Medical imaging comprises a range of powerful diagnostic tools that have become indispensable in a modern healthcare setting.
A computed tomography (CT) scan shows the human body in three dimensions. The x-ray beam passes through the human body in a thin axial slice, which is repeated in various directions. The detectors on the opposite side measure the radiation transmitted through the patient.
More recently CT has been used for preventive medicine or screening for disease, for example, CT colonography for people with a high risk of colon cancer, or full-motion heart scans for people with a high risk of heart disease.
Magnetic resonance Imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from CT and PET scans.
Functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. Physicians use fMRI to assess how risky brain surgery or similar invasive treatment is for a patient and to learn how a normal and a diseased or injured brain is (dys)functioning.
Optical imaging is the use of light as an investigational imaging technique for medical applications. Examples include optical microscopy, spectroscopy, endoscopy, scanning laser ophthalmoscopy, and optical coherence tomography.
PET/CT is a nuclear medicine technique which combines, in a single gantry, a positron emission tomography (PET) scanner and an x-ray computed tomography (CT) scanner, to acquire sequential images from both devices in the same session, which are combined into a single superposed image. Thus, functional imaging obtained by PET, which depicts the spatial distribution of metabolic or biochemical activity in the body can be more precisely aligned or correlated with anatomic imaging obtained by CT scanning.
It is also used to guide biopsies, diagnose heart conditions and assess damage after a heart attack.
Ultrasound uses sound waves. They are reflected, deflected or absorbed in the body. The reflected sound waves produce the ultrasound image. The more sound waves are reflected, the more hyperechogenic (= whiter) the tissue is imaged. With reduced reflection, the image will be more hypoechogenic, and anechogenic if there is no reflection (= black).
Radiography uses X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Since the body is made up of various substances with differing densities, ionising and non-ionising radiation can be used to reveal the internal structure of the body on an image receptor by highlighting these differences using attenuation, or in the case of ionising radiation, the absorption of X-ray photons by the denser substances (like calcium-rich bones).
Radiology provides detailed anatomical and physiological images of the human body, while nuclear imaging provides insight into the body’s physiology, metabolism, and molecular function through the use of radioactive tracers. Next, to that, novel optical imaging techniques display incredibly detailed, real-time structural and functional information.
The mainstay of imaging is and will remain, cross-sectional imaging, with an emphasis on structural imaging. The improved spatial and temporal resolution of imaging techniques like CT and MRI have revolutionized the ability to detect and monitor diseases such as cancer and neurological disorders. Technical developments include brain and tumor perfusion methods, which display physiological information, and fMRI allows the non-invasive study of brain activity. Longitudinal imaging is increasingly used to monitor disease progression, determine the effect of treatment, and detect side effects. The advances of (endoscopic) optical techniques provide a further step towards increased resolution.
Molecular imaging is a crucial element of translational research in most of the Amsterdam UMC research institutes. Development of target-specific contrast agents (‘tracers’) has become a key driver of innovations towards personalized medicine: applying the right therapy for the right patient at the right time. Molecular imaging can be of value for sensitive visualization and quantification of critical disease targets and targeting molecules at a high resolution.
Taken together, integrated structural and molecular imaging (PET-CT, SPECT-CT, optical-CT/MRI) bundle the expertise of all imaging domains to provide scientific and clinical excellence.
Facilitating the cohesion of the multi-modality (hybrid) technologies