Ultrasonography in diagnosing chronic pancreatitis: New aspects

The course and outcome is poor for most patients with pancreatic diseases.Advances in pancreatic imaging are important in the detection of pancreatic diseases at early stages.Ultrasonography as a diagnostic tool has made,virtually speaking a technical revolution in medical imaging in the new millennium.It has not only become the preferred method for first line imaging,but also,increasingly to clarify the interpretation of other imaging modalities to obtain efficient clinical decision.We review ultrasonography modalities,focusing on advanced pancreatic imaging and its potential to substantially improve diagnosis of pancreatic diseases at earlier stages.In the first section,we describe scanning techniques and examination protocols.Their consequences for image quality and the ability to obtain complete and detailed visualization of the pancreas are discussed.In the second section we outline ultrasonographic characteristics of pancreatic diseases with emphasis on chronic pancreatitis.Finally,new developments in ultrasonography of the pancreas such as contrast enhanced ultrasound and elastography are enlightened.

Sonography of the small intestine

In the last two decades, there has been substantial development in the diagnostic possibilities for examining the small intestine. Compared with computerized tomography, magnetic resonance imaging, capsule endoscopy and double-balloon endoscopy, ultrasonography has the advantage of being cheap, portable, flexible and user-and patient-friendly, while at the same time providing the clinician with image data of high temporal and spatial resolution. The method has limitations with penetration in obesity and with intestinal air impairing image quality. The flexibility ultrasonography offers the examiner also implies that a systematic approach during scanning is needed. This paper reviews the basic scanning techniques and new modalities such as contrast-enhanced ultrasound, elastography, strain rate imaging, hydrosonography, allergosonography, endoscopic sonography and nutritional imaging, and the literature on disease-specific findings in the small intestine. Some of these methods have shown clinical benefit, while others are under research and development to establish their role in the diagnostic repertoire. However, along with improved overall image quality of new ultrasound scanners, these methodshave enabled more anatomical and physiological changes in the small intestine to be observed. Accordingly, ultrasound of the small intestine is an attractive clinical tool to study patients with a range of diseases.

Endocrine cells in the oxyntic mucosa of the stomach in patients with irritable bowel syndrome

AIM: To study the different endocrine cell types in the oxyntic mucosa of patients with irritable bowel syndrome(IBS).METHODS: Seventy-six patients with IBS were included in the study(62 females and 14 males; mean age 32 years, range 18-55 years), of which 40 also fulfilled the Rome Ⅲ criteria for functional dyspepsia(FDP). Of the entire IBS cohort, 26 had diarrhea as the predominant symptom(IBS-D), 21 had a mixture of diarrhea and constipation(IBS-M), and 29 had constipation as the predominant symptom(IBS-C). Fortythree age and sex-matched healthy volunteers withoutany gastrointestinal complaints served as controls. The patients were asked to complete the Birmingham IBS symptom questionnaire. Both the patients and controls underwent a standard gastroscopy, during which three biopsy samples were taken from the corpus. Sections from these biopsy samples were immunostained using the avidin-biotin complex(ABC) method, for ghrelin, serotonin, somatostatin and histamine. The densities of these cell types and immunoreactivity intensities were quantified using computerized image analysis with Olympus cellSens imaging software(version 1.7).RESULTS: The densities of the ghrelin cells in the control, IBS-total, IBS-D, IBS-M and IBS-C groups were 389(320, 771), 359(130, 966), 966(529, 1154), 358(120, 966) and 126(0, 262) cells/mm2, respectively. There was a significant difference between the tested groups(P < 0.0001). Dunn's multiple comparison test showed that the ghrelin cell density was significantly higher in IBS-D and lower in IBS-C than in the controls(P = 0.03 and 0.0008, respectively). The ghrelin cell density in patients with both IBS and FDP was 489(130, 966), and in those with IBS only 490(130, 956). There was no statistical significant difference between these 2 groups of patients(P = 0.9). The immunoreactivity intensity did not differ between any of the groups(P = 0.6). The diarrhea score of the Birmingham IBS symptom questionnaire was significantly positively correlated with ghrelin cell density(r = 0.65; P < 0.0001) and significantly inversely correlated with that of constipation(r = 90.69; P < 0.0001). The densities of the serotonin cells were 63(51, 82), 51(25, 115), 120(69, 128), 74(46, 123) and 40(0, 46) cells/mm2 in the control, IBS-total, IBS-D, IBS-M and IBS-C groups, respectively. A statistically significant difference was found between the tested groups(P < 0.0001). Posttest revealed that serotonin cell density was significantly higher in IBS-D and lower in IBS-C than in controls(P = 0.02 and 0.004, respectively), but did not differ in the IBS-total and IBS-M groups from that in controls(P = 0.5 and 0.4, respectively). The serotonin cell densityin patients with both IBS and FDP was 62(25, 115)and in those with IBS only 65(25, 123). There was no statistically significant difference between these2 groups of patients(P = 1). The immunoreactivity intensity of serotonin did not differ significantly between any of the groups(P = 0.0.9). The serotonin cell density was significantly positively correlated with the diarrhea score of the Birmingham IBS symptom questionnaire(r = 0.56; P < 0.0001) and significantly inversely correlated with that of constipation(r = 0.51;P < 0.0001). The densities of the somatostatin cells were 97(72, 126), 72(0, 206), 29(0, 80), 46(0, 103)and 206(194, 314) cells/mm2 in the control, IBS-total,IBS-D, IBS-M and IBS-C groups, respectively(Figures7 and 8). There was a statistically significant difference between the controls and the IBS subgroups(P <0.0001). The density of somatostatin cells was significantly lower in the IBS-D and IBS-M groups but higher in IBS-C patients than in the controls(P < 0.01, P =0.02, and P = 0.0008, respectively). The somatostatin cell density in patients with both IBS and FDP was 86(0-194), and in those with IBS only 110(0-206). There was no statistically significant difference between these 2 groups of patients(P = 0.6). There was no significant difference in somatostatin immunoreactivity intensity between the controls. The diarrhea score of the Birmingham IBS symptom questionnaire was inversely correlated with somatostatin cell density(r =0.38; P = 0.0007) and was positively correlated with that of constipation(r = 0.64; P < 0.0001).CONCLUSION: The finding of abnormal endocrine cells in the oxyntic mucosa shows that the endocrine cell disturbances in IBS are not restricted to the intestine. Furthermore, it appears that ghrelin, serotonin and somatostatin in the oxyntic mucosa of the stomach may play an important role in the changing stool habits in IBS through their effects on intestinal motility.

Morphology and motor function of the gastrointestinal tract examined with endosonography

Endosonography is a useful tool for studying the morphology and motor function of the gastrointestinal tract. Intraluminal ultrasonography is the common denomination of ultrasound examinations using intracorporal transducers which are inserted into the GI tract. Thus, the visceral wall and adjacent structures can be imaged in detail. This review describes the usefulness of endosonography in gastroenterology, in particular with respect to studies of the biomechanical and motor function of the gastrointestinal tract. New techniques such as 3-D EUS, elastography and strain rate imaging are discussed.

Mucosal blood flow measurements using laser Doppler perfusion monitoring

Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insuff iciency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of pe- ripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastroin-testinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

Advanced imaging and visualization in gastrointestinal disorders

Advanced medical imaging and visualization has a strong impact on research and clinical decision making in gastroenterology. The aim of this paper is to show how imaging and visualization can disclose structural and functional abnormalities of the gastrointestinal (GI) tract. Imaging methods such as ultrasonography, magnetic resonance imaging (MRI), endoscopy, endosonography, and elastography will be outlined and visualization with Virtual Reality and haptic methods. Ultrasonography is a versatile method that can be used to evaluate antral contractility, gastric emptying, transpyloric flow, gastric configuration, intragastric distribution of meals, gastric accommodation and strain measurement of the gastric wall. Advanced methods for endoscopic ultrasound, three-dimensional (3D) ultrasound, and tissue Doppler (Strain Rate Imaging) provide detailed information of the GI tract. Food hypersensitivity reactions including gastrointestinal reactions due to food allergy can be visualized by ultrasonography and MRI. Development of multi-parametric and multi-modal imaging may increase diagnostic benefits and facilitate fusion of diagnostic and therapeutic imaging in the future.

Gastric accommodation assessed by ultrasonography

Gastric accommodation is important for the understanding of the pathophysiology in functional dyspepsia and is also relevant for symptom generation in other disorders. The term gastric accommodation has at least three different meanings： The accommodation process, the accommodation reflex, and the accommodation response. The gastric accommodation process is a complex phenomenon that describes how the size of the gastric compartment changes in response to a meal. The electronic barostat is considered the gold standard in assessing gastric accommodation. Imaging methods, including MRI, SPECT, and ultrasonography may also be used, particularly in patients who are stress-responsive, e.g. functional dyspepsia patients, as a non-invasive and less stress-inducing method is favourable. Ultrasonography satisfies these criteria as it does not by itself distort the physiological response in stress-responsive individuals.