VX2 Tumor Research Articles

Hemocoagulase Combined with Microbubble-Enhanced Ultrasound Cavitation for Augmented Ablation of Microvasculature in Rabbit VX2 Liver Tumors

We investigated a new method for combining microbubble-enhanced ultrasound cavitation (MEUC) with hemocoagulase (HC) atrox. Our goal was to induce embolic effects in the vasculature and combine these with an anti-angiogenic treatment strategy. Fourteen days after being implanted with a single slice of the liver VX2 tumor, rabbits were randomly divided into five groups: (i) a control group injected intra-venously with saline using a micropump; (ii) a group given only an injection of HC; (iii) a group treated only with ultrasound cavitation; (iv) a group treated with MEUC; (v) a group treated with MEUC + HC. Contrast-enhanced ultrasound was performed before treatment and 1 h and 7 d post-treatment to measure tumor size, enhancement and necrosis range. QontraXt software was used to determine the time–intensity curve of tumor blood perfusion and microvascular changes. At 1 h and 7 d after treatment with MEUC + HC, the parameters of the time–intensity curve, which included peak value, regional blood volume, regional blood flow and area under the curve value and which were measured using contrast-enhanced ultrasound, were significantly lower than those of the other treatment groups. The MEUC + HC treatment group exhibited significant growth inhibition relative to the ultrasound cavitation only, HC and MEUC treatment groups. No damage was observed in the surrounding normal tissues. These results support the feasibility of reducing the blood perfusion of rabbit VX2 liver tumors using a new method that combines MEUC and HC.

Embolic effects of Bletilla striata microspheres in renal artery and transplanted VX2 liver tumor model in rabbits.

To evaluate the characteristics of Bletilla striata microspheres (BSMs) and its effects as an embolic agent in a rabbit model. BSMs were prepared with an emulsification-cool condensation-chemical cross-linking method. The characteristics of BSMs in vitro were observed. Embolization experiments were performed in renal artery of rabbit and in a rabbit liver VX2 carcinoma model. Seventy-two New Zealand rabbits were divided into 2 groups, and the right renal artery was embolized with BSMs (200 μm in diameter) in the experimental group and with polyvinyl alcohol (PVA) of the same size in the control group. The pathological findings were examined with hematoxylin-eosin and Masson stainings. Liver and renal functions were tested before and after embolization. VX2 tumor was transplanted in 15 New Zealand rabbits, which were randomly divided into 3 groups (n=5). Group A were treated with saline, group B with a mixture of doxorubicin and lipiodol, and group C with hepatic arterial infusion of BSMs (200 μm in diameter). Tumor growth rate was evaluated by magnetic resonance imaging scan. Apoptosis-related factors (bax, bcl-2) and tumor vascular endothelial cell growth factor (VEGF) were evaluated through immunohistochemical staining. The characteristics of BSMs in vitro were in full compliance with the requirements for use in interventional procedures. In the renal artery embolization experiment, after BSMs intervention, it was more difficult to form collateral circulation than that with PVAs, and the kidney manifested atrophy and calcification. There were no significant difference of liver and renal functions in rabbits between groups. In the liver VX2 carcinoma embolization experiment, compared with group A, the growth rate of VX2 liver tumor and Bcl-2 levels was reduced, while apoptosis index, Bax, and VEGF were increased in group B (P<0.05). There were no significant difference between groups B and C (P>0.05). The characteristics of BSMs in vitro and in vivo meet the requirements for its use as an embolic agent in interventional approaches.

Laparoscopic subperitoneal injection of chemo-loaded particles lowers tumor growth on a rabbit model of peritoneal carcinomatosis.

The purpose of our study was to assess the effect of controlled-release chemotherapy on the growth and viability of peritoneal carcinomatosis treated by subperitoneal injection in a rabbit VX2 model. A model of peritoneal carcinomatosis was created by laparoscopic injection of VX2 tumor in the left and right broad ligaments of 12 White New Zealand rabbits. At day 12, each tumor was randomly treated with a peritumoral injection of 0.5 mL microspheres loaded with doxorubicin (DEM-DOX) or unloaded (DEM-BLAND). Seven days after treatment, tumor volume, tumor viability in histology, local tumor necrosis in contact with DEM, and doxorubicin concentration profile around the drug eluting microspheres (DEM) were measured. Tumor volume was significantly lower in the DEM-DOX group (3.6 ± 3.2 cm3) compared with the DEM-BLAND group (8.9 ± 5.4 cm3) (p = 0.0425). The percentage of viable tumor tissue was significantly lower in the DEM-DOX group (38% ± 17%) compared with the DEM-BLAND group (56% ± 20%) (p = 0.0202). Tissue necrosis was observed around all DEM-DOX up to a distance of 1.094 ± 0.852 mm and never observed around DEM-BLAND. Drug concentration was above the therapeutic level of 1.0 µM up to a distance of 1.4 mm from the DEM to the tumor. Laparoscopic subperitoneal injection of chemo-loaded particles is feasible and lowers tumor growth and viability in a rabbit model of peritoneal carcinomatosis after 1 week.

MODELING OF SOLID LIVER CANCER IN A RABBIT

Possibilities of the liver tumor modeling were assessed in rabbits of Soviet Chinchilla strain by implantation into the left lobe of the liver slices of squamous cell VX2 tumor obtained from donor rabbits inoculated with the tumor in the thigh muscles. The basic parameters of the model were established - the dynamics of tumor growth, inoculation rate, incidence of concomitant abdominal tumors. There was offered a method for minimally invasive monitoring of the development of the tumor after implantation to the liver by means of the level of venous blood granulocytes. It was found that the most appropriate way to diagnose liver tumors in rabbits was computed tomography scan.

Enhancing tissue permeability with MRI guided preclinical focused ultrasound system in rabbit muscle: From normal tissue to VX2 tumor

High Intensity Focused Ultrasound (HIFU) is an emerging noninvasive, nonionizing physical energy based modality to ablate solid tumors with high power, or increase local permeability in tissues/tumors in pulsed mode with relatively low power. Compared with traditional ablative HIFU, nondestructive pulsed HIFU (pHIFU) is present in the majority of novel applications recently developed for enhancing the delivery of drugs and genes. Previous studies have demonstrated the capability of pHIFU to change tissue local permeability for enhanced drug delivery in both mouse tumors and mouse muscle. Further study based on bulk tissues in large animals and clinical HIFU system revealed correlation between therapeutic effect and thermal parameters, which was absent in the previous mouse studies. In this study, we further investigated the relation between the therapeutic effect of pHIFU and thermal parameters in bulky normal muscle tissues based on a rabbit model and a preclinical HIFU system. Correlation between therapeutic effect and thermal parameters was confirmed in our study on the same bulk tissues although different HIFU systems were used. Following the study in bulky normal muscle tissues, we further created bulky tumor model with VX2 tumors implanted on both hind limbs of rabbits and investigated the feasibility to enhance tumor permeability in bulky VX2 tumors in a rabbit model using pHIFU technique. A radiolabeled peptidomimetic integrin antagonist, 111In-DOTA-IA, was used following pHIFU treatment in our study to target VX2 tumor and serve as the radiotracer for follow-up single-photon emission computed tomography (SPECT) scanning. The results have shown significantly elevated uptake of 111In-DOTA-IA in the area of VX2 tumors pretreated by pHIFU compared with the control VX2 tumors not being pretreated by pHIFU, and statistical analysis revealed averaged 34.5% enhancement 24h after systematic delivery of 111In-DOTA-IA in VX2 tumors pretreated by pHIFU compared with the control VX2 tumors.

Biocompatible astaxanthin as a novel marine-oriented agent for dual chemo-photothermal therapy.

The photothermal effect of a marine-oriented xanthophyll carotenoid, astaxanthin (AXT), was characterized based on its potential absorption of visible laser light and conversion of optical light energy into heat for thermal treatment. As an antioxidant and anticancer agent, AXT extracted from marine material can be utilized for photothermal therapy due to its strong light absorption. The current study investigated the feasibility of the marine-based material AXT to increase the therapeutic efficacy of chemo-photothermal therapy (PTT) by assessing photothermal sessions in both cells and tumor tissues. A quasi-cw Q-switched 80 W 532 nm laser system was utilized to induce thermal necrosis in in vitro and in vivo models. An in vitro cytotoxicity study of AXT was implemented using squamous cell carcinoma (VX2) and macrophage (246.7) cell lines. In vivo PTT experiments were performed on 17 rabbits bearing VX2 tumors on their eyes that were treated with or without intratumoral injection of AXT at a dose of 100 μl (300 μg/ml) followed by laser irradiation at a low irradiance of 0.11 W/cm2. Fluorescence microscopy images revealed cellular death via apoptosis and necrosis owing to the dual chemo-photothermal effects induced by AXT. In vivo experimental results demonstrated that the AXT-assisted irradiation entailed a temperature increase by 30.4°C after tumor treatment for 4 min. The relative variations in tumor volume confirmed that the tumors treated with both AXT and laser irradiation completely disappeared 14 days after treatment, but the tumors treated under other conditions gradually grew. Due to selective light absorption, AXT-assisted laser treatment could be an effective thermal therapy for various drug-resistant cancers.

Relationship Between Ktrans and K1 with Simultaneous Versus Separate MR/PET in Rabbits with VX2 Tumors.

To compare the relationship between Ktrans from DCE-MRI and K1 from dynamic 13N-NH3-PET, with simultaneous and separate MR/PET in the VX-2 rabbit carcinoma model. MR/PET was performed simultaneously and separately, 14 and 15 days after VX-2 tumor implantation at the paravertebral muscle. The Ktrans and K1 values were estimated using an in-house software program. The relationships between Ktrans and K1 were analyzed using Pearson's correlation coefficients and linear/non-linear regression function. Assuming a linear relationship, Ktrans and K1 exhibited a moderate positive correlations with both simultaneous (r=0.54-0.57) and separate (r=0.53-0.69) imaging. However, while the Ktrans and K1 from separate imaging were linearly correlated, those from simultaneous imaging exhibited a non-linear relationship. The amount of change in K1 associated with a unit increase in Ktrans varied depending on Ktrans values. The relationship between Ktrans and K1 may be mis-interpreted with separate MR and PET acquisition.

Stabilization Improves Theranostic Properties of Lipiodol®-Based Emulsion During Liver Trans-arterial Chemo-embolization in a VX2 Rabbit Model.

To demonstrate that stability is a crucial parameter for theranostic properties of Lipiodol®-based emulsions during liver trans-arterial chemo-embolization. We compared the theranostic properties of two emulsions made of Lipiodol® and doxorubicin in two successive animal experiments (One VX2 tumour implanted in the left liver lobe of 30 rabbits). Emulsion-1 reproduced one of the most common way of preparation (ratio of oil/water: 1/1), and emulsion-2 was designed to obtain a water-in-oil emulsion with enhanced stability (ratio of oil/water: 3/1, plus an emulsifier). The first animal experiment compared the tumour selectivity of the two emulsions: seven rabbits received left hepatic arterial infusion (HAI) of emulsion-1 and eight received HAI of emulsion-2. 3D-CBCT acquisitions were acquired after HAI of every 0.1mL to measure the densities' ratios between the tumours and the left liver lobes. The second animal experiment compared the plasmatic and tumour doxorubicin concentrations after HAI of 1.5mg of doxorubicin administered either alone (n=3) or in emulsion-1 (n=6) or in emulsion-2 (n=6). Emulsion-2 resulted in densities' ratios between the tumours and the left liver lobes that were significantly higher compared to emulsion-1 (up to 0.4mL infused). Plasmatic doxorubicin concentrations (at 5min) were significantly lower after HAI of emulsion-2 (19.0μg/L) than emulsion-1 (275.3μg/L, p<0.01) and doxorubicin alone (412.0μg/L, p<0.001), and tumour doxorubicin concentration (day-1) was significantly higher after HAI of emulsion-2 (20,957ng/g) than in emulsion-1 (8093ng/g, p<0.05) and doxorubicin alone (2221ng/g, p<0.01). Stabilization of doxorubicin in a water-in-oil Lipiodol®-based emulsion results in better theranostic properties.

Abstract B69: Antitumor effects of combining hemocoagulase with the blocking-microvascular action of microbubbles enhanced ultrasound cavitation on rabbit VX2 liver tumors

Abstract Substantial effort is being directed toward investigating the use of microbubble enhanced ultrasound cavitation (MEUC) to promote penetrate vascular wall and disrupting circulation in liver tumor. In this study we propose and investigate a new method for combining MEUC with hemocoagulase (HC) atrox, which is effectively a vascular targeting to induce embolism effects and combine these with an antiangiogenic treatment strategy. HC was administered was inserted precisely into the tumor under the guidance of real- time ultrasound with a 21-gauge needle. MEUC were conducted at1 MHz frequency probe (with a 400-cycle pulse length and a pulse repetition frequency of 9 Hz) at peak positive pressure of 1 MPa in combination with the commercial microbubble agent SonoVue. MEUC treatments were performed on 10 min on and off periods and HC was administered for 1KU. Rabbits were implanted VX2 tumor mass to establish a liver tumor model. 7 days after tumor implantation, rabbits presented with single liver tumor were randomly divided into 4 study groups: (1) control group were given injections of saline use micro- pump intravenously. (2) HC only injection. (3) MEUC treatment. (4) MEUC+HC treatment. The MEUC induced an acute reduction of blood flow as confirmed with contrast enhanced ultrasound (CEUS) imaging. QontraXt software quantitative analysis time intensity curve (TIC) of the tumor blood perfusion and microvascular changes. The MEUC+HC treatment group showed significant growth inhibition relative to the MEUC-only (p &amp;lt; 0.01) and HC-only treatment groups (p &amp;lt; 0.01). These results indicate the feasibility of a new approach to combining microbubble enhanced ultrasound cavitation with hemocoagulase. Citation Format: Qian Yang, Peng Tang, Liwen Liu, Shuping Ge, Xiaodong Zhou. Antitumor effects of combining hemocoagulase with the blocking-microvascular action of microbubbles enhanced ultrasound cavitation on rabbit VX2 liver tumors. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B69.

Abstract No. 20 - Proof of concept of a gene directed enzyme prodrug therapy with intra-arterial delivery of mesenchymal stem cells in a rabbit VX2 tumor hepatic model

Abstract No. 20 - Proof of concept of a gene directed enzyme prodrug therapy with intra-arterial delivery of mesenchymal stem cells in a rabbit VX2 tumor hepatic model

Preparation of thin-slice gross specimens in rabbit VX2 colorectal cancer model

Objective To invest the preparation of thin-slice gross specimens in rabbit VX2 colorectal cancer (CRC) model in order to provide the observation platform for experimental study in CRC. Methods Fifteen New Zealand white rabbits were implanted VX2 tumor piece into the colonic (13 rabbits) or rectal (2 rabbits) wall. Enhanced CT was performed weekly for 4-6 weeks after inoculation to determine the presence of CRC or metastases. Once CRC or metastases occurred or 6 weeks after implantation, the rabbits were sacrificed regardless of the presence or absence of a CRC or metastases on the CT images. The animals were then frozen in a freezer in the supine position as CT imaging. After 24 hours, the frozen rabbits were cut in the coronal plane into 2 mm- (2 rabbits), 3 mm- (10 rabbits), and 5 mm (3 rabbits)-thick slices using a motorized saw with 1.2 mm-thick saw blade. Each slice of the specimens was photographed by number at each interval (0-5 min, 10-15 min, and >20 min, respectively) and then placed in 10% phosphate-buffered formaldehyde for subsequent pathologic examination. Results Total of 182 slices (range: 15-20 slices, mean: 18.2 slices) of specimens were obtained using 3 mm-cut in 10 rabbits with 2 slices of damage resulted in an intact rate of 98.9% (180/182 slices), 40 slices (range: 11-14 slices, mean: 13.3 slices) for 5 mm- cut in 3 rabbits without slices of damage, and 45 slices (range: 21-24 slices, mean: 22.5 slices) for 2 mm-cut in 2 rabbits with 32 slices of damage resulted in an intact rate of 28.9% (13/45 slices). Comparison of intact rates both in 2 mm-versus (vs) 3 mm- and 5 mm-cut was all statistically significant (P=0.009, 0.002, respectively), but 3 mm-vs 5 mm-cut was statistically insignificant (P=0.964). Photography had a distinct gradation within 10-15 min, in which the anatomic structures between organs was immovable. However, the photographic gradation was not clear within 0-5 min because of a frozen layer on the surface of the specimen. Conversely, the anatomic structures occurred displacement over 20 min owing to the thaw of the specimen. The successful inoculation rate was 66.7% (10/15 rabbits). Specifically, 2 inoculated tumors were found in 3 rabbits for 5 mm-cut with 1 liver metastasis (6 mm) and 6 nodes (1 involved node), 7 inoculated tumors in 10 rabbits for 3 mm-cut with 2 lung metastases (range: 7-10 mm) and 29 nodes (7 involved nodes), respectively.3 mm-cut presented more nodes than that of 5 mm-cut (mean: 4.1 vs. 3.0 nodes) and complete metastasis. Conclusion Thin-slice gross specimens in rabbit VX2 CRC model could be obtained when 3 mm-cut was used in this study, which may provide an effectively experimental platform for tumor staging in animal model. Key words: Cancer, colorectal; Rabbit model; Gross specimen, thin-slice; Preparation

Laser-Activatible Gold Particles for Phase Transformation Imaging and Therapy in Metastatic Lymph Nodes

The gold nanoparticles were incorporated into PLGA/PFH (Au-PLGA/PFH) particles to observe their enhanced ultrasound imaging and treatment effect in rabbit metastatic lymph nodes. Double emulsion evaporation method was used to prepare the Au-PLGA/PFH particles. The size distribution, the morphological and structural characterization, the optical obsorbing property were estimated. The rabbit VX2 tumor was inoculated in rabbits subcutaneous thigh muscles to build popliteal lymph node metastasis of tumor models. After the Au-PLGA/PFH particles were introduced into lymph nodes by rabbit footpad, US were used to image the popliteal lymph nodes in real-time, also the Color Doppler Flow Image (CDFI) were acquired. With a wavelength of 532nm laser irradiation in vitro, the image of lymph nodes were observed under 2D and contrast enhance mode. Improving the laser energy, the irradiation was done every 48 h for a total of three times, this process was observed by US and CDFI. 48 h after the last irradiation, the rabbits were sacrificed, and the lymph node tissue were removed to measure the size, also the HE, immunohistochemistry and transmission electron microscopy (TEM) measurement were carried. The Au-PLGA/PFH particle is about 1 μm in diameter, the gold nanoparticles are located around the shell, these are clearly visible as small black dots in the PLGA shell. A UV-Vis shows there is a strong optical obsorbing peak of the particles in 525nm. Thus, with a 532 nm laser irradiation in vitro, the particles in lymph nodes absorb light energy to enhance the local temperature, when the temperature is over the phase transition threshold of PFH, the particles transfer into bubbles and enhance the US imaging. In addition, as the laser fluence increased, the creating bubble that expanded within the tumor cells, eventually destroyed the cells. Therefore, the lymph nodes enlarge slowly or smaller than before. HE, immunohistochemisty and TEM further conform this effect. This work demonstrates PLGA/PFH particles containing gold nanoparticles can use as US contrast agents and theragnostic agents.

Feasibility of Using 3D Contrast Enhanced Ultrasound Technology to Predict the Treatment Effect of Targeted Drugs-Loaded Thermosensitive Hydrogel Therapy on the Rabbit Vx2 Tumor Model

Minimally-invasive ultrasound (US)-guided tumor microwave ablation (MWA) has been increasing clinical use for treatment of focal liver cancer. However, this technique cannot achieve complete ablation in many cases, especially at margins of tumors > 3 cm in diameter and adjacent to blood vessels is challenging. In the present study, we combined targeted thermosensitive hydrogel with microwave ablation in therapy of rabbit VX2 tumour model. 3D-contrast enhanced ultrasound was used to predict the treatment effect. In this animal care and use committee-approved study, study was carried out in accordance with the guidelines issued by the National Institutes of Health for care of laboratory animals. Aplio500 US system (Toshiba, Japan), equipped with a PVT-382 MV high frequency transducer (3.5MHz) was used. 3D-CEUS was performed on the rabbit VX2 hepatic tumor model (600-1000 g, n=40). Combined microwave ablation with targeted drugs-loaded thermosensitive hydrogel was used to enhance therapeutic efficacy. The feasibility and accuracy of 3D-CEUS imaging were verified by immunohistochemistry results and western blot results. Results demonstrated that intratumoral injection thermosensitive hydrogel to sustained release As2O3 in the cavity after microwave ablation significantly improved the tumor growth inhibition efficiency. During 5 weeks follow-up by 3D-CEUS, increased necrotic areas from 34% to 76% were detected intra-tumor. Furthermore, the anti- angiogenesis effects of Gel-MW was mediated by suppression of CD31, CD34 and VEGF. Thermosensitive hydrogel in combination with US - guided MWA has potential clinical applicability for treatment of liver tumors. 3D-CEUS played a fundamental role in monitoring the efficacy of treatment.

Antitumor Effects of Combining Hemocoagulase with the Blocking Microvascular Action of Microbubbles Enhanced Ultrasound Cavitation on Rabbit Vx2 Liver Tumor

Substantial effort is being directed toward investigating the use of microbubble enhanced ultrasound cavitation (MEUC) to promote penetrate vascular wall and disrupting circulation in liver tumor. In this study we propose and investigate a new method for combining MEUC with hemocoagulase (HC) atrox, which is effectively a vascular targeting to induce embolism effects and combine these with an antiangiogenic treatment strategy. Rabbits were implanted VX2 tumor mass to establish a liver tumor model. 7 days after tumor implantation, rabbits presented with single liver tumor were randomly divided into 4 study groups: (1) control group were given injections of saline use micro- pump intravenously. (2) HC only injection. (3) MEUC treatment. (4) MEUC+HC treatment. The MEUC induced an acute reduction of blood flow as confirmed with contrast enhanced ultrasound (CEUS) imaging. QontraXt software quantitative analysis time intensity curve (TIC) of the tumor blood perfusion and microvascular changes. HC was administered was inserted precisely into the tumor under the guidance of real- time ultrasound with a 21-gauge needle. MEUC were conducted at1 MHz frequency probe (with a 400-cycle pulse length and a pulse repetition frequency of 9 Hz) at peak positive pressure of 1 MPa in combination with the commercial microbubble agent SonoVue. MEUC treatments were performed on 10 min on and off periods and HC was administered for 1KU. Post MEUC+HC treatment at 1 h and 7-day, the parameters of TIC including peak value, RBV and AUC were measured using CEUS were significantly lower than that found in the other treatment groups. The MEUC+HC treatment group showed significant growth inhibition relative to the MEUC-only and HC-only treatment groups. The MEUC+HC treatment group showed significant growth inhibition relative to the MEUC-only (p < 0.01) and HC-only treatment groups (p < 0.01). No damage was observed in the surrounding normal tissues. These results indicate the feasibility of a new approach to combining microbubble enhanced ultrasound cavitation with hemocoagulase.

PUB024 Real-Time Computed Tomography Fluoroscopy Guidance in a Rabbit Model of Solitary Lung Cancer

We evaluate the feasibility and safety of a newly developed solitary lung cancer rabbit model that utilizes real-time computed tomography (CT) fluoroscopy-guided inoculation of VX2 single cell suspensions. Thirty-eight rabbits were divided into four groups according to number of VX2 carcinoma cells, Lipiodol amount, Matrigel amount, and injection needle size. The different VX2 tumor cell suspensions were percutaneously injected into rabbits under real-time CT fluoroscopy guidance. Two weeks later, VX2 lung cancers were confirmed by positron emission tomography/CT, necropsy, and histology. Real-time CT fluoroscopy allowed the precise inoculation of tumor cell suspensions containing Lipiodol. Use of Matrigel and a small-sized needle reduced spreading and leakage of tumor cell suspensions in the lung parenchyma. Solitary lung cancers were successfully established in all rabbits in group 4 (22/22, 100%); these rabbits were inoculated with 150 μl VX2 tumor cells filtered through a 100 μm cell strainer, 100 μl Lipiodol, and 150 μl Matrigel, using 26-gauge needles. Pneumothorax was observed in only 2 of 38 rabbits (5.3%).View Large Image Figure ViewerDownload Hi-res image Download (PPT) Real-time CT fluoroscopy-guided inoculation of the appropriate composition of a VX2 tumor cell suspension using a small sized needle is an easy and safe method to model solitary lung cancer in rabbits.

Total liver CT perfusion imaging for evaluation on rabbit liver VX2 tumor perfusion and comparative analysis through immunohistochemisty

To investigate the correlations among total liver CT perfusion parameters, unpaired arteries (UAs) and microvessel area (MVA) in a rabbit liver VX2 tumor model, and to learn the tumoral angiogenesis condition and the mechanisms for perfusion imaging. Methods: Rabbits with or without the inoculated VX2 tumor in the liver underwent total liver CT perfusion imaging 2 weeks after the operation. Perfusion parameters included blood flow (BF), blood volume (BV), arterial liver perfusion (ALP), portal liver perfusion (PVP), hepatic perfusion index (HPI) for the tumor rim and the surrounding liver tissue. After the examination, the UAs and MVA of tumor tissues were obtained by immunohistochemical staining. The differences of perfusion parameters between the vital tumor rim and the surrounding liver tissue were compared. The correlations among perfusion parameters, UAs and MVA were analyzed. Results: There was significant difference between the CT perfusion parameters at the tumor rim and the surrounding liver tissue or liver tissue of the control group (P<0.05), but there was no significant difference between the perfusion parameters at the surrounding liver tissues of the experimental group and the control (P>0.05). There was positive correlation between UAs and MVA. UAs and MVA were positively correlated with BF, ALP and BV at the tumor rim. UAs and MVA were negatively correlated with PVP. HPI positively correlated with UAs, but it was not correlated with MVA. Conclusion: Total liver CT perfusion can provide quantitative information to evaluate the artery and portal vein perfusion of liver VX2 tumor, and to assess the degree of tumor angiogenesis.

Comparative study on blood perfusion and angiogenesis of intrahepatic VX2 tumors and inflammatory pseudotumor by contrast-enhanced ultrasound in rabbits with fatty liver

Objective To analyze contrast-enhanced ultrasound (CEUS) evaluation on blood perfusion of intrahepatic VX2 tumors and inflammatory pseudotumor in rabbits with fatty liver and further compare the angiogenesis expression. Methods Intrahepatic VX2 tumors and inflammatory pseudotumor in rabbit with fatty liver models were well established. The blood perfusion of VX2 tumors and inflammatory pseudotumor in rabbit fatty liver was analyzed using QontraXt CEUS quantitative analysis software, and the microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression were detected by immunohistochemistry, respectively. Results Twenty VX2 tumor models and 20 inflammatory pseudotumor in fatty liver were successfully established in rabbits. The time to peak (TP), peak intensity (PI) and the area under the curve (AUC) of VX2 tumor in rabbits with fat liver were (24.16±6.58) s, (52.29±13.24) dB, 6.09±2.61; The TP, PI and AUC of IPL in fatty liver were (29.86±6.75) s, (41.36±9.50) dB, 3.86±1.00, respectively. Compared with those for inflammatory pseudotumor lesions in fatty liver rabbits, the time to peak for VX2 tumor lesions were earlier, peak intensity was higher, and area under the curve was larger (P<0.05). The MVD count of VX2 tumor in rabbits with fatty liver was 45.21±8.80, VEGF expression of them was 4.00±0.86; MVD count and VEGF expression of IPL in fatty livers was 21.10±3.31, 2.00±0.86, respectively. Compared with those for inflammatory pseudotumor lesions in fatty liver rabbits, MVD count and VEGF protein expression for VX2 tumors were significantly higher (P<0.05). Conclusions The CEUS blood perfusion, MVD count, and VEGF protein expression for VX2 tumor lesions were higher than those for inflammatory pseudotumor lesions in rabbits with fatty liver. Low mechanical index contrast-enhanced ultrasound combined with QontraXt quantitative analysis software can accurately reflect blood perfusion of benign and malignant tumor as well as angiogenesis of malignancies in fatty liver. Key words: Fatty liver; VX2 xenograft tumor; Inflammatory pseudotumor; Contrast-enhanced ultrasound; Microvascular density; Vascular endothelial growth factor

USPIO enhanced lymph node MRI using 3D multi-echo GRE in a rabbit model.

Ultrasmallsuperparamagnetic iron oxide (USPIO) has been suggested to be a negative MR contrast agent to detect metastatic lymph nodes. Previously reported studies have evaluated the diagnostic performance of USPIO-enhanced MR lymph node imaging based on signal intensity. In this study, we investigate the specific performance of three different parametric approaches (normalized signal intensity, R2 * and susceptibility) using 3D multi-echo gradient echo to quantify the USPIO particles in lymph nodes. Nine rabbits with VX2 tumor implants were scanned before and after USPIO injection. From 3D multi-echo GRE magnitude and phase data, we generated multi-echo combined T2 *-weighted images, an R2 * map, and a quantitative susceptibility map. Eighteen lymph nodes (nine reactive and nine metastatic) were evaluated and showed remarkable signal drops in the area of USPIO accumulation. On parametric analysis, the R2 * difference before and after USPIO injection was significantly different (p < 0.05) between reactive and metastatic lymph nodes; in contrast, the normalized signal intensity and susceptibility were not significantly different between the nodes. Our study showed the potential utility of USPIO-enhanced MRI using R2* mapping from 3D multi-echo GRE for the detection of lymph node metastasis and parametric analysis of lymph node status in a rabbit model. Copyright © 2016 John Wiley & Sons, Ltd.

Echo Decorrelation Imaging of Rabbit Liver and VX2 Tumor during In Vivo Ultrasound Ablation

In open surgical procedures, image-ablate ultrasound arrays performed thermal ablation and imaging on rabbit liver lobes with implanted VX2 tumor. Treatments included unfocused (bulk ultrasound ablation, N = 10) and focused (high-intensity focused ultrasound ablation, N = 13) exposure conditions. Echo decorrelation and integrated backscatter images were formed from pulse-echo data recorded during rest periods after each therapy pulse. Echo decorrelation images were corrected for artifacts using decorrelation measured prior to ablation. Ablation prediction performance was assessed using receiver operating characteristic curves. Results revealed significantly increased echo decorrelation and integrated backscatter in both ablated liver and ablated tumor relative to unablated tissue, with larger differences observed in liver than in tumor. For receiver operating characteristic curves computed from all ablation exposures, both echo decorrelation and integrated backscatter predicted liver and tumor ablation with statistically significant success, and echo decorrelation was significantly better as a predictor of liver ablation. These results indicate echo decorrelation imaging is a successful predictor of local thermal ablation in both normal liver and tumor tissue, with potential for real-time therapy monitoring.

An Integrated Nanotechnology-Enabled Transbronchial Image-Guided Intervention Strategy for Peripheral Lung Cancer.

Early detection and efficient treatment modality of early-stage peripheral lung cancer is essential. Current nonsurgical treatments for peripheral lung cancer show critical limitations associated with various complications, requiring alternative minimally invasive therapeutics. Porphysome nanoparticle-enabled fluorescence-guided transbronchial photothermal therapy (PTT) of peripheral lung cancer was developed and demonstrated in preclinical animal models. Systemically administered porphysomes accumulated in lung tumors with significantly enhanced disease-to-normal tissue contrast, as confirmed in three subtypes of orthotopic human lung cancer xenografts (A549, H460, and H520) in mice and in an orthotopic VX2 tumor in rabbits. An in-house prototype fluorescence bronchoscope demonstrated the capability of porphysomes for in vivo imaging of lung tumors in the mucosal/submucosal layers, providing real-time fluorescence guidance for transbronchial PTT. Porphysomes also enhanced the efficacy of transbronchial PTT significantly and resulted in selective and efficient tumor tissue ablation in the rabbit model. A clinically used cylindrical diffuser fiber successfully achieved tumor-specific thermal ablation, showing promising evidence for the clinical translation of this novel platform to impact upon nonsurgical treatment of early-stage peripheral lung cancer. Cancer Res; 76(19); 5870-80. ©2016 AACR.