Imaging of the Head and Brain
CT Overview Structures and planes MRI Overview Structures and planes MRI and brain tissue Table: Interpretation of MRI Tissue T1-weighted images T2-weighted images Fluid (e.g., CSF) Dark Bright White matter Light gray Dark gray Gray matter Gray Light gray Fat Bright Bright Inflammation Dark Bright Other Imaging Ultrasonography Nuclear medicine Intracranial Masses and Anomalies Cerebral […]
Imaging of the Spine and Spinal Cord
Radiography Overview Before the advent of CT and MRI, X-ray imaging was widely used to study the bones of the spine. Views and spine structures: Normal radiographic findings CT Overview A CT scan can evaluate both bone and soft tissue structures. Normal CT findings Anatomy: Different planes can be used: MRI Overview MRI provides superior […]
X-rays
Overview Definition An X-ray is a discrete, high-energy particle of electromagnetic radiation (photon) that propagates through space at the speed of light. X-ray production Effects of X-ray radiation Fetal risk of radiation Table: Fetal risk of radiation Weeks post conception Effects of major exposure 2 10–50 rads: risk of failure to implant > 50 rads: […]
Nuclear Imaging
Terminology and Technological Aspects Mechanism Image creation Equipment: Imaging techniques: Common nuclear medicine exams Hepatobiliary Iminodiacetic Acid Scan Table: Interpretation of HIDA scans Imaging finding Interpretation Bile ducts visible Normal hepatic function Filling of the gallbladder Patent cystic duct Radiotracer is seen in the duodenum Patent common bile duct No radiotracer is seen in the […]
Imaging of the Lungs and Pleura
Introduction Before interpreting any image, the physician should take certain preparatory steps. The same systematic approach should be followed every time. Chest X-ray Indication Medical indications: Nonmedical indications: Advantages: Disadvantages: Exam technique Positioning: Positioning for specific views: Penetration: Penetration is the degree to which radiation has passed through body, resulting in a darker or lighter […]
Ultrasound (Sonography)
Terminology and Technical Aspects Definitions Core components of an ultrasound machine Generation of images with ultrasound The main principle behind ultrasound imaging is the transmission and reflection of sound waves through the tissues. Images Imaging planes: Types of images: Image definition or sharpness of the image generated can be characterized in terms of: Image definition […]
Magnetic Resonance Imaging (MRI)
Terminology and Technological Aspects Mechanism Image generation Interpretation Table: Interpretation of MRI Tissue T1-weighted images T2-weighted images Fluid (e.g., CSF) Dark Bright White matter Light gray Dark gray Gray matter Gray Light gray Fat Bright Bright Inflammation Dark Bright Indications and Contraindications Central nervous system Musculoskeletal system Other systems Contraindications Contraindications relevant in patients with: […]
Computed Tomography (CT)
Terminology and Technology General components Types of CT scanners Helical (“spiral”): Sequential (step-and-shoot): Image processing Digital images are created with a matrix of voxels (3-dimensional pixels), which are measured in Hounsfield units (HU). Postprocessing can be used to accentuate tissues of different densities. Images can also be produced in different viewing planes. Table: Density of […]