Excitation emission spectroscopy (EES) has been used in the past to characterize many different types of tissue. This
technique uses multiple excitation wavelengths and samples a complete optical spectrum for each, yielding an
excitation-emission matrix (EEM). Upon study of the EEM, it is possible to determine the presence of multiple optical
contrast agents since these dyes can have characteristic spectra that can be separated. Here, we demonstrate EES
specifically designed for use in conjunction with MR. This EES is applied with an in-suite control setup that permits
real-time navigation, utilizing active MR tracking catheters, and providing a platform for MR-guided tissue
characterization. The EES system is used in a demonstration experiment to highlight MR imaging, MR guidance in
conjunction with a catheter-based optical measurement.
Daniel Herzka, Jade Quijano, Jianwu Xie, Sascha Krueger, Steffen Weiss, Benjamin Abrat, Anne Osdoit, Charlotte Cavé, Christopher Burnett, S. Narasimhan Danthi, King Li
The concept of the biopsy is ubiquitous in current medical diagnosis of cancer and other diseases. The standard biopsy consists of removing a sample of tissue for evaluation and diagnosis, primarily to ascertain the presence of cancer cells by (histo)pathological analyses. However, the advent of new optical imaging modalities and targeted or "smart" agents, that have affinity for a select target, suggests the possibility of performing in vivo tissue characterization without the need for sample removal or the wait for histopathologic processing. Here we present work testing and validating a fiber-based confocal fluorescence microscopic imaging system intended for combination with a larger scale imaging modality (i.e. MRI or CT) to be used in image-guided in vivo tissue characterization. Fiber-based confocal fluorescence microscopic imaging experiments were performed (Cellvizio, Mauna Kea Technologies, Paris, France) in vivo in two mouse models including: 1) EGFP-expressing mouse melanoma model and 2) M21 mouse melanoma model. Both models are known to express integrin ανβ3, a cell-surface receptor protein. We also performed an experiment in ex vivo chicken muscle tissue labelled with a fluorescein isothiocyanate-lectin targeted compound. In the mouse models, contrast agents that targeted the integrin were injected and the contrast agent localization in tumor was verified by a whole-body multispectral imager. The fiber-based tool was sensitive enough to detect and image the tissue of interest in all different experiments, and was found appropriate for use in interventional catheter-based procedures.
In this paper, a novel approach to cardiac interventional navigation on 3D motion-compensated static roadmaps is presented. Current coronary interventions, e.g. percutaneous transluminal coronary angioplasties, are performed using 2D X-ray fluoroscopy. This comes along with well-known drawbacks like radiation exposure, use of contrast agent, and limited visualization, e.g. overlap and foreshortening, due to projection imaging. In the presented approach, the interventional device, i.e. the catheter, is tracked using an electromagnetic tracking system (MTS). Therefore, the catheters position is mapped into a static 3D image of the volume of interest (VOI) by means of an affine registration. In order to compensate for respiratory motion of the catheter with respect to the static image, a parameterized affine motion model is used which is driven by a respiratory sensor signal. This signal is derived from ultrasonic diaphragm tracking. The motion compensation for the heartbeat is done using ECG-gating. The methods are validated using a heart- and diaphragm-phantom. The mean displacement of the catheter due to the simulated organ motion decreases from approximately 9 mm to 1.3 mm. This result indicates that the proposed method is able to reconstruct the catheter position within the VOI accurately and that it can help to overcome drawbacks of current interventional procedures.
In this contribution, we investigate the spatial and temporal resolution of retrospectively gated cardiac cone-beam CT. Data of a static and a dynamic resolution phantom are acquired for various heart rates, table speeds and scanner rotation times. The projection data are reconstructed in different motion states with the help of a
retrospectively gated helical cardiac cone-beam reconstruction method. This multi-cycle method automatically adapts the number of heart cycles used for the reconstruction, based on the scan parameters and the ECG data. The spatial resolution is derived from a resolution phantom by multi-planar reformation (MPR) along the scan
direction.
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