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.

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.

Magnetic resonance colonography without bowel cleansing: a prospective cross sectional study in a screening population.

BACKGROUND AND AIMS: To evaluate the diagnostic accuracy of magnetic resonance colonography (MRC) without bowel cleansing in a screening population and compare the results to colonoscopy as a standard of reference. METHODS: 315 screening patients, older than 50 years with a normal risk profile for colorectal cancer, were included in this study. For MRC, a tagging agent (5.0% Gastrografin, 1.0% barium sulphate, 0.2% locust bean gum) was ingested with each main meal within 2 days prior to MRC. No bowel cleansing was applied. For the magnetic resonance examination, a rectal water enema was administered. Data collection was based on contrast enhanced T1 weighted images and TrueFISP images. Magnetic resonance data were analysed for image quality and the presence of colorectal lesions. Conventional colonoscopy and histopathological samples served as reference. RESULTS: In 4% of all colonic segments, magnetic resonance image quality was insufficient because of untagged faecal material. Adenomatous polyps >5 mm were detected by means of MRC, with a sensitivity of 83.0%. Overall specificity was 90.2% (false positive findings in 19 patients). However, only 16 of 153 lesions <5 mm and 9 of 127 hyperplastic polyps could be visualised on magnetic resonance images. CONCLUSIONS: Faecal tagging MRC is applicable for screening purposes. It provides good accuracy for the detection of relevant (ie, adenomatous) colorectal lesions >5 mm in a screening population. However, refinements to optimise image quality of faecal tagging are needed.

Whole-body MR vascular screening detects unsuspected concomitant vascular disease in coronary heart disease patients.

Coronary heart disease (CHD) patients often show atherosclerotic vascular disease in other vascular territories. We evaluated how often whole-body MR imaging detects concomitant arterial pathologies in CHD patients, and how often these pathologies were not known to the patients previously. Of 4,814 participants in the population-based Heinz Nixdorf Recall Study, 327 reported CHD (i.e., previous coronary bypass surgery, angioplasty); of those, 160 patients (mean age 66.4 years) were examined using MR of the brain, the heart (excluding the coronary arteries), and whole-body MR angiography. The prevalence of each vascular pathology was assessed, correlated to the others and compared to patients' histories. Of the 160 CHD patients, 16 (10%) showed MR signs of stroke, and 77 (48.1%) had a stenosis >50% in at least one extracerebral peripheral artery (other than the coronaries), including 28 (17.5%) with relevant renal artery stenoses, and 20 (12.5%) with relevant extracerebral internal carotid artery stenoses. False negative histories were reported in 12 of 81 cases with myocardial infarctions, and in 11 of 16 cases with cerebrovascular infarctions. This whole-body atherosclerosis MR screening program allows previously unknown concomitant vascular disease to be detected in coronary heart disease patients. Its prospective value should be assessed in further studies.

Oral contrast agents for small bowel distension in MRI: influence of the osmolarity for small bowel distention.

To assess the effect of the osmolarity for small bowel distension in MRI, ten volunteers ingested at two separate occasions negative oral contrast agents with different quantity and osmolarity: (1) a water solution combined with 2.0% sorbitol and 0.2% locus bean gum (LBG) with a quantity of 1500 ml and an osmolarity of 148 mOsmol/l, (2) a water solution combined with 2.0% sorbitol and 2.0% barium sulphate with a quantity of 1000 ml and an osmolarity of 194 mOsmol/l. Small bowel distension was quantified on coronal 2D-TrueFISP images by measuring the small bowel diameters. There were no statistically significant differences in mean small bowel diameter between both contrast agents. The mean small bowel distension was 19.2 mm after ingestion of 1500 ml of sorbitol-LBG solution and 19.0 mm after ingestion of 1000-ml sorbitol-barium sulphate solution. Furthermore, all volunteers found the ingestion of 1000-ml solution more pleasant than the 1500-ml solution. The ingestion of 1000 ml of sorbitol-barium sulphate solution led to a sufficient small bowel distension compared to 1500 ml of sorbitol-LBG solution. The side effect rate of both solutions was low. Based on these data, we recommend a quantity of 1000 ml of sorbitol-barium sulphate solution as an alternative for 1500-ml sorbitol-LBG solution for optimal bowel distension.