Pearls, Pitfalls, and Conditions that Mimic Mesenteric Ischemia at CT

Computed Tomography Imaging for Suspected Gastrointestinal Bleeding and Bowel Ischemia

Computed tomography (CT) is one of the main diagnostic methods for assessing both acute gastrointestinal bleeding (GIB) and bowel ischemia due to its widespread availability, excellent spatial resolution, and high accuracy. While endoscopy is the preferred diagnostic tool for workup of upper GIB, CT is used in select instances as a complementary modality or when endoscopy is impractical. For lower GIB, CT is one of the first-line imaging tools. Mesenteric ischemia is primarily diagnosed with CT, which can exquisitely assess the vasculature and demonstrate bowel findings of ischemia or infarction.

The radiologic spectrum of neuroendocrine tumors in emergent care

Neuroendocrine tumors (NETs) are a diverse group of neoplasms whose prevalence is increasing globally, primarily due to advancements in diagnostic techniques. NETs arise from cells of the diffuse endocrine system and can occur in various locations, with the gastrointestinal tract being the most common. Their diverse clinical presentations, which range from asymptomatic to severe hormone-induced syndromes, pose significant diagnostic challenges. In emergency care, prompt recognition and management of complications such as bowel obstruction, ischemic events, hormonal crises, and metastases are critical. This review discusses the radiologic spectrum of NETs in emergent care, emphasizing the role of imaging in timely diagnosis and intervention.

Combining clinical and radiological features improves prediction of bowel ischemia in patients with CT findings of pneumatosis intestinalis

BACKGROUND

Pneumatosis intestinalis on CT presents a diagnostic dilemma, because it could reflect bowel ischemia or benign finding.

PURPOSE

To determine radiological and clinical features that can predict bowel ischemia in patients with pneumatosis intestinalis on CT.

MATERIALS AND METHODS

Patients with "pneumatosis" in abdominal CT reports performed between 1/1/2002 and 12/31/2018 were retrospectively included. Pneumatosis intestinalis was confirmed by review of images. Radiological features of pneumatosis, laboratory data, clinical signs and symptoms were collected. Pathologic pneumatosis intestinalis (PPI) was defined as presence of ischemic (viable or dead) bowel on surgery or death during admission or within 30 days of discharge due to ischemia. Univariate statistical analysis was used to identify features associated with PPI, followed by multivariate logistic regression models.

RESULTS

A total of 313 consecutive patients with pneumatosis intestinalis (162 (52%) men, median age 67 years, IQR 55-78 years) were included. Pathologic pneumatosis intestinalis was present in 114/313 (36%) patients. Presence of arterial or venous thrombosis, porto-mesenteric gas, fat stranding, and location in the small bowel were significantly associated with PPI. A combined clinical and radiological model, which included age, WBC, creatinine, abdominal distention, rebound or guarding, shock, presence of porto-mesenteric gas and fat stranding showed an AUC of 0.85 for prediction of PPI, higher than models using clinical (AUC = 0.80, p = 0.005) or radiological factors (AUC = 0.80, p < 0.0001) alone.

CONCLUSION

Improved prediction of pathological pneumatosis intestinalis can be achieved by a model incorporating both clinical and radiological features (AUC = 0.85)rather than by either clinical (AUC = 0.80) or radiological (AUC = 0.80) features alone.

Diagnostic Role of Multi-Detector Computed Tomography in Acute Mesenteric Ischemia

Mesenteric ischemia diagnosis is challenging, with an overall mortality of up to 50% of cases despite advances in treatment. The main problem that affects the outcome is delayed diagnosis because of non-specific clinical presentation. Multi-Detector CT Angiography (MDCTA) is the first-line investigation for the suspected diagnosis of vascular abdominal pathologies and the diagnostic test of choice in suspected mesenteric bowel ischemia. MDCTA can accurately detect the presence of arterial and venous thrombosis, determine the extent and the gastrointestinal tract involved, and provide detailed information determining the subtype and the stage progression of the diseases, helping clinicians and surgeons with appropriate management. CT (Computed Tomography) can differentiate forms that are still susceptible to pharmacological or interventional treatment (NOM = non-operative management) from advanced disease with transmural necrosis in which a surgical approach is required. Knowledge of CT imaging patterns and corresponding vascular pathways is mandatory in emergency settings to reach a prompt and accurate diagnosis. The aims of this paper are 1. to provide technical information about the optimal CTA (CT Angiography) protocol; 2. to explain the CTA arterial and venous supply to the gastrointestinal tract and the relevant ischemic pattern; and 3. to describe vascular, bowel, and extraintestinal CT findings for the diagnosis of acute mesenteric ischemia.

Imaging of Visceral Vessels

The visceral vasculature is inextricably intertwined with abdominopelvic disease staging, spread, and management in routine and emergent cases. Comprehensive evaluation requires specialized imaging techniques for abnormality detection and characterization. Vascular pathology is often encountered on nondedicated routine imaging examinations, which may obscure, mimic, or confound many vascular diagnoses. This review highlights normal arterial, portal venous, and systemic venous anatomy and clinically relevant variants; diagnostic pitfalls related to image-acquisition technique and disease mimics; and characteristics of common and rare vascular diseases to empower radiologists to confidently interpret the vascular findings and avoid misdiagnosis.

Superior mesenteric artery embolism associated with Cisplatin-induced aortic thrombosis

Cardiovascular complications of cancer therapy are among the most important factors affecting cancer prognosis. Cisplatin-induced aortic thrombosis is rare but can be life-threatening in the event of peripheral embolism. In this report, we describe a case of superior mesenteric artery (SMA) embolism associated with cisplatin-induced aortic thrombosis. A 66-year-old male, diagnosed with esophageal cancer, initiated systemic chemotherapy with a regimen consisting of 5-fluorouracil and cisplatin, combined with radiotherapy. After 7 days of chemoradiotherapy, the patient developed a floating thrombus in the ascending aorta and an SMA embolism; chemoradiotherapy was then discontinued. Laparoscopy revealed an ischemic small intestine that required resection; intravenous unfractionated heparin was initiated 3 days after. Computed tomography showed disappearance of the floating aortic thrombus and reduce SMA thrombus size. Early detection of cisplatin-induced aortic thrombosis may prevent fatal outcomes in symptomatic peripheral embolisms, such as SMA embolism, considering anticoagulation, and discontinuation of cisplatin-based chemotherapy may cause resolution of thrombus events.

Small bowel transmural necrosis secondary to acute mesenteric ischemia and strangulated obstruction: CT findings of 49 patients

Rationale and objectives

Transmural bowel necrosis (TBN) is an uncommon surgical emergency that represents an endpoint of occlusive acute mesenteric ischemia (AMI), nonocclusive AMI and small bowel obstruction (SBO). According to limited evidence, each etiology of TBN might demonstrate a different CT finding. This investigation aimed to 1) identify overall CT findings of TBN, and 2) compare CT findings of TBN in each etiology.

Materials and methods

Forty-nine consecutive adults (mean age, 64.6 years; 26 men) with occlusive AMI, nonocclusive AMI or SBO, and pathologically proven TBN were enrolled. All had a CT scan within 24 h before surgery. Clinical information was compiled from medical records. CT examinations were re-reviewed by two radiologists with disagreements resolved by the third radiologist. Data were analyzed and compared.

Results

Transmural bowel necrosis were secondary to arterial AMI, venous AMI, combined arterial and venous AMI, nonocclusive AMI, and SBO in 6, 5, 2, 10, and 26 patients, respectively. The CT findings were ascites (93.9%), abnormal wall enhancement (91.8%), bowel dilatation (89.8%), mesenteric fat stranding (89.8%), abnormal wall thickness (71.5%), pneumatosis (46.9%) and intrinsic hyperattenuation of bowel walls (22.5%). Portovenous gas, mesenteric venous gas, and pneumoperitoneum were present in 4 patients (8.2%). Bowel wall thickness was the only CT findings that showed a statistically significant difference among the 5 etiologies of TBN (P = 0.046).

Conclusions

Most common CT findings of TBN were ascites, abnormal bowel wall enhancement, dilatation, and mesenteric fat stranding. Wall thickness differentiated five etiologies, being most thickened in venous AMI and normal in arterial AMI.

Acute management of mesenteric emergencies: Tailoring the solution to the problem

Acute mesenteric ischemia (AMI) constitutes a life-threatening problem that can result in death, multiorgan failure, and severe nutritional disability. Although AMI is a rare cause of acute abdominal emergencies, ranging between 1 and 2 individuals per 10,000, the morbidity and mortality rates are high. Arterial embolic etiology composes nearly one-half of AMIs, with a sudden onset of severe abdominal pain considered the most common symptom. Arterial thrombosis is the second most common cause of AMI, which presents similarly to arterial embolic AMI, although often more severe due to anatomic differences. Veno-occlusive causes of AMI are the third most common and are associated with an insidious onset of vague abdominal pain. Each patient is unique, and the treatment plan should be tailored to their individual needs. This may include considering the patient's age, comorbidities, and overall health, as well as their preferences and personal circumstances. A multidisciplinary approach involving specialists from different fields, such as surgeons, interventional radiologists, and intensivists, is recommended for the best possible outcome. Potential challenges in tailoring an optimal treatment plan for AMI may include delayed diagnosis, limited availability of specialized care, or patient factors that make some interventions less feasible. Addressing these challenges requires a proactive and collaborative approach, with regular review and adjustment of the treatment plan as needed to ensure the best possible outcome for each patient.

An Update on Acute Mesenteric Ischemia

Acute mesenteric ischemia (AMI) is an uncommon yet highly lethal cause of acute abdomen in the emergency setting. Computed tomography (CT) imaging, in particular a biphasic protocol consisting of angiographic and venous phase scans, is widely used to corroborate non-specific clinical findings when suspicions of AMI are high. Techniques such as low kilovoltage peak scanning, dual energy acquisition, or a combined arterial/enteric phase can improve iodine conspicuity and evaluation of bowel enhancement. Biphasic CT with CT angiography is mandatory to directly assess for the 3 primary etiologies of AMI-arterial, venous, and non-occlusive mesenteric ischemia (NOMI), and the CT angiographic findings may be the first visible in the disease. In addition, numerous non-vascular CT findings have also been reported. Bowel wall thickening, mesenteric stranding, and ascites are common but non-specific findings that correlate poorly with disease severity. Pneumatosis intestinalis and portomesenteric venous gas, while not pathognomonic for ischemia, are highly specific in cases of high clinical suspicion. Bowel wall hypoenhancement is an early and specific sign but requires a protocol optimizing iodine conspicuity to confidently identify. Finally, intraperitoneal free air and solid organ infarcts are also highly specific ancillary findings in AMI. AMI occurs as a complication in 10% of small bowel obstruction (SBO) patients, and understanding imaging findings of ischemia in the context of SBO is necessary to aid in treatment planning and reduce over- and under-diagnosis of strangulation. Familiarity with the imaging features of ischemia by radiologists is vital to establish an early diagnosis before irreversible necrosis occurs.

Imaging of Bowel Ischemia: An Update, From the AJR Special Series on Emergency Radiology

Acute mesenteric ischemia is a life-threatening condition that results from abrupt reduction in or cessation of blood flow to the bowel. Characterized by nonspecific abdominal symptoms, mesenteric ischemia is infrequently encountered and commonly misdiagnosed, with potentially catastrophic consequences. Prompt clinical diagnosis and early implementation of therapeutic interventions are critical to improving patient outcomes. Because cross-sectional imaging plays a key role in the diagnosis of mesenteric ischemia, radiologists must be familiar with the varied imaging manifestations of intestinal ischemia. Thus, the objectives of this article are to review the various types and common causes of mesenteric ischemia and to describe its spectrum of multimodality imaging findings, with special attention to novel imaging techniques and emerging diagnoses.

Intestinal pneumatosis: differential diagnosis

Intestinal pneumatosis (IP) is an infrequent radiological sign defined as pathological gas infiltration into the bowel wall. It may be associated to different underlying clinical conditions-inflammatory bowel diseases, malignancies, chemotherapy, infections, immune deficiency status, trauma, intestinal ischemia, and necrosis-that are often related to emergency state and require a prompt diagnosis. All the imaging techniques, especially abdominal radiography and Computed Tomography, could detect the presence of IP and discern the forms related to emergency conditions. The differential diagnosis is essential to start an immediate clinical or surgical management and treatment. The aim of this article is to review the radiological features of IP in different illnesses, with particular attention to differential diagnosis.

Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process

The objective of this article is to assess the computed tomography (CT) findings of small bowel obstruction (SBO) complicated by ischemia. SBO is a frequent clinical entity characterized by high morbidity and mortality. The radiologic aim is not just to diagnose the obstruction itself but to rule out the presence of complications related to SBO. This is crucial for differentiating which patients can be safely treated non-operatively from the ones who may need an urgent surgical approach. 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 issue is 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.

Dual-energy CT of acute bowel ischemia

Acute bowel ischemia is a condition with high mortality and requires rapid intervention to avoid catastrophic outcomes. Swift and accurate imaging diagnosis is essential because clinical findings are commonly nonspecific. Conventional contrast enhanced CT of the abdomen has been the imaging modality of choice to evaluate suspected acute bowel ischemia. However, subtlety of image findings and lack of non-contrast or arterial phase images can make correct diagnosis challenging. Dual-energy CT provides valuable information toward assessing bowel ischemia. Dual-energy CT exploits the differential X-ray attenuation at two different photon energy levels to characterize the composition of tissues and reveal the presence or absence of faint intravenous iodinated contrast to improve reader confidence in detecting subtle bowel wall enhancement. With the same underlying technique, virtual non-contrast images can help to show non-enhancing hyperdense hemorrhage of the bowel wall in intravenous contrast-enhanced scans without the need to acquire actual non-contrast scans. Dual-energy CT derived low photon energy (keV) virtual monoenergetic images emphasize iodine contrast and provide CT angiography-like images from portal venous phase scans to better evaluate abdominal arterial patency. In Summary, dual-energy CT aids diagnosing acute bowel ischemia in multiple ways, including improving visualization of the bowel wall and mesenteric vasculature, revealing intramural hemorrhage in contrast enhanced scans, or possibly reducing intravenous contrast dose.

Acute Mesenteric Ischemia in a COVID-19 Patient: Delay in Referral and Recommendation for Surgery

Coronavirus (COVID-19) is more common with symptoms such as fever, dry cough, and shortness of breath. However, it may be associated with COVID-19-induced gastrointestinal (GI) symptoms including acute mesenteric ischemia (AMI). These conditions make the diagnosis of AMI challenging. Timely referral with correct diagnosis and attention to the uncommon symptoms of COVID-19 can play an important role in the management and treatment of AMI in COVID-19 patients. We present a patient with AMI due to thrombotic complications of COVID-19, who referred to the hospital too late and ignored the recommendation for abdominal surgery.

SARS-CoV-2 Related Ischemic Colitis in an Adolescent With Trisomy 21: Diagnostic Pitfalls and Considerations

Millions of patients seek medical attention for diarrhea, vomiting, nausea, and abdominal pain. In the current environment, it is important to recognize that these symptoms may be the only manifestation or may precede more serious systemic complications of COVID-19. Herein, we describe the first case of ischemic colitis (IC) in a young adult who presented with diarrhea and highlight the laboratory pitfalls for patients with COVID-19 presenting with gastrointestinal (GI) symptoms.

Thrombosis in abdominal vessels associated with COVID-19 Infection: A report of three cases

Hypercoagulability related to SARS-CoV-2 infection is one of the main extrapulmonary complications of COVID-19. We present three cases of intrabdominal thrombotic complications related to the state of hypercoagulability of COVID-19 and its tomographic features. Hypercoagulability state should be taking into account in the interpretation of radiological images in all infected patients with COVID-19.

CT appearance of gastrointestinal tract mucormycosis

Mucormycosis is a fungal infection caused by fungi of order mucorales. It is most commonly seen in patients with an impaired immune system due to any cause. Gastrointestinal mucormycosis is the least frequent type and may be a primary disease or a feature of generalized mucormycosis. Angioinvasion is the hallmark feature of mucormycosis, leading to bowel infarction which is the responsible for the most common clinical complaint of pain, and is also responsible for most of the imaging findings in this disease. The stomach is most commonly involved organ in the gastrointestinal tract and pneumatosis and lack of gastric wall enhancement are the most common imaging findings. Areas of bowel wall thickening and/ or lack of enhancement are seen in small bowel mucor and perforation can occur due to ischemia. Colonic mucor can present with mural thickening, or complete lack of definition or 'disappearance' of bowel wall with associated air containing collections. Mucormycosis affecting the bowel has a high mortality rate and early recognition and intervention may improve patient outcomes significantly. It should be suspected in immunosuppressed patients with imaging findings of unexplained bowel ischemia, infarction and/or pneumatosis without any obvious visible vascular thrombus.