Exams With Contrast Flashcards
In the brain, normally enhancing structures include:
- Blood vessels
- Choroid plexus
- Dura
Iodinated contrasts ____ cross an intact blood brain barrier.
Does not
Name things that do not have a blood brain barrier and will enhance
Highly vascularized lesions:
Meningioma
Intracerebral lesions:
Glioblastomas
A typical iodinated contras dose for brain scans
100 ml
Scan delay for brain scan with contrast
Up to 5 minutes after complete injection
Scan delay for brain scan with contrast, for metastatic diseases, AIDS, and MS
45 minutes after the injection.
CT studies of the head without contrast include:
Ruling out: Sinusitis Trauma Grave’s disease Early-stage stroke Early-stage hematoma Hydrocephalus Dementia Mastoiditis Labyrinthitis Facial or 7th nerve palsy Petrous or temporal bone studies
Reasons for using contrast when scanning the neck include:
Differentiation of blood vessels from lymph nodes
Outline the epidural venous plexus
Blood vessels and vascular tumors appear more dense than lymph nodes when IV contrast is used.
A typical iodinated contrast dose for neck scans
Approximately 100 ml
A typical rate for injecting iodinated contrast dose for neck scans
3 ml/sec
Scan delay for neck scan with contrast
35 seconds following the START of the injection, assuming a helical scan is used.
Scanning is initiated after a saline flush is complete.
Saline flush after contrast injection for a neck exam, does what?
Reduces high density streaking in the subclavian area.
Neck Studies which call for contrast include
Neck mass Lymph nodes Parathyroid adenoma Parotid mass Oral pharynx Larynx Brachial plexus
When scanning the brachial plexus, where should you inject?
In the arm, opposite the side of interest.
brachial plexus is
a network of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve (C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit.
A typical iodinated contrast dose for chest scans
100 ml
A typical rate for injecting iodinated contrast dose for chest scans
3 ml/sec
Scan delay for chest scan with contrast
Approx 30 second after the start of the injection
Reasons for using contrast in a chest exam include:
Masses of chest
Lymphoma
Hilar or cardiac masses
Pulmonary emboli
For adrenal masses, a ______ delay, with targeted scans through the adrenal glads are done _______.
10 minute delay
After chest scan
A typical iodinated contrast dose for abdominal scans
75 to 150 ml
A typical rate for injecting iodinated contrast dose for abdominal scans
2 to 4 ml/sec
Scan delay for liver scan with contrast
70 to 80 seconds
Scan delay for pancreas scan with contrast
50 to 60 seconds
Scan delay for kidneys scan with contrast
80 to 90 seconds
Bi-phasic study of the liver
Exam performed to differentiate liver lesions with arterial blood supplies from those with venous blood supplies.
Tri-phasic study
Adds a non-contrast set of images
A hepatic arterial phase may be visualized by using a ____ delay following _____.
30 second delay
Initiation of IV contrast injection
Portal venous phase
- After moving th table back to the most superior slice position.
- About 70 seconds after the start of injection
Equilibrium phase is about ____ after the start of the injection.
120 seconds
A typical iodinated contrast dose for pelvic scans
Approx 100ml
A typical rate for injecting iodinated contrast dose for pelvic scans
2 to 3 ml/sec
Scan delay for pelvic scan with contrast
Usually a few minutes, to allow for ureter and bladder enhancement
What conditions require pelvic scan immediately following injection of contrast
Prostate and ovarian cancer
Lymphoma
Melanoma
A typical iodinated contrast dose for pediatric scans
1.0 ml per kg of body weight
Scan delay for pediatric scan with contrast
Scan delay times are slightly less than adult delay times
CT angiography is used for reasons including
- Narrowing caused by atherosclerosis
- Aneurysms
- Dissections
- Traumatic injury
- Congenital anomalies
- Effects of vascular treatments
Why is a higher injection rate of 3 to5 ml/sec used during a CTA?
To keep the concentration of the contrast media in the vessels sufficiently dense.
The slices during a CTA exam. Are acquired in what direction?
In the direction of the blood flow, in order to chase the contrast agent
During a CTA, why are thin slices important?
- For visualizing small structure
- To minimize partial volume averaging.
However, when large distances must be covered, sometimes thicker slices must be used.
What is another way to cover the required distance during a CTA?
Increasing the pitch can scan the vessel more quickly.
When reconstructing the images for a CTA exam, why should they be slightly overlapped?
Increasing the overlap of slices, increases resolution and decreases the effects of partial volume averaging.
As a general rule, a reconstruction interval for a CTA ______ will produce excellent multi-planar recons, MIPS, or other 3D rendering
Interval equal to 1/3 to 1/2 of the slice thickness
