1 What are the clinical indications for computed tomography angiography (CTA) and magnetic resonance angiography (MRA) of the peripheral and visceral arteries? CTA and MRA are noninvasive methods of assessing the arteries and veins, which have all but replaced catheter…
1 What is a radiographic contrast agent? A radiographic contrast agent is a substance that is administered to a patient during an imaging examination to improve its diagnostic performance. Contrast agents are most often administered via the intravenous (IV) and…
1 What is a digital image? A digital image is an image discretized in spatial coordinates and in brightness. It can be represented by a multidimensional array of integers. 2 What is the difference between a pixel and a voxel?…
1 What is molecular imaging? Molecular imaging is the visualization, characterization, and measurement of biologic processes at the molecular and cellular levels in humans and other living systems. It is essentially a noninvasive means to study in vivo biochemistry and…
Ultrasonography (US) 1 What is ultrasonography (US), and how does it work? US is a structural imaging technique that uses high-frequency mechanical ultrasound waves (with frequencies greater than audible sound waves) to create real-time tomographic (cross-sectional) images. A hand-held transducer…
Radiography 1 What is radiography? Radiography is an imaging technique that uses x-rays to create projectional (2D) images of a region of interest in the body. It is performed by shining x-rays on a film or other image detector with…