Ultrasound studies of the intestinal wall in patients with cystic fibrosis

Ultrasound in Pediatric Inflammatory Bowel Disease-A Review of the State of the Art and Future Perspectives

Inflammatory bowel disease (IBD) comprises a group of relapsing, chronic diseases of the gastrointestinal tract that, in addition to adults, can affect children and adolescents. To detect relapses of inflammation, these patients require close observation, frequent follow-up, and therapeutic adjustments. While reference standard diagnostics include anamnestic factors, laboratory and stool sample assessment, performing specific imaging in children and adolescents is much more challenging than in adults. Endoscopic and classic cross-sectional imaging modalities may be invasive and often require sedation for younger patients. For this reason, intestinal ultrasound (IUS) is becoming increasingly important for the non-invasive assessment of the intestine and its inflammatory affection. In this review, we would like to shed light on the current state of the art and provide an outlook on developments in this field that could potentially spare these patients more invasive follow-up procedures.

Bowel ultrasound measurements in healthy children - systematic review and meta-analysis

BACKGROUND

Ultrasound (US) is a noninvasive method of assessing the bowel that can be used to screen for bowel pathology, such as Inflammatory Bowel Disease, in children. Knowledge about US findings of the bowel in healthy children is important for interpreting US results in cases where disease is suspected.

OBJECTIVE

To assess the bowel wall thickness in different bowel segments in healthy children and to assess differences in bowel wall thickness among pediatric age categories.

MATERIALS AND METHODS

We conducted a systematic search in the PubMed, Embase, Cochrane, and CINAHL databases for studies describing bowel wall thickness measured by transabdominal US in healthy children. We excluded studies using contrast agent. We calculated the pooled mean and standard deviation scores and assessed differences among age categories (0-4 years, 5-9 years, 10-14 years, 15-18 years), first with analysis of variance (ANOVA) and further with subsequent Student's t-tests for independent samples, corrected for multiple testing.

RESULTS

We identified 191 studies and included 7 of these studies in the systematic review. Reported bowel wall thickness values ranged from 0.8 mm to 1.9 mm in the small bowel and from 1.0 mm to 1.9 mm in the colon. The mean colonic bowel wall thickness is larger in children ages 15-19 years compared to 0-4 years (range in difference: 0.3-0.5 mm [corrected P<0.02]).

CONCLUSION

The reported upper limit of bowel wall thickness in healthy children is 1.9 mm in the small bowel and the colon, and mean thickness increases slightly with age in jejunum and colon. These values can be used as guidance when screening for bowel-related pathology in children.

Diagnostic Accuracy of Transabdominal Ultrasound in Detecting Intestinal Inflammation in Paediatric IBD Patients-a Systematic Review

BACKGROUND AND AIMS

Currently used non-invasive tools for monitoring children with inflammatory bowel disease [IBD], such as faecal calprotectin, do not accurately reflect the degree of intestinal inflammation and do not provide information on disease location. Ultrasound [US] might be of added value. This systematic review aimed to assess the diagnostic test accuracy of transabdominal US in detecting intestinal inflammation in children with IBD in both diagnostic and follow-up settings.

METHODS

We systematically searched PubMed, Embase [Ovid], Cochrane Library, and CINAHL [EBSCO] databases for studies assessing diagnostic accuracy of transabdominal US for detection of intestinal inflammation in patients diagnosed or suspected of IBD, aged 0-18 years, with ileo-colonoscopy and/or magnetic resonance enterography [MRE] as reference standards. Studies using US contrast were excluded. Risk of bias was assessed with QUADAS-2.

RESULTS

The search yielded 276 records of which 14 were included. No meta-analysis was performed, because of heterogeneity in study design and methodological quality. Only four studies gave a clear description of their definition for an abnormal US result. The sensitivity and specificity of US ranged from 39-93% and 90-100% for diagnosing de novo IBD, and 48-93% and 83-93% for detecting active disease during follow-up, respectively.

CONCLUSIONS

The diagnostic accuracy of US in detecting intestinal inflammation as seen on MRE and/or ileo-colonoscopy in paediatric IBD patients remains inconclusive, and there is currently no consensus on defining an US result as abnormal. Prospective studies with adequate sample size and methodology are needed before US can be used in the diagnostics and monitoring of paediatric IBD.

Appendico-colic fistula complicating appendicitis in cystic fibrosis

The case of a boy with cystic fibrosis who presented with an unusual complication of appendicitis is reported. Delayed presentation, with complications of appendicitis such as perforation and abscess formation, is not uncommon in cystic fibrosis; however, this case represents the first report of an isolated appendico-colic fistula following appendicitis in association with cystic fibrosis.

Dosimetry model for radioactivity localized to intestinal mucosa

BACKGROUND

This paper provides a new model for calculating radiation-absorbed doses to the full thickness of the small and large intestinal walls, and to the mucosal layers. The model was used to estimate the intestinal radiation doses from yttrium-90-labeled-DOTA-biotin binding to NR-LU-10-streptavidin in patients.

METHODS

We selected model parameters from published data and observations, and used the model to calculate energy-absorbed fractions using the EGS4 radiation transport code. We determined the cumulated (90)Y activity in the small and large intestines of patients from gamma camera images, and calculated absorbed doses to the mucosal layer and to the whole intestinal wall.

RESULTS

The mean absorbed dose to the wall of the small intestine was 16.2 mGy/MBq (60 cGy/mCi) administered from (90)Y localized in the mucosa, and 70 mGy/MBq (260 cGy/mCi) to the mucosal layer within the wall. Doses to the large intestinal wall and to the mucosa of the large intestine were lower than those for the small intestine by a factor of about 2.5. These doses are greater by factors of about 5 to 6 than those that would have been calculated using the standard MIRD models that assume the intestinal activity is in the bowel contents.

CONCLUSIONS

The specific uptake of radiopharmaceuticals in mucosal tissues may lead to dose-related intestinal toxicities. Tissue dosimetry at the sub-organ level is useful for a better understanding of intestinal tract radiotoxicity and associated dose-response relationships.

Sonographic evaluation of bowel wall thickness in patients with cystic fibrosis

GOALS AND BACKGROUND

Fibrosing colonopathy causing severe thickening of the colon wall was recently described in cystic fibrosis (CF). Since it has been suspected that subclinical colon-wall thickening is a common feature in CF patients, bowel-wall thickness was measured in a series of patients and compared with controls. Additionally, possible clinical factors influencing wall thickness were investigated.

STUDY

In 83 CF patients and 31 controls transabdominal ultrasound was performed in the terminal ileum, cecum, ascending and descending colon. The relation of the measured wall thickness to age, sex, pancreatic enzyme intake, and intestinal diseases was analyzed.

RESULTS

In controls, mean wall thickness depending on gut region was 1.1 to 1.3 mm (SD 0.19-0.23). In CF patients, no evidence of severe thickening or stricture was found, but wall thickness was significantly higher than in controls in all measured regions (1.5-1.6 mm; SD 0.31-0.41). Patients with meconium ileus and distal intestinal obstruction syndrome had significantly increased thickness of the terminal ileum compared with patients without these complications. Neither the intake of high-strength enzymes nor enzyme dosage, age or sex were associated with wall thickness.

CONCLUSIONS

We found no evidence that a subclinical stage of fibrosing colonopathy is prevalent among the CF patients. Slightly thickened gut walls in CF can be interpreted as an expression of glandular dysfunction in the CF intestine.

Thickened submucosal layer: a sonographic sign of acute gastrointestinal abnormality representing submucosal edema or hemorrhage. 2000 ARRS Executive Council Award II. American Roentgen Ray Society

OBJECTIVE

We correlated the sonographic appearance of bowel wall thickening with the acuity of the underlying disease process.

SUBJECTS AND METHODS

Sonograms of thickened bowel walls were reviewed in 37 patients with proven gastrointestinal abnormalities. Sonographic findings were correlated with clinical presentation, endoscopy, histology, laboratory data, barium studies, and CT.

RESULTS

Twenty-eight patients presented acutely, and nine patients had chronic or subacute disease processes. Two of the 28 patients had concurrent acute and chronic processes. In 27 of 28 patients with acute processes, the abnormal bowel segments were characterized by an echogenic submucosal layer thicker than 2.5 mm. In contrast, nine patients with chronic or subacute processes had relatively uniform hypoechoic thickening of the bowel wall with loss of visualization of a discrete echogenic submucosal layer. CT was available for comparison in 30 of 37 patients. Of the 28 patients with acute abnormalities, the thickened echogenic submucosal layer on sonography corresponded to either low-attenuation submucosal edema (n = 25) or acute submucosal hemorrhage (n = 3).

CONCLUSION

The finding of a thickened submucosal layer suggests an acute disease process of the bowel and corresponds to either submucosal edema or hemorrhage.

Cystic fibrosis colonopathy

An epidemic of fibrosing colonopathy, a new disease caused by the prolonged administration of excessive doses of pancreatic enzymes, was first reported in 1994. More than 60 cases were known to occur worldwide before dosage guidelines were enforced. Predisposing factors were young age, previous intestinal surgery, meconium ileus equivalent, and use of H2 blockers, corticosteroids, and DNase. Abnormal features included foreshortened colon, strictures, marked submucosal fibrosis, ascites, and nodular hyperplasia of the liver. Histologic examination showed eosinophilia, mild cryptitis, epithelial regeneration, and widespread interruption of the muscularis mucosa. These findings are distinct from, but share many of the features of, those of Crohn's's disease and ischemic bowel disease. The pathogenic mechanisms remain unknown.

Findings on routine abdominal ultrasonography in cystic fibrosis patients

BACKGROUND

Right lower quadrant abdominal pain may pose a diagnostic problem in patients with cystic fibrosis. Abdominal ultrasound examination, used commonly in the diagnostic work-up, may reveal abnormalities of the appendix. However, interpretation of such findings is problematic, because the appearance of the gastrointestinal system during routine examination has not been documented in patients with cystic fibrosis. The purpose of this study was to investigate the findings during routine abdominal ultrasound scans in our cohort of patients with cystic fibrosis and in control subjects.

METHODS

Abdominal ultrasound scans were performed prospectively during routine clinic visits in a cohort of patients with cystic fibrosis.

RESULTS

Fifty patients aged 10+/-6 years, (range, 0.5-28 years) were examined; 45 had pancreatic insufficiency. Four patients (3 with pancreatic insufficiency) reported right lower quadrant pain at the time of the scan. According to standard ultrasound criteria, the appearance of the appendix was abnormal in 8 patients (16%), 6 had a mucoid appendix, and 2 had a pathologically thickened appendiceal wall. Only 1 of these 8 patients mentioned abdominal pain at the time of the study. Other incidental findings included gallstones (3 patients), intussusception (2 patients), and pancreatic cyst (1 patient).

CONCLUSIONS

Abnormalities can be observed during routine abdominal ultrasonographic studies in cystic fibrosis. These findings may not be associated with abdominal pain; their clinical relevance needs further investigation.

Colonic wall thickness, pancreatic enzyme dose and type of preparation in cystic fibrosis

Increased colonic wall thickness has been reported in patients exposed to large doses of high strength pancreatic enzyme preparations who did not develop fibrosing colonopathy. This has been interpreted as evidence for a spectrum of subclinical disease. The relation between sonographically measured colonic wall thickness and pancreatic enzyme preparation and dose was studied in 86 children with cystic fibrosis (CF). Colonic wall thickness of a control group was also measured. The average thickness in all colonic regions was higher in the CF group (overall average range 0.7-2.5 mm v 0.6-1.4 mm in the control group). There was no significant relation between colonic wall thickness and age, sex, total dose of lipase, or copolymer. Apart from one patient with an early colonic stricture, none of those exposed to high doses of lipase, or the methacrylic acid copolymer Eudragit L30 D55, showed evidence of subclinical damage to the colon. The reproducibility of the sonographic measurements was poor.