Our findings suggested that UD + CTmay be the most effective implant surgical technique to achieve an ideal primary stability in low-density bone with a thin crestal cortical bone layer. Also, this technique may prevent compression necrosis of the dense cortical bone.
We present a back-to-back (BTB) structured, dual-mode ultrasonic device that incorporates a single-element 5.3 MHz transducer for high-intensity focused ultrasound (HIFU) treatment and a single-element 20.0 MHz transducer for high-resolution ultrasound imaging. Ultrasound image-guided surgical systems have been developed for lesion monitoring to ensure that ultrasonic treatment is correctly administered at the right locations. In this study, we developed a dual-element transducer composed of two elements that share the same housing but work independently with a BTB structure, enabling a mode change between therapy and imaging via 180-degree mechanical rotation. The optic fibers were embedded in the HIFU focal region of ex vivo chicken breasts and the temperature change was measured. Images were obtained in vivo mice before and after treatment and compared to identify the treated region. We successfully acquired B-mode and C-scan images that display the hyperechoic region indicating coagulation necrosis in the HIFU-treated volume up to a depth of 10 mm. The compact BTB dual-mode ultrasonic transducer may be used for subcutaneous thermal ablation and monitoring, minimally invasive surgery, and other clinical applications, all with ultrasound only.
Photoacoustic (PA) imaging has become one of the promising biomedical imaging technologies in the past decade, thanks to its advantages of structural, functional, imaging capabilities and seamless integration with conventional ultrasound imaging. Endoscopic photoacoustic and ultrasound (ePAUS) is the combination of PA imaging technology and endoscopic ultrasound (EUS). In the design of the ePAUS, it is ideal to align the optical beam of the laser and the acoustic beam of the transducer on the same axis to achieve high spatial resolution and long imaging range. Existing ePAUS uses a ring transducer or a beam combiner to obtain a coaxial or rather an off-axis arrangement. However, the ring transducer has a problem in that the diameter and acoustic side lobes are large, and the beam combiner has a disadvantage in that the structure is complicated and the acoustic loss due to multiple acoustic reflections is large. Our approach to solving this problem is the development of ePAUS based on a miniaturized transparent ultrasonic transducer (TUT). In this study, lead-magnesium- niobate lead-titanate and Indium Tin Oxide-based ultra-small TUT was fabricated, and the performance of center frequency of 28.1 MHz and bandwidth of 51.5% was obtained. Thereafter, quasi-focus was used by combining a multimode optical fiber and a gradient index lens, and coaxial alignment was achieved by arranging the optical axis perpendicular to the optically transparent TUT. This results in high spatial resolution and long imaging distances, and the imaging performance of the probe is demonstrated by imaging the rectum and vagina of the rat in vivo.
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