Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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  • Article
    Citation - WoS: 2
    Mr-Guided Focused Ultrasound Application for Moving Target Tumor Ablation in Abdominal Area: Coil Selection
    (SAGE Publications Inc., 2021) Mihçin, Şenay; Gagliardo, Cesare; Toia, Patrizia; Dennison, Andrew; Strehlow, Jan; Melzer, Andreas
    Background Magnetic Resonance Imaging (MRI)-guided Focused Ultrasound Surgery (MRgFUS) is a non-invasive thermal ablation method utilizing high-intensity focused ultrasound (HI-FU) energy for tissue ablation under MRI with real-time thermal mapping. Ablating to a dynamic target as in the liver is very challenging, requiring approval. A novel quality-assured liver tumor ablation system has been proposed for clinics. The paper reports the evaluation of conventional and new MR-receiving coils. Purpose To evaluate the suitability of MR coils as part of the MRgFUS treatment system for liver, while simulating breathing motion in pre-clinical settings. Material and Methods The novel software communicates with the MR scanner and the transducer. To monitor the temperature via proton resonance frequency (PRF) methodology echo planar imaging (EPI) sequence was used while the algorithms of static, static and dynamic tracking were tested with sonications of 100 W for 30 s on tissue-mimicking phantoms. Different coil sets were used to assess the performance of the system for fitness for dynamic thermometry. Finally, in vivo experiments were performed over a porcine model. Results Single-loop four-channel Duoflex and Gem coils provided adequate signal-to-noise ratio and contrast with consistent thermal readings. Body array coils showed severe loss of signal in dynamic cases since the integration of tracking algorithm causes low efficiency. Conclusion Body array coils are unsuitable for MRgFUS of the liver due to signal loss. The dedicated coil set with a single loop around the FUS transducer combined with four-channel arrays might be the best option for liver treatment using dynamic MRgFUS applications.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Tensile Adhesion of Type I Collagen To Titanium Alloy and Calcium Phosphate Coated Surfaces With Different Roughness Values
    (IOS Press, 2002) Özerdem, Barış
    The purpose of total joint arthroplasty is to reduce pain and restore function. Its success depends on the formation of a new bone that stabilizes the prosthesis. The proposed solution for this important problem is to have bio-coated implant surfaces which are more conductive to bone growth. Additionally, collagen has long been used as a matrix for medical applications, because of its biocompatibility and adaptability. In this study, a test method for measuring the tensile adhesion strength of collagen to titanium alloy and calcium phosphate coated surfaces with different roughness values was developed, in order to evaluate how well the collagen adheres to the metallic and bio-coated surfaces. A precision motion system was used to stretch gels that were adherent to the plate surfaces. The tests were done in DMEM solution. The adhesive strength between the collagen gel and plate was significantly higher for calcium phosphate coated surfaces. Adhesive strength was highest in the sample with the highest roughness value.