Abstract
Introduction
Visualization of complex human body structures such as the spine and his malformations such as, foraminal stenosis, spine stenosis, and herniated disk is a challenge. Augmented Reality is the combination of a real scene supplemented, or augmented, by computer generated information, such as image, video or graphical animations. Android and iOS based mobile devices such as smartphones and tablets are being increasingly massive adoption and with higher performance characteristics.
Material and Methods
Sagittal 2D T2w TSE sequence MRI (TR 4420 milliseconds, TE 130 milliseconds, FoV 320x320, Matrix 448x448, Voxel Size 0.7x0.7x3 mm) and sagittal CT (kVp 140, 1 mm slice thickness, 0,30x0,30 mm pixel spacing, B31s kernel) images were scanned in a 57 years old male patient. Both images were co-registered using “Linear registration” algorithm of 3D Slicer v 3.6 software. CT image was segmented using threshold option (113–1303 Hounsfield units) of 3D Slicer and then L4-L5 vertebral bodies was extracted manually using ImageJ v1.49n version. The L4-L5 intervertebral disk was segmented using “simple region growing” algorithm of 3D Slicer, and then was cleaned manually using ImageJ software. Mesh of L4-L5 and intervertebral disk was generated using 3D Slicer “Model Maker” algorithm with default options, and HC Laplacian smoothing (MeshLab software). The iOS-Android application were created using C# language and software tools: Unity 4.5x (graphic engine; www.unity3d.com), 3Ds Max (www.autodesk.com), Visual Studio 2013 (www.microsoft.com), and Qualcomm Vuforia for Unity Android & iOS (Augmented Reality, developer.vuforia.com).
Results
By focusing the printed target image using iOS-Android app,L4-L5 vertebral bodies and the intervertebral disk of the patient was shown in 3D. The user can rotate the spine with the two-finger twist gesture, by rotating the view angle over the target image, or rotating the target image itself. The size of the spine can be changed by modifying the distance between the mobile device and the target image, or by the pinch gesture. Augmented reality demonstrated new views from inside spine (using total immersion feature of augmented reality) and relationship of normal structures and different pathologies.
Conclusion
The application described here demonstrates the use of augmented reality technique with medical images of patients with spine pathologies. The application shows how to use ubiquitous mobile devices to display advanced medical information in a 3D interactive application. The application is useful to show, explain and describe in a 3D, interactive and immersive way the spine pathology that the patient has. More work must be done to create an automatic CT-MRI registration, segmentation, creation of mesh, smoothing and decimation of vertebral bodies and an intervertebral disk.