Radiology
MRI uses strong magnetic fields to align atomic nuclei (usually hydrogen protons) within body tissues, then uses a radio signal to disturb the axis of rotation of these nuclei and observes the radio frequency signal generated as the nuclei return to their baseline states. The radio signals are collected by small antennae, called coils, placed near the area of interest. An advantage of MRI is its ability to produce images in axial, coronal, sagittal and multiple oblique planes with equal ease. MRI scans give the best soft tissue contrast of all the imaging modalities. With advances in scanning speed and spatial resolution, and improvements in computer 3D algorithms and hardware, MRI has become an important tool in musculoskeletal radiology and neuroradiology.
3D reconstruction from multiple images
3-D models are used for planning the operation, morphometric studies and has more reliability in orthopedics.
To reconstruct 3-D images from 2-D images taken by a camera at multiple angles. Medical imaging techniques like CT scanning and MRI are expensive, and although CT scans are accurate, they can induce high radiation doses which is a risk for patients with certain diseases. Methods based on MRI are not accurate. Since we are exposed to powerful magnetic fields during an MRI scan, this method is not suitable for patients with ferromagnetic metallic implants. Both the methods can be done only when in lying position where the global structure of the bone changes. So, we discuss the following methods which can be performed while standing and require low radiation dose.