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The clinical applications of computer aided three-dimensional (3D) data visualization are now numerous. In this paper, we describe the importance of visualization in clinical applications and the methods that are appropriate to particular specialisations. We discuss the requirements of some of these clinical specialisations and describe how developments have taken place over the years to meet these both in terms of new computer algorithms and hardware. We present some selected examples of major clinical applications of data visualization, and end with a note on social, legal and ethical implications.

This chapter focuses on the reconstruction of the portrait mummy of Hermione, which was excavated in 1911. Hermione lived during the reign of the Roman emperor Tiberius and belonged to the Greek immigrants of ancient Egypt who were descendants of the soldiers who have fought Alexander the Great and the Ptolomies. Hermione is believed to have been a school teacher, as her coffin portrait bears the Greek inscription ‘Hermione grammatike’. To reconstruct the face of Hermione, x-ray imaging processes were first employed to gain vital information without moving the painted cartonnage and wrappings of the mummy. Computed tomography and CT scanning technology was also used to provide a measurement of the 3D distribution of x-ray absorption coefficients throughout the scanned volume. This more advanced form of scanning allowed for the creation of 3D reconstruction of the volume. For the 3D reconstruction of the face of Hermione, four methods were necessary. These were the acquisition of 3D data on what lies inside the wrappings, the 3D reconstruction of the skull, the reconstruction of the soft tissues over the skull, and the application of texture to the reconstructed facial surface.

A Case Is reported of a 59-year-old Caucasian male with oculopharyngeal myopathy and sensorineural hearing loss. He presented with progressive ptosis, sensorineural hearing loss over several years and symptoms of mild dysphagia. Further enquiry into his family history revealed that every male member in his family that lived beyond the age of 60 exhibited identical symptoms. Symptoms of ptosis and dysphagia are consistent with the rare autosomal dominant condition of oculopharyngeal myopathy, believed to be due to mitochondrial disease. The combination of ptosis, dysphagia and sensorineural hearing loss with normal distant muscle group biopsy has not been described before.

A case is reported of a HIV–positive patient with severe von Willebrand's disease describing the bleeding complications during and after tonsillectomy. This patient underwent surgery for asymmetrical tonsillar hypertrophy. The tonsils were spontaneously haemorrhaging and there therefore was a suspicion of neoplasia. Despite close cooperation between the ENT Department and the Haemophilia Centre, involving per–operative Factor VIII monitoring and replacement, the patient suffered both protracted primary and secondary haemorrhages. We report this as a cautionary tale as our previous experience with mild to moderate haemophilia has been uncomplicated, but on this occcasion there was massive haemorrhage. We feel that tonsillectomy should not be undertaken in a patient with a severe bleeding disorder without an absolute indicate.

The introduction of computerized systems in medicine started more than a decade ago. The first applications were mainly focused on archiving and the general database management of patient records with the aim of building fully- integrated Hospital Information Systems (HIS) and fast transfer of data and images (e.g. PACS - Picture Archiving and Communication Systems) between HIS. In parallel with this more general development, specialized computer systems were built to process and enhance image data from such systems as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scanners. The use of enhanced CT and MRI images led to the birth of Image Guided Surgery (IGS). Other terminology for similar concepts has since been used, e.g. Computer- Assisted Surgery (CAS), Computer Integrated Surgery and Therapy (CIST) (Lavallée et al, 1997) and Computer-Assisted Medical Interventions (CAMI). In this chapter, we shall look mainly at Computer-Assisted Surgery (CAS) systems and related systems which are aimed at the training of surgeons and the simulation and planning of surgical interventions. The emphasis will be on the Human-Computer Interaction (HCI) aspect rather than the technological issues of such systems. The latter will be briefly discussed in the next section, to make the reader familiar with the terminology, the history and the current state of the art in CASPIT.

The ‘Computer Assisted ENT Surgery using Augmented Reality’ (CAESAR) project aims to improve ENT surgical procedures through augmentation of the real operative scene during surgery: a virtual scene, which shows structures that are normally hidden to the eye of the surgeon, is superimposed onto the real scene. The main distinction of this project as opposed to previous work in the field is to create a hierarchical and stepwise implemented system which allows operations such as calibration, tracking and registration to be assessed on an individual basis. This allows us to compare different alternatives for each operation and eventually apply the best solution without interfering with the performance of other parts of the system. In this paper, we present a framework for the alignment of the objects/subject in the real and virtual operating environment before the onset of surgery, and test its performance on a phantom skull. The operations involved are thus based on a static system and include calibration of the stereo microscope and registration of the virtual patient (as reconstructed from CT data) with the real patient. The final alignment of all objects in the real and virtual operating scene is assessed by cumulating maximum errors of each individual step.

This paper investigates the potential use of a prototype micro-optic twin Liquid Crystal Display (LCD) monitor for stereomicroscopy in microsurgery. The new device displays stereoscopic images via a pair of colour Charge-Coupled Device (CCD) video cameras attached on to a surgical stereo microscope. The paper illustrates the 3D microscope-display system set-up and calibration for stereo viewing. A series of experimental techniques was devised to measure the user-response of the new display system in depth perception of a solid object against the traditional eyepieces of a stereo microscope. As a control, free viewing with the un-aided eyes was also measured. The positional data were collected using a passive mechanical arm. The results showed good correspondence between all three visualisation methods. Error analysis of our numerical findings suggests that the depth accuracy of the new device is well within the precision limits of hand movement for surgical operations. Our study also proves that there are small discrepancies within the sample population of operators using the system. A study based on the psychological and psychophysical factors influencing the system is planned.

As the prevalence of tuberculosis in the U.K. increases, uncommon clinical presentations of the disease may be encountered by the otolaryngologist. We describe just such a case, where a caucasian patient presented with laryngeal lesion, considered to be highly suspicious of a neoplastic process rather than an infective one. We discuss the pathogenesis of tuberculous laryngitis, and review the differential diagnosis and management of the condition.

A low cost, high precision tracking device, developed for the Institute of Laryngology & Otology, University College London for use in augmented reality assisted skull base surgery, is presented. The device achieves sub-millimetric resolution that enables its use with microscope magnified three dimensional imaging. The algorithms used for achieving high resolution and the hardware structure are discussed by the authors. Special emphasis is placed on real time digital signal processing using a DSP processor and the hardware designed to achieve this.

The virtual medical laboratory (VML) was conceived to provide an Internet-accessible resource, offering access for clinicians and scientists to an invaluable data archive at the Institute of Laryngology and Otology, London. The Institute is home to the largest collection of temporal bone, laryngeal, skull and sinus sections in Europe. The skull and sinus collections include an extensive section consisting of animal material. These were contributions from zoos around the world. Over the last 50 years, samples have been carefully sectioned and stained by specialized technicians to produce histology slices of most regions of the head and neck. The aim of the project is to create a virtual medical laboratory, which will provide access to archived histological material as well as computerized tomography and magnetic resonance data. Central to this aim is the reconstruction of the internal anatomy of the temporal bone from two-dimensional histology slices, to create three-dimensional views that can be used for anatomical simulation and surgical training in otolaryngology. State-of-the-art three-dimensional reconstruction and rendering technology allows us to develop such a model. Computer-generated simulation could be made available to all hospitals in which otolaryngology is practised, via digital communication networks. We aim to develop core technology in our own specialty that is applicable to other fields of higher education, which have not been exposed to such modern teaching modalities. This has the potential to become an invaluable teaching resource for anatomists, surgeons and other scientists.