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  • 1
    Keywords: IN-VITRO ; AGENTS ; IN-VIVO ; PERFUSION ; THERAPY ; CT ; HEPATOCELLULAR-CARCINOMA ; liver ; TISSUE ; MRI ; CATHETER ; embolization ; X-RAY ; ARTERIOVENOUS-MALFORMATIONS ; MICROSPHERES ; ARTERY EMBOLIZATION ; ENDOVASCULAR EMBOLIZATION ; multimodal ; THERAPEUTIC EMBOLIZATION ; UTERINE FIBROID EMBOLIZATION
    Abstract: Objectives: Embolization therapy is gaining importance in the treatment of malignant lesions, and even more in benign lesions. Current embolization materials are not visible in imaging modalities. However, it is assumed that directly visible embolization material may provide several advantages over current embolization agents, ranging from particle shunt and reflux prevention to improved therapy control and follow-up assessment. X-ray-as well as magnetic resonance imaging (MRI)-visible embolization materials have been demonstrated in experiments. In this study, we present an embolization material with the property of being visible in more than one imaging modality, namely MRI and x-ray/computed tomography (CT). Characterization and testing of the substance in animal models was performed. Materials and Methods: To reduce the chance of adverse reactions and to facilitate clinical approval, materials have been applied that are similar to those that are approved and being used on a routine basis in diagnostic imaging. Therefore, x-ray-visible Iodine was combined with MRI-visible Iron (Fe3O4) in a macroparticle (diameter, 40-200 mu m). Its core, consisting of a copolymerized monomer MAOETIB (2-methacryloyloxyethyl [2,3,5-triiodobenzoate]), was coated with ultra-small paramagnetic iron oxide nanoparticles (150 nm). After in vitro testing, including signal to noise measurements in CT and MRI (n = 5), its ability to embolize tissue was tested in an established tumor embolization model in rabbits (n = 6). Digital subtraction angiography (DSA) (Integris, Philips), CT (Definition, Siemens Healthcare Section, Forchheim, Germany), and MRI (3 Tesla Magnetom Tim Trio MRI, Siemens Healthcare Section, Forchheim, Germany) were performed before, during, and after embolization. Imaging signal changes that could be attributed to embolization particles were assessed by visual inspection and rated on an ordinal scale by 3 radiologists, from 1 to 3. Histologic analysis of organs was performed. Results: Particles provided a sufficient image contrast on DSA, CT (signal to noise [SNR], 13 +/- 2.5), and MRI (SNR, 35 +/- 1) in in vitro scans. Successful embolization of renal tissue was confirmed by catheter angiography, revealing at least partial perfusion stop in all kidneys. Signal changes that were attributed to particles residing within the kidney were found in all cases in all the 3 imaging modalities. Localization distribution of particles corresponded well in all imaging modalities. Dynamic imaging during embolization provided real-time monitoring of the inflow of embolization particles within DSA, CT, and MRI. Histologic visualization of the residing particles as well as associated thrombosis in renal arteries could be performed. Visual assessment of the likelihood of embolization particle presence received full rating scores (153/153) after embolization. Conclusions: Multimodal-visible embolization particles have been developed, characterized, and tested in vivo in an animal model. Their implementation in clinical radiology may provide optimization of embolization procedures with regard to prevention of particle misplacement and direct intraprocedural visualization, at the same time improving follow-up examinations by utilizing the complementary characteristics of CT and MRI. Radiation dose savings can also be considered. All these advantages could contribute to future refinements and improvements in embolization therapy. Additionally, new approaches in embolization research may open up
    Type of Publication: Journal article published
    PubMed ID: 21263332
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  • 2
    Abstract: AIM: To perform a quantitative, volumetric analysis of therapeutic effects of trans-arterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) patients. PATIENTS AND METHODS: Entire tumor volume and a subset of hypervascular tumor portions were analyzed pre- and post-TACE in magnetic resonance imaging datasets of 22 HCC patients using a semi-automated segmentation and evaluation tool from the Medical Imaging Interaction Toolkit. Results were compared to mRECIST measurements and inter-reader variability was assessed. RESULTS: Mean total tumor volume increased statistical significantly after TACE (84.6 ml pre- vs. 97.1 ml post-TACE, p=0.03) while hypervascular tumor volume decreased from 9.1 ml pre- to 3.7 ml post-TACE (p=0.0001). Likewise, mRECIST diameters decreased significantly after therapy (44.2 vs. 15.4 mm). In the inter-reader assessment, overlap errors were 12.3-17.7% for entire and 36.3-64.2% for the enhancing tumor volume. CONCLUSION: Quantification of therapeutic changes after TACE therapy is feasible using a semi-automated segmentation and evaluation tool. Following TACE, hypervascular tumor volume decreases significantly.
    Type of Publication: Journal article published
    PubMed ID: 27466556
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  • 3
    Keywords: GROWTH ; IN-VITRO ; tumor ; IN-VIVO ; MODEL ; VITRO ; VIVO ; CT ; kidney ; MRI ; BIOLOGY ; PARTICLES ; polymer ; SURFACE ; CONTRAST AGENTS ; CHEMISTRY ; SCIENCE ; CORE ; NANOPARTICLES ; embolization ; CORE PARTICLE ; BIOMEDICAL APPLICATIONS ; BULKING AGENTS ; MICROSPHERES ; PARTICULATE EMBOLI ; MODALITY ; MAGNETIC HYPERTHERMIA ; NARROW SIZE DISTRIBUTION ; RADIOPAQUE POLYMERIC BIOMATERIALS ; RAY-IMAGING APPLICATIONS
    Abstract: Core P(MAOETIB-GMA) microparticles of 40-200 mu m were prepared by suspension copolymerization of the iodinated monomer 2-methacryloyloxyethyl (2,3,5-triiodobenzoate), MAOETIB, with a low concentration of the monomer glycidyl methacrylate, GMA, which formed hydrophilic surfaces on the particles. Magnetic gamma-Fe2O3/P(MAOETIB-GMA) core shell microparticles were prepared by coating the aforementioned core particles through nucleation of iron oxide nanoparticles on the surfaces of the P(MAOETIB-GMA) particles. This was followed by stepwise growth of thin iron oxide layers. The radiopacity and magnetism of these particles were demonstrated in vitro by CT and MRI. In vivo embolization capabilities of these first multimodal visible embolization particles were demonstrated in a rat's kidney tumor embolization model
    Type of Publication: Journal article published
    PubMed ID: 20443579
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  • 4
    Keywords: ONCOLOGY
    Type of Publication: Meeting abstract published
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  • 5
    Publication Date: 2018-01-28
    Description: Aim: The purpose of this IRB-approved, retrospective study was to compare image quality between 2D and high-resolution 3D, T2-weighted (T2WI) magnetic resonance imaging (MRI) sequences and to investigate the additional value of ultra-high b-value diffusion-weighted imaging (DWI; b=2,000 mm/s 2 ) for both rectal cancer staging and evaluating treatment response. Materials and Methods: From 12 February to 24 August 2016, 26 consecutive patients (22 males, four females; mean age: 61.9±14.0 years) with histologically-proven rectal cancer. In total 31 examinations [12 prior to and 19 after chemoradiation (CRT)] were included. The patients underwent pelvic MRI on a 3.0-T scanner (Magnetom Skyra, Erlangen, Germany). Three radiologists (3, 4, and 5 years of experience in MRI, respectively) independently assessed all images and rated the image quality of DWI (b=800 mm/s 2 ), apparent diffusion coefficient map, DWI (b=2,000 mm/s 2 ), 3D sagittal T2WI, 3D axial T2WI, 2D sagittal T2WI, and 2D axial T2WI of each patient, respectively. In addition, signal intensity ratios (SIR) were calculated between rectal cancer and obturator internus muscle (background) in all patients after CRT on DWI (b=2,000 mm/s 2 ) and correlated with histopathological regression grade (RG). Results: Tumor delineation was significantly better by 2D T2WI than 3D T2WI both before and after CRT (before CRT: Z=–3.2, p=0.02; after CRT: Z=–4.408, p〈0.001; all: Z=–5.192; p〈0.001) and was the preferred method, although image quality ratings were not significantly different (3D sagittal: 4.00±0.48; 2D sagittal: 4.03±0.34, p=0.713; 3D axial: 3.85±0.61, 2D axial: 3.78±0.64, p=0.537). Independent t-test showed significantly higher SIR between those with RG 1 or 2 (moderate response: mean score=2.02) and those with RG 3+4 (good response: mean score=0.8) (t=3.044, p=0.011). In those with RG 4 (complete response), SIR of b2000 was 0.946 compared to a 1.41 average of the whole cohort. In two patients, tumor was invisible on b2000 following CRT (RG 3 and 4, respectively). Interobserver agreement was mostly good (≥0.6) regarding image quality assessment, except for poor agreement (=0.4) in DWI (b2000) between the two less-experienced readers. Conclusion: In conclusion, 3D T2WI might be useful for evaluating response to neoadjuvant therapy in a comprehensive, cost-effective protocol, where 2D imaging seems to be preferable. In addition, DWI (b2000) may be beneficial in assessing both the primary and the residual tumor after CRT in rectal cancer and SIR may be helpful in assessing response to CRT.
    Print ISSN: 0250-7005
    Electronic ISSN: 1791-7530
    Topics: Medicine
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