DOI:10.2214/AJR.07.3064
AJR 2008; 190:W271
© American Roentgen Ray Society
Unenhanced MDCT Findings of Acute Bowel Ischemia
Massimo De Filippo,
Concetta Sagone and
Maurizio Zompatori
University of Parma, Parma Hospital Parma, Italy
WEB—This is a Web exclusive article.
We read with interest the article in the November 2006 issue of
AJR, "MDCT of Small-Bowel Disease: Value of 3D Imaging"
[1]. The authors describe the
various clinical applications of MDCT enterography for evaluating small-bowel
disease, with a focus on the added value of 3D imaging. In particular, we
appreciated the detailed discussion and the excellent images. However, a
single point needs further explanation regarding the MDCT protocol: the
authors did not perform unenhanced CT. In our opinion, in some small-bowel
disease, performing unenhanced 3D CT before performing contrast-enhanced CT
can be highly diagnostic. MDCT is playing a larger role in clarifying the
clinical picture in patients with presumed acute bowel infarct. Thus we
believe that unenhanced CT frequently does have a role in the diagnosis of
acute bowel infarct.
The literature highlights the use of contrast material on CT to detect some
primary signs of bowel ischemia, including homogeneous or heterogeneous
hypoattenuating wall thicken ing, dilatation, abnormal or absent wall
enhancement, mesenteric stranding, and vascular engorgement
[2,
3]. We totally agree with the
high accuracy of contrast-enhanced CT in the study of acute bowel infarct.
However, in our opinion the presence of portomesenteric venous gas and
pneumatosis of the bowel indicates an acute bowel infarct.
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Fig. 1 —82-year-old man with chronic renal failure and atheromatous
vasculopathy. Unenhanced MDCT oblique axial plane 3D multiplanar
reconstruction image shows presence of portomesenteric venous gas. Note
air–fluid level in portal oliva (arrows).
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These findings may also be detected with unenhanced CT and better with
unenhanced CT 3D imaging (Figs.
1 and
2). It is known that gas is an
important natural contrast agent consistently detected on CT, and its presence
in the portomesenteric venous system is specific for gangrene of the bowel
wall [2]. Intramural gas is
caused by dissection of luminal gas into the bowel wall across the compromised
mucosa and may manifest with small isolated gas bubbles within the ischemic
bowel wall or as broad rims of air dissecting the entire bowel wall into two
layers
[4–6].
Portomesenteric venous gas represents the propagation of intramural gas into
the mesenteric venous system and may manifest as some small gaseous inclusion
within the mesenteric veins or may extend into the intrahepatic branches of
the portal vein, where it is typically found in the periphery of the liver
[2,
3].
In conclusion, we think the article by Hong and colleagues
[1] is very interesting but
probably somewhat limited in that the authors do not suggest to readers that
in some small-bowel disease, there may be benefit in performing unenhanced CT
before performing enhanced CT.
References
- Hong SS, Kim AY, Byun YH, et al. MDCT of small-bowel disease: value
of 3D imaging. AJR 2006;187
: 1212-122[Abstract/Free Full Text]
- Wiesner W, Khurana B, Ji H, Ros PR. CT of acute bowel ischemia.
Radiology 2003;226
: 635-650[Abstract/Free Full Text]
- Rha SE, Ha HK, Lee SH, et al. CT and MR imaging findings of bowel
ischemia from various primary causes. RadioGraphics2000; 20:29
-42[Abstract/Free Full Text]
- Sebastià C, Quiroga S, Espin E, Alvarez-Castells A,
Aremengol M. Portomesenteric vein gas: pathologic mechanisms, CT findings, and
prognosis. RadioGraphics 2000;20
: 1213-1224[Abstract/Free Full Text]
- Alpern MB, Glazer GM, Francis IR. Ischemic or infarcted bowel: CT
findings. Radiology 1988;166
: 149-152[Abstract/Free Full Text]
- Feczko PJ, Mezwa DG, Farah MC, White BD. Clinical significance of
pneumatosis of the bowel wall. RadioGraphics1992; 12:1069
-1078[Abstract]
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M. De Filippo, N. Sverzellati, and M. Zompatori
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Am. J. Roentgenol.,
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A. Y. Kim
Reply to "Unenhanced MDCT Findings of Acute Bowel Ischemia"
Am. J. Roentgenol.,
June 1, 2008;
190(6):
W383 - W383.
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