after induction of pulmonary injury, the ventilators for mild and moderate injury met the design criteria when matched with the appropriate degree of lung injury. Although the ventilator for severe injury provided the specified design pressures, respiratory rate was elevated with reduced minute ventilation, a result of lung compliance below design parameters. Respiratory rate reflected how well each ventilator matched the injury state of the lungs and could guide selection of ventilator models in clinical use. This simple device could help mitigate shortages of conventional ventilators during pandemics and other disasters requiring rapid access to advanced airway management, or in transport applications for hands-free ventilation.

Comparative analysis of the immune response to RFA and cryoablation in a colon cancer mouse model.

The immune response to radiofrequency ablation (RFA) and cryoablation (CRA) was characterized and compared in a colon cancer mouse model. All studies were conducted under a research protocol approved by the National Institutes of Health, Clinical Center, Animal Care and Use Committee. BALB/cJ mice were inoculated with CT26 cells, and randomized to RFA, CRA, or sham treatment. Mice were sacrificed 3 days post-treatment, and tumor, spleen, and serum were harvested. Cell death was determined by Caspase-3 immunohistochemical and TUNEL stains. Immune response was analyzed using flow cytometry, serum cytokine assay and immunohistochemistry. Cell death, necrosis, and apoptosis induced by ablation were comparable in RFA and CRA. Decreased frequency of systemic T-regulatory cells was found in the CRA group. Both RFA and CRA reduced frequencies of several myeloid-derived suppressor cell (MDSC) subpopulations. RFA induced pro-inflammatory cytokine secretion including TNF-α and IL-12 as well as anti-inflammatory cytokines IL-5, and IL-10. CRA augmented secretion of a wider array of cytokines compared to RFA with both pro- and anti-inflammatory properties including IL-1ß, IL-5, IL-6, IL-10, and KC GRO. In the tumor microenvironment, RFA reduced the number of T-regulatory cells, a finding not observed with CRA. Reduction of immune suppression via decreases in T-regulatory cells and MDSC was found to be induced by RFA or CRA. CRA augmented a wider range of cytokines than RFA, which were mainly pro-inflammatory, but also anti-inflammatory. In the tumor microenvironment, RFA demonstrated more pronounced anti-tumoral immunity. Further delineation of specific immunomodulation induced by ablation could inform drug-device development and may play a role in future hypothesis-driven immunomodulatory paradigms that combine immunotherapy drugs with tumor destruction for the treatment of metastatic colon cancer.

Cone-Beam Computed Tomography-Based Spatial Prediction of Drug Dose After Transarterial Chemoembolization Using Radiopaque Drug-Eluting Beads in Woodchuck Hepatocellular Carcinoma.

OBJECTIVES: The aims of this study were to develop a model to estimate drug dose delivered to tumors after transarterial chemoembolization (TACE) with radiopaque drug-eluting beads (DEBs) based on DEB density on cone-beam computed tomography (CT) and to evaluate drug penetration into tissue in a woodchuck hepatoma model. MATERIALS AND METHODS: Transarterial chemoembolization was performed in woodchucks with hepatocellular carcinoma (N = 5) using DEBs (70-150 µm, LC Bead LUMI) loaded with doxorubicin. Livers were resected 45 minutes after embolization, immediately frozen, and cut using liver-specific, 3D-printed sectioning molds. Doxorubicin levels in tumor specimens were measured by high-performance liquid chromatography and correlated with DEB iodine content that was measured using prototype cone-beam CT-based embolization treatment planning software. Doxorubicin penetration into tissue surrounding DEBs was assessed by fluorescence microscopy of tumor sections. Fluorescence intensity was converted into doxorubicin concentration using calibration standards. Intensity-thresholded color heatmaps were generated representing extravascular drug penetration. RESULTS: Consistent segmentation of DEBs on cone-beam CT was achieved using a semiautomated intensity thresholding method. A positive linear correlation (0.96) was found between DEB iodine content measured on cone-beam CT and the amount of doxorubicin measured in tumor specimens. Prediction of doxorubicin levels in tumor sections that were not included in model development was accurate, with a root-mean-square error of 0.08 mg of doxorubicin. Tumor penetration of eluted doxorubicin resulted in concentration gradients where drug content decreased with increasing distance from blood vessels containing DEBs. Drug penetration was greater for blood vessels containing DEB clusters compared with single DEB, with higher doxorubicin concentrations extending further away from the vessels. CONCLUSIONS: Estimation of drug dose delivered during transarterial chemoembolization in a woodchuck hepatocellular carcinoma model was possible using DEB radiopacity on cone-beam CT as a surrogate marker. Doxorubicin penetration was greatest adjacent to vessels containing DEB clusters compared with single DEB. Intraprocedural estimation of the spatial distribution of drug dose within the tumor could enable real-time adjustments to DEB delivery, to maximize treatment coverage or identify regions of tumor at risk for undertreatment.

Evaluation of immune-modulating drugs for use in drug-eluting microsphere transarterial embolization.

Cancer immunotherapy has yet to reach its full potential due in part to limited response rates and side effects inherent to systemic delivery of immune-modulating drugs. Local administration of immunotherapy using drug-eluting embolic (DEE) microspheres as drug delivery vehicles for direct infusion into tumor-feeding arteries might increase and prolong tumor drug concentrations and reduce systemic drug exposure, potentially improving the risk-to-benefit ratio of these agents. The purpose of this study was to evaluate the ability of four immune modulators affecting two different immune pathways to potentiate replication of immune cells from a woodchuck model of hepatocellular carcinoma. DSR 6434, a Toll-like receptor agonist, and BMS-202, a PD-L1 checkpoint inhibitor, induced immune cell replication and were successfully loaded into radiopaque DEE microspheres in high concentrations. Release of DSR 6434 from the DEE microspheres was rapid (t99% = 0.4 h) upon submersion in a physiologic saline solution while BMS-202 demonstrated a more sustained release profile (t99% = 17.9 h). These findings demonstrate the feasibility of controlled delivery of immune-modulating drugs via a local DEE microsphere delivery paradigm.

Woodchuck Hepatic Anatomy and Vascular Alterations Due to Hepatocellular Carcinoma with Angiographic Atlas of the Abdomen and Pelvis.

PURPOSE: To characterize the hepatic and abdominal angiographic anatomy of woodchucks and vascular changes associated with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty-nine woodchucks (23 with viral-associated HCC, 6 without) underwent multiphasic computed tomography (CT). Fourteen woodchucks (8 with HCC) also underwent diagnostic angiography. Hepatic arterial diameters were measured on the CT scans. Woodchucks were divided into 3 groups: non-tumor-bearing, largest tumor supplied by the right hepatic artery (RHA), and largest tumor supplied by the left hepatic artery (LHA). Statistical analysis with a repeated measures model was performed to determine the effects of tumor location (right, left), vessel measured (RHA, LHA), and interaction between the 2 on vessel diameter. Lobar arteries supplying HCC were compared with those that did not. RESULTS: CT anatomy and normal and variant vascular anatomy were defined. In woodchucks with HCC, LHA and RHA supplying tumors had mean diameters of 2.0 mm ± 0.3 and 1.6 mm ± 0.3 versus 1.5 mm ± 0.3 and 1.1 mm ± 0.2 for non-tumor-supplying arteries (P = .0002 and P < .0001), respectively. Lobar arteries supplying tumors were similarly ectatic. The right lateral lobe artery had the most profound increase in the mean diameter when supplying tumors, measuring 1.7 mm ± 0.1 versus 1.0 mm ± 0.1 in the non-tumor-supplying artery (P < .0001). There were no differences in the diameters of the aorta and celiac, common, and proper hepatic arteries between tumor- and non-tumor-bearing woodchucks. An angiographic atlas of the abdominal vessels was generated. CONCLUSIONS: HCC tumoral vasculature in woodchucks was ectatic compared with normal vasculature. This phenomenon recapitulates human HCC and may facilitate investigation of transcatheter and drug delivery therapies in an HCC animal model.