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 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 SPATIAL RESOLUTION CEREBRAL CTA ABDOMINAL CTA THORACIC CTA 1MM (LOWER mA) 3MM SLICE THICKNESS SPIRAL PITCH PITCHSPATIAL 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 sec. ABDOMINAL AND FEMORAL RUNOFF MANUAL DELAYS CERBRAL CTA CAROTID CTA CHEST CTA (PE) 15 SEC 12 SEC 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 Suttons Radiology Clarks Radiographic positioning and techniques Assignment Two students will be selected for assignment. Question Define Care bolus technique? Thank You