Wind loads on open truss structures: applications of blockage to historic transporter bridges.

The overall aim of this study is to compare and contrast the design of the two remaining working examples of early twentieth-century transporter bridges in the UK, namely, those at Newport and Middlesbrough. With the aid of modern finite-element analysis, the behaviour of the structures under loading is investigated, likely modes of failure determined and the efficiency of each structure evaluated. The important horizontal load component due to wind at the exposed locations of the bridges is examined using 'current blockage', ideas transferred from recent work on wave-current-structure interaction for space-frame structures in offshore engineering. This article is part of the theme issue 'Environmental loading of heritage structures'.

A proposal for the annotation of recurrent colorectal cancer: the 'Sheffield classification'.

AIM: Current classification systems of large bowel cancer only refer to metastatic disease as M0, M1 or Mx. Recurrent colorectal cancer primarily occurs in the liver, lungs, nodes or peritoneum. The management of each of these sites of recurrence has made significant advances and each is a subspecialty in its own right. The aim of this paper was to devise a classification system which accurately describes the site and extent of metastatic spread. METHOD: An amendment of the current system is proposed in which liver, lung and peritoneal metastases are annotated by 'Liv 0,1', 'Pul 0,1' and 'Per 0,1' in describing the primary presentation. These are then subclassified, taking into account the chronology, size, number and geographical distribution of metastatic disease or logoregional recurrence and its K-Ras status. CONCLUSION: This discussion document proposes a classification system which is logical and simple to use. We plan to validate it prospectively.

Sensitivity of magnetic resonance imaging in the detection of colorectal liver metastases.

INTRODUCTION: The aim of this study was to evaluate the sensitivity of magnetic resonance imaging (MRI) in the detection of colorectal liver metastases. PATIENTS AND METHODS: Pre-operative MRI scanning of the liver was performed by a single radiologist and the size and number of definite liver metastases were recorded. Patients then underwent hepatectomy with routine intra-operative ultrasonography (IOUS) and resected specimens were sent for histopathology. Pathology findings were compared with those of MRI scans to determine the sensitivity of this imaging modality. Exclusions were patients undergoing hepatic resection more than 4 weeks after the MRI scan, those undergoing chemotherapy at the time of the scan, and those with conglomerate unilobar metastases. RESULTS: Complete data were available for 84 patients. There was total agreement between MRI, IOUS and histology in 79 patients (101 metastases). MRI missed 5 metastases in 5 patients that were found on IOUS (or palpation of superficial lesions) and subsequently confirmed by histological examination. These measured 5 mm or less (4 patients) and 7 mm (one patient). The sensitivity of MRI in the detection of colorectal liver metastases was thus 94% for all lesions and 100% for lesions 1 cm or larger in diameter. CONCLUSIONS: MRI of the liver is a non-invasive technique with an extremely high degree of sensitivity in the detection of colorectal liver metastases and should be considered as the 'gold standard' in the pre-operative imaging of these patients.

Strictures of the sigmoid colon: barium enema evaluation.

PURPOSE: To assess the accuracy of radiologic interpretation, in the absence of clinical information, in the differentiation of benign and malignant sigmoid strictures at barium enema examination. MATERIALS AND METHODS: On two occasions, four independent observers retrospectively assessed examination findings in 78 patients with documented sigmoid strictures (43 benign, 35 malignant). Each stricture was graded by using a five-point scale (definitely malignant to definitely benign). RESULTS: No significant difference existed between the areas under the receiver operating characteristic curves for the two assessments with any observer. Consensus findings indicated agreement among at least three of the four observers in 68 (87%) and 66 (85%) cases at the first and second assessments, respectively. One benign stricture was called malignant at both assessments. When consensus existed, the positive predictive value for malignant strictures was 96% at both assessments (sensitivity, 63% and 66%). Nine malignant strictures were called benign, three at both assessments. When consensus existed, the positive predictive value for benign strictures was 84% and 88% at the first and second assessments, respectively (sensitivity, 88% and 86%, respectively). CONCLUSION: The differentiation between a benign and a malignant sigmoid stricture can be made in most cases at barium enema examination. When a stricture appears malignant, the diagnosis is usually correct, but caution is advised when a stricture appears benign.

Complications from inflation of a retention rectal balloon catheter in the vagina at barium enema.

We describe two complications arising from the inadvertent introduction and inflation of a retention rectal balloon catheter in the vagina. Barium entered the uterus, fallopian tubes and peritoneal cavity in one and caused a forniceal tear and venous intravasation in the other. In both cases the catheter misplacement was attributed to atrophy of the perineal body. Various recommendations have been made to reduce the risks associated with the use of balloon catheters but we wish to emphasize the importance of a digital rectal examination to define the perineal anatomy and the use of a gloved finger to guide the balloon catheter into the rectum.

Hepatic lesion detection at MR imaging: a comparative study with four sequences.

PURPOSE: To compare results with the following magnetic resonance (MR) imaging sequences in the detection of focal hepatic lesions: fast spin-echo (SE) before and after administration of superparamagnetic iron oxide (SPIO) particles, fat-suppressed T2-weighted SE, and dynamic gadolinium-enhanced fast low-angle shot (FLASH). MATERIALS AND METHODS: In 26 patients with known malignancy and documented focal liver lesions, 1.0-T MR imaging was performed prior to hepatic resection. All images were reviewed independently by four blinded observers. Sensitivity was calculated for each sequence and for each observer by means of alternative-free-response receiver operating characteristic (ROC) methods. RESULTS: The mean area under the alternative-free-response ROC curve with SPIO-enhanced fast SE (0.85) was significantly greater (P < .02) than that with all other sequences. Detection was significantly improved with SPIO-enhanced fast SE compared with dynamic gadolinium-enhanced FLASH (which was the best of the other three sequences) for all lesions (P < .002) and for malignant lesions (P < .0002). CONCLUSION: Findings with the SPIO-enhanced fast SE sequence improved detection of focal liver lesions and had the highest diagnostic accuracy.

Complications of barium enema examinations: a survey of UK Consultant Radiologists 1992 to 1994.

Questionnaires were sent to all Consultant Radiologists in the UK regarding complications from barium enema examinations. The 756 respondents performed a total of 738,216 examinations over the three year period 1992 to 1994. Seventy-seven Consultants (10.2%) reported a total of 82 complications including 13 deaths: an overall mortality rate of 1 in 56,786. Only three of 30 (10%) cases of bowel perforation died, as compared with nine out of 16 (56%) cases of cardiac arrhythmia. The only remaining death was a consequence of vaginal intubation. Details of all the reported complications are recorded. This was an entirely retrospective study.

Retention balloon catheters and barium enemas: attitudes, current practice and relative safety in the UK.

Balloon catheters have been associated with increased morbidity and mortality leading some to believe they should be banned, yet others find them both useful and safe if used properly. Questionnaires were sent to all Consultant Radiologists in the UK to document current practice. Particular attention focused on whether eight safety aspects are considered during their use. In this entirely retrospective study complications with both balloon and standard tip catheters were recorded during the 3-year-period 1992 to 1994 to assess their relative safety. Twenty-two percent of UK Radiologists routinely used a rectal balloon. This was not associated with any increase in mortality, but extraperitoneal rectal perforation was increased by a factor of 2.5. The routine use of retention balloon catheters may not be justified.

Pseudolipoma of inverted Meckel's diverticulum: clinical, radiological and pathological correlation.

Three cases of isolated inverted Meckel's diverticulum are described. In two cases an initial pathological diagnosis of small bowel lipoma was suggested. In a third case central fat was demonstrated on CT and peristalsis of the intraluminal polypoid mass was observed during US examination. In all three cases small bowel enema examination demonstrated the lesion. Correlation of the clinical, radiological and pathological features is emphasised, as this will allow the correct diagnosis.

Case report: The "veiled right kidney sign"--an ultrasound finding in retroperitoneal perforation of the duodenum.

We report a case of traumatic duodenal perforation where the diagnosis was first considered during abdominal ultrasound examination. A subsequent CT scan identified the site of perforation which was confirmed at laparotomy. This condition typically produces few clinical signs or symptoms initially but has a high mortality related to delayed diagnosis. The ultrasound findings that prompted early diagnosis are described.

Case report: cellist's elbow?--vascular entrapment in association with the ligament of Struthers.

We present a case of forearm claudication due to ulnar artery entrapment by the ligament of Struthers. Anatomical, radiological and surgical features of this uncommon syndrome are discussed.

Aversiveness of motion and noise to broiler chickens.

1. The aversiveness of motion and noise to broiler chickens was examined using a passive avoidance technique. Birds were initially trained to peck a key a fixed number of times to obtain food. After training, food could still be obtained by key pecking, but feeding was immediately followed by 1 min exposure to noise or motion. Birds could delay or avoid exposure by delaying or avoiding key pecking, hence foregoing food. Reduced pecking rate was therefore taken as a measure of aversion. 2. In experiment 1, simultaneous motion and noise, but not noise alone, resulted in a significant decrease in pecking rate in comparison with baseline rates obtained after training. 3. In experiment 2 there was no significant difference in the pecking rates of 4 groups of broilers during training. However, after exposure to 1 of 4 types of motion, strongly significant differences in pecking rates were found between the groups. The mean latency to peak 3 times was significantly greater for birds exposed to gentle vibration, with a single jolt after 55 s, than for birds exposed to simple harmonic motion in either the horizontal or vertical plane. Birds exposed to circular motion in the horizontal plane had a significantly greater mean pecking latency than birds exposed to simple harmonic motion in the vertical plane. 4. Baseline latencies to keypeck in experiments 1 and 2 were longer than expected. In experiment 3 a direct comparison of baseline pecking was made between broilers and laying hens. The hens had significantly shorter pecking latencies.

Fracturing and stretching of angioplasty balloon catheters under bending with tension.

Eight catheters from five manufacturers have been subjected to tests which combined bending and tension. Three failure mechanisms have been identified. These included separation of the balloon from its proximal attachment to the shaft, fracture of the shaft at its junction with the balloon, and undue ductility of the shaft. It is concluded that good catheter design should ensure that there is no sudden change in stiffness along the length of the catheter, and that the optimum relationship of ductility to stiffness has not yet been defined for catheters. Recommendations relating to these characteristics could be included in the British Standards relating to angioplasty balloon catheters.

Equipment qualification using the serc earthquake simulator

Earthquakes simulators are commonly used in a primary research role to study the dynamic and seismic behavior of structures and for validating numerical structural analysis techniques. In commercial applications,earthquakes simulators are used for assessing the operational performance of safety - critical structures during simulated earthquakes. The science and Engineering Research Council EarthquakesSimulator and research facilities at the University of Bristol have been adaptedand upgraded for use in full-scale seismic qualification of equipment, and this paper describes some of the relevant standards and specifications and provides details of the experimental and management systems at Bristol (AU)

Assessment of angioplasty balloon catheters: further studies.

Eight millimetre diameter angioplasty balloon catheters of both the Gruntzig and Olbert types from five manufacturers have been tested in vitro to establish bursting pressures and the changes in maximum and deflated diameters following repeated inflations, both when free and within a restraining sleeve. Maximum inflated diameters were within 10% of that stated and all types of balloon except one burst at a pressure greater than the recommended value. Deflated diameters were approximately 1 mm greater than insertion diameters, which are much smaller in the Olbert type. All balloons became a little larger with each of the first few distensions, and became stiffer. The maximum diameter was reached and remained constant after 10-15 distensions. Distension within a latex sleeve did not change bursting pressures, and it is considered that results from unconstrained testing can be extrapolated to behaviour in vivo. Computer modelling and calculation of maximum stress resultants also showed that calculated longitudinal and circumferential stresses are unaffected by applied restrictions. It is concluded that balloon technology is steadily improving and it is suggested that British Standards should be established for dilatation balloon catheters. Amongst other factors these Standards should include maximum recommended inflation pressures that are at least 2 atm less than bursting pressures, whilst the stated maximum diameter should be for fully extended balloons, and should have a tolerance of more than +/- 10%.

Assessment of angioplasty balloon catheters: preliminary studies.

Gruntzig balloon catheters from three manufacturers have been tested in vitro to establish a method of assessing the diameters and bursting pressures of inflated balloons. The method of testing and of measuring the inflated balloons is described. It was found that there were considerable variations in the behaviour of different balloons, and the relevance of this to arterial rupture is discussed. There were significant associations between the manufacturer and premature rupture of the balloon (p less than 0.01), and between co-axial construction of the catheter and overdistension of the balloon by more than 20% (p less than 0.01). The balloon length and the stated maximum diameter were not associated with either premature failure or overdistension.