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CT Procedures
Question | Answer |
---|---|
Plain Brain | Slice Thickness: 2-5mm. Scan range: below skull base - above vertex. Parallel to IOML. |
Angio Brain | Slice Thickness: 1-2 mm. Scan range: C2 - top head. For COW. CRUCIAL: Images during arterial phase. Done by 1) 15-20 sec. delay 2) Test bolus 3) Bolus tracking. Injection rate: 4 mL/sec ~60-80mL. Venogram images brain tissue during venous phase. |
Perfusion Brain | Slice Thickness: 3-5 mm. 60 sec scan, so image only section needed. Eval blood flow in/out brain tissue. Helps ID dead/alive brain tissue. ROI placed over artery/vein to show blood outflow. Injection rate: 5-7 mL/sec ~50mL. |
Orbits | Slice Thickness: 2-3mm. Scan range: Below orbital floor - above orbital roof. Parallel to IOML. If CM needed ~100mL |
Facial Bones | Slice Thickness: 2-3mm. Scan Range: Above frontal sinus - mandible. |
Sinuses | Slice Thickness: 2-3mm. Scan Range: Max/ethmoid-sphenoid sinus. Obtain direct coronal imaging. If CM needed ~100mL |
Soft Tissue Neck | Slice Thickness: 3-5 mm. Parallel to hard palate for orbits-hard palate. After, parallel to body of mand. No swallow/breathe. 45-90 sec delay. Thyroid is hyperdense due to iodine concentration. Injection rate: 2-4 mL/sec ~80-125mL. |
Angio Neck | Slice Thickness: 1-1.5 mm. Scan range: Skull base aortic arch. Injection rate: 4 mL/sec ~60-80mL. CRUCIAL: Images during arterial phase (carotids). Done similarly to Angio Head. IV in RT AC helps reduce streak artifact. |
Larynx | Slice Thickness: 1-2 mm. Scan Range: mid orbit-clavicle. While holding breath. 2nd w/ prolonged “ee” to show odd vocal cords move. Injection rate: 2-4 mL/sec ~80-125mL. |
Chest | Slice Thickness: 2-5mm. Scan range: above lung apices-adrenals. No breathe. IF IV: Scan feet-head b/c reduces artifact from CM as going in. Inject rate: 2-4 mL/sec ~70-120mL. |
High Res. Chest | Slice Thickness: 0.5-2 mm or 10-15mm for interstitial lung disease. Scan range: above lung apices-base. Hold breath IN/OUT. Prone/supine shows edematous changes. |
PE | Slice Thickness: 0.5-2mm. Scan range: above lung apices-bases. See pulm artery. No breathe. Scan feet-head b/c reduces artifact from CM as going in. Post saline flush helps reduce streak artifact in SVC. Inject rate: 4-7 mL/sec ~80-120mL. |
Cardiac | 0.4-0.7mm. Carina-apex heart. ECG gating (only during diastole: 55-75% of R-R interval). Prospect gated: rad off when not diastole. Retrospect gated: all cycles but recon only parts. Inject rate: 4-7 mL/sec ~80-100mL. |
Calcium Score | 2-3mm. Carina-apex heart. ECG gating (only during diastole phase - a defined R-R interval, triggered by T wave of ECG) & no CM. Prospectively gated. Agatston scoring defines # of calcium: Mim 1-10, Mild 11-100, Mod. 101-400, Bad +400. |
Angio Chest (Aorta) | Slice Thickness: 0.5-2mm. Above clavicle-below celiac artery. Rules out dissection. Pro/retrospective Gating used to reduce ascending aorta motion. IV in RT AC reduces streak artifact from aortic branches. Inject rate: 4-7 mL/sec ~80-120mL. |
Cervical Spine | Slice Thickness: 0.5-2mm. Scan range: skull base-T1/T2. Neck straight! If CM needed inject rate: 1-3 mL/sec ~80-120mL during portal venous phase. |
Thoracic Spine | Slice Thickness: 2-5mm. Scan range: C7-L1/L2. If CM needed inject rate: 1-3 mL/sec ~80-120mL during portal venous phase. |
Lumbar Spine | Slice Thickness: 2-5mm. Scan range: T12-L5. Sponge under knees. If CM needed inject rate: 1-3 mL/sec ~80-120mL during portal venous phase. |