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Molecular Imaging

Novel visualization technology allows clinicians to investigate 3D ultrasound, CT and MRI datasets from medical imaging diagnostics. Moreover, functional genomics studies can display RNA and protein expression in 3D using whole mount staining of samples.

MI3The Erasmus MC was the first university medical center to install an I-Space fully immersive virtual reality (VR) system. The I-Space is a so-called 4-walled CAVEtm-like (Cave Automatic Virtual Environment) VR system. This type of system immerses viewers in a virtual world by surrounding them with three dimensional (i.e. stereoscopic) computer generated images. The images are projected on the walls, floor and sometimes ceiling of a small "room" in which the observers stand. Current LCD and DLP projection technology allow high resolution images with a considerable dynamic range to be projected on screens ranging from 2.5 to 4 meters wide. In case of the Erasmus MC I-Space 8 Barco SIM5 DLP projectors are used,  with a resolution of 1400x1050 pixels and a contrast ratio of 2,000:1. The screens are 2.60 m by 1.95 m.

The 3D effect is obtained using the so-called passive stereo method: Two projectors per projection surface are used, fitted with circular polarizing filters, projecting separate images for the left and right eye. The observers wear light-weight "sunglasses" with polarizing lenses, which ensure that each eye sees only the images of one set of projectors, resulting in depth perception.

MI2In the I-Space multiple viewers are surrounded by stereoscopic images of virtual worlds.  These worlds can range from life-like environments for the treatment of phobias, via more than life-size renderings of human anatomy from CT, MRI and ultrasound scans, to abstract cyber spaces built from DNA sequences, gene expression profiles, protein structures and biological pathways. The main focus of our current research in the I-Space lies on volume visualization, both for clinical as well as research purposes using our in-house developed V-Scope application.

The I-Space allows very detailed three dimensional volume visualizations of gene and protein expression in small tissue samples, using confocal microscopy (CSLM) or optical projection tomography (OPT), enabling new insights into the developmental processes of both model organisms as well as humans. OPT is a new imaging technology developed by the UK's Medical Research Council, that allows whole mount imaging of small (1 – 15 mm) specimens. It allows the visualization of unstained anatomy, colored stains and fluorescent labels, with a resolution up to the cellular level (5 – 10 um).

PS3OPT technology is based on the same reconstruction algorithms used in CT and PET scans, to allow non-destructive imaging of samples. However, unlike these technologies, OPT uses visible, ultraviolet or infrared light instead of ionizing radiation to obtain transmission/emission images of the rotating specimen. Like with CT and PET scans, tomographic reconstruction using a back-projection algorithm on these images, results in a stack of image slices, which allow virtual sections along any axis. A maximum resolution of 1024³ voxels per scan can be achieved. Using volume rendering software 3D reconstructions can be made based on these datasets.

OPT technology can be applied to a variety of samples, ranging from embryos to individual organs and tissues, as long as they can be made translucent. These samples can be untreated to allow the visualization of anatomy, and color stained (DAB, NBT/BCIP or X-Gal/NBT) or labeled with fluorescent markers. The OPT 3001 comes with filters for GFP, GFP+ and Cy3 labels. Labeling allows visualization and analysis of gene expression patterns and protein distribution.

PS2Nowadays three dimensional imaging modalities such as CT, MRI and 3D ultrasound play an ever increasing role in research, diagnosis and treatment planning. The combination of V-Scope and the I-Space allows researchers and clinicians to see details that are overlooked on traditional two dimensional displays (i.e. computer monitors) and to obtain highly accurate 3D measurements that are not feasible using standard display equipment.

In addition to such varied fields as cardiology, neurosurgery and orthopedics, the largest application area of our VR technology is currently that of prenatal medicine. The first nine months of human life take place inside the mother, where we are not able to observe the fetus directly. This means that there are still many unanswered questions on what exactly happens during pregnancy, especially during the first trimester. The innovative views that can be obtained by visualizing 3D ultrasound scans of the embryo or fetus in the I-Space therefore offer ample opportunity for groundbreaking research. Three dimensional ultrasound may also be used to detect abnormalities such as congenital malformations or growth retardation. The I-Space allows efficient and precise 3D measurements and evaluation of details such as the position of hands and feet, facial features and other indications of possible congenital malformations or syndromes, making it an ideal tool for enhanced prenatal diagnosis.