Browsing by Subject "Interventional"
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Item Open Access Interactive real-time RF control for MRI transmit channels(Bilkent University, 2019-09) Yılmaz, UğurCardiac catheterization is one of the heavily researched areas of the real-time interventional studies in Magnetic Resonance Imaging (MRI), where elongated conductive wires are prone to excessive radiofrequency (RF) heating and tracking of the devices might be challenging. Previous studies have proposed several techniques for heating reduction at the conductive wire tip and device visualization, using multiple transmit channels but the software platform for real-time RF control of multiple transmit channels has been missing for interventional procedures. In this study, we are presenting a software framework capable of interactive real-time RF control of MRI transmit channels and reception of dynamic images from MR image reconstruction computer. The software consists of three main programs running on three di erent operating systems (Linux, Windows and VxWorks) that communicate with each other over TCP/IP connection. Besides socket programming, multi-threading/multi-tasking is implemented for each platform along with the synchronization semaphores. The graphical user interface end is developed with Qt. Siemens' work-in-progress tip-tracking pulse sequence (BEAT IRTTT) source code is modi ed to serve as the other end in our software system. The interactive real-time experiments are conducted on a copper sulfate phantom including a conductive wire. Dual-port body coil which is a product of Siemens is used as the transmit antenna and each port is driven independently. Results have shown the feasibility of the real-time RF control in the MRI, with an e ective total update latency of two frames on the dynamic image-series. We believe this framework will contribute to real-time interventional procedures in terms of RF safety and catheter tracking.Item Open Access Tracking the position and rotational orientation of a catheter using a transmit array system(IEEE, 2013) Celik, H.; Mahcicek, D. I.; Senel, O.; Wright, G. A.; Atalar, ErginA new method for detecting the rotational orientation and tracking the position of an inductively coupled radio frequency (ICRF) coil using a transmit array system is proposed. The method employs a conventional body birdcage coil, but the quadrature hybrid is eliminated so that the two excitation channels can be used separately. The transmit array system provides RF excitations such that the body birdcage coil creates linearly polarized and changing RF pulses instead of a conventional rotational forward-polarized excitation. The receive coils and their operations are not modified. Inductively coupled RF coils are constructed on catheters for detecting rotational orientation and for tracking purposes. Signals from the anatomy and from tissue close to the ICRF coil are different due to the new RF excitation scheme: the ICRF coil can be separated from the anatomy in real time, and after doing so, a color-coded image is reconstructed. More importantly, this novel method enables a real-time calculation of the absolute rotational orientation of an ICRF coil constructed on a catheter. © 1982-2012 IEEE.Item Open Access Transrectal prostate biopsy and fiducial marker placement in a standard 1.5T magnetic resonance imaging scanner(Elsevier Inc., 2006-01) Susil, R. C.; Menard, C.; Kriegel, A.; Coleman, J. A.; Camphausen, K.; Choyke, P.; Fichtinger, G.; Whitcomb, L. L.; Coleman, C. N.; Atalar, ErginPurpose: We investigated the accuracy and feasibility of a system that provides transrectal needle access to the prostate concurrent with 1.5 Tesla MRI which previously has not been possible. Materials and Methods: In 5 patients with previously diagnosed prostate cancer, MRI guided intraprostatic placement of gold fiducial markers (4 procedures) and/or prostate biopsy (3 procedures) was performed using local anesthesia. Results: Mean procedure duration was 76 minutes and all patients tolerated the intervention well. Procedure related adverse events included self-limited hematuria and hematochezia following 3 of 8 procedures (all resolved in less than 1 week). Mean needle placement accuracy was 1.9 mm for the fiducial marker placement studies and 1.8 mm for the biopsy procedures. Mean fiducial marker placement accuracy was 4.8 mm and the mean fiducial marker placement accuracy transverse to the needle direction was 2.6 mm. All patients who underwent the procedure were able to complete their course of radiotherapy without delay or complication. Conclusions: While studies of clinical usefulness are warranted, transrectal 1.5 T MRI guided prostate biopsy and fiducial marker placement is feasible using this system, providing new opportunities for image guided diagnostic and therapeutic prostate interventions.