3D brain MR angiography displayed by a multi-autostereoscopic screen

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1 3D brain MR angiography displayed by a multi-autostereoscopic screen Magalhães, Daniel S. F. 1 ; Ribeiro, Fádua H. 1 ; Lima, Fabrício O. 1 ; Serra, Rolando L. 2 ; Moreno, Alfredo B. 2 ; Li, Li M. 1 1 Laboratório de Neuroimagem, Hospital das Clínicas da Unicamp - 2º andar - Faculdade de Ciências Médicas - Rua Vital Brasil, 251, CEP Campinas - SP - Brasil 2 Departamento de Física, Instituto Superior Politécnico José Antonio Echeverría (Cujae), Ave. 114, 11901, Marianao, Ciudad de La Habana,CP 19390, Cuba AREA: Image Perception, Observer Performance, and Technology Assessment SHORT ABSTRACT: The use of 3D imaging in the medical field has proven to be a benefit to doctors when diagnosing patients. For different medical domains a stereoscopic display could be advantageous in terms of a better spatial understanding of anatomical structures, better perception of ambiguous anatomical structures and improved communication with patients or between doctors. In this work we describe a multi-autostereoscopic system and how to produce 3D MRA images to be displayed with it. We show results of brain MR angiography images, discussing how a 3D visualization can help physicians to a better diagnosis. ABSTRACT: The magnetic resonance angiography (MRA) can be used to examine blood vessels in key areas of the body, including the brain. In the MRA, a powerful magnetic field, radio waves and a computer produce the detailed images. Physicians use the procedure in brain images mainly to detect atherosclerosis disease in the carotid artery of the neck, which Medical Imaging 2012: Image Perception, Observer Performance, and Technology Assessment, edited by Craig K. Abbey, Claudia R. Mello-Thoms, Proc. of SPIE Vol. 8318, 83181P 2012 SPIE CCC code: /12/$18 doi: / Proc. of SPIE Vol P-1

2 may limit blood flow to the brain and cause a stroke and identify a small aneurysm or arteriovenous malformation inside the brain. Multi-autostereoscopic displays provide multiple views of the same scene, rather than just two, as in autostereoscopic systems. Each view is visible from a different range of positions in front of the display. This allows the viewer to move left-right in front of the display and see the correct view from any position. The use of 3D imaging in the medical field has proven to be a benefit to doctors when diagnosing patients. For different medical domains a stereoscopic display could be advantageous in terms of a better spatial understanding of anatomical structures, better perception of ambiguous anatomical structures, better performance of tasks that require high level of dexterity, increased learning performance, and improved communication with patients or between doctors. In this work we describe a multi-autostereoscopic system and how to produce 3D MRA images to be displayed with it. We show results of brain MR angiography images discussing, how a 3D visualization can help physicians to a better diagnosis. DESCRIPTION OF PURPOSE: In the typical brain magnetic resonance angiographic visualization, that is, the visualization in standard computer monitors, the lack of real depth of the image could cause misunderstanding of anatomical structures or ambiguity in arteriovenous arrangements. The utilization of a multi-autostereoscopic system, which can produce real depth in visualization without the utilization of any special device such as glasses or other equipment, could be advantageous in terms of a better spatial understanding of anatomical structures, better perception of ambiguous anatomical structures, better performance of tasks that require high level of dexterity, increased learning performance, and improved communication with patients or between doctors. METHODS: The chosen MRA images obtained with the local MR equipment (Philips Achieva 3T, Best, Netherlands) and we can opt for two different methods to get the viewpoint of the image: We can convert the DICOM image to SCN format and utilize a software that renders the image, creating one JPG/PNG standard image for each degree rotated. We can use a software (like the OsiriX, from Pixmeo) to create a guided video of 360 degrees and with another software (like a simple one created by our group in Matlab language) extract each frame of the video. In both cases we are interested in generating a full set of images representing a rotation of the MRA. Then we create a 3x3 matrix image, where each element of the matrix should correspond to a different viewpoint of the scene, as shown in Figure 1: Proc. of SPIE Vol P-2

3 Figure 1: Image matrix composed of five viewpoints of an angioresonance image. With the full set of 360 matrix images we create an AVI video that is interpreted for a nine tiles multi-stereoscopic system as a five viewpoints/frame video. RESULTS: The multi-autostereoscopic monitor has a resolution of up to 1680 x 1050 for the viewpoints. The image can be viewed by the observer with great quality and no difficulty in focusing eyes. The design of the system is showed in Figure 2. Proc. of SPIE Vol P-3

The Figure 3 shows two snapshots with a non-professional camera of the position of the eyes of the observer.

4 Figure 2: Multi-autostereoscopic system composed of a computer (PC) and an multiautostereoscopic monitor (AM). The observer (Ob) observes a 3D image. The Figure 3 shows two snapshots with a non-professional camera of the position of the eyes of the observer. Figure 3: Two snapshots taken in the position of the eyes of an observer. The parallax difference between each viewpoint results in a 3D image to the observer. Proc. of SPIE Vol P-4

Figure 6: Two different angles of a MR arteriography. As shown in: http://dx.doi.org/10

5 Figure 6: Two different angles of a MR arteriography. As shown in: When we choose 2 or 3 degrees instead of 1 degree between the viewpoints, the image results more impressive because it appears furthest from the monitor, however the visualization is less comfortable for the observer. This kind of 3D image helps physicians with visualization of MRA to detect aneurysms or other arteriovenous problems. The image gives a better spatial understanding of the anatomical structures and it favors a better perception of ambiguous anatomical structures. NEW OR BREAKTHROUGH WORK TO BE PRESENTED: A simple and portable system that can be used for displaying three-dimensional magnetic resonance angiography. CONCLUSION: We presented how a multi-autostereoscopic system can generate 3D magnetic resonance angiographic images from viewpoints of a MRA, showing results of the 3D images produced. Proc. of SPIE Vol P-5

6 ACKNOWLEDGEMENTS The authors thank FAPESP and CAPES for financial support, J. J. Lunazzi for the helpful discussions about the holographic screens, A. C. Costa for allowing us to use his laboratory, F. H. Ribeiro for the angioresonance image and to T. Ellis for English revision. The authors also thanks A. Falcão for the software which was used as base in our studies. ABOUT THE WORK: This work is derived from the article submitted to Optical and Laser Technologies (OLT) magazine named Glasses-free 3D viewing systems for medical imaging. The present work differs from the one submitted to OLT for presenting a multi-stereoscopic system used to visualize 3D magnetic resonance angiography specifically, the mentioned submitted article presents two different 3D systems, being one a holographic, to create general medical imaging. Proc. of SPIE Vol P-6

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