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46 Cards in this Set
- Front
- Back
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What is a CT scan like?
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Computed Tomography. Like an x-ray, but in 3D and can only be in an axial position.
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What was the first CT scans like?
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Limited to sections of the brain.
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What is done first when taking a CT scan?
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A scout image.
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What is a scout image?
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Taken to plan the exam and it will appear similar to a radiograph.
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what is an MPR?
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Multi planar reconstruction in CT Scan. The simplest method of reconstruction?
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A MPR is used to examine what?
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The spine, and can only show 1 vertebral body at a time and is not reliable for IVD's.
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What happens with helical/spiral CT?
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integrate the data of the moving individual slices to generate three dimensional volumetric information.
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What is a pixel and what is a voxel?
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Pixel- a 2 dimensional unit based on the matrix size and field of view. Voxel- 3D unit.
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What is H U.?
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Hounsfield units- a data stream representing the varying radiographic density.
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What will different items H U. be?
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water- 0 H U. Air -1000 H U. Bone +400 H U. Cranial bone +2000 H U.
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What color on a CT scan will -1000 and +1000 H U be?
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black= -1000. White is around +1000.
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What is windowing?
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using the calculated H U to make an image.
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How many shades of gray are in a CT scan?
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256 shades.
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Artifacts on a CT scan are caused by what?
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abrupt transition between low and high density.
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What can cause an Aliasing artifact or streaks?
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insufficient penetration of the x-ray occurs, or when motion occurs. It looks like dark lines which radiate away from sharp corners.
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What is the most common artifact with CT scans and what will it be like?
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Ring artifacts. One or many rings appears within an image usually due to a detector fault.
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What is a noise artifact and what causes it?
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graining on the image due to low signal to noise ratio.
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What will a motion artifact look like on a CT scan?
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blurring or streaking.
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What causes a windmill artifact with CT scans?
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reduced filters.
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What is beam hardening?
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an artifact that has a cupped appearance. It is easily fixed by filtration and software.
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As CT technology has advanced there have been needs for higher resolution imaging and use more complex scan techniques, but wha tare the disadvantages?
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It will require higher doses of radiation exposure.
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In general when would you use a CT or a MRI?
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CT- bones. MRI- soft tissues.
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Why would you use a CT for the brain?
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To look for evidence of a stroke, embolus, evaluating skull for fractures.
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How will an MRI work?
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body placed in a strong magnetic field. Atoms (particularly H from water) align "axis" with magnetic field. Radio frequencies introduced to tip axis off alignement. Radio frequency is stopped and energy is given back as atoms return to alignment in field is measured.
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How can diseased tissue be identified with an MRI?
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Diseased tissue like tumors can be detected because the protons in different tissues return to their equilibrium state at different rates.
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Will MRI have radiation or other health concerns?
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No radiation, but is not allowed for people with metal implants and cardiac pacemakers.
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CT provides ____1____ and MRI provides ______2_____.
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1. spatial resolution. 2. comparable spatial resolution with far better contrast resolution.
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What is the difference (visually) between T1 and T2 weighted MRI's?
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T1- fat is brightes, cord higher (Black) signal that CSF. 2. Water is brightest(White spine), CSF higher signal that cord, fat will still be white since it has water.
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When will T1 or T2 be used?
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T1- better to look at anatomy and T2 is better at finding edema and therefore pathology.
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What is the different sequence that can be used with T1 and what is it used for?
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STIR. Used to detect fat and therefore edematous tissue is better evaluated, also is helpful in musculoskeletal evaluations.
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What is the different sequence that can be used with T2 and what is it used for?
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FLAIR and is used to evaluate the brain.
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What type of image is good for joints especially the shoulder?
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MRI arthorgram.
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Who is responsible for determining if the patient has a contraindication for an MRI?
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The imaging center.
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Will MRI or CT be able to generate a 3D reconstriction?
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Both.
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What is better at detection and identification of a tumor in the brain?
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MRI.
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What is better at detection and identification of a tumor in the abdomen and chest?
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CT due to less motion artifact.
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Radionuclide imaging is aka?
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Nuclear scintigraphy and bone scan.
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Unlike CT and MRI radionulide imaging shows what?
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Physiological function of the system.
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What is a hot spot and a cold spot?
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Hot Spot is a focal increased radio accumulations or general increase in radio-accumulation throught the physiological system. Coldspot is some diseases result in the exclusion of a tracer.
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What are the 3 ways radionuclide images are taken?
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Static, dynamic and SPECT. (single photon emission computed tomography)
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When will chiropractors typically use radionuclide imaging, and how will the image be taken?
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To evaluate if a spondylolisthesis is active or inactive. SPECT.
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What are the 3 main types of bone scans?
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Whole body, limited, three-phase.
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What is ultrasonography used for?
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To visulaize muscles, tendon, internal organs, babies (or parasitic infestations).
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Ultrasound is good at differentiating what?
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Solid vs. cystic contents.
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What are 5 things routenly scanned with ultrasound?
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obstetrics, cardiac, renal, liver and gallbladder
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What are other, additional structures scanned with ultrasound?
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"musculoskeletal imaging of muscles,
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