MRI Enterography: Indications, Patient Preparation, Technique & Patient Positioning, MR Sequences and protocol
MR Sequences and protocol
Coronal and Axial T2-w single-shot fast spin echo (SS-FSE/HASTE) without fat suppression.
Coronal and Axial FIESTA/True-FISP without fat suppression.
Coronal and/or Axial T2-w single-shot fast spin echo (SS-FSE/HASTE) with fat suppression.
Non-enhanced Axial T1-w GRE with fat suppression.
Non-enhanced Coronal T1-w GRE with fat suppression followed by dynamic contrast-enhanced Coronal T1-w with fat suppression.
Contrast-enhanced Axial T1-w with fat suppression (delayed phase).
MRE dynamic acquisitions are divided as follows: arterial (30 sec), enteric (45 sec), venous (70 sec) and delayed (≥ 90 sec) phases.
In patients with known or suspected inflammatory bowel disease, contrast-enhanced sequences should be obtained during the enteric (45 sec) and/or venous phase (70 sec).
In patients with suspected chronic gastrointestinal (GI) bleeding contrast-enhanced sequences should be obtained during the arterial (30 sec), enteric (45 sec) and/or portal venous phase (70 sec) phase.
Diffusion-weighted imaging (DWI) and cine FIESTA/True-FISP are optional sequences. However, we strongly suggest their routinely usage because these sequences provide very useful biological and functional information.
DWI can better identify the inflamed bowel loops in active phase. Any number of b values between 0 and 1000 s/mm2 provide adequate imaging. This correlates with actively inflamed bowel and lymph nodes, with the appearance of bowel fibrosis on DWI not yet defined.
Cine FIESTA is a fast sequence to evaluate bowel peristalsis and is particularly helpful in cases of obstruction or to confirm presence of strictures.
The MR protocol is summarized in the table below.