Download - CT ANGIOGRAPHY
CT ANGIOGRAPHY
Dr Mohamed El Safwany, MD
Intended learning outcome
• The student should learn at the end of this lecture CT IMAGE OF THE BLOOD VESSEL OPACIFIED BY CONTRAST.
CT IMAGE OF THE BLOOD VESSELS OPACIFIED BY
CONTRAST
REQUIREMENTS FOR CTA
• PATIENT PREPARATION
• ACQUSITION PARAMETERS
• CONTRAST MEDIUM ADMINISTRATION
• POSTPROCESSING TECHNIQUES
PATIENT PREP.
INFORMED CONSENT
PATIENT PREP.
• 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
• CEREBRAL CTA
• ABDOMINAL CTA
• THORACIC CTA
• 1MM (LOWER mA)
• 3MM
• 3MM
SLICE THICKNESS
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
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
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
• CAROTID CTA
• CHEST CTA (PE)
• 15 SEC
• 12 SEC
• 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. 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 ECG-signal 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 ECG-triggered 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
• 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
Text Book
• David Sutton’s Radiology
• Clark’s Radiographic positioning and techniques
Assignment
• Two students will be selected for assignment.
Question
• Define Care bolus technique?
• Thank You