MRI of the small and large bowel

Abstract

Driven by the improvements in gradient technology, breathhold T1- and T2-weighted imaging of the abdominal structures has become possible. These techniques allow exploitation of the advantages inherent to the MR imaging experiment: unsurpassed soft tissue contrast and multiplanar imaging capabilities. Magnetic resonance imaging of the small and large bowel has thus moved from a hypothetical possibility to a practical reality. This manuscript describes some of the underlying fast imaging techniques for display of the small and large bowel. Furthermore, it discusses the plethora of available oral and rectal contrast agents. Finally, clinical indications for MR of the small and large bowel as well as the rectum are described in light of the available literature. Advantages and disadvantages relative to computed tomography and other imaging techniques are discussed.

Dynamic 1.5-Tvs3-T true fast imaging with steady-state precession (trueFISP)-MRI sequences for assessment of velopharyngeal function

“…While a higher field strength is expected to improve image quality, the theoretical doubling of the signal-to-noise ratio was no higher than 25%. 15 In agreement with our results, Debatin and Patak 16 conclude that 3.0-T imaging is subject to significantly more artefacts when using specific sequences such as trueFISP.…”

“…At 3.0 T, for instance, a 40% increase in the longitudinal relaxation time of T1 in tissue signifies a drastic loss of image quality. 16 After doubling magnetic field strength, a further limiting factor may be the four-fold increase of high-frequency fields and the associated specific absorption rate, which is a measure of tissue heating. 17 Compared with videofluoroscopy, one of the potential limitations of MRI is the fact that the latter does not yield 25 pictures per second.…”

Small Bowel Imaging - Still a Radiologic Approach?

“…38 ). Negative contrast agents decrease the extent of noise and motion artifacts related to the bowel peristalsis 44,45 and improve the detection of intramural edema and extramural complications (necrosis, fat edema, mesenterial edema, abscess formation or fistulas). The commercially available negative contrast agents,magnetic iron oxide nanoparticles (Lumirem, Guerbet; Abdoscan, Nycomed) (ref.…”

MR enterography with a new negative oral contrast solution containing maghemite nanoparticles

“…Negative contrast agents decrease noise and motion artifacts related to the bowel peristalsis and improve the detection of intramural edema and extramural complications (necrosis, fat edema, mesenterial edema, abscess formation or fistulas) (ref. 11,12 ). SPIO negative contrast agents are appropriate for MRCP as they decrease the non-homogenous signal of the bowel lumen and the desired organ such as biliary duct or pancreas can be better visualized.…”