Digital Subtraction Angiography (DF
chapter 26)
Digital Subtraction Angiography (DSA) is a fluoroscopic technique used extensively in
_________________ for visualizing blood vessels.
a. CT
b. MRI
c. Interventional Radiology
d. Ultra sound
e. Nuclear medicine - answerc. Interventional Radiology
note: Radiopaque structures such as bones are eliminated ("subtracted") digitally from
the image, thus allowing for an accurate depiction of the blood vessels.
Image formation:
-There are 2 methods
1. _____________ subtraction &
2. ____________ subtraction - answerTemporal subtraction
Energy subtraction
Image obtained at one time is subtracted from an image obtained at a later time. This is
known as what image formation method? - answerTemporal subtraction
Uses 2 alternating x-ray beams operating a 2 different energy levels. Subtracted image
results from differences in photoelectric absorption in contrast vs. non-contrast status of
subject. This is known as what image formation method? - answerEnergy subtraction
A principal advantage of digital fluoroscopy over conventional fluoroscopy for
subtraction studies is:
a. Contrast enhancement
b. Examination speed
c. Less contrast material
d. Low patient dose
e. Noise enhancement - answera. Contrast enhancement
note: Image contrast can be enhanced electronically by subtraction techniques. DF
provides better contrast resolution through postprocessing of image subtraction.
, Which subtraction technique is used more frequently? - answerTemporal subtraction
note: because of high-voltage generator limitations associated with energy subtraction
mode.
When 2 techniques are combined (Temporal & Energy sub), the process is called? -
answerHybrid subtraction
note: Image contrast is enhanced still further by hybrid subtraction because of reduced
patient motion between subtracted images. Hybrid imaging theoretically can produce
the highest-quality DF images.
2 methods of Temporal subtraction are used, what are they? - answerMask mode &
time-interval difference (TID)
For Mask mode, the patient is positioned under normal fluoroscopic control to ensure
that the region of anatomy under investigation is within the field of view.
-A power injector is armed & readied to deliver ______ to _____ mL of contrast at the
rate of approximately ____ to ____mL/s through venous entry.
-If arterial entry, ____ to ____ mL of diluted contrast at _____ to _____mL/s.
- The imaging system is changed from fluoroscopic mode to the ______ mode. -
answer30 to 50 (venous entry)
15 to 20 (venous entry)
10 to 25 (arterial entry)
10 to 12 (arterial entry)
DF "Digital Fluoroscopy"
note: This requires an increase in x-ray tube current of 20 to 100 times the fluoroscopic
mode & activation of a program of pulse image acuisition.
____________ ________ results is successive subtraction images of contrast-filled
vessels. - answerMask mode
The injector is fired, & after a delay of 4 to 10 seconds, before the bolus of contrast
medium reaches the anatomic site, an initial x-ray pulsed exposure is made. The image
obtained is stored in primary memory and is displayed on video monitor A. This is the
___________ image which is followed by a series of additional images that are stored in
adjacent memory locations. - answermask image
chapter 26)
Digital Subtraction Angiography (DSA) is a fluoroscopic technique used extensively in
_________________ for visualizing blood vessels.
a. CT
b. MRI
c. Interventional Radiology
d. Ultra sound
e. Nuclear medicine - answerc. Interventional Radiology
note: Radiopaque structures such as bones are eliminated ("subtracted") digitally from
the image, thus allowing for an accurate depiction of the blood vessels.
Image formation:
-There are 2 methods
1. _____________ subtraction &
2. ____________ subtraction - answerTemporal subtraction
Energy subtraction
Image obtained at one time is subtracted from an image obtained at a later time. This is
known as what image formation method? - answerTemporal subtraction
Uses 2 alternating x-ray beams operating a 2 different energy levels. Subtracted image
results from differences in photoelectric absorption in contrast vs. non-contrast status of
subject. This is known as what image formation method? - answerEnergy subtraction
A principal advantage of digital fluoroscopy over conventional fluoroscopy for
subtraction studies is:
a. Contrast enhancement
b. Examination speed
c. Less contrast material
d. Low patient dose
e. Noise enhancement - answera. Contrast enhancement
note: Image contrast can be enhanced electronically by subtraction techniques. DF
provides better contrast resolution through postprocessing of image subtraction.
, Which subtraction technique is used more frequently? - answerTemporal subtraction
note: because of high-voltage generator limitations associated with energy subtraction
mode.
When 2 techniques are combined (Temporal & Energy sub), the process is called? -
answerHybrid subtraction
note: Image contrast is enhanced still further by hybrid subtraction because of reduced
patient motion between subtracted images. Hybrid imaging theoretically can produce
the highest-quality DF images.
2 methods of Temporal subtraction are used, what are they? - answerMask mode &
time-interval difference (TID)
For Mask mode, the patient is positioned under normal fluoroscopic control to ensure
that the region of anatomy under investigation is within the field of view.
-A power injector is armed & readied to deliver ______ to _____ mL of contrast at the
rate of approximately ____ to ____mL/s through venous entry.
-If arterial entry, ____ to ____ mL of diluted contrast at _____ to _____mL/s.
- The imaging system is changed from fluoroscopic mode to the ______ mode. -
answer30 to 50 (venous entry)
15 to 20 (venous entry)
10 to 25 (arterial entry)
10 to 12 (arterial entry)
DF "Digital Fluoroscopy"
note: This requires an increase in x-ray tube current of 20 to 100 times the fluoroscopic
mode & activation of a program of pulse image acuisition.
____________ ________ results is successive subtraction images of contrast-filled
vessels. - answerMask mode
The injector is fired, & after a delay of 4 to 10 seconds, before the bolus of contrast
medium reaches the anatomic site, an initial x-ray pulsed exposure is made. The image
obtained is stored in primary memory and is displayed on video monitor A. This is the
___________ image which is followed by a series of additional images that are stored in
adjacent memory locations. - answermask image
