Imaging Pearls ❯ Small Bowel ❯ Ischemic Bowel
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- “Pneumatosis intestinalis, although considered a sign of acuteischemic damage to bowel mucosa, it may be associatedwith several benign conditions like connective tissue disease,emphysema, asthma, and intra-abdominal procedures.Patients are usually asymptomatic in these cases with otherwise normal bowel wall thickness and enhancement pattern and absence of portomesenteric gas.”
Mesenteric ischemia: a radiologic perspective
Dimpi Sinha et al.
Abdominal Radiology (2022) 47:1514–1528 - CT mimickers of mesenteric ischemia
- Crohns disease
- Infectious enteritis
- Acute radiation enteritis
- Shock bowel mimicking veno-occlusive disease
- Pneumatosis due to connective tissue disease, emphysema, asthma and intra-abdominal procedures - "Mesenteric ischemia is an uncommon entity with high morbidity and mortality in the acute setting. A high degree of clinical suspicion with imaging correlation is pertinent for early diagnosis to improve clinical outcome. MDCT is the first line imaging modality for the diagnosis of mesenteric ischemia due to its wide spread availability, faster acquisition and great spatial resolution. CT angiography allows for a comprehensive non-invasive assessment of the abdominal vasculature as well as the bowel and mesentery. It not only detects the cause of ischemia but also helps in differentiating reversible and irreversible ischemic event based on the bowel wall and mesenteric findings, thereby predicting outcome.”
Mesenteric ischemia: a radiologic perspective
Dimpi Sinha et al.
Abdominal Radiology (2022) 47:1514–1528 - “Endovascular catheter thrombolysis is the preferred treatment option for early reversible acute ischemia with better patient outcome and lesser morbidity. Percutaneous transluminal angioplasty with stenting is a less invasive, effective treatment option for chronic mesenteric stenosis as compared to surgical revascularization.”
Mesenteric ischemia: a radiologic perspective
Dimpi Sinha et al.
Abdominal Radiology (2022) 47:1514–1528
- • Location of emboli: usually 6–10 cm beyond the SMA ostium, near the origin of the middle colic artery
• The proximal branches (such as the inferior pancreaticoduodenal artery) and the jejunal arteries are preserved in most patients
• Smaller emboli may affect only the small distal branches. Small showering emboli in the small distal branches aredifficult to identify. In this setting, helpful clues—such as infarction of solid organs like the spleen and kidneys—may be suggestive of small, nonocclusive emboli
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - “Venous occlusion accounts for 5–15% of ASBI cases and frequently occurs in younger patients. The symptoms of mesenteric venous ischemia secondary to impaired venous drainage are less acute than those of mesenteric arterial ischemia, but the CT findings are more conspicuous and striking. Mesenteric venous occlusion can be seen inpatients with a mechanical obstruction and venous thrombosis.Venous circulation can be compromised in association with bowel strangulation, which is typically identified in a volvulus, intussusception, or a closed loop obstruction.”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - "Venous thrombosis may be associated with many conditions. They include hypercoagulability (such as antiphospholipid antibody syndrome); protein C/S deficiency; oral contraceptive consumption; and vasculitis (like systemic lupus erythematous) resulting in occlusion or thrombosis of the small, intramural veins. The mesenteric venous ischemia is not frequently associated with postpandrial syndrome, despite the presence of abdominal distension, bloating, fever, and positive stool occult blood. Thrombosis from other local conditions—for example, inflammatory or infectious bowel disease, pancreatitis, and portal hypertension—may uncommonly cause mesenteric ischemia secondary to a slow retrograde distal progression that allows collateral veins to form.”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - "NOMI (Nonocclusive mesenteric ischemia) is the form of mesenteric ischemia withoutmesenteric artery and venous occlusion that develops in the area of a bowel necrosis. It accounts for 20–30% of all cases of mesenteric ischemia. Regarding its pathogenesis,intestinal vasospasm due to consistently low perfusionis believed to be the cause of the ischemic disorder .It commonly occurs in patients older than 50 years whohave conditions that decrease cardiac output, for example,myocardial infarction, congestive heart failure, aortic insufficiency,hepatic or renal diseases, and septic or hemorrhagic shock, a profound decrease in systemic blood pressure, or severe volume depletion NOMI is frequently associatedwith worsened outcomes and high mortality rates, which reach 58–70%.”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - "Pneumatosis intestinalis is sometimes associated with portomesenteric venous gas. Portomesenteric venous gas is differentiated from aerobilia by its characteristic tubular branching lucencies that extend to the periphery of the liver, whereas biliary air is more central. Pneumatosis intestinalis in ASBI is considered an indicator of a poor prognosis when related to advanced necrosis, particularly if it is associated with portomesenteric venous gas.”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - “The main complication of SBO is intestinal ischemia. In the emergency setting, CT imaging is the modality of choice for SBO because of its ability to assess the bowel wall, the supporting mesentery and peritoneal cavity all in one. On the other hand, the radiologist who documents an intestinal ischemia should think about SBO as possible cause. In this case, the main finding which helps the radiologist in the identification of SBO is the presence of multiple and packed valvulae conniventes in the dilated bowel wall and the “transition zone” that indicates the passage between compressed and decompressed small bowel, otherwise the localization of the obstruction cause. Once the site of obstruction has been recognized, the other issueis to assess the cause of obstruction, considering that the most common cause of SBO remains “unidentified” and related to intra-abdominal adhesions. After that, the following most important point is to rule out the presence of an ischemic bowel and mesenteric changes associated to SBO. CT signs of bowel ischemia include reduced or increased bowel wall enhancement, mesenteric edema or engorgement, fluid or free air in the peritoneal cavity. This condition usually leads to an urgent laparotomy and, in some cases, to a surgical resection.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555
- OBJECTIVE. The purpose of this study was to assess whether transmural bowel necrosis has distinct CT features based on the three main causes: occlusive acute mesenteric ischemia (AMI), nonocclusive AMI, and strangulated small-bowel obstruction (SBO).
CONCLUSION. Transmural bowel necrosis has distinct CT findings according to its three main causes. Occlusive AMI is characterized by an absence of bowel wall enhancement and less mesenteric fat stranding, nonocclusive AMI by a high prevalence of pneumatosis intestinalis and portal venous gas, and strangulated SBO by spontaneous hyperattenuation of the bowel wall and an absence of pneumatosis intestinalis and portal venous gas.
Transmural Bowel Necrosis From Acute Mesenteric Ischemia and Strangulated Small-Bowel Obstruction: Distinctive CT Features
Calame P et al.
AJR 2020; 214:90–95 - “The two main causes of transmural bowel necrosis are acute mesenteric ischemia (AMI) and strangulated small-bowel obstruction (SBO). AMI can be separated into occlusive AMI, which accounts for two-thirds of cases, and nonocclusive AMI, which accounts for one- third of cases.”
Transmural Bowel Necrosis From Acute Mesenteric Ischemia and Strangulated Small-Bowel Obstruction: Distinctive CT Features
Calame P et al.
AJR 2020; 214:90–95 - "Occlusive AMI is characterized by vascular occlusion of mesenteric arterial or venous trunks. The origin is atheromatous, embolic, or dissecting, and approximately 70% of cases affect the superior mesenteric artery. Non- occlusive AMI is characterized by splanchnic hypoperfusion commonly caused by a low car- diac output state due to sepsis, congestive cardiac failure, hypovolemia, aortic insufficiency, renal or hepatic disease, or cardiac surgery.”
Transmural Bowel Necrosis From Acute Mesenteric Ischemia and Strangulated Small-Bowel Obstruction: Distinctive CT Features
Calame P et al.
AJR 2020; 214:90–95 - “Mesenteric fat stranding was less frequent in occlusive AMI than in nonocclusive AMI and strangulated SBO. Mazzei et al. specifically studied the diagnostic value of mesenteric features in AMI. Their findings were similar to ours, such as that mesenteric fat stranding can be the consequence of multiples factors. It is usually the consequence of elevation of mesenteric pressure, which explains why it is almost always observed in strangulated SBO, but it can also be a consequence of transmural infarction or be linked to a reperfusion syndrome.”
Transmural Bowel Necrosis From Acute Mesenteric Ischemia and Strangulated Small-Bowel Obstruction: Distinctive CT Features
Calame P et al.
AJR 2020; 214:90–95 - "In this study, we identified distinctive patterns of CT features according to cause of transmural bowel necrosis. Occlusive AMI is characterized by an absence of bowel wall enhancement and less mesenteric fat stranding, nonocclusive AMI by a high prevalence of pneumatosis intestinalis and portal venous gas, and strangulated SBO by spontaneous hyperattenuation of the bowel wall and an absence of pneumatosis intestinalis and portal venous gas.”
Transmural Bowel Necrosis From Acute Mesenteric Ischemia and Strangulated Small-Bowel Obstruction: Distinctive CT Features
Calame P et al.
AJR 2020; 214:90–95 - “Patients with longstanding CD have an increased risk of developing small bowel and anal adenocarcinoma. They present a diagnostic challenge, as the tumor is often indiscernible from the underlying inflammatory bowel disease (IBD). Loss of stratification of the bowel wall and asymmetric marked focal mural thickening are findings suggestive of malignancy in these patients. Small bowel adenocarcinomas most often occur in a specific region of chronic inflammation such as a fistula tract or in strictured segments.”
Unusual intestinal and extra intestinal findings in Crohn's disease seen on T abdominal computed tomography and magnetic resonance enterography
Alida A et al.
Clinical Imaging 59 (2020) 30–38
- Table 1: Common Drugs Associated with Pneumatosis Intestinalis
Drug Class and Common Agents
• Corticosteroids
• Chemotherapeutics
Cytotoxic agents: methotrexate, etoposide,
daunorubicin, cytarabine, fluorouracil,
paclitaxel
Tyrosine kinase inhibitors: imitinib
• Immunosuppressants
• Antidiabetics
• a-glucosidase inhibitors: voglibose ,acarbose
• Other: lactulose, sorbitol - “In addition to medication, other nonemergent causes of pneumatosis intestinalis include pul- monary causes such as asthma, chronic obstruc- tive pulmonary disease, mechanical ventilation with positive end-expiratory pressure, and cystic fibrosis. Inflammatory bowel disease and iatrogenic causes (eg, colonoscopy) are other known sources .”
Imaging of Drug-induced Complications in the Gastrointestinal System McGettigan MJ et al. RadioGraphics 2016; 36:71–87
- “The causes of intestinal ischemia can be occlusive or non occlusive. Occlusive causes are due to the embolic or thrombotic occlusion of arterial or venous vessels and account for about 80% of all cases of intestinal ischemia. Between 36% to 50% of intestinal infarctions are caused by embolic obstruction of the superior mesenteric artery in patients with cardiac pathology, while in 50%-60% of cases intestinal ischemia is caused by arterial thrombosis.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations Moschetta M et al. World J Radiol. 2014 May 28; 6(5): 130-138. - “Venous thrombosis accounts for about 10%-15% of all cases of intestinal ischemia. The most frequent cause of venous infarction is secondary to bowel closed-loop obstruction. This event does not lead to vascular thrombosis but to the twisting of the loops on their vascular pedicle which produces severe venous stasis. Another cause of venous intestinal ischemia is bowel obstruction, which causes an overdistension of the bowel wall, preventing the outflow of the venous blood.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations Moschetta M et al. World J Radiol. 2014 May 28; 6(5): 130-138. - “Non occlusive causes account for about 20%-30% of all intestinal ischemia. In these forms, there is a significant reduction in blood flow within the arteries and veins. Hypovolemic shock, severe heart failure, abnormal blood concentration, episodes of neurogenic vasodilation and vasoconstriction secondary to drugs determine non occlusive bowel infarction in most cases.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations Moschetta M et al. World J Radiol. 2014 May 28; 6(5): 130-138. - “Bowel infarction is an uncommon but often underestimated cause of non traumatic acute abdomen and early diagnosis is crucial in order to avoid irreversible damage to the bowel wall. MDCT is a fundamental imaging technique that must be promptly performed in all patients with acute abdomen and suspected bowel ischemia.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations Moschetta M et al. World J Radiol. 2014 May 28; 6(5): 130-138. - OBJECTIVES: (1) To evaluate the ability of emergency room radiologists to detect acute mesenteric ischemia (AMI) from computed tomography (CT) images in patients with acute abdominal pain. (2) To identify factors affecting radiologists' performance in the CT interpretation and patient outcome.
CONCLUSIONS: AMI is underdiagnosed in the CT of the acute abdomen if there is no clinical suspicion. Detecting acute mesenteric ischemia in CT of the acute abdomen is dependent on clinical suspicion: Review of 95 consecutive patients.
Lehtimäki TT et al. Eur J Radiol. 2015 Sep 11. pii: S0720-048X(15)30098-X. doi: 10.1016/j.ejrad.2015.09.006. [Epub ahead of print] - “The referring clinician had suspected AMI in 30 (31%) cases prior to imaging. The crucial findings of AMI had been stated in 97% of the radiology reports if the clinician had mentioned AMI suspicion in the referral; if not, the corresponding rate was 81% (p=0.04). Patients without suspicion of AMI prior to CT were more prone to undergo bowel resection. CT protocol was optimal for AMI (with contrast enhancement in arterial and venous phases) in only 34 (35%) cases. Intestinal findings were more difficult to detect than vascular findings. Vascular findings were retrospectively detectable in 92% of cases with embolism and 100% in ASVD and MVT.
Detecting acute mesenteric ischemia in CT of the acute abdomen is dependent on clinical suspicion: Review of 95 consecutive patients.
Lehtimäki TT et al. Eur J Radiol. 2015 Sep 11. pii: S0720-048X(15)30098-X. doi: 10.1016/j.ejrad.2015.09.006. [Epub ahead of print] - “The referring clinician had suspected AMI in 30 (31%) cases prior to imaging. The crucial findings of AMI had been stated in 97% of the radiology reports if the clinician had mentioned AMI suspicion in the referral; if not, the corresponding rate was 81% (p=0.04).
Detecting acute mesenteric ischemia in CT of the acute abdomen is dependent on clinical suspicion: Review of 95 consecutive patients.
Lehtimäki TT et al. Eur J Radiol. 2015 Sep 11. pii: S0720-048X(15)30098-X. doi: 10.1016/j.ejrad.2015.09.006. [Epub ahead of print] - “The referring clinician had suspected AMI in 30 (31%) cases prior to imaging. The crucial findings of AMI had been stated in 97% of the radiology reports if the clinician had mentioned AMI suspicion inn the referral; if not, the corresponding rate was 81% (p=0.04). Patients without suspicion of AMI prior to CT were more prone to undergo bowel resection. CT protocol was optimal for AMI (with contrast enhancement in arterial and venous phases) in only 34 (35%) cases.”
Detecting acute mesenteric ischemia in CT of the acute abdomen is dependent on clinical suspicion: Review of 95 consecutive patients. Lehtimäki TT et al. Eur J Radiol. 2015 Sep 11. pii: S0720-048X(15)30098-X. doi: 10.1016/j.ejrad.2015.09.006. [Epub ahead of print] - “Vascular findings were retrospectively detectable in 92% of cases with embolism and 100% in ASVD and MVT. Some evidence of intestinal abnormality was retrospectively found in the CT findings in 92%, 100%, 100% and 67% of cases with embolism, ASVD, NOMI and MVT, respectively.”
Detecting acute mesenteric ischemia in CT of the acute abdomen is dependent on clinical suspicion: Review of 95 consecutive patients. Lehtimäki TT et al. Eur J Radiol. 2015 Sep 11. pii: S0720-048X(15)30098-X. doi: 10.1016/j.ejrad.2015.09.006. [Epub ahead of print] - “CTA can also be helpful in stratifying patients to identify those who would benefit from angiography as opposed to the ones who should undergo emergent surgery. Vascular CT findings include arterial stenosis, embolism, thrombosis, arterial dissection, and mesenteric vein thrombosis; nonvascular CT findings include bowel wall thickening, hypoperfusion and hypoattenuation, bowel dilatation, bowel wall hemor- rhage, mesenteric fat stranding, pneumatosis intesti- nalis, and portal venous gas. Overall, combining vascular findings with the appearance of the bowel wall resulted in a specificity of 94% with a sensitivity of 96%.”
ACR appropriateness criteria imaging of mesenteric ischemia Oliva IB et al. Abdom Imaging (2013) 38:714–719 - “Mesenteric ischemia is a rare disease associated with high morbidity and mortality. Acute mesenteric ischemia is most commonly secondary to embolism followed by arterial thrombosis, nonocclusive ischemia, and less commonly venous thrombosis. Chronic mesenteric ischemia is almost always caused by atherosclerotic disease, with rare causes including fibromuscular dysplasia and vasculitis.”
ACR appropriateness criteria imaging of mesenteric ischemia Oliva IB et al. Abdom Imaging (2013) 38:714–719 - “Acute mesenteric ischemia is most commonly secondary to embolism to the superior mesenteric artery (SMA), which accounts for approximately 40%–50% of all episodes. Acute mesenteric artery thrombosis is the second most common cause of acute mesenteric ischemia (20%–30%) followed by nonocclusive mesenteric ischemia (25%) and less commonly mesenteric and portal venous thrombosis (5%–15%).”
ACR appropriateness criteria imaging of mesenteric ischemia Oliva IB et al. Abdom Imaging (2013) 38:714–719 - “Mesenteric and portal venous thrombosis is the least common cause of acute mesenteric ischemia. Most common risk factors are hypercoagulable states, portal hypertension, and recent surgery. Bowel ischemia occurs if there is no adequate collateral circulation to drain the intestinal mucosa, leading to edema and subsequent arterial hypoperfusion.”
ACR appropriateness criteria imaging of mesenteric ischemia Oliva IB et al. Abdom Imaging (2013) 38:714–719 - “Computed tomography angiography (CTA) is a fast and noninvasive test with high sensitivity and specificity in diagnosing acute and chronic mesenteric ischemia and should be considered the first-line test in most cases. CT imaging of the abdomen also allows accu- rate evaluation of the entire gastrointestinal and genitourinary tract, helping to exclude most of the other causes of acute and chronic abdominal pain, including cholelithiasis, cholecystitis, pancreatitis, appendicitis, diverticulosis with or without diverticulitis, and nephrolithiasis.”
ACR appropriateness criteria imaging of mesenteric ischemia Oliva IB et al. Abdom Imaging (2013) 38:714–719 - “CTA with 3D volume reformatting has sensitivity and specificity of 96% and 94%, respectively, for detecting chronic mesenteric ischemia. Therefore, it should be considered as a first-line alternative to angiography for diagnostic purposes. Moreover, CTA is an accurate diagnosing tool for detecting SMA syndrome. CT can also accurately exclude other causes of chronic abdominal pain.”
ACR appropriateness criteria imaging of mesenteric ischemia Oliva IB et al. Abdom Imaging (2013) 38:714–719 - “CTA is an emerging diagnostic test with high sensitivity and specificity in the setting of both acute and chronic mesenteric ischemia and should be considered the first-line imaging test. CT can also accurately assess for other causes of acute and chronic abdominal pain, and it provides excellent anatomic mapping of the mesenteric vasculature, which is essential in the preoperative planning.”
ACR appropriateness criteria imaging of mesenteric ischemia Oliva IB et al. Abdom Imaging (2013) 38:714–719 
- CT Findings of Ischemia
1. Bowel wall thickening (> 3mm)
2. Mesenteric edema
3. Fluid in mesentery and/or peritoneal cavity
4. Abnormal bowel wall enhancement, either increased or decreased
5. Occlusion of mesenteric vessels
6. Engorged mesenteric veins
7. Whirl sign
8. Closed loop obstruction or volvulus
9. Pneumatosis
10. Mesenteric venous gas
11. Portal venous gas - “Ischemia is the complication that increases the morbidity and mortality associated with SBO. Specifically, the mortality rate in patients who undergo surgery for SBO with ischemic bowel is as high as 25% compared with those with SBO without strangulation, which may be as low as 2%. When ischemia is suspected, immediate surgery is required to avoid trans- mural necrosis and perforation.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “The CT findings associated with ischemic bowel include bowel with thickening, mesenteric edema and/or fluid in the adjacent mesentery or peritoneal space, abnormal decreased bowel wall enhancement, and pneumatosis with or without associated gas in mesenteric or portal veins.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “On contrast-enhanced CT scans, ischemia is associated with abnormal bowel wall enhancement and may manifest as decreased enhancement relative to the uninvolved bowel, hyperenhancement of the mucosa relative to the remainder of the bowel wall creating a “target” appearance, or as heterogeneous enhancement.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “Pneumatosis may be subtle to detect even with CT as gas within the lumen that rims the mucosa may mimic pneumatosis. Gas in mesenteric veins may be identified in conjunction with pneumatosis in the bowel wall. Identification of gas in veins draining a segment of the bowel, or portal venous gas, often confirms the suspicion of pneumatosis.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42.
- "Mesenteric ischemia is a rare disease associated with high morbidity and mortality. Acute mesenteric ischemia is most commonly secondary to embolism followed by arterial thrombosis, nonocclusive ischemia, and less commonly venous thrombosis. Chronic mesenteric ischemia is almost always caused by atherosclerotic disease, with rare causes including fibromuscular dysplasia and vasculitis."
ACR Appropriateness Criteria imaging of mesenteric ischemia.
Oliva I et al.
Abdom Imaging. 2013 Aug;38(4):714-9
- “Increased unenhanced bowel-wall attenuation at 64-section multidetector CT is reliable for the diagnosis of bowel-wall ischemia complicating small-bowel obstruction (SBO) and constitutes a key finding in patients with contraindications to iodinated contrast agent injection.”
Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia complicating small-bowel obstruction.
Geffroy Y et al.
Radiology. 2014 Jan;270(1):159-67 - “ This analysis revealed four readily evaluable clinical parameters that may be used to predict the need for surgery in patients presenting with SBO: persistent abdominal pain, abdominal distention, fever at 48 hours, and CT findings of high-grade obstruction. These factors were combined into a predictive model that may of use in predicting failure of nonoperative SBO management. Early operation in these patients should decrease length of stay and diagnostic costs.”
Letting the sun set on small bowel obstruction: can a simple risk score tell us when nonoperative care is inappropriate?
O'Leary EA et al.
Am Surg. 2014 Jun;80(6):572-9. - “MDCT contributes to appropriate treatment planning and provides important prognostic information thanks to its ability to define the nature and extent of the disease.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
Moschetta M et al.
World J Radiol. 2014 May 28;6(5):130-8. - “Bowel wall hyperdensity reflects vasodilation, which is the first consequence of hypoxic damage. The absence of wall enhancement corresponds to the ensuing vasoconstriction; bowel-loop thickening and dilatation are related to the increased capillary permeability, pneumatosis and the presence of air within the mesenteric-portal system reflect the necrosis of the intestinal mucosa, whereas pneumoperitoneum/pneumoretroperitoneum corresponds to a transmural extension of the necrosis. Therefore, wall hyperdensity, the absence of enhancement and wall thickening are an early stage of the disease, in contrast to loop dilation, parietal and portomesenteric pneumatosis and pneumoperitoneum/pneumoretroperitoneum which reflect an advanced stage of disease and are characterized by high mortality rates.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
Moschetta M et al.
World J Radiol. 2014 May 28;6(5):130-8. - “Bowel wall hyperdensity reflects vasodilation, which is the first consequence of hypoxic damage. The absence of wall enhancement corresponds to the ensuing vasoconstriction; bowel-loop thickening and dilatation are related to the increased capillary permeability, pneumatosis and the presence of air within the mesenteric-portal system reflect the necrosis of the intestinal mucosa, whereas pneumoperitoneum/pneumoretroperitoneum corresponds to a transmural extension of the necrosis.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
Moschetta M et al.
World J Radiol. 2014 May 28;6(5):130-8. - “Bowel infarction is an uncommon but often underestimated cause of non traumatic acute abdomen and early diagnosis is crucial in order to avoid irreversible damage to the bowel wall. MDCT is a fundamental imaging technique that must be promptly performed in all patients with acute abdomen and suspected bowel ischemia. Thanks to the dedicated reconstruction program, its diagnostic potential is much improved compared to the past and currently is superior to that of any other noninvasive technique.”
Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
Moschetta M et al.
World J Radiol. 2014 May 28;6(5):130-8. - “Intravascular thrombosis and thromboembolism are critical diagnoses which are frequently made on contrast-enhanced computed tomography (CECT) or Doppler ultrasound. For a variety of reasons, some patients with acute intravascular pathology are imaged using CT without intravenous contrast. In the acute setting, the increased Hounsfield unit (HU) density of the thrombus compared to the blood pool allows the diagnosis to be made, or at least suggested, on non-enhanced computed tomography (NECT). The increased density of the clot is commonly referred to as the "hyperdense vessel sign." This is a well-known finding in the setting of stroke, but hyperdense vessels can also signal arterial or venous thrombosis in the chest, abdomen, pelvis, and extremities. Once a hyperdense vessel sign is noted on NECT, further exploration with CECT, angiography, or ultrasound may then be performed. Here, we present a pictorial review of the appearance of acute intravascular thrombosis as seen on non-enhanced computed tomography.”
Imaging findings of acute intravascular thrombus on non-enhanced computed tomography.
Whitesell RT, Steenburg SD.
Emerg Radiol. 2014 Jun;21(3):271-7 - “Intravascular thrombosis and thromboembolism are critical diagnoses which are frequently made on contrast-enhanced computed tomography (CECT) or Doppler ultrasound. For a variety of reasons, some patients with acute intravascular pathology are imaged using CT without intravenous contrast. In the acute setting, the increased Hounsfield unit (HU) density of the thrombus compared to the blood pool allows the diagnosis to be made, or at least suggested, on non-enhanced computed tomography (NECT). The increased density of the clot is commonly referred to as the "hyperdense vessel sign." This is a well-known finding in the setting of stroke, but hyperdense vessels can also signal arterial or venous thrombosis in the chest, abdomen, pelvis, and extremities. Once a hyperdense vessel sign is noted on NECT, further exploration with CECT, angiography, or ultrasound may then be performed.”
Imaging findings of acute intravascular thrombus on non-enhanced computed tomography.
Whitesell RT, Steenburg SD.
Emerg Radiol. 2014 Jun;21(3):271-7
- “Diagnosis of acute mesenteric ischaemia in the early stages is now possible with modern computed tomography (CT), using intravenous contrast enhancement and imaging in the arterial and/or portal venous phase. The availability of CT around the clock means that more patients with acute mesenteric ischaemia may be treated with urgent intestinal revascularization.”
Modern treatment of acute mesenteric ischaemia.
Br J Surg. 2014 Jan;101(1):e100-8
Acosta S, Björck M - “Endovascular therapy has become an important alternative, especially in patients with acute thrombotic superior mesenteric artery (SMA) occlusion, where the occlusive lesion can be recanalized either antegradely from the femoral or brachial artery, or retrogradely from an exposed SMA after laparotomy, and stented. Aspiration embolectomy, thrombolysis and open surgical embolectomy, followed by on-table angiography, are the treatment options for embolic SMA occlusion. Endovascular therapy may be an option in the few patients with mesenteric venous thrombosis who do not respond to anticoagulation therapy. Laparotomy is needed to evaluate the extent and severity of visceral organ ischaemia, which is treated according to the principles of damage control surgery.”
Modern treatment of acute mesenteric ischaemia.
Br J Surg. 2014 Jan;101(1):e100-8
Acosta S, Björck M - “ Percutaneous revascularization is a promising alternative to surgery for acute SMA occlusion in selected patients who have no signs of advanced bowel ischemia. Early diagnosis followed by prompt endovascular intervention with close postprocedural monitoring is key. Laparotomy is indicated in patients who develop new or worsening signs of peritonism after endovascular procedure, particularly in those who had complete occlusion of the main trunk of the SMA.”
Early endovascular treatment of superior mesenteric occlusion secondary to thromboemboli.
Jia Z et al.
Eur J Vasc Endovasc Surg. 2014 Feb;47(2):196-203. - “ Computed tomography angiography revealed complete occlusion in seven cases and incomplete occlusion in 14 cases, with no evidence of free gas or bowel necrosis. The median duration from onset of symptoms to revascularization was 8.7 ± 4.1 hours (range, 2-18 hours). Completely successful endovascular revascularization occurred in six cases (aspiration alone, 3 cases; combined aspiration and urokinase, 3 cases); partial success was achieved in 15 cases (aspiration alone, 4 cases; combined aspiration and urokinase, 10 cases; and combined aspiration, urokinase, and stent placement, 1 case). Laparotomy was required in five patients, all of whom had SMA main trunk complete occlusion and required small bowel resection.”
Early endovascular treatment of superior mesenteric occlusion secondary to thromboemboli.
Jia Z et al.
Eur J Vasc Endovasc Surg. 2014 Feb;47(2):196-203. - “The 30-day mortality for all patients was 9.5%. During a median follow-up of 26 months, 15 patients remained asymptomatic, three patients reported occasional abdominal pain, and one patient had temporary short-bowel syndrome.”
Early endovascular treatment of superior mesenteric occlusion secondary to thromboemboli.
Jia Z et al.
Eur J Vasc Endovasc Surg. 2014 Feb;47(2):196-203. - PURPOSE: The goals of this study were to investigate the treatment outcomes of acute mesenteric ischemia caused by superior mesenteric artery (SMA) embolism and identify the posttreatment prognostic factors.
CONCLUSIONS: Prompt diagnosis and treatment before extensive irreversible gangrene is the mainstay in the treatment of SMA embolism. Limited bowel gangrene was not associated with mortality.
Treatment outcome in patients with acute superior mesenteric artery embolism.
Yun WS et al.
Ann Vasc Surg. 2013 Jul;27(5):613-20. - INTRODUCTION: Acute mesenteric ischemia (AMI) is a commonly fatal result of inadequate bowel perfusion that requires immediate evaluation by both vascular and general surgeons. Treatment often involves vascular repair as well as bowel resection and the possible need for parenteral nutrition. Little data exist regarding the rates of bowel resection following endovascular vs open repair of AMI.
CONCLUSIONS: Endovascular intervention for AMI had increased significantly in the modern era. Among AMI patients undergoing revascularization, endovascular treatment was associated with decreased mortality and shorter length of stay. Furthermore, endovascular intervention was associated with lower rates of bowel resection and need for TPN. Further research is warranted to determine if increased use of endovascular repair could improve overall and gastrointestinal outcomes among patients requiring vascular repair for AMI.
Comparison of open and endovascular treatment of acute mesenteric ischemia.
Beaulieu RJ, Arnaoutakis KD, Abularrage CJ, Efron DT, Schneider E, Black JH 3rd.
J Vasc Surg. 2014 Jan;59(1):159-64. - CONCLUSIONS: Endovascular intervention for AMI had increased significantly in the modern era. Among AMI patients undergoing revascularization, endovascular treatment was associated with decreased mortality and shorter length of stay. Furthermore, endovascular intervention was associated with lower rates of bowel resection and need for TPN. Further research is warranted to determine if increased use of endovascular repair could improve overall and gastrointestinal outcomes among patients requiring vascular repair for AMI.
Comparison of open and endovascular treatment of acute mesenteric ischemia.
Beaulieu RJ, Arnaoutakis KD, Abularrage CJ, Efron DT, Schneider E, Black JH 3rd.
- Mesenteric Vein Thrombosis: Facts
- Accounts for 5-15% of all mesenteric ischemic events and is classified as either primary or secondary
- Primary MVT is idiopathic, whereas secondary MVT can result from a variety of underlying diseases and risk factors including primary hypercoagability states, myeloproliferative neoplasms, pancreatic cancer, recent surgery, and portal hypertension
- Clinical symptoms of MVT are usually nonspecific and include abdominal pain - “ Venous causes of acute mesenteric ischemia are less common (5-15% of cases) and are most often the result of a thrombosis of the superior mesenteric vein.”
Multidetector CT Features of Mesenteric Vein Thrombosis
Duran R et al.
RadioGraphics 2012; 32:1503-1522
- “ Intestinal ischemia is a rare but potentially fatal complication of mesenteric metastasis of intestinal carcinoid tumor and its mechanism isn’t entirely clear.”
Severe intestinal ischemia as a presenting feature of netastatic ileal carcinoid tumor: role of MDCT with coronal reformation in the early diagnosis
Martinez-Sapina Llanas MJ et al.
Abdom Imaging (2012) 37:558-560 - “ An enhanced MDCT with multiplanar reformatting is the optimal study for accurate and non-invasive diagnosis of intestinal ischemia secondary to metastatic ileal carcinoid tumor, it helps in detecting the charateristic features, vascular involvement, and extension .”
Severe intestinal ischemia as a presenting feature of netastatic ileal carcinoid tumor: role of MDCT with coronal reformation in the early diagnosis
Martinez-Sapina Llanas MJ et al.
Abdom Imaging (2012) 37:558-560
- “ On the basis of a thorough clinical examination, contrast enhanced multidetector CT allows the diagnosis of primary acute mesenteric ischemia with high sensitivity and specificity. Thus, it may be used as the first line imaging method.”
Diagnostic Accuracy of Multidetector CT in Acute Mesenteric Ischemia: Systematic review and Meta-Analysis
Menke J
Radiology 2010; 256:93-102 - “ Contrast enhanced multidetector CT may be used as the first line imaging method to differentiate patients with from those without acute mesenteric ischemia.”
Diagnostic Accuracy of Multidetector CT in Acute Mesenteric Ischemia: Systematic review and Meta-Analysis
Menke J
Radiology 2010; 256:93-102 - “ Because it provides both good sensitivity and specificity, thin section multidetector CT could become the reference method in studies for which a noninvasive image-based assessment is rewquired.”
Diagnostic Accuracy of Multidetector CT in Acute Mesenteric Ischemia: Systematic review and Meta-Analysis
Menke J
Radiology 2010; 256:93-102
- “The meta-analysis showed a pooled sensitivity of 93.3% and a pooled specificity of 95.9%.”
Diagnostic Accuracy of Multidetector CT in Acute Mesenteric Ischemia: Systemic Review and
Meta-Analysis
Menke J
Radiology 2010; 256:93-101 - “ Contrast enhanced multidetector CT may be used as the first line imaging method to
differentiate patients with from those without acute mesenteric ischemia.”
Diagnostic Accuracy of Multidetector CT in Acute Mesenteric Ischemia: Systemic Review and
Meta-Analysis
Menke J
Radiology 2010; 256:93-101 - “ On the basis of a thorough clinical examination, contrast enhanced multidetector CT allows the
diagnosis of primary acute mesenteric ischemia with high sensitivity and specificity. Thus, it may
be used as the first line imaging method.”
Diagnostic Accuracy of Multidetector CT in Acute Mesenteric Ischemia: Systemic Review and
Meta-Analysis
Menke J
Radiology 2010; 256:93-101 - Acute Bowel Ischemia: CT Findings Beyond the Bowel
- Mesenteric vessel abnormalities (thrombus of artery or veins, dilatation of veins)
- Stranding of the mesentery
- Air in portal or mesenteric veins - Acute Bowel Ischemia: CT Findings of Bowel
- Bowel wall thickening
- Bowel wall thinning (arterial ischemia)
- Bowel wall attenuation (high attenuation means hemorrhage)
- Pneumatosis intestinalis
- Bowel dilatation
- Dilated mesenteric vessels to bowel - Acute Mesenteric Ischemia: Etiology
- Arterial occlusion
- Venous occlusion
- Strangulating obstruction
- Hypo-perfusion associated with non-occlusive vascular disease "Recognition of characteristic CT appearances and the variations associated with each cause may help in the accurate interpretation of CT in the diagnosis of mesenteric ischemia."
CT Diagnosis of Acute Mesenteric Iscemia form Various Causes
Furukawa A et al.
AJR 2009; 192:408-416- Mesenteric Venous Occlusion: CT Findings
- Clot in SMV
- Edematous bowel
- Stranding in the mesentery
- Decreased bowel enhancement common but may also present with increased bowel wall enhancement - Mesenteric Venous Occlusion: Facts
Causes include
- Portal hypertension
- Hypercoagability states
- Infection
- Pancreatitis - Arterial Mesenteric Occlusion: facts
- 60-75% of all bowel ischemia cases
- Can be arterial embolism or arterial thrombosis
- Arterial embolism usually in mid vessel and proximal involvement usually due to thrombosis - Acute Bowel Ischemia: CT Evaluation of the Dataset
- Dilatation of the bowel lumen
- Can be due to adynamic ileus
- Increased fluid in bowel usually in venoocclusive disease - Acute Bowel Ischemia: CT Evaluation of the Dataset
- Bowel wall attenuation
- High density to bowel wall mean hemorrhagic infarction
- Lack of enhancement suggests ischemia but uncommon finding
- Halo or target sign
- Hyperenhancement which can represent shock bowel or strangulation for example pneumatosis - Acute Bowel Ischemia: CT Evaluation of the Dataset
- Bowel wall thickness
- Bowel wall attenuation
- Dilatation of the bowel lumen
- Mesenteric vessel occlusion or stenosis
- Mesenteric fat inflammation - Acute Bowel Ischemia: CT Evaluation of the Dataset
- Bowel wall thickness
- normal is 3 mm
- most cases are in the 8-9 mm range and rarely up to 15 mm
- In pure arterial occlusion wall is actually thin rather than thick (no flow) - Acute Mesenteric Ischemia: Causes
- Arterial occlusion
- Venous occlusion
- Strangulating obstruction
- Hypoperfusion associated with nonocclusive vascular disease "Because acute mesenteric ischemia can be caused by various conditions, the CT findings vary widely, depending on the cause and underlying pathophysiology and the presence of associated complications."
CT Diagnosis of Acute Mesenteric Ischemia from Various Causes
Furukawa A et al.
AJR 2009; 192:408-416"Recognition of characteristic CT appearance and the variations associated with each cause may help in the accurate interpretation of CT in the diagnosis of mesenteric ischemia."
CT Diagnosis of Acute Mesenteric Ischemia from Various Causes
Furukawa A et al.
AJR 2009; 192:408-416- "In comparison with axial image display and 2D multiplanar reformatting, 3D volume rendering adds incremental value when evaluating the small bowel mesentery because of the complex anatomic configuration."
Nonvascular Mesenteric Disease: Utility of Multidetector CT with 3D Volume Rendering
Johnson PT, Horton KM, Fishman EK
RadioGraphics 2009; 29:721-740