Small bowel patency assessment using the patency device and a novel targeted (limited radiation) computed tomography-based protocol.

BACKGROUND AND AIM: Excretion of the patency capsule (PC) within a certain time frame may be used to demonstrate luminal patency prior to capsule endoscopy (CE). We aimed to determine how often further radiological imaging is needed to confirm luminal patency after PC, assess radiologists' ability to locate the PC on plain abdominal films, and evaluate the outcomes of a novel computed tomography (CT) protocol for PC localization. METHODS: A study of the ability of radiologists to localize PC using plain abdominal films was performed. A novel protocol targeting a limited CT at the level of the PC identified on the "scout" film if retained 30 h post-ingestion was prospectively evaluated in 400 consecutive patients undergoing PC. RESULTS: In a study of the confidence with which radiologists could localize the PC on plain films, radiologists preferred abdominal CT to localize PCs identified on plain films in 74% of cases. In a protocol based on the use of a PC and targeted, limited CT scan to confirm small bowel patency in those failing to excrete the PC 30 h post-ingestion, the sensitivity, specificity, positive, and negative predictive value were 99.4%, 90.0%, 99.7%, and 81.0%, respectively. Crohn's disease was the only statistically significant predictor associated with higher risk of luminal stricture (P=0.001) in post-hoc analysis. CONCLUSIONS: Excretion of the PC 30 h post-ingestion reliably predicts safe CE passage. Plain abdominal radiology is unreliable and a scout film targeted, limited CT scan offers an accurate minimal radiation method of determining small bowel patency.

Reconfiguring practice: the interdependence of experimental procedure and computing infrastructure in distributed earthquake engineering.

When transitioning local laboratory practices into distributed environments, the interdependent relationship between experimental procedure and the technologies used to execute experiments becomes highly visible and a focal point for system requirements. We present an analysis of ways in which this reciprocal relationship is reconfiguring laboratory practices in earthquake engineering as a new computing infrastructure is embedded within three laboratories in order to facilitate the execution of shared experiments across geographically distributed sites. The system has been developed as part of the UK Network for Earthquake Engineering Simulation e-Research project, which links together three earthquake engineering laboratories at the universities of Bristol, Cambridge and Oxford. We consider the ways in which researchers have successfully adapted their local laboratory practices through the modification of experimental procedure so that they may meet the challenges of coordinating distributed earthquake experiments.

Enhancement of liver parenchyma after injection of hepatocyte-specific MRI contrast media: a comparison of gadoxetic acid and gadobenate dimeglumine.

PURPOSE: To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte-specific contrast media. MATERIALS AND METHODS: Patients (n = 295) with known/suspected focal liver lesions randomly received 0.025 mmol gadoxetic acid/kg body weight or 0.05 mmol gadobenate dimeglumine/kg body weight by means of bolus injection. MR imaging was performed before and immediately after injection, and in the delayed phase at approved time points (20 min after injection of gadoxetic acid and 40 min after injection of gadobenate dimeglumine). The relative liver enhancement for the overall population and a cirrhotic subgroup was compared in T1-weighted GRE sequences. An independent radiologist performed signal intensity measurements. Enhancement ratios were compared using confidence intervals (CIs). RESULTS: The relative liver enhancement in the overall population was superior with gadoxetic acid (57.24%) versus gadobenate dimeglumine (32.77%) in the delayed-imaging phase. The enhancement ratio between the contrast media was statistically significant at 1.75 (95% CI: 1.46-2.13). In the delayed phase, the enhancement of cirrhotic liver with gadoxetic acid (57.00%) was comparable to that in the overall population. Enhancement with gadobenate dimeglumine was inferior in cirrhotic liver parenchyma (26.85%). CONCLUSION: In the delayed, hepatocyte-specific phase, liver enhancement after injection of gadoxetic acid was superior to that obtained with gadobenate dimeglumine.

Gluteal nodules in patients with metastatic midgut carcinoid disease treated with depot somatostatin analogs.

CONTEXT AND OBJECTIVES: We were referred a patient with metastatic well-differentiated endocrine tumor of the small intestine (midgut carcinoid) in whom asymptomatic sc gluteal nodules had been identified on routine abdominal computed tomography and labeled as metastases. This prompted us to assess the prevalence and cause of these nodules. DESIGN AND SETTING: This was a retrospective, cross-sectional study at a university teaching hospital. METHODS: Routine abdominal computed tomography scans of 56 patients with metastatic midgut carcinoid were analyzed by two independent radiologists, blinded to treatment status (depot somatostatin analogs). MAIN OUTCOME MEASURES: Number of patients with nodules, number of injections, and duration and total cumulative dose per patient were assessed. RESULTS: No nodules were detected in 13 patients not on depot somatostatin therapy. Nodules were found in 29 of 43 patients (67%) on somatostatin analog therapy: 16 of 22 patients on lanreotide Autogel, five of 12 patients on octreotide LAR only, and eight of nine patients who had been treated with both somatostatin analogs. There was no difference in the clinical state of those with or without nodules. Per patient, the average number was seven, and average size was 1 cm. Presence of nodules was significantly associated with total number of injections (P = 0.024), duration on treatment (P = 0.022), and cumulative dose of lanreotide Autogel (P < 0.001). Nodules underwent involution on follow-up imaging. CONCLUSION: Patients with metastatic midgut carcinoid tumors have large numbers of asymptomatic sc nodules in the gluteal area when on either depot somatostatin analog, but these resolve over time. This clear observation gives reassurance to patients and those managing them that such nodules are unlikely to represent metastases.

Diagnostic efficacy of gadoxetic acid (Primovist)-enhanced MRI and spiral CT for a therapeutic strategy: comparison with intraoperative and histopathologic findings in focal liver lesions.

A multicenter study has been employed to evaluate the diagnostic efficacy of magnetic resonance imaging (MRI) using the new liver-specific contrast agent gadoxetic acid (Gd-EOB-DTPA, Primovist), as opposed to contrast-enhanced biphasic spiral computed tomography (CT), in the diagnosis of focal liver lesions, compared with a standard of reference (SOR). One hundred and sixty-nine patients with hepatic lesions eligible for surgery underwent Gd-EOB-DTPA-enhanced MRI as well as CT within 6 weeks. Pathologic evaluation of the liver specimen combined with intraoperative ultrasound established the SOR. Data sets were evaluated on-site (14 investigators) and off-site (three independent blinded readers). Gd-EOB-DTPA was well tolerated. Three hundred and two lesions were detected in 131 patients valid for analysis by SOR. The frequency of correctly detected lesions was significantly higher on Gd-EOB-DTPA-enhanced MRI compared with CT in the clinical evaluation [10.44%; 95% confidence interval (CI): 4.88, 16.0]. In the blinded reading there was a trend towards Gd-EOB-DTPA-enhanced MRI, not reaching statistical significance (2.14%; 95% CI: -4.32, 8.6). However, the highest rate of correctly detected lesions with a diameter below 1 cm was achieved by Gd-EOB-DTPA-enhanced MRI. Differential diagnosis was superior for Gd-EOB-DTPA-enhanced MRI (82.1%) versus CT (71.0%). A change in surgical therapy was documented in 19 of 131 patients (14.5%) post Gd-EOB-DTPA-enhanced MRI. Gd-EOB-DTPA-enhanced MRI was superior in the diagnosis and therapeutic management of focal liver lesions compared with CT.

MRCP compared to diagnostic ERCP for diagnosis when biliary obstruction is suspected: a systematic review.

BACKGROUND: Magnetic resonance cholangiopancreatography (MRCP) is an alternative to diagnostic endoscopic retrograde cholangiopancreatography (ERCP) for investigating biliary obstruction. The use of MRCP, a non-invasive procedure, may prevent the use of unnecessary invasive procedures. The aim of the study was to compare the findings of MRCP with those of ERCP by the computation of accuracy statistics. METHODS: Thirteen electronic bibliographic databases, covering biomedical, science, health economics and grey literature were searched. A systematic review of studies comparing MRCP to diagnostic ERCP in patients with suspected biliary obstruction was conducted. Sensitivity, specificity, likelihood ratios, acceptability and adverse events were reported. RESULTS: 25 studies were identified reporting several conditions including choledocholithiasis (18 studies), malignancy (four studies), obstruction (three studies), stricture (two studies) and dilatation (five studies). Three of the 18 studies reporting choledocholithiasis were excluded from the analysis due to lack of data, or differences in study design. The sensitivity for the 15 studies of choledocholithiasis ranged from 0.50 to 1.00 while specificity ranged from 0.83 to 1.00. The positive likelihood ratio ranged: from 5.44-47.72 and the negative likelihood ratio for the 15 studies ranged from 0.00-0.51. Significant heterogeneity was found across the 15 studies so the sensitivities and specificities were summarised by a Receiver Operating Characteristic (ROC) curve. For malignancy, sensitivity ranged from 0.81 to 0.94 and specificity from 0.92 to 1.00. Positive likelihood ratios ranged from 10.12 to 43 and negative likelihood ratios ranged from 0.15 to 0.21, although these estimates were less reliable. CONCLUSION: MRCP is a comparable diagnostic investigation in comparison to ERCP for diagnosing biliary obstruction.

Economic evaluation of MR cholangiopancreatography compared to diagnostic ERCP for the investigation of biliary tree obstruction.

BACKGROUND: Use of magnetic resonance cholangiopancreatography (MRCP) for confirmation of presence of biliary obstruction is virtually risk-free. However, unlike diagnostic endoscopic retrograde cholangiopancreatography (ERCP), no therapeutic option can be offered simultaneously with MRCP. The aim of the study is to assess the cost-effectiveness of MRCP when compared with the conventional practice of diagnostic ERCP for the investigation of biliary obstruction in adults. METHODS: Cost-effectiveness analysis from the perspective of the health care provider. Sensitivity analysis includes presentation of a family of cost effectiveness acceptability curves and the impact of different risks of common bile duct stones associated with ultrasound and liver function test results. The main outcome measure is cost per quality adjusted life year (QALY). RESULTS: Baseline results, at 37% probability of common bile duct stones, show that MRCP is the dominant strategy, with expected savings of 149 pounds sterling (325 pounds sterling to - 15 pounds sterling) and expected QALY gain of 0.011 (0-0.030) per case. The probability of avoiding unnecessary therapeutic ERCP is 30%. For patients at high risk of common bile duct stones (probability >60%) ERCP is the preferable strategy. CONCLUSIONS: The baseline estimate is that MRCP would be both cost saving and would result in improved quality of life outcomes compared to diagnostic ERCP, but its potential sources of economic benefit are highly dependent on access to, and waiting lists for adequate MRI technology at hospital level.

Improved detection of focal liver lesions at MR imaging: multicenter comparison of gadoxetic acid-enhanced MR images with intraoperative findings.

PURPOSE: To evaluate the safety and efficacy of gadoxetic acid disodium-enhanced magnetic resonance (MR) imaging for the detection of focal liver lesions, with results of histopathologic examination and/or intraoperative ultrasonography used as a standard of reference. MATERIALS AND METHODS: One hundred sixty-nine patients who were known to have or suspected of having focal liver lesions and were scheduled for liver surgery were included in this study. Results in 131 patients could be included in the efficacy analysis. MR imaging was performed before and immediately and 20 minutes after bolus injection of 0.025 mmol/kg of the liver-specific hepatobiliary contrast agent gadoxetic acid. T1-weighted gradient-echo (with and without fat saturation and including dynamic data sets) and T2-weighted fast spin-echo/turbo spin-echo sequences were performed. All images were evaluated on site and by three independent and blinded off-site reviewers. Lesion matching based on the standard-of-reference results was performed. Differences in lesion detection with precontrast and with postcontrast MR images were assessed with the two-sided Wilcoxon signed rank test. RESULTS: Gadoxetic acid was well tolerated. In the on-site review, the number of patients in whom all lesions were correctly matched increased from 89 of 129 patients at precontrast MR imaging to 103 of 129 patients at postcontrast MR imaging. In the off-site evaluation, the number of patients in whom all lesions were correctly matched and the corresponding sensitivity values increased from 72 (55.8%), 68 (52.7%), and 66 (51.2%) with the precontrast images to 88 (68.2%), 69 (53.5%), and 76 (58.9%) with the postcontrast images for readers 1, 2, and 3, respectively. Two of the three blinded readers showed a statistically significant difference in lesion detection between precontrast and postcontrast MR imaging (P <.001 and P =.008). A large number of additionally correctly detected and localized lesions were smaller than 1 cm. CONCLUSION: MR imaging with gadoxetic acid is safe and improves lesion detection and localization.