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Liver tumors account for a considerable number of deaths every year (World Health Organization, 2004). One of type of primary liver tumors is hepatocellular carcinoma, which arises frequently as a complication of liver cirrhosis. Additionally, almost any tumor can seed metastasis within the liver, colorectal cancer being at the top of the list. [ABSTRACT FROM AUTHOR]

The economic advantages and increased precision persistently demonstrated by industrial robots have stimulated the application of robots in the medical arena (Fichtinger et al. 2001; Cleary and Nguyen 2001; Nathoo et al. 2005). The main advantages of medical robotic systems include accurate needle guidance and stable access, leading to increased precision, accuracy and reproducible sampling of different parts of a lesion. Robotic-assisted procedures also involve the insertion of tubular therapy devices (ablation probes, catheters, bone drills, screws, tissue ablating devices, etc.) into the body, with the guidance of intra-operative imaging devices, such as CT, MRI, ultrasound or fluoroscopy (Cleary and Nguyen 2001; Cleary et al. 2006; Davies 2000; Fichtinger et al. 2001; Howe and Matsuoka 1999; Pott et al. 2005). The potential advantages are well known in the technical community (Fichtinger et al. 2001) and a variety of medical robots have been developed in recent years, including robotics for rehabilitation, or miniature robots that might be placed inside the body (Fichtinger et al. 2001; Kassim et al. 2005; Masamune et al. 2001; Nathoo et al. 2001; Satava 2003; Yanof et al. 2001). [ABSTRACT FROM AUTHOR]

After the introduction of multislice CT in 1992 with the advent of dual-slice scanners, this technology was improved in 1998 by the implementation of 4-slice, in 2000 with 8-slice, in 2002 with 16-slice, and in 2004 with 64-slice scanners. Development continues and at the turn of 2006 the first 64-slice dual-source devices with a very high temporal and spatial resolution were installed; thus one seems to observe a 2-year cycle for the launch of new CT devices. The technical enhancement that CT devices have experienced in recent years resulted in a considerable improvement of image quality and clinical applications. Scanning can be performed much faster, resulting in improved temporal resolution and reduced motion artifacts. The spectrum of indications has extended, and the algorithm of examinations changed, resulting in major advantages of multislice CT in traumatic and emergency imaging. On the one hand, the new scanners allow rapid and detailed examinations of the musculoskeletal system in submillimeter slices without limitation of scan volume; on the other hand, the high-resolution source images are the basis for high quality 2D and 3D reconstructions. [ABSTRACT FROM AUTHOR]

During the past decade, numerous attempts have been made to develop computerized methods that process, analyze, and display multidimensional medical images in radiology. A typical example is the three-dimensional (3D) visualization of semiautomatically segmented organs (e.g. segmentation of the liver, endoluminal visualization of the colon and bronchus), or image processing of a part of an organ for the generation of an image that is more easily interpreted by human readers (e.g. peripheral equalization of the breast in mammograms, digital subtraction bowel cleansing in virtual colonoscopy). These computerized methods often automate only one of the image-processing tasks and depend on user interaction for the remaining tasks. [ABSTRACT FROM AUTHOR]

The breast consists of two main types of tissues — glandular tissues and supporting (stromal) tissues. The glandular part is responsible for milk production during lactation and mainly consists of lobules and ducts. The support tissue of the breast includes fatty tissue and fibrous connective tissue, which consist of ligaments that support the shape of the breast. [ABSTRACT FROM AUTHOR]

Musculoskeletal applications of three-dimensional (3D) imaging were among the first to be developed and remain its most common clinical application, as this noninvasive method offers a unique tool to characterize the bone morphology and to understand the architecture and kinematics of normal and pathologic joints in vivo. Indeed, accurate evaluation of complex anatomy or complex spatial relationships between the lesions and adjacent anatomic structures plays a major role in clinical applications of 3D imaging, as it represents a dramatic improvement over the use of planar cross-sectional imaging alone. This imaging has been shown to have an impact on diagnosis and surgical management in a number of skeletal applications including trauma, malformations and tumors. Moreover, 3D images frequently integrate hundreds of sections in a form that is often easier to interpret than the sections themselves (Calhoun et al. 1999). [ABSTRACT FROM AUTHOR]

In recent years, the advent of endoscopic biliary surgery and the introduction of MR cholangiopancreatography (Barish et al. 1995; Becker et al. 1997; Guibaud et al. 1994; Hall-Craggs et al. 1993; Ishizaki et al. 1993; Macaulay et al. 1995; Morimoto et al. 1992; Reinhold et al. 1995; Reinhold and Bret 1996; Soto et al. 1995) have renewed an interest in the techniques of pancreatobiliary tract imaging. [ABSTRACT FROM AUTHOR]

The radiological evaluation of patients with common and complex urologic disease is changing rapidly. Historically, intravenous urography has been recommended as the initial imaging test in the evaluation of upper urinary tract disease in patients with flank pain, hematuria and other suspected urologic disease. Recent improvements in image processing and three-dimensional (3D) visualization increased the potential of current imaging techniques for the study of the urinary tract. In this setting, computed tomography and magnetic resonance imaging - improved by post-processing displays - have become crucial techniques for the accurate evaluation of anatomy and pathology. [ABSTRACT FROM AUTHOR]

Pancreatic evaluation obtained by diagnostic imaging techniques has strongly improved in these last few years, especially after the advent of multidetector CT (MDCT) (Sata et al. 2006); this new type of CT has, in fact, permitted to obtain a finer image resolution and an increased velocity on the z-axis, allowing to acquire a larger amount of row data per exam and to avoid breath and motion artefacts (Hu et al. 2000); last but not least, the faster imaging acquisition has allowed the improvement of intravenous contrast medium administration and the achievement of the optimisation of post-contrastographic scans. [ABSTRACT FROM AUTHOR]

Colorectal cancer represents the third most commonly diagnosed cancer and is the second leading cause of cancer deaths in the United States (Gazelle et al. 2000). In addition, colorectal cancer is responsible for about 11% of all new cancer cases per year (Gazelle et al. 2000). Five-year prognosis is about 90% for patients with localized disease compared to 60% if there is a regional spread and a drop to 10% in patients with distant metastasis (Gazelle et al. 2000). In the field of medicine there is a widely accepted opinion that most colorectal cancers arise from pre-existent adenomatous polyps (Johnson 2000). Therefore, different societies, such as the American Cancer Society, have proposed screening for colorectal cancer (Byers et al. 1997; Winawer et al. 1997). Today, different options exist for detection of colorectal cancer, including digital rectal examination, fecal occult blood testing, flexible and rigid sigmoidoscopy, barium enema and its variants, colonoscopy and recently computed tomography or magnetic resonance-based virtual colonography (Gazelle et al. 2000). [ABSTRACT FROM AUTHOR]

Image processing is a very important tool in improving the quantity and quality of information given by ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) of the liver. The liver is the largest organ in the body, has a very complex anatomy and can be affected by many different diseases, including diffuse and focal diseases. Among diffuse diseases, cirrhosis has the highest prevalence and can be associated with portal hypertension and hepatocellular carcinoma (HCC) (Bartolozzi and Lencioni 1999). Cirrhotic patients are even more often candidates for orthotopic liver transplantation (OLT), and need an accurate evaluation of the liver itself and of its vascularization. Post-processing with three-dimensional (3D) evaluation of surfaces, volumes and vessels is of crucial importance in surgical planning. [ABSTRACT FROM AUTHOR]

In the evaluation of computed tomography (CT) colonography examinations generally two different approaches exist: [ABSTRACT FROM AUTHOR]

CT or MR colonography, first described as virtual colonoscopy by Vining in 1994, is a non-invasive imaging method that uses CT or MR data sets combined with specialised imaging software to examine the colon. Various names have been given to virtual colonoscopy, including CT pneumocolon and CT or MR colonography. Since 2002, CT colonography (CTC) and MR colonography (MRC) have been definitively included as standard reference terms in medical databases. [ABSTRACT FROM AUTHOR]

Almost every year, new CT scanners are introduced, allowing investigation of any part of the body with the highest spatial and temporal resolution within the shortest scan time. CT angiography performed with multi-detector-row CT (MDCT) and dedicated contrast protocols visualize even the smallest of vessels in the periphery of any vascular tree. Coronary arteries are of particular challenge for imaging by CT because of their small size and their continuous rapid movement. With the newest MDCT scanners, however, any vascular territory, including the coronary arteries, is now assessable with detailed anatomic (Achenbach et al. 2006). [ABSTRACT FROM AUTHOR]

Although the introduction of double-contrast radiographic techniques has reduced the comparative advantage of endoscopy over barium studies, most papers suggest that upper gastrointestinal endoscopy is more accurate, particularly regarding the evaluation of inflammatory mucosal abnormalities, bleeding lesions, (Thoeni and Cello 1980) and the post-operative stomach (Ominsky and Moss 1979). [ABSTRACT FROM AUTHOR]

Today computed tomography (CT) represents the standard examination technique for the chest region when there is still no diagnosis after conventional radiography. The thorax with its mainly air-filled lungs contains less X-ray-absorbing tissue than other regions such as the abdomen, for example. Therefore, lower radiation exposure suffices to yield reasonably good images. Furthermore, the high contrast between air and vessels or pathologic structures in the lungs provides very good natural contrast. Nonetheless, the evaluation of the mediastinum can be difficult in the presence of high image noise. Modern multislice CT scanners allow for an entire chest scan in about 10-15 s with a slice thickness of 1 mm and below, which is crucial to yield good results in subsequent post processing. CT is a widely available, fast, robust and relatively simple to use modality, which gives high-resolution three-dimensional images with a reasonable amount of radiation exposure. [ABSTRACT FROM AUTHOR]

Facial imaging is one of the areas that has been most influenced over the last two decades by the dramatic move of image processing from simple reformatting programmes to a wide range of complex post-processing methods designed to extract further information from image data. This development has been aided by significant falls in both processing times and cost of technology. The result in facial imaging is that some of these techniques are, or should be, regarded as routine in the clinical management of disease. [ABSTRACT FROM AUTHOR]

Conventional endoscopy is currently the gold standard for evaluation of the upper airways, such as the larynx or the tracheal lumen. Rigid endoscopes, however, require general anesthesia, which may limit clinical application in high-risk patients, whereas flexible endoscopy depends on a cooperative patient and on a very experienced endoscopist. Furthermore, congenital anomalies or acquired stenoses may inhibit passage of the endoscope. In addition, viewing is limited strictly to the lumen, which limits the transmural evaluation of lesions. Cross-sectional imaging, using spiral computed-tomography (CT) or magnetic resonance imaging (MRI) and postprocessing of imaging data sets, may offer an additional evaluation tool for those difficult clinical situations and provide additional information about the larynx that cannot be obtained with laryngoscopy. Multiplanar reformations (MPRs), shaded surface displays (SSDs), or three-dimensional (3D) reconstructions have been the subject of research in otolaryngology-head and neck surgery (Altobelli et al. 1993; Cline et al. 1987; Eisele et al. 1994; Girod et al. 1995; Kerberle et al. 2003; Korves et al. 1995; Marsh and Vannier 1983; Schubert et al. 1996; Vannier and Marsh 1996). [ABSTRACT FROM AUTHOR]

The concept of functional endoscopic sinus surgery, developed by Messerklinger in the early 1970s revolutionized and radically altered the techniques used for the diagnosis and treatment of patients with sinus disease (Messerklinger 1994; Stammberger and Posawetz 1990). Messerklingers initial work, however, was conducted with information derived from plain films and conventional polytomography. This technique has been replaced by computed tomography (CT) for many years, which is now considered an essential component to identify anatomic variants that may compromise the ventilation of the sinuses and can demonstrate areas of diseased mucosa that are responsible for recurrent disease. The CT scan further provides valuable information about the presence of potential hazards such as septations of the frontal or sphenoid sinuses, the proximity and location of the orbit, the internal carotid artery and optic nerve to areas of disease. Furthermore, CT is the ideal method for the demonstration of the delicate bony structures of the ethmoid labyrinth. [ABSTRACT FROM AUTHOR]

The routine production of 3D imaging data from modern imaging systems has led to a rapid growth in image post-processing methods. As described in previous chapters, many of these can be applied to single 3D data sets to improve data interpretation by producing 3D visualizations of data content, or by allowing automatic identification of specific features using segmentation techniques. However, in many cases the data content of a single 3D image is inadequate to provide all the information required. Under these circumstances a combination of information from two or more separate data sets may be necessary. As practicing radiologists we subconsciously perform this type of data fusion when we use images from for example, CT and MRI sequences to attempt to better characterise an abnormality, or when we compare images from a single case taken at different times to allow monitoring of disease progression. For example, faced with a cystic mass at the base of the brain we would routinely request T1 and T2W MRI to determine the presence of free fluid in the cyst and the presence and extent of oedema, MR angiography to determine the spatial relationship of the lesion to the major vessels and CT scanning to determine the presence of any bony abnormality. [ABSTRACT FROM AUTHOR]

As well as other anatomical districts, to generate three-dimensional (3D) reconstructions of the middle ear structures, a volumetric acquisition is required. In the case of the tympanic cavity, high-resolution computed tomography is the imaging modality of choice; although the term "high-resolution" traditionally means acquisitions performed with millimetric or sub-millimetric collimation (even with conventional CT), volumetric study is more properly used when a single or multi-row spiral CT is used. CT is generally introduced in the diagnostic workup of middle ear pathologies when external otoendoscopy is unsuccessful to demonstrate the cause of the disease. Volumetric acquisitions allow evaluating most of the components of the tympanic cavity, such as walls and ossicular chain, but fail to demonstrate the mucosal layer and ligaments. [ABSTRACT FROM AUTHOR]

Medical workstations have developed into the super-assistants of radiologists. The overwhelming production of images, hardware that rapidly became cheaper and powerful 3D visualization and quantitative analysis software have all pushed the developments from simple PACS viewing into a really versatile viewing environment. This chapter gives an overview of these developments, aimed at radiologists' readership. Many references and internet are given which discuss the topics in more depth than is possible in this short paper. This paper is necessarily incomplete. [ABSTRACT FROM AUTHOR]

Virtual endoscopy is a computer-generated simulation of the endoscopic perspective obtained by processing computed tomography (CT) or magnetic resonance (MR) datasets (Rubin et al 1996; Yuh et al. 1999) and is one of the applications of virtual reality in medicine (Geiger and Kikinis 1994). [ABSTRACT FROM AUTHOR]

Digital images assume a fundamental importance in the practice of radiologists or technicians. The understanding of the processes that are at the root of the digital processing allow a more acute and responsible management of the processing stream of the radiology laboratory. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) medical image processing is a large field that has evolved in recent years, leading to a major improvement in patient care. The revolutionary capabilities of new 3D and 4D medical imaging modalities, along with computer reconstruction, visualization, and analysis of multi-dimensional medical volume image data, provide powerful new opportunities for medical diagnosis and treatment. 3D image processing provides an extensive set of tools for 3D volume calculation, measurement, and quantitative analysis. Starting from 3D models of the patient, automatically identified and extracted from anatomical structures, diagnosis and surgical simulation can be supported. Moreover, using augmented reality capabilities, it is possible to merge pre-operative or intra-operative data with reality, which is a valuable tool in the field of image guided surgery. [ABSTRACT FROM AUTHOR]

Today's typical hospital environment is well-equipped with medical scanners that routinely provide valuable information to aid with the diagnosis or treatment planning for a particular patient. Computerised tomography (CT), magnetic resonance imaging (MRI), ultrasound, and positron emission tomography (PET) are examples of imaging modalities that are frequently used. An experienced radiologist can gain much insight by viewing the individual images that a scanner produces. However, segmentation of the radiological images to extract or classify a specific region or volume of interest is often required to partition the image data into its constituent components. Image segmentation provides quantitative information about relevant anatomy, for example to determine the size or volume. It also enables an accurate three-dimensional (3D) visualisation of a particular structure using surface triangulation, isosurfacing or volume rendering. There is no single approach that can generally solve the problem of segmentation, and different methods will be more effective depending on the image modality being processed. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) ultrasonography, even if recently gaining large popularity, is a relatively new tool compared with 3D reconstructions obtained by CT and MR. Ultrasonography offers unique qualities including real-time imaging, physiologic measurements, use of non-ionizing radiations and invasiveness. Sonographic image quality has benefited from increasingly sophisticated computer technology: to date several systems, able to generate 3D ultrasound images, have been introduced. [ABSTRACT FROM AUTHOR]

When considering an abdominal multi-detector-row CT (MDCT) protocol to enable optimal diagnostic capability, there are several important factors that need to be considered. Most importantly, what is the clinical indication for the study? This will enable the radiologist to tailor the CT protocol appropriately to obtain the diagnostic information requested. Appropriate tailoring of the protocol requires consideration of: •The kind of oral contrast that should be administered (none, neutral, or positive) and over what period of time.•What kind of IV contrast should be administered and at what rate?•What slice collimation and dose that should be employed to enable a confident diagnosis to be made at axial imaging and how that data can be utilized for 3D rendering? [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is one of the most important imaging modalities that have played a role in the development of three-dimensional (3D) representations of human organs. With its lack of radiation exposure and its rich soft-tissue contrast, MRI has inherent 3D imaging capabilities, providing images in all three orthogonal planes, as well as in oblique or even double oblique orientations. [ABSTRACT FROM AUTHOR]