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CT ANGIOGRAPHY
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CT IMAGE OF THE BLOOD VESSEL OPACIFIED BY CONTRAST
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REQUIREMENTS FOR CTA PATIENT PREPARATION ACQUSITION PARAMETERS
CONTRAST MEDIUM ADMINISTRATION POSTPROCESSING TECHNIQUES
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PATIENT PREP.
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INFORMED CONSENT
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PATIENT PREP. BUN 7-20 mg/dl CREAT.- 0.6 –1.2 mg/dl
IODINE ALLERGY- STEROID THERAPY HYPERVENTILATION BEFORE EXAM FOR BETTER BREATHOLD
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UTILIZED
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GAUGE SUITABLE FOR CTA 18 OR 20
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CONTRAST ADMINISTERED WITH POWER INJECTOR
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ACQUSITION PARAMETERS
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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.
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SLICE THICKNESS SPATIAL RESOLUTION SLICE THICKNESS
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SLICE THICKNESS CEREBRAL CTA ABDOMINAL CTA THORACIC CTA 1MM (LOWER mA)
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SPIRAL PITCH PITCH SPATIAL RESOLUTION
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SPIRAL PITCH UP TO 2
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kVp, mA, TIME SIMILAR TO NON- CTA EXAM OF THE SAME BODY PART
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RECONSTRUCTION INTERVAL
50% OF OVERLAP
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UTILIZE SUBSECOND SCANNING
INCREASED TISSUE VOLUME COVERAGE REDUCTION IN MOTION ARTIFACT
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CONTRAST ADMINISTRATION
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POWER INJECTOR
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POWER INJECTOR PARAMETERS
VOLUME OF CONTRAST-ml RATE ml/sec TIME OF INJECTION – sec SCAN DELAY TIME - sec
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CONTRAST WARMER WHY???
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RATE OF INJECTION 3-5 ml/sec
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ORAL CONTRAST???? WATER NEGATIVE CONTRAST
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AUTOMATED CONTRAST ADMINISTRATION SYSTEMS
SMARTPREP CARE SURESTART
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CONTRAST ADMINISTRATION AND SCANNING METHODS
BOLUS TRACKING BOLUS TIMING MANUAL PRESET TIME
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CARE BOLUS
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SMART PREP
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SURE START
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Bolus tracking- PE
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PE?
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Tracking slice
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Bolus tracking- Carotids and Circle of Willis
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Circle of Willis
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Circle of Willis?! 40 SEC
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Renal arteries sec.
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ABDOMINAL AND FEMORAL RUNOFF
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MANUAL DELAYS CERBRAL CTA CAROTID CTA CHEST CTA (PE) 15 SEC 12 SEC
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CARDIAC CT
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TWO TECHNIQUES TO REDUCE MOTION ARTIFACTS IN CARDIAC CT
PROSPECTIVE TRIGGERING RETROSPECTIVE GATING
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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
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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.
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BOTH METHODS REQUIRE ECG MONITORING
DIASTOLIC PHASE
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SCANNING DURING RR INTERVAL
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Retrospective ECG-Gating
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CARDIAC CT PROCEDURES CARDIAC ANGIOGRAM CALCIUM SCORING
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PERFORMED WITH CONTRAST INJECTION 4-5 cc/sec 150 cc total volume
CARDIAC ANGIOGRAM PERFORMED WITH CONTRAST INJECTION 4-5 cc/sec 150 cc total volume
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CALCIUM SCORING NO IV CONTRAST USED
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CARDIAC ANGIOGRAM
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CALCIUM SCORING
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3-D VISUALIZATION TOOLS IN CTA
MPR MIP SSD VR CINE
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CARDIAC ANGIOGRAM
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CTA - MPR PLANE?
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MPR PLANE?
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MIP - CTA
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SSD -CTA
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VR - CTA
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CINE CTA
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MPR SIMPLE FAST ANY PLANE VISUALIZATION
LESS USEFUL IN COMPLEX VESSEL VISUALIZATION
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SSD FAST LITTLE EDITING LITTLE AXIAL DATA USAGE
CONTOUR , RELATIONSHIP OF VESSELS ARTIFACT GENERATION INACCURATE
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MIP CALCIFICATION DETECTION THROMBUS DETECTION AILIASING ARTIFACT
EDITING REQUIRED
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VR ACCURATE ALL DATA USED GOOD STENOSIS DETECTION
COMPLEX COMPUTER PROCESSING (PAST)
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STEREOSCOPIC VIEWING
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