Physics technologies in medicine

Modern medicine is a large consumer of physics technologies. The series of lectures covers medical imaging starting with an overview and the history of medical imaging. Then follows four lectures covering <ul> <li>x-ray imaging</li> <li>positron emission tomography</li> <li>imaging blood flow by ultrasound</li> <li>magnetic resonance</li> </ul> 10 June 2002 100 Years of Medical Imaging Pr. Gustav K. von Schulthess MD, PhD, University of Zurich History and overview of Medical Imaging 11 June 2002 X-rays: still going strong Dr. Simon Wildermuth, MD, University Hospital Zurich Multidetector computed tomography: New developments and applications Since its introduction in 1992, spiral computed tomography (CT) scanners constructed with a single row of detectors have revolutionized imaging of thoracic and abdominal diseases. Current state-of-the-art models use up to 16 detectors and are capable of acquiring 16 contiguous slices of data with each gantry rotation; systems with 32 data acquisition units (and more) are currently in development. The principal advantages offered by these systems are increased scanning speed and the ability to obtain volumetric data in high resolution. These features enable imaging with enhanced contrast concentration, decreased contrast load, decreased respiratory and cardiac motion artifact, and multiplanar and 3-dimensional reconstruction capabilities. This presentation reviews the technical aspects of multidetector spiral CT scanning. The arrangement and various combinations of the detector rows are discussed. Key scanning variables, including collimation (slice thickness), pitch (the rate of table travel per gantry rotation divided by the beam collimation), and gantry speed, are briefly addressed in the context of their interrelationships. Comparison is made with single-detector-row systems to emphasize the superior scanning speed and resolution. Furthermore, the various clinical applications of multidetector spiral CT, including CT pulmonary angiography, CT aortography, virtual bronchoscopy, and multiplanar and 3-dimensional reconstructions are discussed. 12 June 2002 Nuclear Medicine: PET Positron Emission Tomography Dr. Alfred Buck, MD, MSc, University Hospital Zurich Elucidating healthy and pathological human physiology with PET Positron emission tomography (PET) is the only tool that allows to non-invasively and quantitatively investigate human physiology and biochemistry in vivo. The method allows to measure glucose metabolism, aminoacid biochemistry, blood flow, receptor densities and neurotransmitter synthesis. These parameters are of interest in the healthy human and in disease. Of special importance is glucose metabolism (GM). The ligand used to investigate GM is a glucose analogue labelled with 18F, 18F-fluorodeoxyglucose (FDG). FDG enters the cell like glucose but cannot be completely metabolised. The intermediary product is trapped in the cell, accumulates and allows for excellent imaging. The amount of accumulated tracer is a quantitative measure for GM. Initially one was especially interested in GM of the brain. In disease GM is highly important in tumors and PET with FDG has become one of the major methods to evaluate cancer patients. Another application of PET concerns the working of the brain. Such studies are performed with labelled water (H215O). This tracer measures blood flow. Whenever areas in the brain are active, blood flow is increased and this increase can be measured with PET. The pattern of activations during specially designed tasks allows conclusions about information processing in the brain. 13 June 2002 Ultrasound Pr. Kurt Jäger, MD, University Hospital Basel Imaging blood flow with ultrasound Diagnostic ultrasound relies on the reflection of short pulses of ultrasound (2 - 14 MHz) from structures within the body to construct images of an organ, or to measure/image velocities of moving structures such as blood. The most common modalities are pulse-echo B-scanning, spectral Doppler and color flow imaging. Many recent innovations including tissue harmonic imaging, contrast agents, 3-D imaging and tissue Doppler have extended the scope of ultrasound. It is estimated that there are more installed ultrasound machines than all other diagnostic techniques combined. Arteriosclerotic narrowing of the arterial lumen and the resulting blood flow reduction are responsible for stroke, peripheral arterial disease and cardiovascular morbidity and mortality. Thrombus formation in the venous system leads to pulmonary embolism and chronic venous insufficiency. Thus, the application of ultrasound in the diagnosis of vascular disease is an exciting medical innovation. 14 June 2002 Magnetic Resonance Pr. Roland Kreis, M.Sc., PhD, University Hospital Bern Magnetic Resonance in Medicine: Morphology and Way Beyond Nuclear magnetic resonance is a phenomenon with extremely wide-varying applications ranging from solid-state physics to conformation analysis of macromolecules, to a plethora of uses in medicine. The most basic one is the determination of soft tissue morphology by MR imaging (MRI). MRI's success relies on the fact that it is truly non-invasive and that different contrast mechanisms can be invoked by simply changing the data acquisition parameters. MR contrast can be based on proton density, molecular mobility, water diffusivity, blood perfusion, water-macromolecule interaction, motion, or magnetic susceptibility gradients. Furthermore, nuclei other than protons can be interrogated, or extrinsic and intrinsic contrast media can be used to image morphology and pathology. Metabolism and function can be elucidated specifically. The basic methodology and various applications will be presented to prove that magnets can also be put to good use outside of CERN.