An artificial intelligence deep learning model for identification of small bowel obstruction on plain abdominal radiographs.

OBJECTIVES: Small bowel obstruction is a common surgical emergency which can lead to bowel necrosis, perforation and death. Plain abdominal X-rays are frequently used as a first-line test but the availability of immediate expert radiological review is variable. The aim was to investigate the feasibility of using a deep learning model for automated identification of small bowel obstruction. METHODS: A total of 990 plain abdominal radiographs were collected, 445 with normal findings and 445 demonstrating small bowel obstruction. The images were labelled using the radiology reports, subsequent CT scans, surgical operation notes and enhanced radiological review. The data were used to develop a predictive model comprising an ensemble of five convolutional neural networks trained using transfer learning. RESULTS: The performance of the model was excellent with an area under the receiver operator curve (AUC) of 0.961, corresponding to sensitivity and specificity of 91 and 93% respectively. CONCLUSION: Deep learning can be used to identify small bowel obstruction on plain radiographs with a high degree of accuracy. A system such as this could be used to alert clinicians to the presence of urgent findings with the potential for expedited clinical review and improved patient outcomes. ADVANCES IN KNOWLEDGE: This paper describes a novel labelling method using composite clinical follow-up and demonstrates that ensemble models can be used effectively in medical imaging tasks. It also provides evidence that deep learning methods can be used to identify small bowel obstruction with high accuracy.

Routes to diagnosis and missed opportunities in the detection of renal cancer.

AIM: To determine the proportion of renal cancers for which incidental detection was the route to diagnosis, the characteristics of tumours identified in this way, and the frequency with which opportunities to make this diagnosis were missed. MATERIALS AND METHODS: Consecutive patients with renal cancers treated at Royal Cornwall Hospitals NHS Trust (April 2011 and July 2018 inclusive) were identified from the Trust's cancer registry database, and a retrospective review of the imaging and electronic case notes was undertaken. Mann-Whitney U-tests for comparison of patient age and tumour size at diagnosis, and chi-squared tests for comparing cell type distribution and grade were performed. Logistic regression was then used to identify the characteristics of patients in whom a renal tumour was missed initially. RESULTS: Of 327 patients, 194 (63%) presented incidentally, and 133 (37%) symptomatically. Incidentally detected cancers were found in younger patients, (median of 65 years versus 69 p=0.01) and were smaller at presentation (median of 5.5 versus 7.2 cm, p<0.00001). Thirty-six different reporters missed opportunities to diagnose renal cancer in 50 (16%) patients on 78 occasions, 28 lesions (35%) being missed more than once. Thirty were imaged incompletely; four were visible only on a single image and three on a scout view at magnetic resonance imaging. CONCLUSION: The commonest route to diagnosis of renal cancer is by incidental detection of a mass. In 16% of patients in whom renal cancer is diagnosed, there is at least one prior examination on which the lesion is visible at an earlier date. The clinical impact of these missed diagnostic opportunities remains uncertain.

Case report: Thromboembolic and septic complications of migrated cyanoacrylate injected for bleeding gastric varices.

Endoscopic injection of N-butyl-2-cyanoacrylate combined with radio-opaque lipiodol is widely used to achieve haemostasis in bleeding gastric varices. We present a case of migration of injected cyanoacrylate, thrombus formation and subsequent septic embolisation.

An unusual complication of oesophageal stent deployment.

Insertion of a self-expanding metal stent is commonly used to palliate dysphagia secondary to oesophageal carcinoma. Displacement of the stent itself is a recognized complication which can result in perforation of the upper gastrointestinal tract. We report the first case of bowel obstruction and perforation resulting from the olive of the deployment system. This was probably due to peritoneal deposits on the small intestine obstructing passage of the olive.

Pineapple juice as a negative oral contrast agent in magnetic resonance cholangiopancreatography: a preliminary evaluation.

The quality of magnetic resonance cholangiopancreatography (MRCP) images is frequently degraded by high signal from the gastrointestinal tract. The aim of this study is to evaluate pineapple juice (PJ) as an oral negative contrast agent in MRCP. Preliminary in vitro evaluation demonstrated that PJ shortened T(2) relaxation time and hence decreased T(2) signal intensity on a standard MRCP sequence to a similar degree to a commercially available negative contrast agent (ferumoxsil). Electrothermal atomic absorption spectrometry assay demonstrated a high manganese concentration in PJ of 2.76 mg dl(-1), which is likely to be responsible for its T(2) imaging properties. MRCP was subsequently performed in 10 healthy volunteers, before and at 15 min and 30 min following ingestion of 400 ml of PJ. Images were assessed blindly by two Consultant Radiologists using a standard grading technique based on contrast effect (degree of suppression of bowel signal), and image effect (diagnostic quality). There were statistically significant improvements in contrast and image effect between pre and post PJ images. There was particularly significant improvement in visualization of the pancreatic duct, but no significant difference between 15 min and 30 min post PJ images. Visualization of the ampulla, common bile duct, common hepatic and central intrahepatic ducts were also significantly improved at 15 min following PJ. Our results demonstrate that PJ, may be used as an alternative to commercially available negative oral contrast agent in MRCP.

CT appearances of HIV-related lipodystrophy syndrome.

Highly active antiretroviral therapy in HIV-1 infected patients is associated with a lipodystrophy syndrome, characterized by wasting of peripheral fat, central adiposity, hyperlipidaemia and insulin resistance. The CT findings are presented and the differential diagnosis is discussed.

Core biopsy of the bowel wall: efficacy and safety in the clinical setting.

OBJECTIVE: The purpose of this study was to evaluate the efficacy and complications of percutaneous 18-gauge core biopsies of lesions of the bowel wall using CT and sonographic guidance. A retrospective study was made of 15 biopsy procedures performed on 12 patients with suspected neoplasia of the gastrointestinal tract. The biopsies were performed when there were no sites of metastatic disease more readily accessible to biopsy and the lesion was inaccessible to endoscopic techniques or when the endoscopic biopsy findings were negative. CONCLUSION: Three biopsy procedures provided inadequate samples and the biopsies were repeated, giving a total of 15 biopsy procedures. A tissue diagnosis was made in all 12 patients. All procedures were well tolerated, and no immediate or delayed complications occurred. Percutaneous core biopsy of bowel wall masses is a safe technique that allows a histologic diagnosis to be obtained in difficult cases when other methods cannot provide an adequate tissue sample.

Pain after small bowel meal and pneumocolon: a randomized controlled trial of carbon dioxide versus air insufflation.

AIM: To determine whether the use of CO2 rather than air insufflation results in less pain and/or distension in patients undergoing small bowel meal (SBM) and pneumocolon (PC). MATERIALS AND METHODS: One hundred patients for SBM and PC were randomized to receive either air or carbon dioxide (CO2) as the insufflating gas. Both the patient and radiologist were blinded to the gas being used. Patients were given a questionnaire to complete the following day. The degree and duration of abdominal pain and swelling were scored on a visual analogue scale from 0 to 100. RESULTS: Seventy-nine patients replied. The mean pain score was 28.1 for patients receiving air and 20.35 for those receiving CO2 (P < 0.05). The duration of pain was 9.0 h in the air group and 6.0 h in the CO2 group (P < 0.05). The mean abdominal swelling score was 27.1 for patients receiving air and 17.1 for those receiving CO2 (P < 0.05). The duration of swelling was 8.8 h in the air groups and 7.3 h in the CO2 group (P = 0.16). CONCLUSION: In patients presenting for SBM and PC, the severity and duration of abdominal pain and distension are significantly reduced by the use of CO2 rather than air.

Technical report: perirectal abscess drainage--a simple modification in technique using a vascular sheath.

Two patients with pelvic abscesses underwent fluoroscopic guided transrectal catheter drainage using a simple modification in standard technique. A 9F vascular sheath allows contrast to be instilled through the side port and the seal avoids any leakage back through the sheath. It also provides a safe, quick and precise needle puncture at the selected site.

Case report: intravascular lipoma of the superior vena cava--CT and MRI appearances.

Intravascular lipomata are rare tumours occurring in the major central veins. We report a case in which an asymptomatic lipoma of the superior vena cava presented as mediastinal widening on a chest radiograph. The CT and MR features are presented.

Computed tomography of the lung in Wegener's granulomatosis.

Computed tomography of the thorax was performed in 30 patients with Wegener's granulomatosis to define the anatomical basis of pulmonary involvement. A wide variety of parenchymal and bronchial abnormalities was demonstrated in addition to the cavitary nodules commonly described. The high incidence (40%) of bronchial abnormalities in these patients may suggest that bronchocentric injury is more important in the pathogenesis of lung involvement in this disease than has previously been considered. Serial scans in individual patients showed broad correlation between the extent of the pulmonary abnormalities and the clinical and immunological markers of disease activity.

Artifacts in the ascending aorta on computed tomography: another measure of aortic distensibility?

The appearance of the ascending aorta was studied in 53 patients undergoing computed tomography on a modern system capable of routine 1 second data acquisition times. Motion artifact caused a blurred aortic outline in 48 patients; the extent was objectively and subjectively assessed. The maximum and minimum cross-sectional aortic areas were measured at the margins of the blur. The area of the blur, expressed as a fraction of the minimum aortic cross-sectional area, decreased with age (P < 0.001) and was significantly smaller in the 13 patients with known cardiovascular problems (P < 0.05). These findings were substantiated by the subjective gradings which showed less marked artifacts amongst elderly patients (although this observation did not reach statistical significance). Artifacts were less prominent in 16 patients with evidence of aortic wall calcification, both on subjective grading (P < 0.05) and formal area measurements (P < 0.05). These observations lead us to believe our postulation that this artifact is an indicator of aortic distensibility and thus, indirectly, of cardiovascular status.

Radiology for cochlear implants.

One fifth of patients selected for cochlear implants have such bony irregularities in the cochlear duct that full insertion of a multichannel electrode array is impossible. Three cases of cochlear deafness are presented where pre- and post-operative radiology played an important part in the management. Standard CT at 2 mm cuts is compared with ultra high resolution CT at 1 mm cuts. The pitfall of poor definition is that the inexperienced surgeon may find himself unexpectedly drilling out an obliterated cochlear duct. Sections 30 degrees caudal to Reid's infra orbito-meatal base line at 1 mm intervals give maximum information for minimum radiation. Plain films show the placement of individual platinum electrode contacts in relation to the spiral 'frequency map' of the cochlea. This is vital information for the audiologist who has to route specific frequencies to specific sites within the ear for a good hearing result.