CT with IV contrast
Contrast CT is CT scan using radiocontrast, and in Radlines it refers to a CT scan using IV contrast except otherwise noted.
Bolus tracking is where a specified location within the circulatory system is monitored during IV contrast infusion, and the timing of the main imaging is counted from when the contrast reaches this location (sufficiently to achieve a specified threshold).
Washout is where tissue loads radiocontrast during arterial phase, but then returns to a rather hypodense state in venous or later phases. This is a property of for example hepatocellular carcinoma as compared to the rest of the liver parenchyma.[1]
Phases
Depending on the purpose of the investigation, there are standardized protocols for time intervals between intravenous radiocontrast administration and image acquisition, in order to visualize the dynamics of contrast enhancements in different organs and tissues.[2] The main phases thereof are as follows:[3]
| Phase | Time from injection[3] | Time from bolus tracking in proximal aorta[3] | Targeted structures and findings[3] |
|---|---|---|---|
| Non-enhanced CT (NECT) | - | - |
|
| Pulmonary arterial phase | 6-13 sec[4] | - | |
| Pulmonary venous phase | 17-24 sec[4] | - | |
| Early systemic arterial phase | 15-20 sec | immediately |
|
| Late systemicarterial phase Sometimes also called "arterial phase" or "early venous portal phase" |
35-40 sec | 15-20 sec |
|
| Pancreatic phase | 30[5] or 40[6] - 50[6] sec | 20-30 sec |
|
| Hepatic (most accurate) or late portal phase | 70-80 sec | 50-60 sec |
|
| Nephrogenic phase | 100 sec | 80 sec |
|
| Systemic venous phase | 180 sec[7] | 160 sec |
|
| Delayed phase Sometimes called "wash out phase" or "equilibrium phase" |
6[3]-15[7] minutes | 6[3]-15[7] minutes |
|
Gastrointestinal contrast
Rectally administered contrast is indicated in cases where a suspicion remains of penetrating trauma to the colon where an initial CT shows no reason for immediate surgery.[8]
References
- ↑ Choi, Jin-Young; Lee, Jeong-Min; Sirlin, Claude B. (2014). "CT and MR Imaging Diagnosis and Staging of Hepatocellular Carcinoma: Part II. Extracellular Agents, Hepatobiliary Agents, and Ancillary Imaging Features ". Radiology 273 (1): 30–50. doi:. ISSN 0033-8419. PMID 25247563.
- ↑ Bae, Kyongtae T. (2010). "Intravenous Contrast Medium Administration and Scan Timing at CT: Considerations and Approaches ". Radiology 256 (1): 32–61. doi:. ISSN 0033-8419.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Robin Smithuis. CT contrast injection and protocols. Radiology Assistant. Retrieved on 2017-12-13.
- ↑ 4.0 4.1 Page 584 in: Ákos Jobbágy (2012). 5th European Conference of the International Federation for Medical and Biological Engineering 14 - 18 September 2011, Budapest, Hungary. Volume 37 of IFMBE Proceedings . Springer Science & Business Media. ISBN 9783642235085.
- ↑ Raman SP, Fishman EK (2012). "Advances in CT Imaging of GI Malignancies. ". Gastrointest Cancer Res 5 (3 Suppl 1): S4-9. PMID 22876336. PMC: 3413036. Archived from the original. .
- ↑ 6.0 6.1 6.2 Otto van Delden and Robin Smithuis. Pancreas - Carcinoma. Radiology Assistant. Retrieved on 2017-12-15.
- ↑ 7.0 7.1 7.2 7.3 Dongqing Wang (2013). Selected Topics on Computed Tomography . ISBN 9789535111023. License: CC-BY-3.0. Chapter 1: "Computed Tomography in Abdominal Imaging: How to Gain Maximum Diagnostic Information at the Lowest Radiation Dose" by Kristie Guite, Louis Hinshaw and Fred Lee. DOI: 10.5772/55903
- ↑ Stephen Ledbetter and Robin Smithuis (2007-08-02). Acute Abdomen - Role of CT in Trauma. Radiopaedia.
