Intraluminal sonography in the diagnosis of gastrointestinal diseases

Endosonography is an imaging method whereby a high frequency ultrasound probe is inserted into a body cavity with or without under endoscopic control. Examination of the gastrointestinal tract is performed using special echo-endoscopes or trans-endoscopic mini-probes. The gastrointestinal wall, mediastinum, pancreas, bile ducts, retroperitoneum, and other structures surrounding the gastrointestinal tract are target organs for endosonography. A detailed image of pathological processes can thus be obtained. The method can be used both for primary diagnosis of lesions and in follow-up of gastrointestinal diseases. It is accurate in local staging of cancer and in detecting small lesions. There are some limitations for optimal examination like stenoses or other factors prohibiting a precise positioning of the ultrasound transducer. The clinical importance of endo-sonographic examinations must be continuously evaluated on the basis of new technical modalities and changes in therapeutic procedures.     

Use of single-dose ofloxacin to eradicate tonsillopharyngeal carriage of Neisseria meningitidis.

After an outbreak of three cases of serogroup B meningococcal disease at a Norwegian college, 84 of 392 (21%) subjects were tonsillopharyngeal carriers of Neisseria meningitidis. To eradicate meningococcal carriage, 80 volunteers received a single dose of 400 mg of ofloxacin. Three days after treatment, all 75 evaluable volunteers were culture negative for N. meningitidis, and after 7 days none carried the strain that they carried initially, as judged by DNA fingerprinting. A single dose of ofloxacin was found to be 97.2% effective in eradicating carriage of N. meningitidis for a period of 33 days. The carriage acquisition rate among treated students was four times higher than that among nontreated noncarriers (P = 0.02). After ofloxacin treatment, no case of meningococcal disease occurred for 6 months. Ofloxacin may thus prevent the outbreak and spread of meningococcal disease.     

Freehand real-time elastography: impact of scanning parameters on image quality and in vitro intra- and interobserver validations

Real-time elastography is a method for visualization of the elastic properties of soft tissue and may potentially enable differentiation between malignant and benign pathologic lesions. Our aim was to validate the method on a tissue-mimicking (TM) phantom and to evaluate the influence of different scanning parameters and investigator variability. A TM-phantom containing eight spherical inclusions with known storage modulus was examined using two different transducers on an ultrasound (US) scanner equipped with software for real-time elasticity imaging. The ultrasound transducers were moved vertically in a repetitive manner to induce strain. Two investigators performed series of standardized elastography scans applying a 0-4 categorical quality scale to evaluate the influence of seven parameters: dynamic range of elasticity, region-of-interest, frequency of transducer movement, rejection of elastogram noise, frame rate, persistence and smoothing. Subsequently, repeated examinations of four selected inclusions were performed using a visual analog scale (VAS) where investigators marked a 100 mm horizontal line representing the span in image quality based on experience from the first examination. The hardest and softest inclusions were imaged more clearly than the inclusions with elasticity more similar to the background material. Intraobserver agreement on elastogram quality was good (kappa: 0.67 - 0.75) and interobserver agreement average (kappa: 0.55 - 0.56) when using the categorical scale. The subsequent VAS evaluation gave intraclass-correlation coefficients for the two observers of 0.98 and 0.93, respectively, and an interclass-correlation coefficient of 0.93. Real-time elastography adequately visualized isoechoic inclusions with different elastic properties in a TM-phantom with acceptable intra- and interobserver agreement. Dynamic range of elasticity was the parameter with most impact on the elastographic visualization of inclusions.     

In vitro volume estimation of kidneys using three-dimensional ultrasonography and a position sensor.

OBJECTIVE: A new 3D ultrasound system using a position sensor based on magnetic scanhead tracking and new software utilising automatic contour tracing between manually traced contours was tested for volume estimation of kidneys in vitro. METHODS: Kidneys from piglets and pigs were fixed in formaldehyde. A reservoir with 0.9% saline kept at 37 degrees C was used. The kidneys were scanned either by a linear translational movement along the organ or by a tilting movement. The outer contour of the kidneys was traced manually, by two independent investigators. The volume of each kidney was also measured using the Archimedes principle (true volumes). RESULTS: Good agreement between 3D ultrasound volume estimates and true volumes was found for both probe movements. For translational movement of the transducer, the mean errors between the methods were 4.17 and 4.31 ml for the two independent investigators, and the volume range was 96-203 ml. The corresponding error values for tilting movement were 1.10 and 0.19 ml. The interobserver variation was also small, there was no difference in the volumes obtained by the two investigators, or by the two scanning movements. CONCLUSION: Volume estimates using this 3D ultrasound method showed very good agreement with true volumes, both mean errors and interobserver variation were low.     

Effect of Glyceryl Trinitrate on Gastric Accommodation and Symptoms in Functional Dyspepsia

The purpose of this study was to investigatewhether sublingual glyceryl trinitrate influences thesize of the proximal stomach and postprandial symptomsin patients with functional dyspepsia. Twenty patients with functional dyspepsia were included in adouble-blind, placebo-controlled crossover study withsublingual glyceryl trinitrate. All patients werescanned twice on consecutive days, receiving eitherplacebo or 0.5 mg glyceryl trinitrate randomly 5 minprior to ingestion of 500 ml meat soup. Total symptoms,pain, nausea, and bloating were scored on a visualanalog scale before and after the meal. Standardized ultrasonograms were obtained 1, 10, and 20 minpostprandially of the proximal and distal stomach. Theproximal stomach was larger in the sagittal section at1 min postcibally (26.5 ± 3.9 vs 24.8 ±4.9 cm², P = 0.036) and 10 min postprandially (22.0± 5.1 vs 19.8 ± 5.3 cm², P =0.009) after administration of glyceryl trinitratecompared with placebo, whereas a tendency was observedafter 20 min (18.7 ± 5.5 vs 17.3 ± 5.7 cm², P = 0.076). The correspondingchanges in the frontal diameters were 8.3 ± 1.1vs 7.8 ± 1.2 cm (P = 0.067) after 1 min, 7.2± 0.9 vs 6.4 ± 0.8 cm (P = 0.001) after 10min, and 6.3 ± 1.1 vs 5.6 ± 1.2 cm (P =0.016) after 20 min. The area of the distal stomach was notdifferent (P = 0.31) in the two groups. Afteradministration of glyceryl trinitrate, the patientsreported less pain (P = 0.048) and nausea (P = 0.023) 5min postprandially, but this effect was reduced 15min later. Total symptom score was improved by glyceryltrinitrate treatment (P = 0.042). Sublingual glyceryltrinitrate improves accommodation of the proximal stomach to a meal and reduces postprandialsymptoms in a group of patients with functionaldyspepsia.     

Multimodal approach to assess tumour vasculature and potential treatment effect with DCE‐US and DCE‐MRI quantification in CWR22 prostate tumour xenografts

The aim of this study was to compare intratumoural heterogeneity and longitudinal changes assessed by dynamic contrast‐enhanced ultrasound (DCE‐US) and dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) in prostate tumour xenografts. In vivo DCE‐US and DCE‐MRI were obtained 24 h pre‐ (day 0) and post‐ (day 2) radiation treatment with a single dose of 7.5 Gy. Characterization of the tumour vasculature was determined by Brix pharmacokinetic analysis of the time–intensity curves. Histogram analysis of voxels showed significant changes (p < 0.001) from day 0 to day 2 in both modalities for k_ep, the exchange rate constant from the extracellular extravascular space to the plasma, and k_el, the elimination rate constant of the contrast. In addition, k_ep and k_el values from DCE‐US were significantly higher than those derived from DCE‐MRI at day 0 (p < 0.0001) for both groups. At day 2, k_el followed the same tendency for both groups, whereas k_ep showed this tendency only for the treated group in intermediate‐enhancement regions. Regarding k_ep median values, longitudinal changes were not found for any modality. However, at day 2, k_ep linked to DCE‐US was correlated to MVD in high‐enhancement areas for the treated group (p = 0.05). In contrast, correlation to necrosis was detected for the control group in intermediate‐enhancement areas (p < 0.1). Intratumoural heterogeneity and longitudinal changes in tumour vasculature were assessed for both modalities. Microvascular parameters derived from DCE‐US seem to provide reliable biomarkers during radiotherapy as validated by histology. Furthermore, DCE‐US could be a stand‐alone or a complementary technique. Copyright © 2015 John Wiley & Sons, Ltd.     

Ultrasonography in gastroenterology

Abstract

Ultrasonography (US) is a safe and available real-time, high-resolution imaging method, which during the last decades has been increasingly integrated as a clinical tool in gastroenterology. New US applications have emerged with enforced data software and new technical solutions, including strain evaluation, three-dimensional imaging and use of ultrasound contrast agents. Specific gastroenterologic applications have been developed by combining US with other diagnostic or therapeutic methods, such as endoscopy, manometry, puncture needles, diathermy and stents. US provides detailed structural information about visceral organs without hazard to the patients and can play an important clinical role by reducing the need for invasive procedures. This paper presents different aspects of US in gastroenterology, with a special emphasis on the contribution from Nordic scientists in developing clinical applications.     

Demonstration of pre-S polypeptides of hepatitis B virus in infected livers

The large (pre-S1), middle (pre-S2) and major (P24) polypeptides of HBsAg have been defined in detail, but their role in hepatitis B virus infection is not known. Therefore, we studied the expression of pre-S1, pre-S2 and P24 in the liver of 15 patients with acute or chronic hepatitis B virus infection using monoclonal and polyclonal antibodies in a double staining immunofluorescence method. The pre-S and major HBsAg polypeptides were co-expressed in the hepatocyte cytoplasm of all patients except for one case of chronic active hepatitis and cirrhosis. HBcAg was present in hepatocyte nuclei of nine patients suggestive of active hepatitis B virus replication. These studies support the hypothesis that the pre-S polypeptides represent essential components of the envelope of hepatitis B virus.     

Impaired accommodation of proximal stomach to a meal in functional dyspepsia

In patients with functional dyspepsia, scanning by a novel ultrasonographic method was carried out to investigate postprandial accommodation of the proximal stomach. Twenty patients with functional dyspepsia and 20 controls were scanned fasting in a sitting position after drinking 500 ml meat soup. Images were recorded up to 25 min after the ingestion period using an ultrasound sector scanner with a 3.25-MHz transducer. The area in a sagittal section and the maximal diameter in an oblique frontal section were chosen as the main variables for calculating the emptying fraction of the proximal stomach, defined as: (aV _2.5min-aV _actual/aV _2.5min. All subjects were asked to score total symptoms (1–9) provoked by the meal. From 7.5 to 25 min after the ingestion period the patients exhibited both smaller area in the sagittal section (P<0.018) and shorter diameter in the frontal section (P<0.046) compared with healthy controls, and they suffered more symptoms in response to the meal (P=0.002). Dyspeptic patients revealed higher emptying fractions (P=0.0005, ANOVA), andH. pylori status did not influence the emptying fractions. Diagnostic sensitivity of the method at 20 min postprandially was 70% and the specificity was 65%. Patients with functional dyspepsia have impaired accommodation of the proximal stomach to a meal, temporarily related to symptom induction.     

Abdominal ultrasound after colonoscopy with insufflation of carbon dioxide versus air

Objective. To investigate whether the use of carbon dioxide (CO₂) compared with air insufflation during colonoscopy improves ultrasonography after the procedure. Material and methods. In a double-blind trial, 30 patients were randomized to insufflation with CO₂ or air. Thirty minutes after colonoscopy abdominal ultrasound was performed. Immediately after ultrasonography, the ultrasound quality of the liver, gallbladder, biliary ducts, pancreas, spleen, kidneys, abdominal vessels, antrum, bowel, urinary bladder and prostate/uterus was evaluated for optimal ultrasound scanning quality, minor reduction of scanning conditions, major reduction of scanning conditions and unacceptable scanning conditions. Results. Ultrasound quality 30 min after colonoscopy was significantly better when using CO₂ insufflation instead of air (p<0.003). Significant improvement in imaging quality was observed for the liver, portal vein, splenic vein, all three divisions of the pancreas, aorta, coeliac trunk, superior mesenteric artery, iliac vessels, left kidney and uterus. Conclusions.Ultrasound investigation can be done after a colonoscopy with CO₂ insufflation, whereas it is not recommended after a colonoscopy with air insufflation. In selected cases, this approach may enable and improve post-colonoscopy ultrasound scanning.