Transcript CT ANGIOGRAPHY

CT ANGIOGRAPHY
CT IMAGE OF THE BLOOD
VESSEL OPACIFIED BY
CONTRAST
REQUIREMENTS FOR CTA
• PATIENT PREPARATION
• ACQUSITION PARAMETERS
• CONTRAST MEDIUM
ADMINISTRATION
• POSTPROCESSING TECHNIQUES
PATIENT PREP.
INFORMED CONSENT
PATIENT PREP.
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•
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•
BUN 7-20 mg/dl
CREAT.- 0.6 –1.2 mg/dl
IODINE ALLERGY- STEROID THERAPY
HYPERVENTILATION BEFORE EXAM
FOR BETTER BREATHOLD
UTILIZED
GAUGE SUITABLE FOR CTA
18 OR 20
CONTRAST ADMINISTERED
WITH POWER INJECTOR
ACQUSITION PARAMETERS
PARAMETERS
• USUALLY ROUTINE CT PRECEDES A
CTA EXAM. THE ROUTINE EXAM IS
USED AS A REFERENCE SCAN
HELPING TO DETERMING THE
SCANNING RANGE IN CTA.
SLICE THICKNESS
• SLICE
THICKNESS
• SPATIAL
RESOLUTION
SLICE THICKNESS
• CEREBRAL CTA
• 1MM (LOWER mA)
• ABDOMINAL CTA
• 3MM
• THORACIC CTA
• 3MM
SPIRAL PITCH
• PITCH
• SPATIAL
RESOLUTION
SPIRAL PITCH
• UP TO 2
kVp, mA, TIME
• SIMILAR TO NON- CTA EXAM OF THE
SAME BODY PART
RECONSTRUCTION
INTERVAL
• 50% OF OVERLAP
UTILIZE SUBSECOND
SCANNING
• INCREASED TISSUE VOLUME
COVERAGE
• REDUCTION IN MOTION ARTIFACT
CONTRAST
ADMINISTRATION
POWER INJECTOR
POWER INJECTOR
PARAMETERS
VOLUME OF CONTRAST-ml
RATE ml/sec
TIME OF INJECTION – sec
SCAN DELAY TIME - sec
CONTRAST WARMER
WHY???
RATE OF INJECTION
3-5 ml/sec
ORAL CONTRAST????
WATER
NEGATIVE CONTRAST
AUTOMATED CONTRAST
ADMINISTRATION SYSTEMS
• SMARTPREP
• CARE
• SURESTART
CONTRAST
ADMINISTRATION AND
SCANNING METHODS
• BOLUS TRACKING
• BOLUS TIMING
• MANUAL PRESET TIME
CARE BOLUS
SMART PREP
SURE START
Bolus tracking- PE
PE?
Tracking slice
Bolus tracking- Carotids and
Circle of Willis
Circle of Willis
Circle of Willis?!
40 SEC
Renal arteries 25-30 sec.
ABDOMINAL
AND FEMORAL RUNOFF
MANUAL DELAYS
• CERBRAL CTA
• 15 SEC
• CAROTID CTA
• 12 SEC
• CHEST CTA (PE)
• 10-20 SEC
CARDIAC CT
TWO TECHNIQUES TO REDUCE
MOTION ARTIFACTS IN CARDIAC
CT
• PROSPECTIVE TRIGGERING
• RETROSPECTIVE GATING
Prospectively ECG-Triggered Sequential
Scanning
Cardiac CT applications require the
synchronization of data acquisition to the cardiac
cycle, i.e. to the movement of the heart. For
sequential imaging, a prospective trigger is
derived from the ECG-trace to initiate the CT-scan
with a certain delay time after the R-wave. The
true delay time is calculated from a given phase
parameter (e.g. a percentage of the RR-interval
time) for each cardiac cycle individually based on
a prospective estimation of the RR-intervals.
Usually, the delay is defined such that the scans
are acquired during the diastolic phase of the
heart
Retrospectively ECG-Gated Spiral Scanning
For "retrospectively ECG-gated spiral scanning" a
continuous spiral scan is acquired with the ECGsignal recorded simultaneously. The acquired scan
data is selected for image reconstruction with
respect to a pre-defined cardiac phase. Similar to
ECG-triggered sequential scanning a certain R-wave
delay time defines the start point of data that is
used for image reconstruction. ECG-gated spiral
scanning has several advantages over ECGtriggered sequential scanning. The continuous
acquisition allows for reconstruction of overlapping
slices. Due to the retrospective analysis of the ECG,
the technique is less sensitive to arrhythmia
.
BOTH METHODS REQUIRE
ECG MONITORING
DIASTOLIC PHASE
SCANNING DURING
RR INTERVAL
Retrospective ECG-Gating
CARDIAC CT PROCEDURES
• CARDIAC ANGIOGRAM
• CALCIUM SCORING
CARDIAC ANGIOGRAM
PERFORMED WITH CONTRAST
INJECTION
4-5 cc/sec
150 cc total volume
CALCIUM SCORING
NO IV CONTRAST USED
CARDIAC ANGIOGRAM
CALCIUM SCORING
3-D VISUALIZATION TOOLS
IN CTA
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MPR
MIP
SSD
VR
CINE
CARDIAC ANGIOGRAM
CTA - MPR
PLANE?
MPR
PLANE?
MIP - CTA
SSD -CTA
VR - CTA
CINE CTA
MPR
• SIMPLE
• FAST
• ANY PLANE
VISUALIZATION
• LESS USEFUL IN
COMPLEX VESSEL
VISUALIZATION
SSD
• FAST
• LITTLE EDITING
• LITTLE AXIAL
DATA USAGE
• CONTOUR ,
RELATIONSHIP OF
VESSELS
• ARTIFACT
GENERATION
• INACCURATE
MIP
• CALCIFICATION
DETECTION
• THROMBUS
DETECTION
• AILIASING
ARTIFACT
• EDITING
REQUIRED
VR
• ACCURATE
• ALL DATA USED
• GOOD STENOSIS
DETECTION
• COMPLEX
COMPUTER
PROCESSING
(PAST)
STEREOSCOPIC VIEWING