小肠梗阻的CT诊断

<正> 小肠梗阻是最常见的急腹症之一,快速、正确地诊断肠梗阻的部位、病因、性质及严重程度,无疑具有重要的临床意义。随着CT在临床的广泛应用和CT重建技术的进展,其在小肠梗阻部位、病因、性质及梗阻程度的诊断中,发挥越来越重要的作用,并成为研究热点。现对46例小肠梗阻的CT表现进行回顾性分析,探讨CT检查对小肠梗阻部位、病因、性质、程度及肠壁血供状况的诊断和鉴别诊断价值。     

CT diagnosis of strangulation in patients with small-bowel obstruction: current status and future direction

The pathophysiology of strangulating small bowel obstruction and the limitations of known CT criteria of strangulation are reviewed. The concept of coronal mapping of the course of the superior mesenteric vessels based on axial abdominal CT in order to aid the radiologic diagnosis of intestinal strangulation is introduced.     

CT of small-bowel obstruction in children: sensitivity and specificity.

OBJECTIVE.:The aim of this study was to determine the sensitivity, specificity, and accuracy of CT in the diagnosis of small-bowel obstruction in children. MATERIALS AND METHODS: The CT scans of 30 children with surgically proven small-bowel obstruction, 22 children with ileus, and 29 children who served as controls were retrospectively reviewed by two of four interpreters who were unaware of the children's final diagnoses. Causes of obstruction in the patients included 19 adhesions, six cases of volvulus, five intussusceptions, four strictures, and two cases each of internal hernia and abscess. Eight obstructions had multiple causes. The CT scans were evaluated for the presence of small-bowel obstruction using a scale with five degrees of confidence. In cases of discrepancy of more than one level of certainty, a third interpreter was consulted. Criteria for small-bowel obstruction included a discrepancy in caliber between the proximal dilated and the more distal small bowels or generalized small-bowel dilatation (>2.5 cm) in the presence of a collapsed colon. An interpreter's rating that an obstruction was either present or probable was considered a positive finding; a rating indicating that the interpreter was not sure whether an obstruction was present or believed that an obstruction was not probable or saw normal anatomic structures was considered a negative finding for small-bowel obstruction. The cause and level of obstruction also were recorded. RESULTS: There were 26 true-positive (87%) and four false-negative (13%) interpretations for small-bowel obstruction. Among the interpretations of scans of patients with ileus, 68% were true-negative and 32% were false-positive interpretations for small-bowel obstruction. Among the control group, there were no false-positive readings. Sensitivity of CT was 87%, specificity was 86%, and accuracy was 86%. In the scans of children 2 years and younger, CT had a sensitivity of 100% and specificity of 0%. Of the patients with surgically confirmed levels of obstruction, the correct level of obstruction was described by both interpreters in 12 (86%) of 14 scans. The causes of obstruction were correctly identified in 14 (47%) of 30 scans. CONCLUSION: CT is both sensitive and specific for use in diagnosing small-bowel obstruction in children, especially in children older than 2 years.     

Helical CT signs in the diagnosis of intestinal ischemia in small-bowel obstruction

OBJECTIVE: The purpose of our study was to determine prospectively the value of helical CT and of various signs of ischemia in the context of acute bowel obstruction. SUBJECTS AND METHODS: All patients seen over a 3-year period with a CT diagnosis of small-bowel obstruction were included. There were 144 examinations in 142 patients. Images were interpreted prospectively with consensus by a fellow and an experienced gastrointestinal radiologist. Attention was focused on the presence of the following signs of strangulation and ischemia: reduced enhancement of the small-bowel wall, mural thickening, mesenteric fluid, congestion of small mesenteric veins, and ascites. A diagnosis of ischemia was made if enhancement of the bowel wall was reduced or if at least two of the other signs were found. Results were correlated with surgical findings in 73 cases and clinical follow-up in 71 cases. RESULTS: A diagnosis of ischemia was made at surgery in 24 patients. CT diagnosis was correct in 23 patients (96% sensitivity). There were nine false-positive diagnoses (93% specificity). The negative predictive value of CT was 99%. Reduced enhancement of the bowel wall had a sensitivity of 48% and specificity of 100%, mural thickening had a sensitivity of 38% and specificity of 78%, mesenteric fluid had a sensitivity of 88% and specificity of 90%, congestion of mesenteric veins had a sensitivity of 58% and specificity of 79%, and ascites had a sensitivity of 75% and specificity of 76%. CONCLUSION: Helical CT is a highly sensitive method to diagnose or rule out intestinal ischemia in the context of acute small-bowel obstruction.     

Identification of adhesions on CT in small-bowel obstruction

Identification of adhesions on computed tomography (CT) in cases of small-bowel obstruction (SBO) is currently a diagnosis of exclusion. The purpose of this study is to examine whether the presence of findings suggestive of an extraluminal band can be used as a CT sign for adhesive SBO. CT scans of 142 patients with surgically proven SBO performed within 72 h of exploratory surgery were reviewed. The studies were evaluated for the cause of SBO and the presence of extraluminal bands. An extraluminal band was considered present if there was a change in the conformation of the transition zone, suggesting extraluminal compression of the bowel by a linear obstructive band. The presence of extraluminal bands in the area of the transition zone had a high positive predictive value for adhesive SBO. Of the 73 cases in which bands were present, SBO was due to adhesions in 52 instances, with a corresponding positive predictive value of 71% (95% confidence interval 0.60–0.80) and a p value of 0.008. The extraluminal band was 61% sensitive and 63% specific for adhesive SBO. The presence of an extraluminal band on CT in the area of the transition zone in cases of SBO correlates well with a diagnosis of SBO secondary to adhesions. In the absence of a source of SBO, the presence of an extraluminal band can serve as a helpful diagnostic adjunct for adhesive SBO.An editorial comment on this paper is available at .     

Frequency and relevance of the "small-bowel feces" sign on CT in patients with small-bowel obstruction

OBJECTIVE: We sought to determine the incidence of the "small-bowel feces" sign (SBFS) in patients with small-bowel obstruction (SBO) and whether it can be used to accurately locate the point of obstruction. SUBJECTS AND METHODS: From November 2002 until March 2003, 34 consecutive adult patients with CT findings of small-bowel obstruction were prospectively evaluated. The CT findings used to diagnose small-bowel obstruction were a dilated proximal small bowel and a collapsed distal small bowel and colon. CT scans were evaluated to determine the degree of obstruction (mild, moderate, or high-grade), the presence or absence of the SBFS (defined as particulate-type material in the dilated small bowel), the location of the SBFS in relation to the transition zone, and the cause of the obstruction. Mild obstruction was defined as a slight discrepancy between the caliber of the proximal and that of the distal small bowel; moderate SBO was defined as a discrepancy of 50% or more between the calibers of the proximal and the distal small bowel; and high-grade SBO was considered to be present if the distal small bowel and the colon had collapsed. The cause of the obstruction was determined from surgical findings or a combination of CT findings, follow-up barium studies, and clinical assessment. RESULTS: The SBFS was present in 19 (55.9%) of 34 patients with SBO. The degree of SBO was mild in six, moderate in 11, and high-grade in 17 of the patients. The SBFS was present in one of the six patients (16.6%) with mild, eight (72.7%) of the 11 with moderate, and 10 (58.8%) of the 17 with high-grade SBO. In all patients in whom the SBFS was present, the particulate material could be traced to the point of transition and was most conspicuous in the transition zone. The length of fecallike material ranged from 2 to 25 cm and was longer in moderate and high-grade SBO than in mild SBO. The cause of the SBO was an adhesion in 20 patients, a hernia in four patients, Crohn's disease in four patients, a tumor in three patients, and other miscellaneous causes in three patients. CONCLUSION: When present on CT, the SBFS can be used to help locate the transition zone in patients with SBO. The sign is present more frequently in patients with moderate and high degrees of SBO.     

CT of small-bowel ischemia associated with obstruction in emergency department patients: diagnostic performance evaluation

PURPOSE: To retrospectively evaluate the diagnostic performance of computed tomography (CT) for detection of small-bowel ischemia in emergency department patients with abdominal pain and to compare the prospective interpretation with a retrospective interpretation by using surgical or pathologic findings as the reference standard. MATERIALS AND METHODS: The HIPAA-compliant study was approved by the institutional review board, and patients consented to research authorization. Sixty patients (61 examinations) (25 male, 35 female patients; median age, 67 years; range, 0.9-89.7 years) with acute abdominal pain underwent immediate abdominal and pelvic CT and subsequent surgery of the small bowel within 7 days of CT. Prospective radiologic reports were reviewed for diagnosis of small-bowel obstruction and ischemia. Two gastrointestinal radiologists performed blinded, independent, retrospective review of the CT studies with no clinical data other than presence of acute abdominal pain. The reviewers categorized CT signs of obstruction and ischemia and estimated diagnostic certainty. Discordant findings were resolved by consensus review by a third gastrointestinal radiologist. CT interpretations were compared with prospective interpretations and surgical or pathologic findings. Sensitivity and specificity estimates with confidence intervals were calculated. Fisher exact and chi2 tests were used to assess associations between CT signs and the diagnosis of ischemia; kappa statistics were used to estimate agreement between readers. RESULTS: In 27 (44%) of 61 CT studies, small-bowel ischemia was surgically or pathologically confirmed. Sensitivity and specificity for the diagnosis of ischemia were, respectively, 14.8% and 94.1% for prospective interpretations, 29.6% and 91.2% for reader 1, 40.7% and 85.3% for reader 2, and 51.9% and 88.2% for the consensus review. Decreased segmental enhancement was the most specific sign for small-bowel ischemia (P = .001), and its recognition would have improved the diagnostic performance of all readers. There was a significant association of the small-bowel feces sign with the presence of small-bowel ischemia (P = .046). CONCLUSION: Diagnostic performance assessment of CT for the diagnosis of small-bowel ischemia revealed poor prospective interpretation sensitivity.     

CT findings in patients with small-bowel transplants.

Orthotopic small-bowel transplantation procedures are being performed increasingly often worldwide. CT plays an important role in both the preoperative assessment and the postoperative care of these patients. This pictorial essay serves to acquaint radiologists with the CT findings related to small-bowel transplantation.     

The efficacy of helical CT in the diagnosis of small bowel obstruction

OBJECTIVE: To evaluate the usefulness and reliability of helical computed tomography (CT) for patients with small bowel obstruction. METHODS AND MATERIAL: Helical CT findings of 41 patients were evaluated prospectively on the basis of the presence and the cause of obstruction, and the presence of strangulation. RESULTS: In the determination of the cause of the obstruction sensitivity and specificity of CT were 84 and 90%, respectively. Of the 19 patients undergoing surgery, 6 had strangulation and were correctly identified by CT. CONCLUSION: Helical CT is an accurate method in the detection of small bowel obstruction, especially for evaluating the cause and vascular complications of obstruction.     

Value of multidetector CT in decision making regarding surgery in patients with small-bowel obstruction due to adhesion

The aim of this study was to evaluate the value of use of multidetector CT (MDCT) to predict the need for subsequent surgery in patients with small-bowel obstruction (SBO) due to adhesion. During a 3-year period, 128 patients with an SBO due to adhesion were enrolled in this prospective study. Initially, all patients were treated conservatively. Surgery was performed in patients who developed signs of strangulation or did not improve, despite a conservative treatment for at least 5 days. Of the 128 patients, 37 patients eventually underwent surgery. Two radiologists interpreted MDCT findings regarded as predictive indicators for subsequent surgery in consensus. The findings included degree of SBO, presence of transition zone, and an abnormal vascular course. These findings were statistically compared between the group operated on and the group not operated on. A higher degree of SBO, an abnormal vascular course, and the presence of transition zone were more frequently seen in the group of patients operated on (p?<?0.001). Sensitivities, specificities, positive and negative predictive values, and risks for the use of MDCT to predict the need for surgery were 100%, 46.1%, 43%, 100%, and 1.9 (1.5?≤?95% confidence interval (CI)?≤?2.2) for a high-grade obstruction; 100%, 23%, 34.5%, 100%, and 1.3 (1.2?≤?95% CI?≤?1.5) for the presence of a transition zone; and 70.2%, 90.1%, 74.2%, 88.1%, and 7.1 (3.7?≤?95% CI?≤?13.7) for the presence of an abnormal course of the mesenteric vessels, respectively. The presence of a high degree of SBO and an abnormal vascular course around transition zone are useful indicators on MDCT to predict the need for surgery in patients with an SBO due to adhesion.     

Malignant biliary obstruction: efficacy of thin-section dynamic CT in determining resectability.

OBJECTIVE. Several authorities advocate the use of preoperative angiography to determine the resectability of pancreatic and periampullary tumors, claiming that CT alone is not sufficiently accurate for this purpose. Our objective was to assess the value of CT in predicting surgical resectability in patients with malignant biliary obstruction. MATERIALS AND METHODS. We performed a retrospective analysis of 380 consecutive cases of malignant biliary obstruction spanning a 4-year period. Most patients (230) were treated nonoperatively. Sixty-seven patients had surgery, pathologic confirmation of malignancy, and preoperative CT scans available for review. The CT scans were assessed for surgical resectability of tumor by an interpreter who did not know the patient's history. RESULTS. Forty-two patients had pancreatic adenocarcinoma, six had ampullary carcinoma, seven had cholangiocarcinoma, and 12 had other malignant neoplasms. Of 47 patients with tumors thought to be unresectable on the basis of CT findings, 42 had tumors that were found to be unresectable at surgery (positive predictive value, 89%). Of 20 patients with tumors thought to be resectable, 16 had tumors that were surgically resectable (positive predictive value, 80%). CT did not show metastases to duodenal lymph nodes (n = 2), portal vein infiltration (n = 1), and small hepatic metastases (n = 1). Visualization of most of these at angiography would not be expected. The CT finding of infiltration of the periarterial fat around the celiac or superior mesenteric arteries was reliable for predicting surgical unresectability. Lymphadenopathy and infiltration of nonperivascular fat planes were less reliable predictors of unresectability. CONCLUSION. Although some findings on CT that suggest unresectability are less reliable than others, the accuracy of CT compares favorably with reports on the accuracy of angiography for assessing tumor resectability in cases of malignant biliary obstruction. The addition of angiography to the examination of patients with potentially resectable lesions is not justified when high-quality, thin-section dynamic CT has been performed.     

机械性肠梗阻CT诊断

目的：总结机械性肠梗阻CT表现及诊断价值。方法：分析30例经手术（16例）及临床（14例）证实的肠梗阻CT及临床资料,比较腹部平片与CT对肠梗阻存在、定位、病因、有否绞窄以及治疗方法选择的价值。结果：CT证实肠梗阻存在100%,平片的70%;病因诊断准确性CT为96%,平片13%;CT能对肠肿瘤及时发现并分期（9例）,及早诊断肠绞窄（2例）及发现肠外肿块（4例）,有助于及早选择外科治疗,结核、局限炎症、肠套叠等首选保守治疗,常规CT检查发现肠管异常扩张应扩大扫描范围,往往能发现引起肠梗阻的病因（本组因此偶然发现肠肿瘤3例）。结论：肠梗阻或疑有肠梗阻的病人在平片、B超诊断信息不足时尽早CT检查对于明确病因,治疗选择及改善预后有较大意义。     

Imaging of acute small-bowel obstruction

OBJECTIVE: The objective of this pictorial essay is to review the different imaging techniques used for diagnosing small-bowel obstruction. CONCLUSION: Small-bowel obstruction is a common presentation, for which safe and effective management depends on a rapid and accurate diagnosis. Conventional radiographs remain the first line of imaging. CT is used increasingly more because it provides essential diagnostic information not apparent from radiographs. MRI may play a role in the future as technology improves and it becomes more readily available.     

Helical CT in the diagnosis of small bowel obstruction.

With recent technologic developments, the role of computed tomography (CT) in the diagnosis of bowel obstruction has expanded. CT is recommended when clinical and initial radiographic findings remain indeterminate or strangulation is suspected. This modality clearly demonstrates pathologic processes involving the bowel wall as well as the mesentery, mesenteric vessels, and peritoneal cavity. CT should be performed with intravenous injection of contrast material, and use of thin sections is recommended to evaluate a particular region of interest. CT is reported to have a sensitivity of 78%-100% for the detection of complete or high-grade small bowel obstruction but may not allow accurate diagnosis in cases involving incomplete obstruction. In such cases, the use of adjunct enteroclysis is indicated. Furthermore, multiplanar reformatted imaging may help identify the site, level, and cause of obstruction when axial CT findings are indeterminate. CT can also demonstrate findings that indicate the presence of closed-loop obstruction or strangulation, both of which necessitate emergency exploratory laparotomy. Unfortunately, these pathologic conditions may be missed, and patients with suspected severe obstruction or bowel ischemia in whom CT and clinical findings are widely disparate must also undergo laparotomy. In general, however, CT allows appropriate and timely management of these emergency cases.     

Ureteric obstruction by the right testicular vein: CT diagnosis.

The close relationship of the ureter and gonadal blood vessels is often clearly demonstrated by computed tomography (CT). A case of ureteral obstruction in a man possibly caused by the crossing testicular vein is presented. Unlike the ovarian vein syndrome in women, which is often related to pregnancy and/or venous thrombosis, no predisposing factors were found.