Fracture of a covered stent used for pseudoaneurysm exclusion in a prosthetic femoro-infrapopliteal bypass

PURPOSE: To present a case of fracture in a stent-graft used for exclusion of a pseudoaneurysm in a prosthetic femoro-infrapopliteal bypass. CASE REPORT: A Hemobahn stent-graft was inserted into a Dacron femoro-infrapopliteal bypass to avoid repeat surgery for a recurrent distal anastomotic pseudoaneurysm that had been excluded 2 years earlier by a Dacron interposition graft in a 69-year-old woman. Three months after stent-graft implantation, the patient complained of pain around the left knee; plain radiography showed stent fractures at 2 sites coinciding with the proximal and distal anastomoses of the interposition graft, and ultrasonography detected a new pseudoaneurysm at the distal anastomosis. The stent-graft was explanted and the pseudoaneurysm excluded with a new interposition graft. CONCLUSION: Although some stents have high flexibility and radial strength that make them suitable for use in periarticular vessels, interventionists should take into account the possibility of stent fracture when weighing the treatment option

Hepatic iron concentration: noninvasive estimation by means of MR imaging techniques

PURPOSE: To identify a magnetic resonance (MR) imaging method sufficiently sensitive and specific in the estimation of hepatic iron content to obviate liver biopsy. MATERIALS AND METHODS: Thirty-eight patients underwent percutaneous needle biopsy of the liver with chemical measurement of the hepatic iron concentration and hepatic MR imaging with several spin-echo and gradient-recalled-echo (GRE) techniques. Correlations between MR imaging parameters and the hepatic iron concentration were determined. . RESULTS: Inverse curvilinear relationships were noted between several MR parameters and hepatic iron concentrations. GRE sequences with short repetition and echo times were more accurate and precise than spin-echo sequences for the estimation of hepatic iron concentration. A GRE sequence with a repetition time of 18 msec, an echo time of 5 msec, and a flip angle of 10 degrees showed close correlation between the hepatic iron concentration and the natural logarithm of the ratio of the signal intensity of liver to the SD of background noise (r = -0.94) and low coefficient of variation (12%). CONCLUSION: MR imaging with these parameters is a rapid, noninvasive, and accurate modality for estimation of hepatic iron concentration; it is sufficiently accurate and precise to obviate liver biopsy for the purpose of measuring hepatic iron concentration

Constipation and Colonic Transit Times in Children With Morbid Obesity

Objectives: The aim of the study was to determine the frequency of functional constipation according to the Rome III criteria in children with morbid obesity and to evaluate by measuring colonic transit times (CTTs) whether decreased colonic motility is present in these children. Patients and Methods: Ninety-one children with morbid obesity ages 8 to 18 years, entering a prospective, randomized controlled study evaluating the effect of an outpatient versus inpatient treatment program of obesity, participated. All of the children filled out a standardized questionnaire regarding their bowel habits, and CTTs were measured using radioopaque markers. Food diaries were also recorded to evaluate their diet. Results: A total of 19 children (21%) had functional constipation according to the Rome III criteria, whereas 1 child had functional nonretentive fecal incontinence. Total CTT exceeded 62 hours in only 10.5% of the children with constipation, and among them, 2 had a total CTT of >100 hours. In the nonconstipated group 8.3% had a delayed CTT. Furthermore, no difference was found between the diet of children with or without constipation, specifically not with respect to fiber and fat intake. Conclusions: Our study confirms a high frequency of functional constipation in children with obesity, using the Rome III criteria. However, abnormal colonic motility, as measured by CTT, was delayed in only a minority of patients. No relation was found between constipation in these children and fiber or fat intak

Comparison of diagnostic accuracy of screening tests ALT and ultrasound for pediatric non-alcoholic fatty liver disease

Alanine aminotransferase (ALT) and ultrasound (US) are the most commonly used tools for detecting non-alcoholic fatty liver disease (NAFLD). No direct comparison of these two modalities in children exists. We aimed to compare head-to-head the diagnostic accuracy of ALT and US and their combination for detecting NAFLD in children with obesity. Ninety-nine children with severe obesity underwent simultaneous serum-ALT and abdominal ultrasound (US steatosis score 0–3). Proton magnetic resonance spectroscopy was used as reference standard for detecting steatosis/NAFLD. ROC curve analyses were performed to determine diagnostic performance and to determine optimum screening cut-points aiming for a specificity ≥ 80%. The area under the ROC (AUROC) of ALT and US were not significantly different (0.74 and 0.70, respectively). At the optimal ALT threshold (≥40 IU/L), sensitivity was 44% and specificity was 89%. At the optimal US steatosis score (≥ 2), sensitivity was 51% and specificity was 80%. Combining ALT and US did not result in better accuracy than ALT or US alone. Conclusion: ALT and US have comparable and only moderate diagnostic accuracy for detecting hepatic steatosis in children with obesity. A stepwise screening strategy combining both methods does not improve diagnostic accuracy.What is Known:• Alanine aminotransferase (ALT) and ultrasound (US) are the most commonly used tools for detecting non-alcoholic fatty liver disease (NAFLD).• ALT and ultrasound have mediocre accuracy in detecting steatosis in children with obesity.What is New:• In a head-to-head comparison, the difference in diagnostic accuracy of ALT and ultrasound in detecting steatosis is not significant.• A stepwise screening strategy combining both methods does not improve diagnostic accuracy

Comparison of diagnostic accuracy of screening tests ALT and ultrasound for pediatric non-alcoholic fatty liver disease

Alanine aminotransferase (ALT) and ultrasound (US) are the most commonly used tools for detecting non-alcoholic fatty liver disease (NAFLD). No direct comparison of these two modalities in children exists. We aimed to compare head-to-head the diagnostic accuracy of ALT and US and their combination for detecting NAFLD in children with obesity. Ninety-nine children with severe obesity underwent simultaneous serum-ALT and abdominal ultrasound (US steatosis score 0–3). Proton magnetic resonance spectroscopy was used as reference standard for detecting steatosis/NAFLD. ROC curve analyses were performed to determine diagnostic performance and to determine optimum screening cut-points aiming for a specificity ≥ 80%. The area under the ROC (AUROC) of ALT and US were not significantly different (0.74 and 0.70, respectively). At the optimal ALT threshold (≥40 IU/L), sensitivity was 44% and specificity was 89%. At the optimal US steatosis score (≥ 2), sensitivity was 51% and specificity was 80%. Combining ALT and US did not result in better accuracy than ALT or US alone. Conclusion: ALT and US have comparable and only moderate diagnostic accuracy for detecting hepatic steatosis in children with obesity. A stepwise screening strategy combining both methods does not improve diagnostic accuracy.What is Known:• Alanine aminotransferase (ALT) and ultrasound (US) are the most commonly used tools for detecting non-alcoholic fatty liver disease (NAFLD).• ALT and ultrasound have mediocre accuracy in detecting steatosis in children with obesity.What is New:• In a head-to-head comparison, the difference in diagnostic accuracy of ALT and ultrasound in detecting steatosis is not significant.• A stepwise screening strategy combining both methods does not improve diagnostic accuracy

US Cannot Be Used to Predict the Presence or Severity of Hepatic Steatosis in Severely Obese Adolescents

Purpose: To evaluate the diagnostic accuracy of ultrasonography (US) for the assessment of hepatic steatosis in severely obese adolescents, with proton magnetic resonance (MR) spectroscopy as the reference standard, and to provide insight on the influence of prevalence on predictive values by calculating positive and negative posttest probabilities. Materials and Methods: This prospective study was institutional review board approved. All participants, and/or their legal representatives, gave written informed consent. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the overall presence of steatosis and for the presence of substantial (moderate to severe) steatosis. Positive and negative posttest probabilities were calculated and plotted against prevalence. Results: A total of 104 children (47 male, 57 female) were prospectively included. Mean age was 14.5 years (range, 8.3-18.9 years) and mean age-adjusted standard deviation body mass index (BMI) score (BMI z score) was 3.3 (range, 2.6-4.1). The overall prevalence of hepatic steatosis was 46.2% (48 of 104). Sensitivity of US was 85.4% (41 of 48), specificity was 55.4% (31 of 56), PPV was 62.1% (41 of 66), and NPV was 81.6% (31 of 38). The prevalence of substantial steatosis was 15.4% (16 of 104), with US sensitivity of 75.0% (12 of 16) and specificity of 87.5% (77 of 88). PPV was 52.2% (12 of 23) and NPV was 95.1% (77 of 81). Plotting of posttest probabilities against prevalence for both disease degrees demonstrated how disease prevalence influences US accuracy. Conclusion: Positive US results in severely obese adolescents cannot be used to accurately predict the presence and severity of hepatic steatosis, and additional imaging is required. Negative US results exclude the presence of substantial steatosis with acceptable accuracy. Steatosis prevalence differs among specific populations, strongly influencing posttest probabilities. (C) RSNA, 201