CT and MR diagnoses of intestinal ischemia

Is there a faster and easier method for assessing the severity of acute mesenteric ischemia?

Acute mesenteric ischemia (AMI) is a potentially fatal abdominal emergency. The estimation of the severity of AMI is of great importance since changes in disease severity may have different impacts on the treatment options. This study aims to define laboratory and radiological parameters that can successfully predict the severity of AMI. Data from 100 patients who were treated conservatively and underwent an operation with a diagnosis of AMI between the years 2010 and 2019 were reviewed. The patients were divided into 3 groups as those treated with a conservative approach (group 1), those with partial intestinal ischemia (group 2), and those with complete intestinal ischemia (group 3) according to the pathology results. Laboratory findings of the patients were recorded and matched with radiological findings. The white blood cell (WBC) count, neutrophil (NEUT) count, neutrophil/lymphocyte ratio, and C-reactive protein/albumin ratios were the considered distinctive parameters for distinguishing the third group from the first group. However, the same result cannot be applied to the first and the second groups since only the WBC and NEUT counts showed distinctive performance. The measurement of neutrophil/lymphocyte ratio, WBC, NEUT, and albumin levels can be used to predict the severity of AMI. We believe that evaluating these laboratory parameters will greatly prevent possible morbidity and mortality in the patient. Also, we were able to observe that the parameters used in predicting AMI severity can be verified with rapid and low-cost radiological imaging techniques.

Study of ischemic progression in different intestinal tissue layers during acute intestinal ischemia using swept-source optical coherence tomography angiography

In acute intestinal ischemia, the progression of ischemia varies across different layers of intestinal tissue. We established a mouse model and used swept-source optical coherence tomography (OCT) to observe the intestinal ischemic process longitudinally in different tissue layers. Employing a method that combines asymmetric gradient filtering with adaptive weighting, we eliminated the vessel trailing phenomenon in OCT angiograms, reducing the confounding effects of superficial vessels on the imaging of deeper vasculature. We quantitatively assessed changes in vascular perfusion density (VPD), vessel length, and vessel average diameter across various intestinal layers. Our results showed a significant reduction in VPD in all layers during ischemia. The mucosa layer experienced the most significant impact, primarily due to disrupted capillary blood flow, followed by the submucosa layer, where vascular constriction or decreased velocity was the primary factor.

Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls

Acute small bowel ischemia is a life-threatening condition with a high mortality rate due to its lack of specific symptoms and laboratory profile, which render difficulty in establishing early diagnosis. The etiology of acute small bowel ischemia includes occlusive forms (arterial embolism, arterial thrombosis, and venous thrombosis) and nonocclusive mesenteric ischemia, of which arterial causes are far more common than venous causes. CT, the mainstay of accurate diagnoses, allows the identification of the features of vascular abnormalities and intestinal ischemic injuries, and helps clinicians to restore intestinal blood flow. Without treatment, the prognosis for acute small bowel ischemia is poor. A high index of suspicion and familiarity with the CT spectral findings of bowel ischemia are required to ensure rapid recognition of this condition.

A pilot study investigating the use of 4D flow MRI for the assessment of splanchnic flow in patients suspected of mesenteric ischaemia

The most common cause of chronic mesenteric ischaemia is atherosclerosis which results in limitation of blood flow to the gastrointestinal tract. This pilot study aimed to evaluate 4D flow MRI as a potential tool for the analysis of blood flow changes post-prandial within the mesenteric vessels. The mesenteric vessels of twelve people were scanned; patients and healthy volunteers. A baseline MRI scan was performed after 6 h of fasting followed by a post-meal scan. Two 4D flow datasets were acquired, over the superior mesenteric artery (SMA) and the main portal venous vessels. Standard 2D time-resolved PC-MRI slices were also obtained across the aorta above the coeliac trunk, superior mesenteric vein, splenic vein and portal vein (PV). In the volunteer cohort there was a marked increase in blood flow post-meal within the PV (p = 0.028), not seen in the patient cohort (p = 0.116). Similarly, there were significant flow changes within the SMA of volunteers (p = 0.028) but not for the patient group (p = 0.116). Our pilot data has shown that there is a significant haemodynamic response to meal challenge in the PV and SMA in normal subjects compared to clinically apparent CMI patients. Therefore, the interrogation of mesenteric venous vessels exclusively is a feasible method to measure post-prandial flow changes in CMI patients.

Evaluation of Bowel and Mesentery in Abdominal Trauma

Since the advent of multidetecter computed tomography (CT), radiologist sensitivity in detection of traumatic bowel and mesenteric abnormalities has significantly improved. Although several CT signs have been described to identify intestinal injury, accurate interpretation of these findings can remain challenging. Early detection of bowel and mesenteric injury is important as it alters patient management, disposition, and follow-up. This article reviews the common imaging findings of traumatic small bowel and mesenteric injury.

Acute Mesenteric Ischaemia

Acute mesenteric ischaemia (AMI) is a surgical emergency, and has a high mortality. The term AMI covers arterial embolism, arterial thrombosis, non-occlusive mesenteric ischaemia and venous thrombosis which all lead to ischaemia/reperfusion syndrome of the bowel. Multi-detector row helical CT (MDCT) technology has dramatically improved the performance of CT by allowing rapid volumetric data acquisition to provide increased resolution, leading to better identification of the site, level and cause of ischaemia. CT angiography for diagnosing mesenteric ischaemia is now highly sensitive and specific, and should be used as first line when AMI is suspected. The aim of management is to restore intestinal blood flow in a timely manner. Therapeutic decisions are based on the presence of peritonitis, the presence of irreversible ischaemia or infarcted segments of the bowel, the general condition of the patient and the pathophysiological process underlying the ischaemia. AMI remains a challenging condition with high mortality. There is a need for good general surgical cover on the intensive care unit, with continuing care and clinical review by experienced senior surgeons with an interest in this condition.

Bowel wall thickening at CT: simplifying the diagnosis

Objective

In this article we present a simplified algorithm-based approach to the thickening of the small and large bowel wall detected on routine computed tomography (CT) of the abdomen.

Background

Thickening of the small or large bowel wall may be caused by neoplastic, inflammatory, infectious, or ischaemic conditions. First, distinction should be made between focal and segmental or diffuse wall thickening. In cases of focal thickening further analysis of the wall symmetry and perienteric anomalies allows distinguishing between neoplasms and inflammatory conditions. In cases of segmental or diffuse thickening, the pattern of attenuation in light of clinical findings helps narrowing the differential diagnosis.

Conclusion

Focal bowel wall thickening may be caused by tumours or inflammatory conditions. Bowel tumours may appear as either regular and symmetric or irregular or asymmetric thickening. When fat stranding is disproportionately more severe than the degree of wall thickening, inflammatory conditions are more likely. With the exception of lymphoma, segmental or diffuse wall thickening is usually caused by benign conditions, such as ischaemic, infectious and inflammatory diseases.

Key points

• Thickening of the bowel wall may be focal (<5 cm) and segmental or diffuse (6-40 cm or >40 cm) in extension.

• Focal, irregular and asymmetrical thickening of the bowel wall suggests a malignancy.

• Perienteric fat stranding disproportionally more severe than the degree of wall thickening suggests an inflammatory condition.

• Regular, symmetric and homogeneous wall thickening is more frequently due to benign conditions, but can also be caused by neoplasms such as well-differentiated adenocarcinoma and lymphoma.

• Segmental or diffuse bowel wall thickening is usually caused by ischaemic, inflammatory or infectious conditions and the attenuation pattern is helpful in narrowing the differential diagnosis.

[Acute mesenteric ischemia: analysis of cases over a ten-years period (2001-2010)]

Acute mesenteric ischemia is a rare disorder; it occurs on average of 0.4% of acute surgery cases. Its diagnosis is often difficult because of the poor symptoms, and mortality of the patients is still as high as 70-90%.

AIMS

The aims of the study were to assess the importance of time factor that may influence the outcome and to find out whether it is possible to decrease the high mortality rate in this disease.

METHOD

Among patients admitted to Saint Pantaleon Hospital in Hungary between January 2001 and December 2010, patients whose surgery or autopsy findings confirmed intestinal necrosis were analyzed. A total of 114 patients with acute mesenteric ischemia were included in the study.

RESULTS

55% of the patients had typical symptoms. 43.8% of the patients underwent surgery and among these patients the mortality rate was 70% despite surgical intervention. The survival rate was 72.3% when surgery was performed within less than 12 hours after the onset of symptoms, but only 20% of patients survived when surgery was delayed between 24 and 48 hours after the onset of symptoms.

CONCLUSION

With early diagnosis and intervention, patients with acute mesenteric ischemia may have a better a chance to survive.

How Predictive are the Signs and Symptoms of Small Bowel Obstruction

OBJECTIVE

The present study aims to determine the diagnostic significance of signs and symptoms of Small Bowel Obstruction (SBO) and to ascertain if there was any delay in presentation of the patients to the hospital.

METHODS

This retrospective case study spanning 3 years was conducted at Riyadh Medical Complex, Saudi Arabia. All adult patients admitted from the ER with a diagnosis of SBO were included in the study. The medical records of the patients with International Classification of Diseases (ICD) 9 codes 552.8, 560, 560.8, 560.81 and 560.9 were searched and retrieved.

RESULTS

A total of 195 patients were included in the study out of which 174 patients had a definitive diagnosis of SBO. The study group was composed of 76.4% males and 71.8% were aged between 20 years to 60 years. The mean duration of symptoms was 4.8 days, ranging from 6 hours to 17 days. The cardinal signs and symptoms of obstruction had low sensitivity (Range: 56-75), and specificity (Range: 28-61), but relatively high positive predictive value (PPV) (Range: 86-93). The morbidity was 13.8% while mortality was 3.4%.

CONCLUSION

The cardinal features of SBO are neither specific nor sensitive, and though they may have an acceptable PPV, the predicted rate of false positive diagnosis is unacceptable. Therefore, the clinician may not rely on the clinical picture alone for the diagnosis of SBO. The presentation of the studied patients was delayed compared to the literature and it may be an important factor in increasing morbidity and mortality, but this aspect needs to be studied further.

Multidetector CT imaging in mesenteric ischemia--pearls and pitfalls

Mesenteric ischemia is a complex and devastating disease which still remains a diagnostic challenge to the clinicians due to non-specific clinical and laboratory findings. Several imaging features have been described with multidetector computed tomography which allows the diagnosis of mesenteric ischemia with high sensitivity and specificity. However, there are imaging features which overlap with other pathologies including benign inflammation and infection. Knowledge of imaging findings in mesenteric ischemia and its potential mimics is important in early and definitive diagnosis.

CT diagnosis of acute mesenteric ischemia from various causes

OBJECTIVE

Acute mesenteric ischemia can be caused by various conditions such as arterial occlusion, venous occlusion, strangulating obstruction, and hypoperfusion associated with nonocclusive vascular disease, and the CT findings vary widely depending on the cause and underlying pathophysiology. The aim of this article is to review the CT appearances of acute mesenteric ischemia in various conditions.

CONCLUSION

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.

Imaging in intestinal ischemic disorders

Intestinal ischemia and infarction are a heterogeneous group of diseases that have as their unifying theme hypoxia of the small bowel or colon. The incidence of bowel ischemia and infarction is on the rise for several reasons: the aging of the population, the ability of intensive care units to salvage critically ill patients, and heightened clinical awareness of these disorders. Improvements in diagnostic imaging techniques have greatly contributed to the earlier diagnosis of intestinal ischemia, which can have a positive influence on patient outcomes. In this article, role of radiology in the detection, differential diagnosis, and management of patients who have intestinal ischemia and infarction is discussed.

Acute mesenteric ischemia after cardio-pulmonary bypass surgery

Acute mesenteric ischemia (AMI) is a highly-lethal surgical emergency. Several pathophysiologic events (arterial obstruction, venous thrombosis and diffuse vasospasm) lead to a sudden decrease in mesenteric blood flow. Ischemia/reperfusion syndrome of the intestine is responsible for systemic abnormalities, leading to multi-organ failure and death. Early diagnosis is difficult because the clinical presentation is subtle, and the biological and radiological diagnostic tools lack sensitivity and specificity. Therapeutic options vary from conservative resuscitation, medical treatment, endovascular techniques and surgical resection and revascularization. A high index of suspicion is required for diagnosis, and prompt treatment is the only hope of reducing the mortality rate. Studies are in progress to provide more accurate diagnostic tools for early diagnosis. AMI can complicate the post-operative course of patients following cardio-pulmonary bypass (CPB). Several factors contribute to the systemic hypo-perfusion state, which is the most frequent pathophysiologic event. In this particular setting, the clinical presentation of AMI can be misleading, while the laboratory and radiological diagnostic tests often produce inconclusive results. The management strategies are controversial, but early treatment is critical for saving lives. Based on the experience of our team, we consider prompt exploratory laparotomy, irrespective of the results of the diagnostic tests, is the only way to provide objective assessment and adequate treatment, leading to dramatic reduction in the mortality rate.

Computed tomographic imaging findings of bowel ischemia

LEARNING OBJECTIVES

Learning objectives of this paper are to review and to summarize the pathogenesis of bowel ischemia and to describe its clinical, pathological, and radiological manifestations.

BACKGROUND

Bowel ischemia is a common disorder produced by several causes, and it shows various clinical presentations connected with an high mortality. With the increase in average life expectancy, bowel ischemia represents one of the most threatening abdominal conditions in elderly patients. In the last decade, computed tomography has tremendously altered the diagnostic approach to bowel ischemia also influencing the therapeutic approach in the current practice.

IMAGING FINDINGS

Computed tomographic imaging findings include bowel wall thickening, portal venous gas, intramural pneumatosis, engorgement of mesenteric veins, loss or increase of bowel wall enhancement, and infarction of other abdominal organs.

CONCLUSIONS

Bowel ischemia shows a broad spectrum of radiological manifestations, and regardless of the primary causes, it produces similar radiological features. Bowel ischemia may simulate cancer or inflammatory conditions; so it is a mandatory tight integration between radiological and clinical signs.

Progress in the diagnosis and treatment of acute mesenteric ischemia

Acute mesenteric ischemia (AMI) is a life-threatening vascular emergency that requires early diagnosis and intervention to adequately restore mesenteric blood flow and prevent bowel necrosis and patient's death. The underlying cause of AMI is varied, and the prognosis depends on the precise pathologic findings. Despite the progress in understanding the pathogenesis of mesenteric ischemia and the development of modern treatment modalities, AMI remains a diagnostic challenge for clinicians, and the delay in diagnosis contributes to the continued high mortality rate. Early diagnosis and prompt effective treatment are essential to improve the clinical outcome.

Multidetector row CT of the small bowel

Multidetector row CT (MDCT) has become an imaging technique of choice to study routinely the small bowel. Thin collimation and fast scanning allow coverage of the entire abdomen within a single suspended respiration phase allowing the use of multiple enhancement phases after intravenous contrast administration. MDCT of the small bowel can identify and stage most of the common diseases of the small bowel. MDCT is changing the paradigm for diagnosing small bowel disease by becoming the first diagnostic line for almost all small bowel diseases. MDCT has the needed sensitivity and specificity, the availability, and the safety for a front-line diagnostic method.

Ischemia/reperfusion: a clinically relevant model of intestinal injury yielding systemic inflammation

BACKGROUND/PURPOSE

Multisystem organ failure (MSOF) is a major cause of morbidity and mortality in the critically ill patient. Animal models of endotoxin-induced sepsis were used to develop therapeutic regimens, which thus far have failed in clinical trials. Because multiple etiologies of MSOF affect the intestine, the authors hypothesized that during sepsis the gut may act as a possible trigger of the inflammatory cascade. As ischemia and reperfusion of the small intestine disrupts gut barrier function, thereby activating systemic inflammatory responses, the authors evaluated a murine model of ischemia/reperfusion to investigate these systemic responses to local mucosal and epithelial injury.

METHODS

C57BL/10 and Balb/c mice underwent variable amounts of gut ischemia by superior mesenteric artery occlusion. Animals were evaluated for survival as well as gross and microscopic intestinal damage.

RESULTS

Maximal ischemic damage occurred in the distal jejunum and proximal ileum. More severe epithelial damage and transmural inflammation were observed in C57BL/10 mice, which correlated with a higher mortality.

CONCLUSIONS

This model mimics what is observed clinically with intestinal injury resulting from a progressive ischemic insult with eventual systemic manifestations. This reproducible model of systemic inflammation elicits variable responses from genetically different animals, the results of which may lead to a better understanding of MSOF.

Intestinal ischemia as the first manifestation of vasculitis

OBJECTIVE

To summarize current knowledge regarding the diagnosis and management of gastrointestinal vasculitis.

METHODS

Three cases of gastrointestinal vasculitis with acute abdominal ischemia as their first manifestation are presented. Underlying diseases were microscopic polyangiitis, systemic lupus erythematosus (SLE), and polyarteritis nodosa (PAN). Relevant English-language articles collected from the PubMed database were reviewed.

RESULTS

Among the angiitides, PAN, SLE, and Henoch-Schönlein are those most commonly accompanied by gastrointestinal complications. Intestinal vasculitis usually occurs when there is evidence of generalized disease activity. Abdominal computerized tomography is a valuable tool for diagnosing intestinal ischemia and suspected vasculitis.

CONCLUSIONS

In young patients presenting with intestinal ischemia, it is essential to assess the possibility of an underlying systemic disease. With prompt initiation of immunosuppressive treatment, surgery may be avoided. Prognosis is improved when there is minimal delay in surgical intervention.

Accuracy of multidetector row computed tomography for the diagnosis of acute bowel ischemia in a non-selected study population

The diagnostic accuracy of multidetector row computed tomography for the prospective diagnosis of acute bowel ischemia in the daily clinical routine was analyzed. Two hundred ninety-one consecutive patients with an acute or subacute abdomen, examined by MDCT over a time period of 5 months, were included in the study. All original CT diagnoses made during the daily routine by radiological generalists were compared to the final diagnoses made by using all available medical information from endoscopies, surgical interventions, autopsies and follow-up. Finally, all CT examinations of patients with an initial CT diagnosis or a final diagnosis of bowel ischemia were reread by a radiologist specialized in abdominal imaging in order to analyze the CT findings and the reasons for initially false negative or false positive CT readings. Twenty-four patients out of 291 (8.2%) had acute bowel ischemia. The age of affected patients ranged from 50 to 94 years (mean age: 75.7 years). Eleven patients were male, and 13 female. Reasons for acute bowel ischemia were: arterio-occlusive (n=11), non-occlusive (n=5), strangulation (n=2), over-distension (n=3) and radiation (n=3). The prospective sensitivity, specificity, PPV and NPV of MDCT for the diagnosis of acute bowel ischemia in the daily routine were 79.17, 98.51, 90.48 and 98.15%. MDCT reaches a similarly high sensitivity in diagnosing acute bowel as angiography. Furthermore, it has the advantage of being helpful in most of its clinical differential diagnoses and of being less invasive with the consecutive possibility of being used earlier in the diagnostic process with all the resulting positive effects on the patients prognosis. Therefore, nowadays MDCT should probably be used as the first step imaging modality of choice in patients with suspected acute bowel ischemia.

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Helical CT diagnosis of small bowel obstruction in the acute clinical setting

Definite confirmation or exclusion closed loop obstruction (CLO) is one of the most difficult tasks the radiologist has to face in the clinical practice. Aim of this retrospective work was to study the value of spiral computed tomography (CT) in the diagnosis of closed loop obstruction complicated by intestinal ischemia. The state of the art CT signs of closed loop obstruction were taken into consideration. Serrated beaks with poor or no contrast enhancement of the bowel walls, ascites or engorgement of the mesenteric vasculature allowed the CT diagnosis of CLO complicated by ischaemia. U or C-sharped of dilated loops, radial distribution of the mesenteric vessels, beaks and whirls suggested CLO, but did not help differentiate CLO from strangulation. CLO is a dynamic entity which may regress or need laparotomy depending on the time and degree of rotation of the incarcerated loops. CT is a reliable imaging modality able to differentiate CLO from strangulation, which is rarely simple and obvious. Detection of ischemic changes in the bowel walls and/or attached mesentery on CT scans imply strangulation highlighting the need for laparotomy; if only signs of CLO are detected, the existence and/or development of strangulation cannot be predicted.

Imagerie des ischémies intestinales

Ischemic bowel disease includes acute and chronic mesenteric ischemia, and colon ischemia. Cross-sectional imaging, and more particularly computed tomography, has an increasing role in the detection of acute and chronic mesenteric ischemia. Vascular obstructions or stenoses and changes in the bowel wall can be observed. Functional information can be added with MRI by using sequences that are sensitive to oxygen saturation in the superior mesenteric vein. Arteriography remains the reference examination in patients with acute mesenteric ischemia.

MRI for small bowel diseases

The role of radiologic studies has been well established in the diagnosis and management of patients with small bowel diseases. While small bowel follow-through examination or enteroclysis is widely accepted as the primary imaging method for small bowel investigation, additional cross-sectional imaging studies are often required for an accurate diagnosis and the precise evaluation of the extraluminal disease. Since fast magnetic resonance imaging (MRI) sequences have become available, there is increasing interest in the use of MRI for small bowel evaluation, attributed to its inherent advantages such as the lack of radiation exposure, excellent soft tissue contrast, and direct multiplanar capabilities. In this article, we review the current techniques, clinical applications, and limitations of MRI for the evaluation of patients with small bowel diseases.

Acute small bowel ischemia: CT imaging findings

Small bowel ischemia is a disorder related to a variety of conditions resulting in interruption or reduction of the blood supply of the small intestine. It may present with various clinical and radiologic manifestations, and ranges pathologically from localized transient ischemia to catastrophic necrosis of the intestinal tract. The primary causes of insufficient blood flow to the small intestine are various and include thromboembolism (50% of cases), nonocclusive causes, bowel obstruction, neoplasms, vasculitis, abdominal inflammatory conditions, trauma, chemotherapy, radiation, and corrosive injury. Computed tomography (CT) can demonstrate changes because of ischemic bowel accurately, may be helpful in determining the primary cause of ischemia, and can demonstrate important coexistent findings or complications. However, common CT findings in acute small bowel ischemia are not specific and, therefore, it is often a combination of clinical, laboratory and radiologic signs that may lead to a correct diagnosis. Understanding the pathogenesis of various conditions leading to mesenteric ischemia and being familiar with the spectrum of diagnostic CT signs may help the radiologist recognize ischemic small bowel disease and avoid delayed diagnosis. The aim of this article is to provide a review of the pathogenesis and various causes of acute small bowel ischemia and to demonstrate the contribution of CT in the diagnosis of this complex disease.

Diagnosis and management of intestinal ischaemic disorders

Although intestinal ischaemia is an infrequent event, early recognition and appropriate treatment can reduce the potential for a devastating outcome

CT of acute bowel ischemia

Bowel ischemia may be caused by many conditions and manifest with typical or atypical and specific or nonspecific clinical, laboratory, and radiologic findings. It may mimic various intestinal diseases and be confused with certain nonischemic conditions clinically and at computed tomography (CT). Bowel ischemia severity ranges from mild (generally transient superficial changes of intestinal mucosa) to more dangerous and potentially life-threatening transmural bowel wall necrosis. Causes of critically reduced blood flow to the bowel are diverse, ranging from occlusions of mesenteric arteries or veins to complicated bowel obstruction and overdistention. CT can demonstrate changes in ischemic bowel segments accurately, is often helpful in determining the primary cause of ischemia, and can demonstrate important coexistent findings or complications. Unfortunately, common CT findings in bowel ischemia are not specific, and specific findings are rather uncommon. Therefore, it often is a combination of nonspecific clinical, laboratory, and radiologic findings-especially detailed knowledge about the pathogenesis of acute bowel ischemia in different conditions-that helps most in correct interpretation of CT findings. To improve understanding of this complex heterogeneous entity, this article provides an overview of the anatomy and physiology of mesenteric perfusion and discussions of causes and pathogenesis of acute bowel ischemia, CT findings in various types of acute bowel ischemia, and potential pitfalls of CT.