Gadolinium Chelates
- Most commonly used contrast agent
- Standard dose 0.1 mmol Gd/kg
- Bolus injection, dynamic study during arterial (20-30s) to detect hypervascular lesions, portovenous phase (60-90s) to detect hypovascular lesions, and equilibrium phase (between 2-10 min) to allow hemangiomas to fill-in and cholangiocarcinoma and inflammation to enhance
Liver-Specific Agents
- Teslascan (Mn-DPDP)
- MultiHance (gadobenate dimeglumine)
- Primovist (gadoxetic acid)
- SPIO (Endorem/Feridex)
Teslascan
- Hepatocyte-specific MR contrast agent
- Uptake into hepatocyte and partially excretes into the bile
- Drip infusion
- Increased T1 signal intensity
- Differentiate tumors of hepatocellular origin from nonhepatocellular origin
MultiHance
- 4% biliary excretion
- Can be bolus injected, images also taken 1-2 hours later for tumor detection (uptake into liver parenchyma to increase conspicuity of metastases)
Primovist
- Strong biliary excretion
- Can be bolus injected (doses 0.025 mmol/kg), images on delayed phase can be taken as early as 20 min
Superparamagnetic Iron Oxide Particles (SPIO)
- Accumulates within phagocytes in the liver (typically, there is absence of phagocytes in malignancy)
- On T2WI, normal tissues or lesions with phagocytes (ie, FNH, hepatocellular adenoma, well-differentiated HCC) appear dark
- Drip infusion
- Imaging done several hours after contrast administration
Above image: gadolinium metal, from www.emovendo.net
Reference:
Reimer P, Parizel PM, Meaney JFM, Stichnoth FA. Clinical MR Imaging, 2010
No comments:
Post a Comment