Neuroimaging Acquisition
CTA H&N and CTV and DE
CTA H&N
Note
-1 CTA radiation is equal to 13 mo
Patient preparation
-Large‑bore peripheral IV (usually 18–20 G)
-Preferred site: antecubital vein (2/2 resistance)
Contrast parameters
-Volume: 50–100 mL
-Injection rate: 3–6 mL/s
-Saline flush: 20–40 mL
Timing the scan
Bolus tracking
-A small ROI is placed over a target artery (e.g., aortic arch, carotid)
-The scanner automatically triggers acquisition when attenuation reaches a preset threshold (e.g., 100–150 HU)(our hospital 130); or can manually press ☢️
Graph pressure vs timing
-Maximum pressure: 300 psi (standard)
*peak injection pressure
1, contrast injection; 2, finish of contrast injection
-Arterial phase 20-22s
-Venous phase 45s
-Venous phase 45s
*dependent of cardiac output
CTV acquisition
-Separate imaging
-If more than 3 minutes of last CTA H&N, wait 4h
-Acquisition window 40–60s
Dual Energy (DECT)
-Usual CTH is 120 Kvp
>DE is low (80–90) and high (140–150) energy acquisition
*Low→ iodine; High→ blood
-Creates 2 maps→ iodine (IOM) & non-iodine (VNC-Virtual non-contrast)
>Siemens SOMATOM Force / Drive→ 2 tubes
>Philips Spectral CT→ dual-layer
>GE Revolution→ rapid switch