Examination of the liver with MRI requires numerous sequences and imaging at multiple times after the administration of contrast.
Note: This article is intended to outline some general principles of protocol design. The specifics will vary depending on MRI hardware and software, radiologist's and referrer's preference, institutional protocols, patient factors (e.g. allergy) and time constraints.
Sequences
Many variations exist, but a standard protocol might look like:
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T2 weighted
plane: axial and coronal
sequence: e.g. T2 HASTE and T2 fat-saturated (TSE)
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purpose:
T2 HASTE: rapid acquisition images with an anatomical overview
T2 fat-saturated: longer acquisition that is more susceptible to motion; important to assess T2 signal of focal liver lesions
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T1 weighted
plane: axial
sequence: T1 in-phase and out-of-phase (IP-OOP), T1 fat-saturated
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purpose:
IP-OOP: assess for fat-containing liver lesions and hepatic steatosis (OOP signal drop); IP signal drop is usually seen in iron deposition
T1 fat-saturated: assess for lesions with intrinsic hyperintense T1 signal (e.g. haemorrhage, melanin, and proteinaceous debris)
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diffusion-weighted imaging (DWI)
plane: axial
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sequence: fat-saturated single-shot diffusion-weighted EPI
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purpose:
liver masses, like hepatocellular carcinoma, metastasis hepatoblastoma, solid part of undifferentiated embryonal sarcoma in children or HCC
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post-contrast sequences
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T1 2D or 3D gradient-echo sequences (e.g. VIBE) at
arterial phase: 20-30 seconds
portal venous phase: 60-70 seconds
equilibrium phase: 3-5 minutes
hepatobiliary delayed phase: 10-30 minutes (after gadoxetate, but if gadobenate has been given its 45-60 min) with and without fat sat
later delayed phase: 1 hour +/- 3 hours in some institutions
subtracted images are useful in the evaluation of lesions with intrinsic high T1 signal
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