Mr enteroclysis using iron oxide particles (ferristene) as an endoluminal contrast agent: An open phase III trial

Imaging of Gastrointestinal Tract Ailments

Gastrointestinal (GI) disorders comprise a diverse range of conditions that can significantly reduce the quality of life and can even be life-threatening in serious cases. The development of accurate and rapid detection approaches is of essential importance for early diagnosis and timely management of GI diseases. This review mainly focuses on the imaging of several representative gastrointestinal ailments, such as inflammatory bowel disease, tumors, appendicitis, Meckel's diverticulum, and others. Various imaging modalities commonly used for the gastrointestinal tract, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT), and photoacoustic tomography (PAT) and multimodal imaging with mode overlap are summarized. These achievements in single and multimodal imaging provide useful guidance for improved diagnosis, staging, and treatment of the corresponding gastrointestinal diseases. The review evaluates the strengths and weaknesses of different imaging techniques and summarizes the development of imaging techniques used for diagnosing gastrointestinal ailments.

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

AIM

The aim of this study was to test an oral contrast solution with maghemite for the magnetic resonance imaging of small bowel diseases.

PATIENTS AND METHODS

The study sample included 3 cohorts: 17 healthy volunteers (group A), 22 patients with small bowel disease (group C). Both groups underwent MR enterography and 24 patients with small bowel disease (group B) underwent magnetic resonance cholecystopancreaticography. Various concentrations in 1000 ml vs 500 ml of experimental solution were tested. All cohorts completed questionnaires evaluating the solution characteristics and side-efects during and after drinking.

RESULTS

A maghemite concentration of 800 mg /4 g bentonite in 1000 ml solution was sufficient for proper intraluminal lay-out. An experimental solution of 500 ml was sufficient for magnetic resonance cholecystopancreaticography and 1000 ml for MR enterography. There were no statistically significant differences between groups for taste, taste characteristic or appearance of the experimental solution. Side-effects experienced during drinking were: nausea (29.4%) and eructation (29.4%) in group A, in group B (42%) and diarrhoea (27.3%) in group C. Side-effects 2 h after drinking occured in group A (nausea 17.6%) and in group C (diarrhoea 47%). The best tolerance of experimental solution was found in group B with a higher median patient age than groups A and C. The experimental solution was evaluated more favorably in the older subjects (age over 50 years).

CONCLUSION

The experimental oral solution with maghemite was well tolerated in all 3 groups. Our study supports its use in magnetic resonance practice.

Magnetic resonance enterography in Crohn’s disease: Standard and advanced techniques

Crohn’s disease (CD) is a chronic autoimmune disorder that affects mainly young people. The clinical management is based on the Crohn’s Disease Activity Index and especially on biologic parameters with or without additional endoscopic and imaging procedures, such as barium and computed tomography examinations. Recently, magnetic resonance (MR) imaging has been a promising diagnostic radiologic technique with lack of ionizing radiation, enabling superior tissue contrast resolution due to new pulse-sequence developments. Therefore, MR enterography has the potential to become the modality of choice for imaging the small bowel in CD patients.

MR imaging of the small bowel

Cross-sectional imaging techniques are playing an increasing role in the evaluation of suspected small-bowel disorders, and a growing awareness of the risks of ionizing radiation exposure has prompted the exploration of alternative imaging techniques. Advantages of magnetic resonance (MR) imaging include a lack of ionizing radiation, the ability to provide dynamic information regarding bowel distention and motility, improved soft-tissue contrast, and a relatively safe intravenous contrast agent profile. Limitations of MR imaging include cost, imager access, variability in examination quality, and lower spatial and temporal resolution compared with those of computed tomography (CT). MR imaging of the small bowel is indicated for patients with Crohn disease, those for whom exposure to radiation is a concern, those with contraindications to CT, and those with low-grade small-bowel obstruction. MR imaging may be performed with enterography or enteroclysis. In enterography, large volumes of fluid are ingested. Several different contrast agents may be used. These agents are classified according to their signal intensity on T1- and T2-weighted images. In enteroclysis, enteric contrast material is administered through a nasoenteric tube. Crohn disease is the primary indication for MR imaging of the small bowel because many patients require multiple follow-up examinations. Findings suggestive of active inflammation include bowel wall thickening and hyperenhancement, ulcerations, increased mesenteric vascularity, and perienteric inflammation. Complications are well depicted and may include penetrating disease and small-bowel obstruction.

MR imaging of the small bowel in Crohn's disease

MR and CT techniques optimized for small bowel imaging are playing an increasing role in the evaluation of small bowel disorders. Several studies have shown the advantage of these techniques over tradition barium fluoroscopic examinations secondary to improvements in spatial and temporal resolution combined with improved bowel distending agents. The preference of MR vs. CT has been geographical and based on expertise and public policy. With the increasing awareness of radiation exposure, there has been a more global interest in implementing techniques that either reduce or eliminate radiation exposure [Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med 2007;357:2277-84]. This is especially important in patients with chronic diseases such as inflammatory bowel disease who may require multiple studies over a lifetime or in studies that require sequential imaging time points such as in assessment of gastrointestinal motility [Froehlich JM, Patak MA, von Weymarn C, Juli CF, Zollikofer CL, Wentz KU. Small bowel motility assessment with magnetic resonance imaging. J Magn Reson Imaging 2005;21:370-75]. A recent study showed that certain subgroups of patients with Crohn's disease may be exposed to higher doses of radiation; those diagnosed at an early age, those with upper tract inflammation, penetrating disease, requirement of intravenous steroids, infliximab or multiple surgeries [Desmond AN, O'Regan K, Curran C, et al. Crohn's disease: factors associated with exposure to high levels of diagnostic radiation. Gut 2008;57:1524-29]. Therefore it has been suggested that techniques that can reduce or eliminate radiation exposure should be considered for imaging [Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med 2007;357:2277-84]. Owing to the excellent softtissue contrast, direct multiplanar imaging capabilities, new ultrafast breath-holding pulse sequences, lack of ionizing radiation and availability of a variety of oral contrast agents, MR is well suited to play a critical role in the imaging of small bowel disorders. In this article we will review the technical issues related to the performance of MR enterography and enteroclysis and discuss the role and controversies of using MR in the assessment of inflammatory bowel disease.

MR imaging of the small bowel

Cross-sectional imaging techniques such as CT and MR imaging have advantages over traditional barium fluoroscopic techniques in their ability to visualize superimposed bowel loops better and to improve visualization of extraluminal findings and complications. This article discusses MR imaging of the small bowel with enterography and enteroclysis techniques. It reviews the advantages, limitations, technique, and indications and reviews the results that have been obtained in evaluating different disease processes.

Magnetically modified bentonite as a possible contrast agent in MRI of gastrointestinal tract

A composite of iron oxide nanoparticles and mineral matrix has been studied by XRD, Mössbauer spectroscopy, and TEM. Magnetite and superparamagnetic magnetite have been identified by Mössbauer spectroscopy in the nanocomposite. A relationship between the hyperfine parameters and iron oxide particle size has been confirmed by TEM. The optimal concentration of “magnetite—bentonite” composite, when the MRI signal is fully reduced, was found for using this composite as a negative contrast agent.