Diagnostic Imaging Flashcards
What are the two types of digital radiology detector systems? Describe each and their advantages.
Computed radiography or direct digital radiography. CR systems use plates to generate a digital image, less expensive. DR faster. Both generate good images.
Why are plain film of digital radiographs preferrable over MRI or CT?
Cost and time-effective
To be of greatest diagnostic value, how should NHP thoracic rads be taken?
With NHP in an upright position at full inspiration.
What type of US transducer is adequate for most areas to be scanned? What does ocular ultrasonography require?
3.0-7.5 MHz transducer. Ocular requires 10.0 mHz
How does MRI function? What tissues generate the strongest signal? Weakest? How does this impact imaging modality selection?
Uses a strong magnetic field to obtain detailed images via excitation of hydrogen protons. Greater signal produced from tissues with highest amount of hydrogen, including fat and cerebrospinal fluid, and is thus preferred for soft tissues. Poor for bone and lung.
What is the difference between T1-weighted and T2-weighted MRI?
T1-weighted enhances fat, T-2 water
What is an advantage of MRI compared to CT? A disadvantage? How do IV contrast agents appear on CT?
MRI does not use ionizing radiation, and thus does not increase risk for radiation-induced cancers. MRI contra-indicated with certain implants (cardiac pacemakers and defibrillators). Gadolinium bright wight on T1-weighted images.
How does CT work? How does this differ from radiographs? CT is preferred for what tissues?
Uses X-rays to acquire images that are superior to radiography due to higher scan power, shorter rotation time, and smaller focal spots. CT preferred for bone, thoracic structures, and certain masses/neoplasia.
