imaging procedures Flashcards
during axial scanning
spatial resolution?
scan time ?
patient dose?
increased spatial resolution
increased scan time
increased patient dose
helical scanning
spatial resolution?
scan time ?
patient dose?
decreased spatial resolution
decreased scan time
decreased patient dose
What does volume mean in CT
entire area acquired with one tube rotation
Thin slices =
_______ noise and ______ resolution
high noise and high resolution
thick slices =
________ noise and ______ resolution
low noise and low resolution
slice interval
interval = thickness
interval > thickness
interval < thickness
slices start where another stops
gaps between slices
overlapping slices
contrast volume for pedi patients
1mL per lb
what happens during a contrast injection using timing bolus?
small bolus of contrast is injected into the patient and monitored. post test, the tech will look at images and pick the highest contrast enhancement time. the scan will be preformed at that injection time
Initial evaluation of stroke, headache, vertigo, and seizures are an indication for which type of scan?
ct head wo
CT head wo:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- axial preferred
slice parameters- 2.5 thick in posterior fossa and 5.0mm thick through vertex
gantry tilt- parallel to OML
contrast- wo for trauma or stroke. with for tumors or infection
algorithm- standard (80 ww and 30 wl) and bone (2500 ww and 600 wl)
CT facial bones
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- 1.25mm
gantry tilt- parallel to hard palate
contrast- wo for fracture or trauma and with for mass swelling, abscess) 45 seconds post injection
algorithm- standard (400 ww and 40 wl) bone (2500 ww and 600 wl)
facial trauma, mass, swelling, infection, and dental abscess indicates which type of scan?
CT facial bones
Proptosis (budging in the eye), pain, vision changes, abnormalities are indications of which type of scan?
CT orbits
CT orbits
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- 1.5 higher spatial resolution
gantry tilt- parallel to hard palate
contrast- wo for trauma or fracture. with for mass or swelling 60 seconds post injection
algorithm- standard (400 ww and 40 wl) bone (3500 ww and 600 wl)
survey of sinuses, sinusitis, sinus pain indicates which type of scan?
CT sinuses
CT sinuses
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- 3.75mm
gantry tilt- direct coronals perpendicular to hard palate (pt prone with head up for air fluid levels)
contrast- none
algorithm- bone (2500ww and 600 wl)
pain, ataxia (loss of coordination), and hearing loss are indications for which type of scan?
CT temporal bone
CT temporal bone
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- .625 thickness and .315 interval with overlapping slices
gantry tilt- direct coronals with pt prone and head up
contrast- none
algorithm- bone (2500ww and 600wl)
Vascular abnormalities, aneurysm, AV malformation, not stroke are indications for which type of scan?
CTA head
CTA head
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical and inferior to superior
slice parameters- .625mm
gantry tilt- none
contrast- 100-150mL @ 4 using bolus tracking or timing bolus ROI at aortic arch
algorithm- standard (400 ww and 40 wl)
stroke, aneurysm, and dissection are indications for which type of scan
CTA head and neck
CTA head and neck:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical (inferior to superior)
slice parameters- 1.25
gantry tilt- none
contrast- 100-150mL @ 4 using bolus tracking or timing bolus with ROI at ascending aorta or aortic arch
algorithm-standard (400ww and 40wl)
stroke, sinusitis, cerebral sinus thrombosis are indications for which type of scan?
CT head venogram
CT head venogram:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical (superior to inferior)
slice parameters- 2.5
gantry tilt- none
contrast- 45 second delay
algorithm- standard (400ww and 40wl)
Which scan is best for a brain tumor?
MRI
which scan is best for spinal stenosis?
myelogram
which scan is best for a spinal tumor?
MRI
CT Spine:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- cervical: 1.25 thoracic: 2.5 lumber: 2.5
gantry tilt- none
contrast-none
algorithm- bone (2500ww and 600wl) standard (400ww and 40wl)
spinal cord impingement, radiculopathy, disc injuries, fractures are indications for which type of scan?
CT myelogram
CT myelogram:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- 1.25
gantry tilt- none
contrast- intrathecal contrast injected into subarachnoid space and roll patient before scanning
algorithm- bone
CT chest
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- 5mm and include adrenal glands
gantry tilt- none
contrast- 100mL @ 3 with 30 second delay
algorithm- standard (400 ww and 40wl) lung (1800ww and -600wl)
aortic aneurysm, chest or back pain, dyspnea, or pressure changes are indications of which type of scan?
CTA chest aorta
CTA Chest aorta:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters-2.5 include thyroid gland to adrenal glands
gantry tilt- none
contrast- 100-150mL @ 4 with bolus tracking with ROI at descending aorta
algorithm- standard (400ww and 40wl) lung (1800ww and -600wl)
CTA chest PE:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters-2.5mm
gantry tilt- none
contrast- 100-150mL @ 4 using bolus tracking with ROI at Carina or left atrium
algorithm- standard (400ww and 4wl) lung (1800ww and -600wl)
lung disease, emphysema, and COPD are indications for which type of scan?
CT high resolution chest
CT high resolution chest:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- axial
slice parameters- 1.25 with interval 10-20mm
gantry tilt- none
contrast-none
algorithm- edge enhancing, lung, bone
CTA abdomen and pelvis:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- 2.5mm above diaphragm through pubic symphysis
gantry tilt- none
contrast-150mL @4 using bolus tracking with ROI at abdominal aorta at diaphragm
algorithm- standard (400ww and 40wl)
CTA runoff:
scan type-
slice parameters-
gantry tilt-
contrast-
algorithm-
scan type- helical
slice parameters- 1.25
gantry tilt- none
contrast- 150mL @ 4 using bolus
algorithm- standard (400ww and 40 wl)
what is prospectively scanning mean?
patient is only scanned during diastole
what is retrospectively scanning mean
continuous scan
what does beta blocker medication do?
slows the heart rate and prevent arrhythmias
what does nitroglycerin do?
dilates coronary arteries and prevents spasms
CT multiphase liver.
the 2nd scan is performed in an arterial phase using how long of a delay? what pathologies will be visible?
30 seconds
primary liver cancer or hepatocellular carcinoma
CT multiphase liver.
the 3rd scan is performed in a portal venous phase using how long of a delay? what pathologies will be visible?
60 seconds
metastatic liver cancer
CT multiphase liver.
the 4th scan is performed in a delay phase using how long of a delay? what pathologies will be visible?
5+ minutes
benign tumors or hemangiomas
what is metoclopramide or raglan used for during a scan?
stimulates stomach emptying
what is glucagon used for during a scan?
stops peristalsis
what are they delay phases on a CT soft tissue head and neck?
20 seconds=arterial
45seconds=venous
90 seconds = delay
CT of the kidneys.
the 2nd scan is performed using a 30 second delay which is what phase? what does it show?
arterial
corticomedullary
renal arteries and cortex
CT of the kidneys.
the 3rd scan is performed using a 90 second delay which is what phase? what does it show?
venous
nephron evaluation
CT of the kidneys.
the 3rd scan is performed using a 4 minute delay which is what phase? what does it show?
delay
excretory
collecting system and renal pelvis
a CT of the adrenals require 2 sets of delayed scans. what are they?
60 second = portal venous
15 minute
what is the scan delay time on a CT urogram?
4 minutes
