AJR 2002; 179:538-539
© American Roentgen Ray Society
Small-Bowel Obstruction Caused by Phytobezoar: MR Imaging Findings
Jae Mun Lee,
Seung Eun Jung and
Kyo-Young Lee colleagues
St. Mary's Hospital The Catholic University of Korea Seoul 150-713,
Korea
A 64-year-old man presented with acute abdominal pain and distention. The
patient had no surgical history, and the results of laboratory examinations
were unremarkable. Abdominal radiography showed a typical small-bowel
mechanical ileus. We obtained MR images for further evaluation of the
small-bowel obstruction using two-dimensional T1-weighted fast low-angle shot
and T2-weighted half-Fourier single-shot turbo spin-echo techniques. MR
imaging revealed a well-defined ovoid mass in the distal ileum that had a
heterogeneous signal intensity and contained mottled, confluent, low signal
intensities on both T1-weighted and T2-weighted MR images. A thick, uniformly
hyperintense rim was seen on the periphery of the mass on T1-weighted MR
images; the rim was not seen on T2-weighted MR images (Figs.
4A and
4B). We diagnosed the cause of
the obstruction to be a bezoar that had become impacted in the distal ileum.
Two days after MR imaging, the patient's abdominal pain was relieved after he
evacuated a hard mass while defecating. Histologic findings revealed that the
hard mass was a phytobezoar (Fig.
4C). The patient was discharged with no recurrence of the
symptoms.
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Fig. 4A. —64-year-old man with phytobezoar obstructing small bowel.
Coronal T1-weighted fast low-angle shot (FLASH) (A) and T2-weighted
half-Fourier acquisition single-shot turbo spin-echo (B) images reveal
well-defined ovoid mass (arrows) in distal ileum showing
heterogeneous signal intensity and containing mottled, confluent, low signal
intensities. Thick, uniformly hyperintense rim is visible on periphery of mass
on T1-weighted FLASH image (A).
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Fig. 4B. —64-year-old man with phytobezoar obstructing small bowel.
Coronal T1-weighted fast low-angle shot (FLASH) (A) and T2-weighted
half-Fourier acquisition single-shot turbo spin-echo (B) images reveal
well-defined ovoid mass (arrows) in distal ileum showing
heterogeneous signal intensity and containing mottled, confluent, low signal
intensities. Thick, uniformly hyperintense rim is visible on periphery of mass
on T1-weighted FLASH image (A).
|
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Bezoars are an unusual cause of acute small-bowel obstruction. Various
imaging modalities have been recommended for detection of bezoars. CT has been
reported to be the most useful as a diagnostic tool in patients with bezoars
because it reveals the location of the bowel obstruction and shows the bezoar
as a well-defined intraluminal mass in the transitional zone of the
obstruction. A mottled gas pattern in the mass is reported to be
characteristic of a bezoar and is believed to be air bubbles retained within
the bezoar [1,
2]. Recently, several
researchers have advocated MR imaging for the evaluation of small-bowel
disease because advances in fast imaging techniques coupled with the
advantages of breath-holding have resulted in improved MR visualization of
bezoars. The researchers reported MR imaging to be equal or even superior to
CT as an aid in determining both the site and cause of small-bowel
obstructions [3,
4].
In our patient, the phytobezoar appeared as an ovoid mass in the distal
small bowel and contained mottled, confluent, low signal intensities on both
T1- and T2-weighted MR images; these low signal intensities represented air
bubbles retained in the interstices of the phytobezoar that were identical to
those in previously reported CT findings and that were characteristic of a
small-bowel bezoar. In addition, a uniformly hyperintense rim was seen
surrounding the mass on T1-weighted MR images but was not seen on T2-weighted
MR images. It is difficult to say what the hyperintense rim on T1-weighted
images represented. At pathologic examination, the evacuated bezoar was found
to be a phytobezoar surrounded by a thick mixture of a bacterial colony.
Therefore, the hyperintense rim may have represented a collection of
high-protein substances with bacterial cellular components. A paramagnetic
effect due to unknown causes may have been another possible mechanism for the
visualization of the hyperintense rim.
In our patient, MR imaging revealed the small-bowel bezoar as an
intraluminal mass containing mottled, confluent, low signal intensities on T1-
and T2-weighted MR images showing air bubbles in the interstices of the bezoar
and a hyperintense rim on T1-weighted images. Both of these characteristics
may be diagnostic for bezoar.
References
- Licht M, Gold BM, Katz DS. Obstructing small-bowel bezoar:
diagnosis using CT. AJR
1999;173:500
-501[Free Full Text]
- Ripolles T, Garcia-Aguayo J, Martinez MJ, Gil P. Gastrointestinal
bezoars: sonographic and CT characteristics. AJR
2001;177:65
-69[Abstract/Free Full Text]
- Ha HK, Lee EH, Lim CH, et al. Application of MRI for small
intestinal disease. J Magn Reson Imaging
1998;8:374
-383
- Debatin JE, Patak MA. MRI of the small and large bowel.
Eur Radiol
1999;9:1523
-1534[Medline]
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