Dual source hybrid spectral micro-CT using an energy-integrating and a photon-counting detector.

Preclinical micro-CT provides a hotbed in which to develop new imaging technologies, including spectral CT using photon counting detector (PCD) technology. Spectral imaging using PCDs promises to expand x-ray CT as a functional imaging modality, capable of molecular imaging, while maintaining CT's role as a powerful anatomical imaging modality. However, the utility of PCDs suffers due to distorted spectral measurements, affecting the accuracy of material decomposition. We attempt to improve material decomposition accuracy using our novel hybrid dual-source micro-CT system which combines a PCD and an energy integrating detector. Comparisons are made between PCD-only and hybrid CT results, both reconstructed with our iterative, multi-channel algorithm based on the split Bregman method and regularized with rank-sparse kernel regression. Multi-material decomposition is performed post-reconstruction for separation of iodine (I), gold (Au), gadolinium (Gd), and calcium (Ca). System performance is evaluated first in simulations, then in micro-CT phantoms, and finally in an in vivo experiment with a genetically modified p53fl/fl mouse cancer model with Au, Gd, and I nanoparticle (NP)-based contrasts agents. Our results show that the PCD-only and hybrid CT reconstructions offered very similar spatial resolution at 10% MTF (PCD: 3.50 lp mm-1; hybrid: 3.47 lp mm-1) and noise characteristics given by the noise power spectrum. For material decomposition we note successful separation of the four basis materials. We found that hybrid reconstruction reduces RMSE by an average of 37% across all material maps when compared to PCD-only of similar dose but does not provide much difference in terms of concentration accuracy. The in vivo results show separation of targeted Au and accumulated Gd NPs in the tumor from intravascular iodine NPs and bone. Hybrid spectral micro-CT can benefit nanotechnology and cancer research by providing quantitative imaging to test and optimize various NPs for diagnostic and therapeutic applications.

Murine Models of Bone Sarcomas.

This chapter describes the procedures for inducing bone sarcoma in mice. Two models based on inoculation of cancer cells in paraosseous and intraosseous site will be described. In addition to providing technical aspects of anesthesia and surgical options, key information of cell preparation and postoperative follow-up will be discussed.

Dual-Energy CT Imaging of Tumor Liposome Delivery After Gold Nanoparticle-Augmented Radiation Therapy.

Gold nanoparticles (AuNPs) are emerging as promising agents for both cancer therapy and computed tomography (CT) imaging. AuNPs absorb x-rays and subsequently release low-energy, short-range photoelectrons during external beam radiation therapy (RT), increasing the local radiation dose. When AuNPs are near tumor vasculature, the additional radiation dose can lead to increased vascular permeability. This work focuses on understanding how tumor vascular permeability is influenced by AuNP-augmented RT, and how this effect can be used to improve the delivery of nanoparticle chemotherapeutics. Methods: Dual-energy CT was used to quantify the accumulation of both liposomal iodine and AuNPs in tumors following AuNP-augmented RT in a mouse model of primary soft tissue sarcoma. Mice were injected with non-targeted AuNPs, RGD-functionalized AuNPs (vascular targeting), or no AuNPs, after which they were treated with varying doses of RT. The mice were injected with either liposomal iodine (for the imaging study) or liposomal doxorubicin (for the treatment study) 24 hours after RT. Increased tumor liposome accumulation was assessed by dual-energy CT (iodine) or by tracking tumor treatment response (doxorubicin). Results: A significant increase in vascular permeability was observed for all groups after 20 Gy RT, for the targeted and non-targeted AuNP groups after 10 Gy RT, and for the vascular-targeted AuNP group after 5 Gy RT. Combining targeted AuNPs with 5 Gy RT and liposomal doxorubicin led to a significant tumor growth delay (tumor doubling time ~ 8 days) compared to AuNP-augmented RT or chemotherapy alone (tumor doubling time ~3-4 days). Conclusions: The addition of vascular-targeted AuNPs significantly improved the treatment effect of liposomal doxorubicin after RT, consistent with the increased liposome accumulation observed in tumors in the imaging study. Using this approach with a liposomal drug delivery system can increase specific tumor delivery of chemotherapeutics, which has the potential to significantly improve tumor response and reduce the side effects of both RT and chemotherapy.

Evaluation of fluorescence-guided surgery agents in a murine model of soft tissue fibrosarcoma.

BACKGROUND AND OBJECTIVES: Soft tissue sarcomas (STS) are mesenchymal malignancies. Treatment mainstay is surgical resection with negative margins ± adjuvant treatment. Fluorescence-guided surgical (FGS) resection can delineate intraoperative margins; FGS has improved oncologic outcomes in other malignancies. This novel strategy may minimize resection-associated morbidity while improving local tumor control. METHODS: We evaluate the tumor-targeting specificity and utility of fluorescence-imaging agents to provide disease-specific contrast. Mice with HT1080 fibrosarcoma tumors received one of five probes: cetuximab-IRDye800CW (anti-EGFR), DC101-IRDye800CW (anti-VEGFR-2), IgG-IRDye800CW, the cathepsin-activated probe Prosense750EX, or the small molecule probe IntegriSense750. Tumors were imaged daily using open- and closed-field fluorescence imaging systems. Tumor-to-background ratios (TBR) were evaluated. On peak TBR days, probe sensitivity was evaluated. Tumors were stained and imaged microscopically. RESULTS: At peak, closed-field imaging TBR of cetuximab-IRDye800CW (16.8) was significantly greater (P < 0.0001) than Integrisense750 (7.0), Prosense750EX (5.8), and DC101-IRDye800CW (3.7). All agents successfully localized as little as 1.0 mg of tumor tissue in the post-resection bed; cetuximab-IRDye800CW generated the greatest contrast (2.5). Cetuximab-IRDye800CW revealed strong tumor affinity microscopically; tumor fluorescence intensity was significantly greater (P < 0.0004) than 0.2 mm away from tumor border. CONCLUSION: This study demonstrates cetuximab-IRDye800CW superiority. FGS has the potential to improve post-resection morbidity and mortality by improving disease detection.

Analgesic effects of adenylyl cyclase inhibitor NB001 on bone cancer pain in a mouse model.

BACKGROUND: Cancer pain, especially the one caused by metastasis in bones, is a severe type of pain. Pain becomes chronic unless its causes and consequences are resolved. With improvements in cancer detection and survival among patients, pain has been considered as a great challenge because traditional therapies are partially effective in terms of providing relief. Cancer pain mechanisms are more poorly understood than neuropathic and inflammatory pain states. Chronic inflammatory pain and neuropathic pain are influenced by NB001, an adenylyl cyclase 1 (AC1)-specific inhibitor with analgesic effects. In this study, the analgesic effects of NB001 on cancer pain were evaluated. RESULTS: Pain was induced by injecting osteolytic murine sarcoma cell NCTC 2472 into the intramedullary cavity of the femur of mice. The mice injected with sarcoma cells for four weeks exhibited significant spontaneous pain behavior and mechanical allodynia. The continuous systemic application of NB001 (30 mg/kg, intraperitoneally, twice daily for three days) markedly decreased the number of spontaneous lifting but increased the mechanical paw withdrawal threshold. NB001 decreased the concentrations of cAMP and the levels of GluN2A, GluN2B, p-GluA1 (831), and p-GluA1 (845) in the anterior cingulate cortex, and inhibited the frequency of presynaptic neurotransmitter release in the anterior cingulate cortex of the mouse models. CONCLUSIONS: NB001 may serve as a novel analgesic to treat bone cancer pain. Its analgesic effect is at least partially due to the inhibition of AC1 in anterior cingulate cortex.

Dose painting based on tumor uptake of Cu-ATSM and FDG: a comparative study.

BACKGROUND: Hypoxia and increased glycolytic activity of tumors are associated with poor prognosis. The purpose of this study was to investigate differences in radiotherapy (RT) dose painting based on the uptake of 2-deoxy-2-[(18) F]-fluorodeoxyglucose (FDG) and the proposed hypoxia tracer, copper(II)diacetyl-bis(N(4))-methylsemithiocarbazone (Cu-ATSM) using spontaneous clinical canine tumor models. METHODS: Positron emission tomography/computed tomography scans of five spontaneous canine sarcomas and carcinomas were obtained; FDG on day 1 and (64)Cu-ATSM on day 2 and 3 (approx. 3 and 24 hours pi.). Sub-volumes for dose escalation were defined by a threshold-based method for both tracers and five dose escalation levels were formed in each sub-volume. Volumetric modulated arc therapy plans were optimized based on the dose escalation regions for each scan for a total of three dose plans for each dog. The prescription dose for the GTV was 45 Gy (100%) and it was linearly escalated to a maximum of 150%. The correlations between dose painting plans were analyzed with construction of dose distribution density maps and quality volume histograms (QVH). Correlation between high-dose regions was investigated with Dice correlation coefficients. RESULTS: Comparison of dose plans revealed varying degree of correlation between cases. Some cases displayed a separation of high-dose regions in the comparison of FDG vs. (64)Cu-ATSM dose plans at both time points. Among the Dice correlation coefficients, the high dose regions showed the lowest degree of agreement, indicating potential benefit of using multiple tracers for dose painting. QVH analysis revealed that FDG-based dose painting plans adequately covered approximately 50% of the hypoxic regions. CONCLUSION: Radiotherapy plans optimized with the current approach for cut-off values and dose region definitions based on FDG, (64)Cu-ATSM 3 h and 24 h uptake in canine tumors had different localization of the regional dose escalation levels. This indicates that (64)Cu-ATSM at two different time-points and FDG provide different biological information that has to be taken into account when using the dose painting strategy in radiotherapy treatment planning.

Fully automated synthesis of ¹¹C-acetate as tumor PET tracer by simple modified solid-phase extraction purification.

INTRODUCTION: Automated synthesis of (11)C-acetate ((11)C-AC) as the most commonly used radioactive fatty acid tracer is performed by a simple, rapid, and modified solid-phase extraction (SPE) purification. METHODS: Automated synthesis of (11)C-AC was implemented by carboxylation reaction of MeMgBr on a polyethylene Teflon loop ring with (11)C-CO2, followed by acidic hydrolysis with acid and SCX cartridge, and purification on SCX, AG11A8 and C18 SPE cartridges using a commercially available (11)C-tracer synthesizer. Quality control test and animals positron emission tomography (PET) imaging were also carried out. RESULTS: A high and reproducible decay-uncorrected radiochemical yield of (41.0 ± 4.6)% (n=10) was obtained from (11)C-CO2 within the whole synthesis time about 8 min. The radiochemical purity of (11)C-AC was over 95% by high-performance liquid chromatography (HPLC) analysis. Quality control test and PET imaging showed that (11)C-AC injection produced by the simple SPE procedure was safe and efficient, and was in agreement with the current Chinese radiopharmaceutical quality control guidelines. CONCLUSION: The novel, simple, and rapid method is readily adapted to the fully automated synthesis of (11)C-AC on several existing commercial synthesis module. The method can be used routinely to produce (11)C-AC for preclinical and clinical studies with PET imaging.

Experimental model of naturally occurring post-radiation sarcoma: interest of positron emission tomography (PET) for early detection.

Radiotherapy is an integral part of overall cancer therapy. One of the most serious adverse effects of irradiation concern, for long-term survivors, the development of post-radiation sarcoma (PRS) in healthy tissues located within the irradiated area. PRS have bad prognosis and are often detected at a late stage. Therefore, it is obvious that the early detection PRS is a key-point and the development of preclinical models is worthy to evaluate innovative diagnostic and therapeutic procedures. The aim of this study was to develop a spontaneous rodent model of PRS and to evaluate the potency of Positron Emission Tomography (PET) for early detection. Fifteen Wistars rats were irradiated unilateraly on the hindlimb with a single dose of 30 Gy. Sequential analysis was based on observational staging recordings, Computerized Tomography (CT) scanning and PET. Tumors were removed and, histopathological and immunochemistry analyses were performed. Among the irradiated rats, 12 sarcomas (80%) were detected. All tumors occurred naturallty within the irradiated hindlimb and were highly aggressive since most tumors (75%) were successfully transplanted and maintained by serial transplantation into nude mice. Upon serial staging recordings, using PET, was found to enable the detection of PRS earlier after irradiation than with the other methods (i.e. 11.9 ± 1.8 vs 12.9 ± 2.6 months). These results confirmed the interest of experimental models of PRS for the preclinical evaluation of innovative diagnostic strategies and confirmed the potency of PET for early detection of PRS. This preclinical model of PRS can also be proposed for the evaluation of therapeutic strategies.

High resolution SPECT imaging for visualization of intratumoral heterogeneity using a SPECT/CT scanner dedicated for small animal imaging.

OBJECTIVES: Tumor interiors are never homogeneous and in vivo visualization of intratumoral heterogeneity would be an innovation that contributes to improved cancer therapy. But, conventional nuclear medicine tests have failed to visualize heterogeneity in vivo because of limited spatial resolution. Recently developed single photon emission computed tomographic (SPECT) scanners dedicated for small animal imaging are of interest due to their excellent spatial resolution of <1 mm, but few studies have focused on the evaluation of intratumoral heterogeneity. We investigated the optimal conditions related to high resolution imaging of heterogeneous tumor interiors using a small animal SPECT scanner. METHODS: The conditions related to SPECT/CT visualization of heterogeneous tumor interiors were investigated using phantoms with (111)In and simulations of actual small animal imaging. The optimal conditions obtained were validated by in vivo imaging of sarcoma 180-bearing mice. RESULTS: Larger number of counts must be obtained within limited acquisition time to visualize tumor heterogeneity in vivo in animal imaging, compared to cases that simply detect tumors. At an acquisition time of 30 min, better image quality was obtained with pinhole apertures diameter of 1.4 mm than of 1.0 mm. The obtained best spatial resolution was 1.3 mm, it was acceptable for our purpose, though a little worse than the best possible performance of the scanner (1.0 mm). Additionally, the reconstruction parameters, such as noise suppression, voxel size, and iteration/subset number, needed to be optimized under the limited conditions and were different from those found under the ideal condition. The minimal radioactivity concentration for visualization of heterogeneous tumor interiors was estimated to be as high as 0.2-0.5 MBq/mL. Liposomes containing (111)In met this requirement and were administered to tumor-bearing mice. SPECT imaging successfully showed heterogeneous (111)In distribution within the tumors in vivo with good spatial resolution. A threshold of 0.2 MBq/g for clear visualization of tumor heterogeneity was validated. Autoradiograms obtained ex vivo of excised tumors confirmed that the in vivo SPECT images accurately depicted the heterogeneous intratumoral accumulation of liposomes. CONCLUSION: Intratumoral heterogeneity was successfully visualized under the optimized conditions using a SPECT/CT scanner.

The biological characterization of (99m)Tc-BnAO-NI as a SPECT probe for imaging hypoxia in a sarcoma-bearing mouse model.

OBJECTIVES: Tumor growth beyond the region where vascular oxygen can reach creates a hypoxic domain. In this study, BnAO, a ligand that had been labeled with (99m)Tc-pertechnetate for hypoxia imaging, was conjugated with 2-nitroimidazole to give 3,3,10,10-tetramethyl-1-(2-nitro-1H-imidazo-1-y1)-4,9-diazadodecane-2,11- dionedioxime (BnAO-NI) as a potential ligand for hypoxia detection. Pentoxifylline is a peripheral vasodilator and has been used as a radiosensitizer in tumor radiotherapy. (99m)Tc-BnAO-NI/SPECT was applied to noninvasively assess the pharmacological effect of pentoxifylline in reducing tumor hypoxia in vivo. METHODS: BnAO-NI was synthesized and formulated with methylene diphosphonate (MDP), stannous chloride and carbonate buffer to afford kits. After mixing with (99m)Tc-pertechnetate, (99m)Tc-BnAO-NI injection can be readily prepared. The partition coefficient, radiochemical purity and in vitro stability were determined. Cellular uptake of radiotracers in KHT cells under hypoxia was conducted in a CO(2) incubator at 37°C under hypoxia or normoxia. A biodistribution study after intravenous injection of (99m)Tc-BnAO-NI in KHT sarcoma-implanted C3H mice was performed. The effect of pentoxifylline (100 mg/kg) on reducing tumor hypoxia was also studied. RESULTS: The radiochemical purity (RCP) of the (99m)Tc-BnAO-NI preparation was greater than 96% and stable at ambient temperature for 24h (RCP>90%). The accumulation of (99m)Tc-BnAO-NI and (99m)Tc-BnAO in KHT cells under hypoxia were 3.57 and 4.13-fold higher than those under normoxic environment, indicating unambiguous oxygen-dependent uptakes of these two probes. The distribution of (99m)Tc-BnAO-NI in KHT sarcoma-bearing mice revealed rapid clearance from the blood circulation. The tumor uptake peaked at 2h post-injection (0.32 ± 0.05%ID/g) with tumor-to-blood and tumor-to-muscle ratios of 10.32 and 3.96, respectively. The effect of pentoxifylline on the tumor blood perfusion was obvious. The tumor-to-muscle ratios at 2h post-injection of (99m)Tc-BnAO-NI with and without pentoxifylline pretreatment were 1.67 ± 0.38 and 2.59 ± 0.25, respectively (p = 0.025, n = 3). CONCLUSION: This study demonstrates that (99m)Tc-BnAO-NI is a hypoxia-sensitive radio probe for monitoring hypoxic regions in a malignant neoplasm. However, (99m)Tc-BnAO-NI, though with higher lipophilicity than (99m)Tc-BnAO, did not achieve better specific accumulation in hypoxic tissues. (99m)Tc-BnAO-NI/SPECT could be applied in clinics to noninvasively evaluate the feasibility of using pentoxifylline as a radiosensitizer by reducing tumor hypoxia in vivo.

Improved diagnostics through quantitative ultrasound imaging.

Conventional B-mode imaging in ultrasound consists of displaying the log-compressed envelope of the backscattered signal. While clinical ultrasonic B-mode images have good spatial resolution, i.e., better than a millimeter, the contrast resolution of ultrasonic B-mode images is typically low. However, additional information is contained in the ultrasonic backscattered signal, which can be used to create images related to tissue microstructure. Because diagnosis of disease is typically based on histological examination of tissue microstructure, the ability to quantify and describe tissue microstructure through ultrasound may result in improved diagnostic capabilities of ultrasound. Tissue-mimicking phantoms and animal models of breast cancer were used to assess the ability of novel ultrasonic imaging techniques to quantify microstructure. Four parameters were extracted from the ultrasonic backscattered signal and related to the microstructure. The effective scatterer diameter (ESD) and the effective acoustic concentration (EAC) parameters were based on modeling the frequency dependence of the backscatter. The k parameter (which quantifies the periodicity of scatterer locations) and the mu parameter (which estimates the number of scatterers per resolution cell) were based on modeling the statistics of the backscattered envelope. Images constructed with these parameters resulted in an increase in contrast between diseased tissue and normal tissues but at the expense of spatial resolution. Specifically, in simulation, quantitative ultrasound (QUS) increased the contrast-to-noise ratio (CNR) between targets and background by more than 10 times in some cases. Statistically significant differences were observed between three kinds of tumors using the ESD, EAC, and k parameters. QUS imaging was also improved with the addition of coded excitation. A novel coded excitation technique was used that improved the variance of estimates over conventional pulsing methods, e.g- , the variance of ESD estimates were reduced by a factor of up to 10.

Preparation and in-vivo evaluation of (188)Re(CO)(3)-colchicine complex for use as tumor-targeting agent.

The Re(I)-tricarbonyl synthon, [(188)Re(H(2)O)(3)(CO)(3)](+), was prepared by using carbon monoxide gas and amine-borane as the reducing agent. Colchicine, a naturally occurring cytotoxic alkaloid, was derivatized to iminodiacetic acid, the required array for the tridentate ligand system for coordination to the Re(I)-tricarbonyl core. (188)Re(CO)(3)-colchicine iminodiacetic acid (IDA) complex could be prepared in >95% radiochemical purity, as determined by high-performance liquid chromatography. The chemical characterization of (188)Re(CO)(3)-colchicine-IDA complex has been carried out by preparing the corresponding cold Re(CO)(3)-complex. The radiolabeled complex was stable at room temperature, even after 48 hours postpreparation, as well as against histidine and cysteine ligand exchange studies. Biodistribution studies were carried out in the murine fibrosarcoma tumor model. Tumor uptake of 1.7 +/- 0.03 percent injected dose per g (%ID/g) was observed at 3 hours postinjection (h.p.i.), which increased to 4.1 +/- 1.3 %ID/g at 24 h.p.i. Tumor-blood and tumor-muscle ratios were 0.14 and 1 at 1 h.p.i. that increased to 0.95 and 4 at 24 h.p.i., respectively. Retention of the complex in tumor for more than one half-life of (188)Re(t(1/2) = 17 hours) indicates its potentiality for tumor therapy.

Extended three-dimensional impedance map methods for identifying ultrasonic scattering sites.

The frequency-dependent ultrasound backscatter from tissues contains information about the microstructure that can be quantified. In many cases, the anatomic microstructure details responsible for ultrasonic scattering remain unidentified. However, their identification would lead to potentially improved methodologies for characterizing tissue and diagnosing disease from ultrasonic backscatter measurements. Recently, three-dimensional (3D) acoustic models of tissue microstructure, termed 3D impedance maps (3DZMs), were introduced to help to identify scattering sources [J. Mamou, M. L. Oelze, W. D. O'Brien, Jr., and J. F. Zachary, "Identifying ultrasonic scattering sites from 3D impedance maps," J. Acoust. Soc. Am. 117, 413-423 (2005)]. In the current study, new 3DZM methodologies are used to model and identify scattering structures. New processing procedures (e.g., registration, interpolations) are presented that allow more accurate 3DZMs to be constructed from histology. New strategies are proposed to construct scattering models [i.e., form factor (FF)] from 3DZMs. These new methods are tested on simulated 3DZMs, and then used to evaluate 3DZMs from three different rodent tumor models. Simulation results demonstrate the ability of the extended strategies to accurately predict FFs and estimate scatterer properties. Using the 3DZM methods, distinct FFs and scatterer properties were obtained for each tumor examined.

Production and tumour uptake of [64Cu]Pyruvaldehyde-bis (N4-methylthiosemicarbazone) for PET and/or therapeutic purposes.

BACKGROUND: Copper-64 (T(1/2)=12.7 degrees h) is an important radionuclide used both in PET imaging and therapy. [(64)Cu]-pyruvaldehyde- bis(N(4)-methylthiosemicarbazone) ([64Cu]-PTSM) has already been used in the detection of cerebral and myocardial blood flow. In this study, a simple production method and tumor accumulation of [(64)Cu]-PTSM in fibrosarcoma-bearing mice were reported. MATERIAL AND METHODS: Cu-64 was produced via the 68Zn(p, alpha n)(64)Cu nuclear reaction. [(64)Cu]-PTSM was prepared using in-house made PTSM ligand and [(64)Cu]cuprous acetate and injected to fibrosarcoma-bearing mice. RESULTS: Copper-64 was prepared in chloride form ( approximately 200 mCi, > 95% chemical yield at 180 degrees microA for 1.1 h irradiation, radionuclidic purity > 96%, copper-67 as impurity). The solution of (64)Cu- PTSM was prepared in > 80% radiochemical yield and more than 98% radiochemical purity. A significant tumor uptake was observed 2 hours post injection in tumor-bearing mice (tumor/muscle: 9, tumor/blood: 6). CONCLUSION: [(64)Cu]-PTSM was prepared on a radiopharmaceutical scale using readily available zinc-68, with high quality and was shown to possess application in the therapy and/or imaging of fibrosarcoma.

The effect of electromagnetic field and local inductive hyperthermia on nonlinear dynamics of the growth of transplanted animal tumors.

AIM: To examine the effects of electromagnetic field with amplified magnetic component and local inductive hyperthermia (IH) on nonlinear dynamics of the growth of animal tumors. MATERIALS AND METHODS: Guerin carcinoma, Lewis lung carcinoma, sarcoma 45, Walker 256 carcinosarcoma and Pliss lymphosarcoma were studied. The animal tumors were exposed inside of loop aerial, 3 cm in diameter locally for 30 min. Parameters of electromagnetic irradiation (EI): frequency 40 MHz, magnetic intensity 72 A/m, electric intensity 200 V/m and the output power 50 W. The temperature measured by immersion of thermocouple inside the center of the tumor didn't exceed 38.5-39.5 degrees C. Nonlinear dynamics of the growth of animal tumors was analyzed by autocatalytic equation. The heterogeneity of ultrasonic image of the tumor was analyzed by Moran spatial autocorrelation. RESULTS: The strongest inhibition effect under the influence of EI was in Pliss lymphosarcoma and sarcoma 45. The growth stimulation of animal tumors after EI was recorded in Walker 256 carcinosarcoma. The use of mild IH increased the blood flow in the tumor of Guerin carcinoma. CONCLUSION: These results are important for clinical application because they testify the necessity of optimization of schemes for local EI during anticancer neoadjuvant therapy with the use of drugs or magnetic nanoparticles. The use of mild IH as a basis for the monotherapy of malignant tumors is not expedient.

EWS/FLI-1 oncoprotein subtypes impose different requirements for transformation and metastatic activity in a murine model.

Ewing sarcoma/primitive neuroectodermal tumors (EWS/PNET) are characterized by specific chromosomal translocations most often generating a chimeric EWS/FLI-1 gene. Depending on the number of juxtaposed exons assembled, several fusion types have been described with different incidences and prognoses. To assess the impact of each fusion type on the specific phenotypic, tumorigenic, and metastatic features of EWS/PNET, we developed an amenable system using a murine mesenchymal multipotent C3H10T1/2 cell line. Upon transduction of EWS/FLI-1, cells acquired dramatic morphological changes in vitro, including a smaller size and "neurite-like" membrane elongations. Chimeric fusion proteins conferred oncogenic properties in vitro, including anchorage-independent growth and an increased rate of proliferation. Furthermore, EWS/FLI-1 expression blocked mineralization, with concomitant repression of osteoblastic genes, and induced a dramatic repression of the adipocytic differentiation program. Moreover, EWS/FLI-1 promoted an aberrant neural phenotype by the de novo expression of specific neural genes. The intramuscular injection of transduced cells led to tumor development and the induction of overt osteolytic lesions. Analogously, to what was observed in human tumors, type 2 EWS/FLI-1 cells formed primary tumors in immunodeficient mice with a higher incidence and a lower latency than cells bearing types 1 and 3 fusions. By contrast, cells expressing types 2 and 3 fusions showed specific metastatic activity with a higher number of macroscopic metastases in soft tissues and osteolytic lesions in the limbs as compared to type-1-expressing cells. Therefore, the structure of each oncoprotein strongly influenced its tumorigenicity and metastagenicity. Thus, this model provides a basis for understanding the genetic determinants involved in Ewing tumor development and metastatic activity and represents a cellular system to analyze other oncoproteins involved in human sarcomagenesis.

[Characteristics and applications of a flat panel computer tomography system]. / Eigenschaften und Anwendungen der Flächendetektor-basierten Volumen-Computertomographie.

PURPOSE: To assess a new flat panel volume computed tomography (FP-VCT) with very high isotropic spatial resolution as well as high Z-axis coverage. MATERIALS AND METHODS: The prototype of an FP-VCT scanner with a detector cell size of 0.2 mm was used for numerous phantom studies, specimen examinations, and animal research projects. RESULTS: The high spatial resolution of the new system can be used to accurately determine solid tumor volume, thus allowing for earlier assessment of the therapeutic response. In animal experimentation, whole-body perfusion mapping of mice is feasible. The high spatial resolution also improves the classification of coronary artery atherosclerotic plaques in the isolated post mortem human heart. With the depiction of intramyocardial segments of the coronary arteries, investigations of myocardial collateral circulation are feasible. In skeletal applications, an accurate analysis of the smallest bony structures, e. g., petrous bone and dental preparations, can be successfully performed, as well as investigations of repetitive studies of fracture healing and the treatment of osteoporosis. CONCLUSION: The introduction of FP-VCT opens up new applications for CT, including the field of molecular imaging, which are highly attractive for future clinical applications. Present limitations include limited temporal resolution and necessitate further improvement of the system.

Effect of the second-generation vascular disrupting agent OXi4503 on tumor vascularity.

PURPOSE: As first-generation small-molecule vascular disrupting agents (VDA) have begun to enter clinical trials, second-generation agents are under active development. One such agent is the combretastatin A4 disodium phosphate (CA4P) analogue OXi4503 (CA1P). EXPERIMENTAL DESIGN: C3H/HeJ mice bearing KHT sarcomas were treated with CA4P and OXi4503 and the effect on tumor vasculature was determined by evaluating the extent of vascular shutdown (Hoechst-33342 vessel staining) and tumor perfusion inhibition (dynamic contrast-enhanced magnetic resonance imaging). Dynamic contrast-enhanced magnetic resonance imaging and tumor necrosis end points also were used to examine the pathophysiologic tumor effects following repeated exposures to these agents. RESULTS: Single doses of either agent (CA4P, 100 mg/kg; OXi4503, 25 mg/kg) resulted in an 80% to 90% reduction in tumor perfusion 4 hours after treatment. Whereas recovery in tumor perfusion was observed 48 hours posttreatment, this recovery was significantly slower in mice treated with OXi4503. Tumors re-treated with either VDA 72 hours after the first drug exposure showed a similar reduction and recovery in tumor perfusion. Histologic evidence showed the presence of a smaller viable rim after exposure to OXi4503 than that observed after CA4P treatment. Furthermore, the extent of recovery of tumor necrosis 72 hours after drug treatment was less for OXi4053. CONCLUSIONS: The present studies show that the second-generation VDA OXi4503 possesses significant antivascular effects in solid tumors. Importantly, the vasculature of tumors of mice that had received an initial dose this agent was as responsive to a subsequent treatment.

Visualization of a primary anti-tumor immune response by positron emission tomography.

Current methodologies that monitor immune responses rely on invasive techniques that sample tissues at a given point in time. New technologies are needed to elucidate the temporal patterns of immune responses and the spatial distribution of immune cells on a whole-body scale. We describe a noninvasive, quantitative, and tomographic approach to visualize a primary anti-tumor immune response by using positron emission tomography (PET). Bone marrow chimeric mice were generated by engraftment of hematopoietic stem and progenitor cells transduced with a trifusion reporter gene encoding synthetic Renilla luciferase (hRluc), EGFP, and Herpes virus thymidine kinase (sr39TK). Mice were challenged with the Moloney murine sarcoma and leukemia virus complex (M-MSV/M-MuLV), and the induced immune response was monitored by using PET. Hematopoietic cells were visualized by using 9-[4-[(18)F]fluoro-3-(hydroxymethyl)butyl]guanine ([(18)F]FHBG), a radioactive substrate specific for the sr39TK PET reporter protein. Immune cell localization and expansion were seen at the tumor and draining lymph nodes (DLNs). 2-[(18)F]fluoro-2-deoxy-D-glucose ([(18)F]FDG), which is sequestered in metabolically active cells, was used to follow tumor growth and regression. Elevated glucose metabolism was also seen in activated lymphocytes in the DLNs by using the [(18)F]FDG probe. When M-MSV/M-MuLV-challenged mice were treated with the immunosuppressive drug dexamethasone, activation and expansion of immune cell populations in the DLNs could no longer be detected with PET imaging. The method we describe can be used to kinetically measure the induction and therapeutic modulations of cell-mediated immune responses.