38 Questions
What is the term used to describe an imaging finding that does not directly correspond to the reality of the patient?
Artifact
What is the initial imaging study of choice for a 65-year-old male presenting with shortness of breath and chest pain?
Chest Radiograph
What type of imaging modality uses ionizing radiation to produce an image?
Radiography
What is the term used to describe the border between two different radiodensities?
Interface
What is the modality of choice for a patient with blunt trauma to the chest after a high-speed MVA?
Chest Radiograph
What is the term used to describe structures that block x-rays and appear white on a radiograph?
Radiopaque
What is the main purpose of Radiography?
To visualize bony structures
Who discovered x-rays in 1895?
Roentgen
What is image contrast in Radiography?
The difference in brightness between an area of interest and its surroundings
What is the term used to describe medical images that are the “shadows” projected onto a flat plane when x-rays pass through a patient?
Radiograph
What is the primary indication for ordering a CT scan of the chest?
All of the above
What is the preferred clinical indication for selecting MRI of the chest?
Soft tissue injury
What is the term used to describe structures that allow x-rays to pass through and appear gray to black on a radiograph?
Radiolucent
What is the term used to describe the categories of imaging modalities?
Radiating and Non-radiating
What is the primary advantage of Ultrasound over other imaging modalities?
Real-time imaging
Which of the following imaging modalities is typically used to evaluate metabolic activity?
Nuclear Medicine/PET
What is the characteristic of the flow in a carotid artery with a build-up of fatty deposits?
Turbulent, like rapids in a river
Which of the following is NOT a clinical indication for Doppler sonography?
Measuring bone density
What is the primary advantage of using ultrasound in gynecologic exams?
Lack of radiation
What is the purpose of using Doppler effects in ultrasound?
To assess volume, speed, and direction of flow
What is the term for the ultrasound examination used to evaluate the torso for free fluid in cases of trauma?
Focused assessment with sonography for trauma (FAST)
What is the name of the type of ultrasound used to detect wall motion abnormalities in the heart?
Echocardiography
What is a limitation of ultrasound in obese patients?
Penetration is difficult due to increased soft tissue
What is the primary route of excretion for intravascular iodinated contrast material in patients with normal renal function?
Renal system
What is the typical duration of contrast agent elimination in dialysis patients?
2 to 4 hours
What type of reaction can occur in response to contrast agent administration?
Both anaphylactoid and chemotoxic reactions
What is the primary purpose of administering contrast agents in imaging?
To create a temporary, artificial density difference
What type of MRI contrast agents can delineate vessels as well as parenchymal tissues?
Diffusion agents
What is a benefit of using ultrasound in medical imaging?
Portability
What is a common precaution taken in patients with a history of contrast allergy?
Pretreatment with antihistamines and corticosteroids
What type of signal is produced by cartilage and muscle?
Hypoechoic signal
What is the typical feature of cysts and homogeneous solid masses, such as lymphomas?
Anechoic signal
What does color Doppler display?
Velocity and direction of blood flow
What is plotted on the vertical scale (y-axis) in Doppler spectral display?
Velocity
What is the significance of brighter colors in color Doppler?
Higher mean velocities
What is the direction of flow represented by the color above the black bar in color Doppler?
Flow towards the Doppler beam
What is the purpose of Doppler sonography?
To provide functional information about blood flow
What is the typical feature of acoustic enhancement?
Structures appear brighter
Study Notes
Radiography
- Radiography is a type of medical imaging that uses x-rays to produce images.
- It is also known as x-ray, plain film, radiograph, and conventional radiograph.
- Radiography was discovered by Roentgen in 1895.
- Radiography refers to the medical images that are the "shadows" projected onto a flat plane (planar) when x-rays pass through a patient.
Image Contrast
- Image contrast is the difference in brightness between an area of interest and its surroundings.
- The larger the difference in brightness between different tissue types, the easier it is to differentiate them from each other.
Artifacts and Interfaces
- An artifact is an imaging finding that does not directly correspond to the reality of the patient.
- Artifacts may mimic a clinical feature, degrade image quality, or obscure anatomy.
- Radiological interfaces are between different radiodensities, such as the border of the heart against the lung.
Planar vs Cross-Sectional Imaging
- Planar images are shadows of complex three-dimensional objects, e.g. radiography.
- Cross-sectional images show the three-dimensional reality of anatomy, e.g. CT, ultrasound, and MRI.
Categories of Medical Imaging
- Radiating imaging modalities: use ionizing radiation to produce an image, e.g. radiography, CT, nuclear medicine.
- Non-radiating imaging modalities: do not use ionizing radiation to produce an image, e.g. MRI, ultrasound.
Five Basic Densities Seen on Conventional Radiography
- Radiopaque: denser structures block x-rays better, appear white on radiograph.
- Radiolucent: less dense structures allow x-rays to pass through, appear gray to black on radiograph.
- Cartilage and muscle: produce a hypoechoic signal, appear dark as most waves pass through the tissue.
- Fluid and fluid-filled structures: produce an anechoic signal, appear black as there is no reflection of ultrasound waves.
Ultrasound
- Ultrasound uses high-frequency sound waves to produce images.
- It is also known as sonography.
- Doppler sonography provides valuable information regarding the presence, direction, and velocity of blood flow.
- Clinical indications for ultrasound include gynecologic exams, echocardiography, abdominal exams, and procedures.
Strengths and Weaknesses of Ultrasound
- Strengths: lack of ionizing radiation, low cost, portability, lack of use of contrast.
- Weaknesses: cannot penetrate gas or bone, obese patients may be difficult to penetrate, dependent on the skills of the operator scanning.
Contrast Agents
- Contrast agents are used to distinguish adjacent tissues in imaging by creating a temporary, artificial density difference between objects.
- Contrast agents can be used in radiography and CT.
- Iodinated contrast material is excreted through the renal system.
- Contrast reactions can be anaphylactoid or chemotoxic reactions.
Magnetic Resonance Contrast Agents
- The two classes of MRI contrast agents are diffusion and non-diffusion agents.
- Diffusion agents can delineate vessels as well as parenchymal tissues.
- Non-diffusion agents remain in the bloodstream and are primarily useful for MRA.
This quiz covers the principles of Radiography, CT, Molecular Imaging, MRI, and Ultrasound, including image generation processes, terminology, and clinical indications.
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