Magnetic resonance colonography without bowel cleansing using oral and rectal stool softeners (fecal cracking)—a feasibility study

Imaging techniques for assessment of inflammatory bowel disease: joint ECCO and ESGAR evidence-based consensus guidelines

The management of patients with IBD requires evaluation with objective tools, both at the time of diagnosis and throughout the course of the disease, to determine the location, extension, activity and severity of inflammatory lesions, as well as, the potential existence of complications. Whereas endoscopy is a well-established and uniformly performed diagnostic examination, the implementation of radiologic techniques for assessment of IBD is still heterogeneous; variations in technical aspects and the degrees of experience and preferences exist across countries in Europe. ECCO and ESGAR scientific societies jointly elaborated a consensus to establish standards for imaging in IBD using magnetic resonance imaging, computed tomography, ultrasonography, and including also other radiologic procedures such as conventional radiology or nuclear medicine examinations for different clinical situations that include general principles, upper GI tract, colon and rectum, perineum, liver and biliary tract, emergency situation, and the postoperative setting. The statements and general recommendations of this consensus are based on the highest level of evidence available, but significant gaps remain in certain areas such as the comparison of diagnostic accuracy between different techniques, the value for therapeutic monitoring, and the prognostic implications of particular findings.

Magnetic resonance (MR) colonography in the detection of colorectal lesions: a systematic review of prospective studies

Objective

To determine the diagnostic accuracy of MR-colonography for the detection of colorectal lesions.

Methods

A comprehensive literature search was performed for comparative MR-colonography studies, published between May 1997 and February 2009, using the MEDLINE, EMBASE and Cochrane databases. We included studies if MR-colonography findings were prospectively compared with conventional colonoscopy in (a)symptomatic patients. Two reviewers independently extracted study design characteristics and data for summarising sensitivity and specificity. Heterogeneity in findings between studies was tested using I² test statistics. Sensitivity and specificity estimates with 95% confidence intervals (CI) were calculated on per patient basis and summary sensitivity on per polyp basis, using bivariate and univariate statistical models.

Results

Thirty-seven studies were found to be potentially relevant and 13 fulfilled the inclusion criteria. The study population comprised 1,285 patients with a mean disease prevalence of 44% (range 22–63%). Sensitivity for the detection of CRC was 100%. Significant heterogeneity was found for overall per patient sensitivity and specificity. For polyps with a size of 10 mm or larger, per patient sensitivity and specificity estimates were 88% (95% CI 63–97%; I² = 37%) and 99% (95% CI 95–100%; I² = 60%). On a per polyp basis, polyps of 10 mm or larger were detected with a sensitivity of 84% (95% CI 66–94%; I² = 51%). The data were too heterogeneous for polyps smaller than 6 mm and 6–9 mm.

Conclusion

MR-colonography can accurately detect colorectal polyps more than 10 mm in size

Diagnostic accuracy of MR colonography with fecal tagging

BACKGROUND

MR colonography (MRC) is a non-invasive method of examining the colon, but it is still only used in a few specialized centers on a daily basis. The purpose of this study was to evaluate the performance of MRC with improved fecal tagging vs. conventional colonoscopy (CC).

METHODS

Between March 2006 and February 2007, consecutive patients who received first-time referrals to CC were asked to participate in the study. Two days prior to MRC, a new contrast mixture (barium/ferumoxsil) was ingested together with four meals each day. Standard bowel cleansing was performed before CC. MRC was evaluated by two blinded observers. MRC results were compared with CC.

RESULTS

A total of 56 patients were included. The per-polyp sensitivity was 85.7% for polyps 6-10 mm and 81.3% for polyps >10 mm. The per-patient sensitivity/specificity was 100%/80% for polyps >6 mm and 100%/91.4% for polyps >10 mm.

CONCLUSION

MRC showed acceptable per-patient sensitivities, but the per-polyp sensitivities are still compromised by the fecal tagging. MRC may be implemented, but at the present time MRC with fecal tagging is not ready for widespread use, although it remains a very promising diagnostic tool.

MR colonography after oral administration of polyethylene glycol-electrolyte solution

This prospective study was approved by the local institutional ethics committee, and written informed consent was obtained from all patients. The aim of this study was to determine whether the oral administration of a polyethylene glycol (PEG)-electrolyte solution induces adequate luminal distention for magnetic resonance (MR) colonography to be performed and to assess patient acceptance of this procedure. Fifty-five patients (26 women, 29 men; mean age, 60.5 years +/- 14 [standard deviation]; age range, 40-75 years) who were referred for optical colonoscopy (OC) owing to symptoms and findings that included rectal bleeding, altered bowel habits, and positive fecal occult blood test results participated in this study. Standard bowel preparation was performed 1 day before the procedure. MR colonography was performed and followed by OC on the same day. Before undergoing MR colonography, the patients received 2.0-2.5 L of the PEG-electrolyte solution orally. Adequate distention of all colonic segments was achieved in 50-53 (91%-96%) of patients imaged in the supine position and in 51-53 (93%-96%) of patients imaged in the prone position. Oral administration of the solution yielded uniform luminal darkening and sufficient colonic distention for MR colonography in 91%-96% of patients.

MR colonography

Combining the advantages of unsurpassed soft tissue contrast and lack of ionizing radiation, MR imaging of the gastrointestinal tract has become increasingly used clinically. Both bowel inflammation and tumor disease of the large bowel can be well visualized by means of MR colonography (MRC). This article describes current techniques of MRC and gives an overview of its clinical outcome. Special focus is directed toward the evaluation of patients' acceptance of MRC.

MR colonography with fecal tagging: do individual patient characteristics influence image quality?

PURPOSE

To evaluate if different patient characteristics influence performance of fecal tagging (a new MR colonography (MRC) technique to label stool to avoid bowel cleansing) and, consecutively, MR image quality.

MATERIALS AND METHODS

A total of 333 patients (mean age = 61 years) underwent MRC with fecal tagging. Four segments of the large bowel (ascending, transverse, descending, and sigmoid colon) were assessed as for the presence of nontagged stool particles, which can impede an assessment of the colonic wall. Ratings were correlated with patients' characteristics including patient age (<55 vs. > or =55 years), body mass index (BMI) (<25 vs. > or =25), gender, and acceptance levels for fecal tagging. Statistical analysis was performed using a Mann-Whitney U-test.

RESULTS

A total of 1332 colonic segments were evaluated. Among them, 327 segments (25%) did not contain any visible stool particles. Considerably reduced image quality was found in 61 segments (5%). Best image quality was found in the sigmoid colon (mean value = 1.9), while image quality of the ascending colon turned out to be worst (mean value = 2.6). Fecal tagging effectiveness showed a reverse correlation with patient age. However, all other characteristics did not have a statistically significant influence on fecal tagging outcome.

CONCLUSION

MRC in conjunction with barium-based fecal tagging led to diagnostic image quality in 95% of all colonic segments. Since tagging results were significantly decreased in patients > or =55 years, tagging protocols should to be modified in this group, i.e., by increasing the time interval of tagging administration.

MR colonography vs. optical colonoscopy: comparison of patients’ acceptance in a screening population

The aim of this study was to compare optical colonoscopy to fecal-tagging-based MR colonography in a screening population in terms of comfort and acceptance ratings as well as for future preferences as colorectal cancer screening examinations. Two hundred eighty-four asymptomatic patients (mean age 59 years) underwent MRC and OC within 4 weeks. While MRC was based on a fecal tagging technique, OC was performed after bowel cleansing. For OC, sedatives and analgesics were used. Patients evaluated both modalities and certain aspects of the examination according to a 10-point-scale with higher scores denoting a worse experience. Furthermore, preferences for future examinations were evaluated. No significant difference was noted for the overall acceptance of OC (mean value 3.0) and MRC (mean value 3.4). For MRC, the placement of the rectal tube was rated as the most unpleasant part, whereas bowel purgation was regarded most inconvenient for OC. Patients aged 55 years and older perceived most aspects less unpleasant than younger patients. Of the patients, 46% preferred MRC for future screening examinations (OC: 44%). OC and MRC have comparable general acceptance levels in a screening population. Especially for patients declining endoscopy as a screening method MRC may evolve as an attractive alternative.

Utility of dark-lumen MR colonography for the assessment of extra-colonic organs

The aim of the study was to evaluate the utility of dark-lumen MR colonography (MRC) for the assessment of extra-colonic organs. Three hundred seventy-five subjects with suspected colonic disease underwent a complete MRC examination. MRC data were evaluated by two radiologists in a blinded fashion. In addition to the large bowel, the extra-intestinal organs from the lung bases to the pelvis were assessed for the presence of pathologies. All findings were divided into known or unknown findings and therapeutically relevant or irrelevant findings. If deemed necessary, other diagnostic imaging tests to further assess those findings were performed. In total, 510 extra-colonic findings were found in 260 (69%) of the 375 subjects. Known extra-colonic findings were found in 140 subjects (54%) and unknown findings in 120 subjects (46%). Thirty-one (12%) of the 260 subjects had therapeutically relevant findings (45 findings); 229 patients (88%) had irrelevant findings (465 findings). Dark-lumen MRC is a useful tool not only for the assessment of the entire colon, but also for the evaluation of extra-colonic organs. Thus, intra- and extra-colonic pathologies can be diagnosed within the same examination.

MR imaging of the colon: "technique, indications, results and limitations"

In the last few years virtual colonography using MR imaging has shown a proceeding development regarding detection and quantification of colorectal pathologies. Dark-lumen MR colonography (MRC) has been a leading tool for the diagnosis of the entire colon and their pathologies. This review article describes some of the underlying techniques of MRC concerning data acquisition, the need for intravenously applied paramagnetic contrast agent, as well as indications, results and limitations of MRC for the detection of colorectal pathologies. In addition, new techniques to improve patient acceptance are discussed.

MR colonography: current status

Magnetic resonance colonography (MRC) has gained access into clinical routine as a means for the assessment of the large bowel. There are widely accepted indications for MRC, especially in patients with incomplete conventional colonoscopy. Furthermore, virtual MRC is more and more propagated as a screening tool, with advantages especially inherent to the non-invasive character of this procedure and the lack of ionizing radiation exposition. Beyond a sufficiently high diagnostic accuracy, outstanding patient acceptance is a major advantage of MRC as a diagnostic modality. This review article describes indications, techniques and clinical outcome of current MRC approaches. Furthermore, the impact of fecal tagging concepts is discussed.

Virtual colonoscopy by MRI: state-of-the-art and future directions

MR colonography has been shown to be an appropriate diagnostic tool for the detection of colorectal lesions. The technique is based on the acquisition of T1-weighted sequences after the administration of water enema and the intravenous administration of paramagnetic contrast. This article describes the technical requirements for MR colonoscopy and the procedures of data acquisition and image interpretation. The advantages and drawbacks of MR colonoscopy also are outlined.

MR Imaging of the Large Bowel

MR colonography (MRC) is an accurate diagnostic tool for the detection of colorectal masses and inflammatory diseases. This article describes the underlying techniques of MRC that concern data acquisition and image interpretation. Indications for MRC are discussed, and technical developments are explained.