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Computed tomography of the superior mesenteric artery syndrome
ELSEVIER
COMPUTED TOMOGRAPHY OF THE SUPERIOR MESENTERIC ARTERY SYNDROME G. C. 001,
K. L. CHAN, K. F. KO, AND W. C. G. PEH
An acute presentation of the superior mesenteric artery syndrome was diagnosed in a l%year-old Chinese boy in whom no predisposing cause was found at surgery. Duodenogram combined with dynamic computed tomography, including Z-dimensional multiplanar reconstructions, was useful in confirming the diagnosis prior to definitive surgery. 0 Elsevier Science Inc., 1997
duly divided. The lesser sac and small bowel anatomy were normal. High volumes of fluid continued to be aspirated via the nasogastric tube postoperatively. Postoperative AXR revealed persistent gaseous distention of
KEY WORDS:
Arteries, superior mesenteric; Computed tomography (CT); Duodenum, dilatation; Intestine, obstruction
CASE REPORT A previously healthy 13-year-old boy presented acutely with bile-stained vomiting, abdominal pain, and distension. No predisposing cause was apparent. On clinical examination, his epigastrium was slightly distended with moderately increased bowel sounds. An abdominal radiograph (AXR) demonstrated a large fluid-filled stomach with air-fluid levels at the gastric fundus and the duodenal cap (Figure 1). The rest of the abdomen was gasless. Bile (3750 ml) was aspirated from his stomach and upper gastrointestinal obstruction was diagnosed. At emergency laparotomy, the second and third parts of the duodenum were dilated. A large sheet of fibrous tissue extended across the duodenum to the hepatic flexure; this was thought to be the cause of the obstruction and was
From the Departments of Diagnostic Radiology (G.C.O., W.C.G.P.), Surgery (Paediatric Surgery Division) (K.L.C.), and Medicine (K.F.K.), The University of Hong Kong, Queen Mary Hospital, Hong Kong. Address reprint requests to: Dr. Wilfred C.G. Peh, Department of Diagnostic Radiology, The University of Hong Kong, Room 415, Block K, Queen Mary Hospital, Hong Kong. Received May 1,1995;accepted June 20, 1995. CLINICAL IMAGING 1997;21:210-212 0 Elsevier Science Inc., 1997 655 Avenue of the Americas, New York, NY 10010
FIGURE 1. Abdominal radiograph shows a grossly dis-
tended fluid-filled stomach. Duodenal cap air-fluid level is arrowed.
0899-7071J97/$17.00
PI1 s0a99-7071(96)00027-7
MAYlIUNE
1997
CT OF THE SUPERIOR
MESENTERIC
ARTERY
SYNDROME
271
FIGURE 4. Reconstructed coronal CT image shows the SMA (arrows) crossing the third part of the duodenum. The proximal duodenum is dilated [arrowheads).
the stomach and duodenal C-loop. The patient had to be commenced on total parental nutrition. Upper endoscopy showed extrinsic anterior compression, with arterial pulsation at the third part of the duodenum, suggestive of the superior mesenteric artery (SMA) syndrome. As the patient did not respond to conservative measures, a combined duodenographic-computed tomography (CT) study was performed. After aspiration of stomach contents via the nasogastric tube, diluted gastrografin was manipulated into the duodenal loop. Abrupt vertical “cut-off” sign and typical “to and fro” peristaltic movements at the third part of dilated duodenum were observed (Figure 2). There was no relief noted with postural change. The
patient was then transferred, lying in the right lateral decubitus position, to the CT suite. Spiral CT was performed using a General Electric Advantage Plus scanner. Dynamic CT confirmed dilatation of the proximal duodenal loop, which tapered acutely between the superior mesenteric vessels and the aorta. Only a small amount of contrast was demonstrated distal to the point of obstruction (Figure 3). Reconstruction in the coronal plane showed the superior mesenteric artery crossing and compressing the third part of the duodenum (Figure 4). Reduced aortomesenteric distance and angle were seen in the sagittal plane reconstruction (Figure 5). No mass lesions were noted around the root of the superior mesenteric vessels. At a second laparotomy, adhesions were noted around the second to the fourth parts of duodenum. Due to vascularity of the surrounding fibrous tissue, the superior mesenteric vessels were not explored. To exclude the remote likelihood of malignancy or tuberculosis, multiple biopsies and frozen sections were obtained from the fibrous tissue before they
FIGURE 3. Axial CT shows beak-like compression of the third part of duodenum (arrowheads] between the superior mesenteric vessels [arrows] and the aorta (A).
FIGURE 5. Reconstructed sagittal CT image shows a markedly compressed duodenum [arrow) sandwiched between the SMA (arrowheads) and the aorta (A). Note the narrowed distance and very acute angle between these two vessels.
FIGURE 2. Gastrografin upper gastrointestinal study confirms obstruction at the third part of the duodenum and demonstrates a sharp cut-off sign (arrows).
212
CLINICAL IMAGING VOL. 21, NO. 3
001 ET AL.
FIGURE 6. A schematic diagram showing the duodenojejunostomy bypass procedure performed in our patient.
were lysed and a duodenojejunostomy fashioned (Figure 6). The patient improved dramatically postoperatively and was able to commence oral feeding within 5 days. Histology of the biopsies revealed normal fibrous tissue without evidence of malignancy. The patient has remained well on follow-up.
sogastric fluid obtained prior to the first laparotomy, it is most likely that duodenal obstruction was present from the outset. An unusual aspect of this case is the lack of a predisposing cause for this syndrome on either radiology or surgery. From the surgeon’s perspective, other causes of extrinsic duodenal obstruction in this patient such as lymphoma, pancreatic malignancy, and tuberculous lymph node involvement had to be excluded, hence the biopsy of the fibrous tissue. However, as the findings of the combined duodenogram and dynamic CT refuted any suggestion of a mass lesion, the surgeons proceeded to a duodenojejunostomy without dangerous dissection and exploration of the superior mesenteric vessels and the pancreatic bed. Although hypotonic duodenography combined with simultaneous SMA angiography has been regarded as the definitive radiologic study in the past, CT has been reported to be useful in diagnosing this syndrome (7, 8). This case illustrates that a tailored dynamic examination, using a modern CT scanner with multiplanar reconstruction capability, can succinctly demonstrate the aortomesenteric-duodenal relationship and confirm the diagnosis of the SMA syndrome precisely.
DISCUSSION The clinical and radiographic features of the SMA syndrome are well documented (l-4). The most common presentation is one of chronic illness, frequently associated with longstanding emaciating diseases. An acute presentation is rare and invariably follows prolonged supine position, trauma, severe weight loss, or a surgical procedure (5-6). Rearrangement of the anatomy around the third part of the duodenum during surgery, thought to compromise the superior mesenteric-duodenal relationship, was the only possible etiological factor in this patient. In our case, however, as neither the small nor large bowel was mobilized during the first laparotomy, compromise of the mesenteric-duodenal relationship could not have occurred. Additionally, the patient’s symptoms and signs continued unabated in the immediate postoperative period. From the initial clinical presentation and the copious volumes of na-
REFERENCES 1. Wayne ER, Burrington JD. Duodenal obstruction by the superior mesenteric artery in children. Surgery 1976;72:762-768. 2. Burrington JD. Superior mesenteric artery syndrome in children. Am J Diseases Childhood 1976;130:1367-1370. 3. Hines JR, Gore RM, Ballantyne GH. Superior mesenteric artery syndrome: diagnostic criteria and therapeutic approaches. Am J Surgery 1982;148:630-632. 4. Anderson JR, Earnshaw PM, Fraser GM. Extrinsic compression of the third part of the duodenum. Clin Radio1 1982;33:75-81. 5. Yerdel MA, Moreira LF, Iwagaki H, Kamokawa Y, Tanaka N, Orita K. Acute superior mesenteric artery syndrome following left hemicolectomy: A case report. Acta Med Okayama 1992; 46:479-482. 6. Mindell HJ, Holm JL. Acute superior drome. Radiology 1976;94:229-362.
mesenteric
artery syn-
7. Santer R, Young C, Rossi T, Riddlesberger MM. Computed tomography in superior mesenteric artery syndrome. Pediatr Radiol 1992;21:164-1%. 8. Applegate GR, Cohen AJ. Dynamic CT in superior mesenteric artery syndrome. J Comput Assist Tomogr 1988;12:976-980.
COMPUTED TOMOGRAPHY OF THE SUPERIOR MESENTERIC ARTERY SYNDROME G. C. 001,
K. L. CHAN, K. F. KO, AND W. C. G. PEH
An acute presentation of the superior mesenteric artery syndrome was diagnosed in a l%year-old Chinese boy in whom no predisposing cause was found at surgery. Duodenogram combined with dynamic computed tomography, including Z-dimensional multiplanar reconstructions, was useful in confirming the diagnosis prior to definitive surgery. 0 Elsevier Science Inc., 1997
duly divided. The lesser sac and small bowel anatomy were normal. High volumes of fluid continued to be aspirated via the nasogastric tube postoperatively. Postoperative AXR revealed persistent gaseous distention of
KEY WORDS:
Arteries, superior mesenteric; Computed tomography (CT); Duodenum, dilatation; Intestine, obstruction
CASE REPORT A previously healthy 13-year-old boy presented acutely with bile-stained vomiting, abdominal pain, and distension. No predisposing cause was apparent. On clinical examination, his epigastrium was slightly distended with moderately increased bowel sounds. An abdominal radiograph (AXR) demonstrated a large fluid-filled stomach with air-fluid levels at the gastric fundus and the duodenal cap (Figure 1). The rest of the abdomen was gasless. Bile (3750 ml) was aspirated from his stomach and upper gastrointestinal obstruction was diagnosed. At emergency laparotomy, the second and third parts of the duodenum were dilated. A large sheet of fibrous tissue extended across the duodenum to the hepatic flexure; this was thought to be the cause of the obstruction and was
From the Departments of Diagnostic Radiology (G.C.O., W.C.G.P.), Surgery (Paediatric Surgery Division) (K.L.C.), and Medicine (K.F.K.), The University of Hong Kong, Queen Mary Hospital, Hong Kong. Address reprint requests to: Dr. Wilfred C.G. Peh, Department of Diagnostic Radiology, The University of Hong Kong, Room 415, Block K, Queen Mary Hospital, Hong Kong. Received May 1,1995;accepted June 20, 1995. CLINICAL IMAGING 1997;21:210-212 0 Elsevier Science Inc., 1997 655 Avenue of the Americas, New York, NY 10010
FIGURE 1. Abdominal radiograph shows a grossly dis-
tended fluid-filled stomach. Duodenal cap air-fluid level is arrowed.
0899-7071J97/$17.00
PI1 s0a99-7071(96)00027-7
MAYlIUNE
1997
CT OF THE SUPERIOR
MESENTERIC
ARTERY
SYNDROME
271
FIGURE 4. Reconstructed coronal CT image shows the SMA (arrows) crossing the third part of the duodenum. The proximal duodenum is dilated [arrowheads).
the stomach and duodenal C-loop. The patient had to be commenced on total parental nutrition. Upper endoscopy showed extrinsic anterior compression, with arterial pulsation at the third part of the duodenum, suggestive of the superior mesenteric artery (SMA) syndrome. As the patient did not respond to conservative measures, a combined duodenographic-computed tomography (CT) study was performed. After aspiration of stomach contents via the nasogastric tube, diluted gastrografin was manipulated into the duodenal loop. Abrupt vertical “cut-off” sign and typical “to and fro” peristaltic movements at the third part of dilated duodenum were observed (Figure 2). There was no relief noted with postural change. The
patient was then transferred, lying in the right lateral decubitus position, to the CT suite. Spiral CT was performed using a General Electric Advantage Plus scanner. Dynamic CT confirmed dilatation of the proximal duodenal loop, which tapered acutely between the superior mesenteric vessels and the aorta. Only a small amount of contrast was demonstrated distal to the point of obstruction (Figure 3). Reconstruction in the coronal plane showed the superior mesenteric artery crossing and compressing the third part of the duodenum (Figure 4). Reduced aortomesenteric distance and angle were seen in the sagittal plane reconstruction (Figure 5). No mass lesions were noted around the root of the superior mesenteric vessels. At a second laparotomy, adhesions were noted around the second to the fourth parts of duodenum. Due to vascularity of the surrounding fibrous tissue, the superior mesenteric vessels were not explored. To exclude the remote likelihood of malignancy or tuberculosis, multiple biopsies and frozen sections were obtained from the fibrous tissue before they
FIGURE 3. Axial CT shows beak-like compression of the third part of duodenum (arrowheads] between the superior mesenteric vessels [arrows] and the aorta (A).
FIGURE 5. Reconstructed sagittal CT image shows a markedly compressed duodenum [arrow) sandwiched between the SMA (arrowheads) and the aorta (A). Note the narrowed distance and very acute angle between these two vessels.
FIGURE 2. Gastrografin upper gastrointestinal study confirms obstruction at the third part of the duodenum and demonstrates a sharp cut-off sign (arrows).
212
CLINICAL IMAGING VOL. 21, NO. 3
001 ET AL.
FIGURE 6. A schematic diagram showing the duodenojejunostomy bypass procedure performed in our patient.
were lysed and a duodenojejunostomy fashioned (Figure 6). The patient improved dramatically postoperatively and was able to commence oral feeding within 5 days. Histology of the biopsies revealed normal fibrous tissue without evidence of malignancy. The patient has remained well on follow-up.
sogastric fluid obtained prior to the first laparotomy, it is most likely that duodenal obstruction was present from the outset. An unusual aspect of this case is the lack of a predisposing cause for this syndrome on either radiology or surgery. From the surgeon’s perspective, other causes of extrinsic duodenal obstruction in this patient such as lymphoma, pancreatic malignancy, and tuberculous lymph node involvement had to be excluded, hence the biopsy of the fibrous tissue. However, as the findings of the combined duodenogram and dynamic CT refuted any suggestion of a mass lesion, the surgeons proceeded to a duodenojejunostomy without dangerous dissection and exploration of the superior mesenteric vessels and the pancreatic bed. Although hypotonic duodenography combined with simultaneous SMA angiography has been regarded as the definitive radiologic study in the past, CT has been reported to be useful in diagnosing this syndrome (7, 8). This case illustrates that a tailored dynamic examination, using a modern CT scanner with multiplanar reconstruction capability, can succinctly demonstrate the aortomesenteric-duodenal relationship and confirm the diagnosis of the SMA syndrome precisely.
DISCUSSION The clinical and radiographic features of the SMA syndrome are well documented (l-4). The most common presentation is one of chronic illness, frequently associated with longstanding emaciating diseases. An acute presentation is rare and invariably follows prolonged supine position, trauma, severe weight loss, or a surgical procedure (5-6). Rearrangement of the anatomy around the third part of the duodenum during surgery, thought to compromise the superior mesenteric-duodenal relationship, was the only possible etiological factor in this patient. In our case, however, as neither the small nor large bowel was mobilized during the first laparotomy, compromise of the mesenteric-duodenal relationship could not have occurred. Additionally, the patient’s symptoms and signs continued unabated in the immediate postoperative period. From the initial clinical presentation and the copious volumes of na-
REFERENCES 1. Wayne ER, Burrington JD. Duodenal obstruction by the superior mesenteric artery in children. Surgery 1976;72:762-768. 2. Burrington JD. Superior mesenteric artery syndrome in children. Am J Diseases Childhood 1976;130:1367-1370. 3. Hines JR, Gore RM, Ballantyne GH. Superior mesenteric artery syndrome: diagnostic criteria and therapeutic approaches. Am J Surgery 1982;148:630-632. 4. Anderson JR, Earnshaw PM, Fraser GM. Extrinsic compression of the third part of the duodenum. Clin Radio1 1982;33:75-81. 5. Yerdel MA, Moreira LF, Iwagaki H, Kamokawa Y, Tanaka N, Orita K. Acute superior mesenteric artery syndrome following left hemicolectomy: A case report. Acta Med Okayama 1992; 46:479-482. 6. Mindell HJ, Holm JL. Acute superior drome. Radiology 1976;94:229-362.
mesenteric
artery syn-
7. Santer R, Young C, Rossi T, Riddlesberger MM. Computed tomography in superior mesenteric artery syndrome. Pediatr Radiol 1992;21:164-1%. 8. Applegate GR, Cohen AJ. Dynamic CT in superior mesenteric artery syndrome. J Comput Assist Tomogr 1988;12:976-980.