CT ANGIOGRAPHY

CT IMAGE OF THE BLOOD VESSEL OPACIFIED BY CONTRAST

REQUIREMENTS FOR CTA PATIENT PREPARATION ACQUSITION PARAMETERS CONTRAST MEDIUM ADMINISTRATION POSTPROCESSING TECHNIQUES

PATIENT PREPARATION

ACQUSITION PARAMETERS

CONTRAST MEDIUM ADMINISTRATION

POSTPROCESSING TECHNIQUES

PATIENT PREP.

INFORMED CONSENT

PATIENT PREP. BUN 7-20 mg/dl CREAT.- 0.6 –1.2 mg/dl IODINE ALLERGY- STEROID THERAPY HYPERVENTILATION BEFORE EXAM FOR BETTER BREATHOLD

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

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.

USUALLY ROUTINE CT PRECEDES A CTA EXAM. THE ROUTINE EXAM IS USED AS A REFERENCE SCAN HELPING TO DETERMING THE SCANNING RANGE IN CTA.

Remember SLICE THICKNESS SLICE THICKNESS SPATIAL RESOLUTION

SLICE THICKNESS

SPATIAL RESOLUTION

CEREBRAL CTA ABDOMINAL CTA THORACIC CTA 1MM (LOWER mA) 3MM 3MM SLICE THICKNESS

CEREBRAL CTA

ABDOMINAL CTA

THORACIC CTA

1MM (LOWER mA)

3MM

3MM

SPIRAL PITCH PITCH SPATIAL RESOLUTION

PITCH

SPATIAL RESOLUTION

SPIRAL PITCH UP TO 2

UP TO 2

kVp, mA, TIME SIMILAR TO NON- CTA EXAM OF THE SAME BODY PART

SIMILAR TO NON- CTA EXAM OF THE SAME BODY PART

RECONSTRUCTION INTERVAL 50% OF OVERLAP

50% OF OVERLAP

UTILIZE SUBSECOND SCANNING INCREASED TISSUE VOLUME COVERAGE REDUCTION IN MOTION ARTIFACT

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

Power injector specs Flow rate: 0.1-9.9 ml/s Variable pressure limitation: 25-300 psi Syringe sizes: 200 ml empty syringes (frontload method); 50, 100, 125 ml Mallinckrodt Ultraject prefilled ready syringes; 30, 50 Mallinckrodt Ultraject hand-held ready syringes Filling rate: 2-7 ml/s Volume: 0.1 ml up to stated syringe volume Scan delay: 0-99 s Injection delay: 0-255 s Phase number: 4 Storage capacity: 12 programs

Flow rate: 0.1-9.9 ml/s

Variable pressure limitation: 25-300 psi

Syringe sizes: 200 ml empty syringes (frontload method); 50, 100, 125 ml Mallinckrodt Ultraject prefilled ready syringes; 30, 50 Mallinckrodt Ultraject hand-held ready syringes

Filling rate: 2-7 ml/s

Volume: 0.1 ml up to stated syringe volume

Scan delay: 0-99 s

Injection delay: 0-255 s

Phase number: 4

Storage capacity: 12 programs

CONTRAST WARMER WHY ???

RATE OF INJECTION 3-5 ml/sec

ORAL CONTRAST WATER NEGATIVE CONTRAST

AUTOMATED CONTRAST ADMINISTRATION SYSTEMS SMARTPREP CARE SURESTART These systems are designed to monitor contrast until it reaches a pre-determined threshold or set value to ensure that contrast flow in the vessels is optimal

SMARTPREP

CARE

SURESTART

CONTRAST ADMINISTRATION AND SCANNING METHODS BOLUS TRACKING BOLUS TIMING MANUAL PRESET TIME Technique used in computed tomography imaging, to visualise vessels more clearly. A bolus of radio-opaque contrast media is injected into a patient via a peripheral intravenous cannula . Depending on the vessel being imaged, the volume of contrast is tracked using a region of interest at a certain level and then followed by the CT scanner once it reaches this level. Images are acquired at a rate as fast as the contrast moving through the blood vessels.

BOLUS TRACKING

BOLUS TIMING

MANUAL PRESET TIME

CARE BOLUS

SMART PREP

Bolus tracking- 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

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

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 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

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

MPR

MIP

SSD

VR

CINE

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

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

FAST

LITTLE EDITING

LITTLE AXIAL DATA USAGE

CONTOUR , RELATIONSHIP OF VESSELS

ARTIFACT GENERATION

INACCURATE

MIP CALCIFICATION DETECTION THROMBUS DETECTION AILIASING ARTIFACT EDITING REQUIRED

CALCIFICATION DETECTION

THROMBUS DETECTION

AILIASING ARTIFACT

EDITING REQUIRED

VR ACCURATE ALL DATA USED GOOD STENOSIS DETECTION COMPLEX COMPUTER PROCESSING (PAST)

ACCURATE

ALL DATA USED

GOOD STENOSIS DETECTION

COMPLEX COMPUTER PROCESSING (PAST)

STEREOSCOPIC VIEWING