CT diagnosis of closed loop bowel obstruction mechanism is not sufficient to indicate emergent surgery.

PURPOSE: To identify computed tomography (CT) findings associated with successful conservative treatment of closed loop small bowel obstruction (CL-SBO) due to adhesions or internal herniation. MATERIAL AND METHODS: The local institutional review board approved this study while waiving informed consent. Clinical and CT data were collected retrospectively for 96 consecutive patients with a CT diagnosis of CL-SBO due to adhesions or internal herniation established by experienced radiologists who had no role in patient management. Mechanical obstruction with at least two transition zones on the bowel at a single site defined CL-SBO. Two radiologists blinded to patient data independently performed a retrospective review of the CT scans. The patient groups with successful versus failed initial conservative therapy were compared. Univariate and multivariate analyses were performed to look for CT findings associated with successful conservative therapy. Interobserver agreement was assessed for each CT finding. RESULTS: Of the 96 patients, 34 (35%) underwent immediate surgery and 62 (65%) received first-line conservative treatment, which succeeded in 19 (31%) and failed in 43 (69%). The distance between the transition zones was the only independent predictor of successful conservative therapy (odds ratio, 4.6 when ≥ 8 mm; 95% confidence interval [95% CI], 1.2-18.3). A distance ≥ 8 mm had 84% (95% CI, 60-97) sensitivity and 46% (95% CI, 31-62) specificity for successful conservative treatment. The correlation coefficient for the distance between transition zones between readers 1 and 2 was fair (r = 0.46). CONCLUSION: CL-SBO can be resolved without surgery. When there is no CT sign of ischemia, the distance between the transition zones should be assessed. KEY POINTS: • Twenty percent (19/96) of all cases of closed loop small bowel obstruction (CL-SBO) representing 31% of the patients given first-line conservative therapy, were resolved without surgery. • The distance between the transition zones may help to choose between conservative and surgical management in patients with a CL-SBO but no CT evidence of ischemia. • A distance < 8 mm between the transition zones suggests a need for emergent surgery.

Revised Atlanta classification for CT pancreatic and peripancreatic collections in the first month of acute pancreatitis: interobserver agreement.

PURPOSE: To assess interobserver agreement when using the revised Atlanta classification (RAC) to categorize pancreatic and peripancreatic collections during the first month of acute pancreatitis (AP), and to correlate type of collection to outcome. MATERIAL AND METHODS: This retrospective study of 115 consecutive patients admitted for 123 AP episodes, 178 CTs performed within the first month showed peripancreatic abnormalities. Each AP episode was classified as mild, moderately severe, or severe based on the RAC. Two radiologists, blinded to clinical data, used RAC criteria to retrospectively categorize the collections as acute peripancreatic fluid collections (APFC) or acute necrotic collections (ANC). Interobserver agreement was assessed based on Cohen's κ statistics and compared according to CT timing. RESULTS: Interobserver agreement for categorizing peripancreatic collections was moderate (κ = 0.45) and did not improve with time to CT (κ values, 0.53 < day 3, 0.34 on days 3-6, and 0.43 ≥ day 7). For detecting parenchymal necrosis, interobserver agreement was also moderate (κ = 0.45). AP was less severe in patients with APFC versus ANC (p = 0.04). CONCLUSION: Our finding of moderate interobserver agreement when using the RAC to categorize pancreatic and peripancreatic collections by CT indicates that the accurate diagnosis of APFC or ANC by CT in the first 4 weeks after symptom onset is often challenging. KEY POINTS: • Interobserver agreement was moderate for categorizing peripancreatic collections. • Interobserver agreement did not improve with time from onset to CT. • Interobserver agreement was moderate for detecting parenchymal necrosis.

Increased unenhanced bowel-wall attenuation: a specific sign of bowel necrosis in closed-loop small-bowel obstruction.

OBJECTIVES: To identify computed tomography (CT) findings associated with bowel necrosis in patients with surgically confirmed strangulating closed-loop small-bowel obstruction (CL-SBO) due to adhesions or internal hernia. METHODS: This retrospective study was approved by our institutional review board, and informed consent was waived. To identify CT signs of bowel necrosis, two gastrointestinal radiologists performed blinded, independent, retrospective reviews of 41 CT studies from consecutive patients who had CL-SBO due to adhesions or internal hernias and who underwent surgery within 48 h. On the basis of surgical and pathological findings, patients were classified as having reversible ischemia or histologically documented necrosis. Univariate statistical analyses were performed to assess associations between CT signs and bowel necrosis. Kappa statistics were computed to assess interobserver agreement. RESULTS: We included 25 (61%) women and 16 (39%) men with a median age of 79 years. Bowel necrosis was found in 25/41 (61%) patients and ischemic but viable bowel in 16/41 (39%) patients. Increased unenhanced bowel-wall attenuation was the only CT finding significantly associated with bowel necrosis (p = 0.0002). This sign had 58% (95% CI, 37-78) sensitivity and 100% (95% CI, 79-100) specificity for necrosis. Interobserver agreement was fair (0.59; 95% CI, 0.37-0.82). CONCLUSION: Increased unenhanced bowel-wall attenuation is specific for bowel necrosis and should lead to prompt surgery for bowel resection. KEY POINTS: • Increased unenhanced bowel-wall attenuation is the only sign specific for necrosis • Decreased bowel-wall enhancement is not relevant for differentiating reversible ischemia from necrosis • Preoperative knowledge of bowel necrosis is helpful to plan adequate surgery.

Acute Jejunoileal Diverticulitis: Multicenter Descriptive Study of 33 Patients.

OBJECTIVE: Acute jejunoileal diverticulitis is a very rare and potentially serious disease affecting mostly elderly patients. The diagnosis is based on imaging but remains underrecognized. The purpose of this study is to describe the clinical and CT features and the outcomes of patients with acute jejunoileal diverticulitis. MATERIALS AND METHODS: Cases of acute jejunoileal diverticulitis managed at three French hospitals November 2005 through January 2015 were identified retrospectively. The final diagnosis relied either on a clinical and radiologic data review by a panel of experts or on surgical findings. Demographic, clinical, laboratory, and 18-month outcome data were collected. CT scans were reviewed by two radiologists who reached a consensus about the presence of an inflammatory diverticulum, evidence of complications, and presence of other bowel diverticula. RESULTS: We identified 33 cases of acute jejunoileal diverticulitis in 33 patients with a median age of 78 years, including 30 (91%) patients in whom an inflammatory diverticulum was identified at the jejunum (n = 26, 87%) or ileum (n = 4, 13%). Extraintestinal gas was seen in 10 (30%) patients and extraintestinal fluid in 11 (33%) patients. Other small-bowel diverticula were visible in all 33 patients. The diverticulitis was mild and resolved with nonoperative treatment in 22 (67%) patients and was severe in the remaining 11 (33%) patients, eight of whom required emergent surgery. CONCLUSION: Acute jejunoileal diverticulitis is a rare and usually nonserious condition that chiefly involves the jejunum. A detailed CT assessment may allow nonoperative treatment.

Clinical Relevance of the Feces Sign in Small-Bowel Obstruction Due to Adhesions Depends on Its Location.

OBJECTIVE: The objective of our study was to evaluate if the feces sign can be used to predict successful nonoperative treatment or progression to ischemia in patients with small-bowel obstruction (SBO) due to adhesions. MATERIALS AND METHODS: For this single-center retrospective observational study involving a blinded independent review by two radiologists of 237 consecutive CT examinations of 216 patients with SBO due to adhesions (age: mean, 70.9 years; median, 74 years; interquartile range, 62-84 years), the location of the transition zone (TZ), number of TZs, and presence and location of the feces sign relative to the TZ were recorded. The reference standard for diagnosing ischemia was surgical and pathologic findings (n = 108 CT examinations) or, when treatment was nonoperative (n = 129 CT examinations), clinical outcome. Factors associated with successful nonoperative treatment and ischemia were identified by univariate and multivariate analyses. RESULTS: A feces sign was seen in 88 of 237 CT examinations (37.1%). The feces sign was at the TZ, which we refer to as the "TZ feces" sign, in 82 of 88 (93.2%) patients; between two TZs, which we refer to as the "trapped feces" sign, in 14 (15.9%) patients; and in both locations in eight (9.1%) patients. By univariate analysis, an isolated TZ feces sign was associated positively with successful nonoperative treatment (odds ratio [OR], 3.37; 95% CI, 1.71-6.66; p < 0.001) and negatively with ischemia (OR, 0.33; 95% CI, 0.13-0.85; p = 0.02). Combined TZ and trapped feces signs were associated with ischemia (OR, 24.16; 95% CI, 2.86-203.89; p = 0.003). By multivariate analysis, regardless of the location of the feces sign, the feces sign was not significantly associated with successful nonoperative treatment or progression to ischemia. CONCLUSION: The feces sign is common and helps to identify the TZ. Among the CT signs of SBO, the feces sign does not independently help to predict successful nonoperative treatment or progression to ischemia.

Feasibility and Diagnostic Accuracy of Supersonic Shear-Wave Elastography for the Assessment of Liver Stiffness and Liver Fibrosis in Children: A Pilot Study of 96 Patients.

PURPOSE: To evaluate the feasibility of using supersonic shear-wave elastography (SSWE) in children and normal values of liver stiffness with the use of control patients of different ages (from neonates to teenagers) and the diagnostic accuracy of supersonic shear wave elastography for assessing liver fibrosis by using the histologic scoring system as the reference method in patients with liver disease, with a special concern for early stages of fibrosis. MATERIALS AND METHODS: The institutional review board approved this prospective study. Informed consent was obtained from parents and children older than 7 years. First, 51 healthy children (from neonate to 15 years) were analyzed as the control group, and univariate and multivariate comparisons were performed to study the effect of age, transducer, breathing condition, probe, and position on elasticity values. Next, 45 children (from 1 month to 17.2 years old) who underwent liver biopsy were analyzed. SSWE measurements were obtained in the same region of the liver as the biopsy specimens. Biopsy specimens were reviewed in a blinded manner by a pathologist with the use of METAVIR criteria. The areas under the receiver operating characteristics curve (AUCs) were calculated for patients with fibrosis stage F0 versus those with stage F1-F2, F2 or higher, F3 or higher, and F4 or higher. RESULTS: A successful rate of SSWE measurement was 100% in 96 patients, including neonates. Liver stiffness values were significantly higher when an SC6-1 probe (Aixplorer; SuperSonic Imagine SA, Aix-enProvence, France) was used than when an SL15-4 probe (Aixplorer) was used (mean ± standard deviation, 6.94 kPa ± 1.42 vs 5.96 kPa ± 1.31; P = .006). There was no influence of sex, the location of measurement, or respiratory status on liver elasticity values (P = .41-.93), although the power to detect such a difference was low. According to the degree of liver fibrosis at liver biopsy, 88.5%-96.8% of patients were correctly classified, with AUCs of 0.90-0.98 (95% confidence interval [CI]: 0.8, 1.0). The AUC for patients with stage F0 versus stage F1-F2 was 0.93 (95% CI: 0.87, 0.99). CONCLUSION: SSWE allows accurate assessment of liver fibrosis, even in children with early stage (F1-F2) disease, and the choice of transducer influences liver stiffness values.

Assessment of Bowel Wall Enhancement for the Diagnosis of Intestinal Ischemia in Patients with Small Bowel Obstruction: Value of Adding Unenhanced CT to Contrast-enhanced CT.

Purpose To determine whether adding unenhanced computed tomography (CT) to contrast material-enhanced CT improves the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia complicating mechanical small bowel obstruction (SBO). Materials and Methods This retrospective study was approved by the institutional review board, which waived the requirement for informed consent. Two gastrointestinal radiologists independently performed retrospective assessments of 164 unenhanced and contrast-enhanced CT studies from 158 consecutive patients (mean age, 71.2 years) with mechanical SBO. The reference standard was the intraoperative and/or histologic diagnosis (in 80 cases) or results from clinical follow-up in patients who did not undergo surgery (84 cases). Decreased bowel wall enhancement was evaluated with contrast-enhanced images then and both unenhanced and contrast-enhanced images 1 month later. Diagnostic performance of decreased bowel wall enhancement and confidence in the diagnosis were compared between the two readings by using McNemar and Wilcoxon signed rank tests. Interobserver agreement was assessed by using κ statistics and compared with bootstrapping. Results Ischemia was diagnosed in 41 of 164 (25%) episodes of SBO. For both observers, adding unenhanced images improved decreased bowel wall enhancement sensitivity (observer 1: 46.3% [19 of 41] vs 65.8% [27 of 41], P = .02; observer 2: 56.1% [23 of 41] vs 63.4% [26 of 41], P = .45), Youden index (from 0.41 to 0.58 for observer 1 and from 0.42 to 0.61 for observer 2), and confidence score (P < .001 for both). Specificity significantly increased for observer 2 (84.5% [104 of 123] vs 94.3% [116 of 123], P = .002), and interobserver agreement significantly increased, from moderate (κ = 0.48) to excellent (κ = 0.89; P < .0001). Conclusion Adding unenhanced CT to contrast-enhanced CT improved the sensitivity, diagnostic confidence, and interobserver agreement of the diagnosis of ischemia, a complication of mechanical SBO, on the basis of decreased bowel wall enhancement. (©) RSNA, 2016.

Initial Diagnosis and Staging of Pancreatic Cancer Including Main Differentials.

Computed tomography (CT) remains the optimal imaging modality for both diagnosis and staging of pancreatic adenocarcinoma. Especially, CT is highly accurate in assessing the relationship of the tumor to critical arterial and venous structures, since their involvement can preclude surgical resection or indicate a neoadjuvant strategy in borderline resectable or locally advanced lesions. MRI provides additional staging information in isodense tumors or regarding presence of small liver metastases not seen at CT. Endoscopic ultrasound is the reference technique to be used for obtaining histologic proof. The introduction of perfusion modalities and radiomics may benefit the evaluation of pancreatic lesion parameters, thus helping to rule out differentials. However, these techniques require further investigation and standardization.

Differentiation between cavernous hemangiomas and untreated malignant neoplasms of the liver with free-breathing diffusion-weighted MR imaging: comparison with T2-weighted fast spin-echo MR imaging.

OBJECTIVE: To test interobserver variability of ADC measurements and compare the diagnostic performances of free-breathing diffusion-weighted (FBDW) with that of T2-weighted FSE (T2WFSE) MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms. MATERIALS AND METHODS: Thirty-five patients with cavernous hemangiomas and 35 with untreated hepatic malignant neoplasms had FBDW and T2WFSE MR imaging. Hepatic lesions were characterized with ADC measurement and visual evaluation. Interobserver agreement for ADC measurement was calculated. Association between ADC value and lesion type was assessed using univariate analysis. Sensitivity, specificity and accuracy of ADC values and visual evaluation of MR images for the diagnosis of untreated malignant hepatic neoplasm were compared. RESULTS: ADC measurements showed excellent interobserver correlation (intraclass correlation coefficient=0.980). Malignant neoplasms had lower ADC values than hemangiomas for the two observers (1.11×10(-3) mm2/s±.21×10(-3) vs. 1.77×10(-3) mm2/s±.29×10(-3) for observer 1 and 1.11×10(-3) mm2/s±.19×10(-3) vs. 1.79×10(-3) mm2/s±.32×10(-3) for observer 2) and univariate analysis found significant correlations between lesion type and ADC values. Depending on ADC threshold value, accuracy for the diagnosis of malignant neoplasm varied from 82.9% to 94.3%. Using visual evaluation, FBDW showed better specificity and accuracy than T2WFSE MR images for the diagnosis of malignant neoplasm (97.1% vs. 77.1% and 94.3% vs. 62.9%, respectively). CONCLUSION: FBDW imaging provides reproducible quantitative information and surpasses the value of T2WFSE MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms.