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Original Report |
1 Department of Radiology, University of Rome "La Sapienza,"
Policlinico Umberto I, Viale Regina Elena 324, 00161 Rome, Italy.
2 Department of Pediatrics, University of Rome "La Sapienza," 00161
Rome, Italy.
Received April 3, 2002;
accepted after revision June 19, 2002.
Address correspondence to A. Laghi.
Abstract
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CONCLUSION. Polyethylene glycolenhanced MR imaging is a noninvasive (no ionizing radiation is used), feasible, and reproducible imaging technique in both adult and pediatric populations. Findings on polyethylene glycolenhanced MR imaging, similar to those of conventional barium studies, may suggest a diagnosis of celiac disease because the technique can not only reveal intestinal involvement but also show extraintestinal findings.
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Traditionally, a small-bowel follow-through examination has been used to document radiologic abnormalities [3]; CT findings of celiac disease have also been described [4, 5]. More recently, MR imaging has been advocated as a possible diagnostic method for imaging of the small bowel because of its excellent soft-tissue contrast and multiplanar imaging capabilities. MR evaluation of the small bowel may be performed through different technical approaches by distending the small bowel with either positive or negative contrast agents. In our experience, bowel distention can be obtained using a recently reported technique [6] based on the ingestion of a polyethylene glycol isosmotic and nonabsorbable solution as an oral contrast agent.
The aim of our study was to assess the feasibility of polyethylene glycolenhanced MR imaging in the evaluation of morphologic abnormalities of the small bowel in a population of patients with known celiac disease.
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After the study was approved by the institutional review board of our institution, we obtained written consent from each adult patient and from the parents of pediatric patients before MR imaging was performed.
MR Imaging Protocol
MR imaging was performed on a 1.5-T MR scanner (Magnetom Vision Plus;
Siemens Medical Systems, Erlangen, Germany) with a maximum gradient field
strength of 25 mT/m. We used a phased array body coil to examine the patients,
who were placed in a supine position.
After an overnight fast, each patient was asked to drink, immediately before MR imaging, a fixed amount (600 mL for adults and 10 mL/kg of body weight for children) of a polyethylene glycol solution made from a granular powder. The solution was prepared by dissolving the powder, which contains 34.8 g of polyethylene glycol 4000 (Isocolan; Bracco, Princeton, NJ), 1.42 g of anhydrous sodium sulfate, 0.42 g of sodium bicarbonate, 0.36 g of sodium chloride, and 0.18 g of potassium chloride, in 500 mL of tap water. No antispasmodic or other drugs were administered.
After we obtained localizing images in three axes, coronal and axial T2-weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences (TR/TE, infinite/90; echo-train length, 104; section thickness, 6 mm; intersection gap, 20%; field of view, 350-400 mm; effective matrix, 192 x 256; signal average, 1; and half-Fourier reconstruction) were sequentially acquired. Fifteen slices for each acquisition were obtained during a single breath-hold of 20 sec. Images were acquired every 5 min until the cecum was observed to be filled by the oral contrast agent for a maximum of 30 min.
Image Analysis
Images were reviewed by two gastrointestinal radiologists experienced in
both gastrointestinal radiology and MR imaging. Agreement was by consensus.
Images were quantitatively and qualitatively analyzed to evaluate signs of
celiac disease using the same criteria as are used when looking at
conventional barium small-bowel follow-through. Quantitative evaluation was
performed on a dedicated off-line workstation to minimize errors in
measurement. The quantitative evaluation included measurement of bowel caliber
(normal values, <30 mm in adults and <24 mm in children
[6]) at the site of the most
distended bowel loop; wall thickening (normal value, <3 mm
[6]); and number of intestinal
folds measured at two sites in the jejunum and distal ileum (normal values:
proximal jejunum, >five folds per inch; distal ileum, <five folds per
inch [7]). Qualitative
evaluation included identification of a jejunoileal fold pattern reversal
[8,
9] and intestinal
intussusception [10] and
evaluation of extraintestinal findings, including mesenteric lymphadenopathy
and reduced splenic size (hyposplenism).
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MR imaging showed dilatation of small-bowel loops greater than 30 mm (range, 33-43 mm; mean value, 38 mm) in six adult patients and greater than 24 mm (range, 28-35 mm; mean value, 32 mm) in seven children. Bowel-wall thickening greater than 3 mm was observed in four patients (Fig. 1).
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Qualitative evaluation showed alterations in the mucosal pattern of ileal loops with an increased number of folds (five or more folds per inch; "ileal jejunalization") in 12 patients (Fig. 2A,2B) and jejunoileal fold pattern reversal in four patients. Intestinal intussusception was observed in two patients (Fig. 3A,3B) and hyposplenism, in one patient (Fig. 4).
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Polyethylene glycolenhanced MR imaging findings were suggestive of the diagnosis of celiac disease in 70.4% (19/27) of the patients. No morphologic abnormalities were identified in 29.6% (8/27) of the patients.
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The role of imaging is important in celiac disease, although not for confirmation of the diagnosis: approximately one quarter of patients with untreated celiac disease have no radiologic abnormality [2]. However, imaging is especially useful in the presence of abdominal pain to exclude complicating lesions such as jejunal ulceration with stricture, lymphoma, or carcinoma [2]. We report the use of MR imaging after the administration of an isosmotic polyethylene glycol solution as an oral contrast agent, using a technique previously described [6], in the evaluation of the small bowel in both adult and pediatric patients with celiac disease.
In our study, polyethylene glycolenhanced MR imaging provided excellent bowel distention in all patients. Imaging findings were similar to those from conventional barium small-bowel follow-through examinations because of the technique we used, in which T2-weighted water-sensitive sequences (HASTE) were performed after the oral administration of a watery contrast medium. Patterns of presentation of celiac disease at barium small-bowel follow-through studies include dilatation of bowel loops due to parietal atonia, thickening of mucosal folds and increase of their separation in the proximal small bowel (an indirect sign of thickening of the bowel wall), and an increased number of mucosal folds in the ileum (ileal jejunization) [3]. Similar findings were observed on polyethylene glycolenhanced MR imaging.
Small-bowel dilatation was the most common finding in our study, occurring in 13 of 17 adults; the next most common finding was an increased number of ileal mucosal folds. Both findings were easily evaluated on these MR imaging studies, which had semeiologic criteria resembling those of conventional barium studies. A prime advantage of polyethylene glycolenhanced MR imaging compared with barium small-bowel follow-through is that MR imaging allows direct visualization and measurement of thickening of the bowel wall, with no need for indirect measurements.
A major reason for radiologic examination of patients with celiac disease is the identification of complications, and, in particular, transient jejunal intussusception and small-bowel neoplasms. In two adult patients of our series who presented with vague abdominal symptoms, we were able to correctly identify transient jejunal intussusception by the presence of the typical target sign described in CT studies [4, 5]. No small-bowel tumors occurred in our relatively small series of patients; therefore, we cannot assess the diagnostic value of polyethylene glycolenhanced MR imaging in detecting neoplastic complications. However, we think that the technique is likely to allow easy identification of neoplastic strictures and bulky solid masses in lymphomatous lesions, whereas recognition of subtle findings of small-bowel lymphoma, such as irregular nodularity of folds over a limited length of bowel, would be difficult, if not impossible, on polyethylene glycolenhanced MR imaging.
A further advantage of MR imaging, similar to that of other cross-sectional imaging modalities (e.g., CT), when compared with conventional barium studies is that evaluation of extraintestinal findings is possible during the examination. In particular, mesenteric adenopathy and splenic atrophy represent the most common findings, with the latter identified in one patient in our series.
Finally, in five (29%) of 17 adults with biopsy-proven celiac disease, no small-bowel abnormalities were observed. This finding is not surprising; it reflects data from conventional barium studies, in which as many as a quarter of known patients with celiac disease were reported to present with normal findings [2].
In conclusion, polyethylene glycolenhanced MR imaging is a noninvasive (no ionizing radiation is necessary), feasible, and reproducible imaging technique in both adult and pediatric populations. Because it has findings similar to those of conventional barium studies, polyethylene glycolenhanced MR imaging may suggest a diagnosis of celiac disease and enable identification of potential intestinal complications and extraintestinal findings.
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