Image registration and subtraction for the visualization of change in diabetic retinopathy screening.

Diabetic retinopathy (DR) is a leading cause of blindness in people of working age in developed countries. DR is characterized by lesions of the retinal microvasculature. This paper describes a technique for visualizing the changes which occur in retinal pathology over a 1 year interval. Pairs of retinal images of the same eye were acuired 12 months apart within a DR screening programme. The images were normalized, registered and subtracted to generate a contrast-enhanced difference image displaying changes in retinal appearance. The normalization factor and registration error were quantified for 104 pairs of retinal images.

Virtual surgical planning and CAD/CAM in the treatment of cranial defects.

The purpose of this work was to enhance the clinical outcome in the neurosurgical treatment of cranial defects and fibrous dysplasia. Cranial defects require repair using a variety of materials to protect the brain and provide a good cosmetic outcome for the patient. Virtual neurosurgery and CAD/CAM techniques have been employed to increase the implant 3-dimensional accuracy. The source data was 3D Computed Tomography scans. The CT scans were visualised using surface shading and rotation with volume rotation and re-sizing being used to review the complete data set. The volume data was manipulated using 3D image editing and surface modelling. Physical models of the patients' skulls were created using computed numerical milling which provided a physically accurate template for the production of a cranial implant. This has led to improved fitting for titanium plates requiring less theatre time and in the case of fibrous dysplasia a change in the operative technique from a two stage operation to one stage.