Svein Odegaard | University of Bergen (original) (raw)
Papers by Svein Odegaard
Scandinavian Journal of Gastroenterology, 1998
Dieulafoy's vascular malformation may cause severe, potentially life-thre... more Dieulafoy's vascular malformation may cause severe, potentially life-threatening gastrointestinal bleeding. Endoscopic diagnosis may be difficult because of minute mucosal lesions, and additional intramural abnormalities are usually not encountered. Endoluminal high-frequency ultrasonography is a new modality for imaging intramural and perivisceral structures. We report two cases of recurrent severe gastric bleeding in which different endosonographic modalities were used in the diagnosis of Dieulafoy's malformation, and the impact of endosonography on therapeutic strategy is discussed. In the first case a radial-scanning 7.5/12-MHz echoendoscope and a linear 20-MHz miniature probe were applied for B-mode imaging in a stable-state patient who had undergone previous endoscopic sclerotherapy, and arterial flow signals from the small intramural lesion were recorded using a 10-MHz transendoscopic pulsed Doppler probe. In the other case urgent endosonography was performed shortly after a bleeding episode, disclosing an aberrant large-calibre artery entering the gastric wall with a long submucosal branch. Both patients were successfully operated on with a transabdominal approach. Endosonography is a quick and safe diagnostic method and should be considered when vascular malformations are suspected as the cause of gastric bleeding.
Ultraschall in der Medizin - European Journal of Ultrasound, 2012
Subject headings gastric emptying; stomach/ ultrasonography; stomach/pathophysiology A number of ... more Subject headings gastric emptying; stomach/ ultrasonography; stomach/pathophysiology A number of different methods have been used to estimate gastric emptying in humans, and all have their advantages and disadvantages. The method of choice will depend on whether solid or liquid meals are studied, the level of precision required, the degree of invasiveness that the subject or patient will tolerate, ethical considerations, and not at least the facilities available. Scintigraphy, with appropriate labelling of the test meal components and appropriate corrections applied, is considered so far the gold standard for measurement of gastric empty ing. However, its application is limited by the need to restrict exposure to ion ising radiation. Other methods are gastric aspiration techniques, radiography, ultrasonography, magnetic resonance imaging, epigastric impedance measurements, applied potential tomography, tracer methods (e.g. paracetamol), and breath tests. Regardless of the method used, the investigator must be aware of the limitations of the method in use, the large inter-individual variability and of the facto rs known to influence gastric emptying.
European Journal of Ultrasound, 1998
Tidsskrift for den Norske laegeforening
We examined the usefulness and image quality of a mobile miniaturised ultrasound scanner in a med... more We examined the usefulness and image quality of a mobile miniaturised ultrasound scanner in a medical ward. The instrument (SonoSite 180), weighing 2.4 kg, is a hand-carried system powered by batteries. In 25 days we recruited consecutively 36 patients aged 23-92. Four different operators evaluated the use of the scanner. We examined one group of patients with relatively simple diagnostic challenges (e.g. gallbladder stone) and one group of patients demanding more advanced visualisation (e.g. peptic ulcer, colitis). The scanner was easy to carry around and scanning was initiated in 10 seconds. We found satisfactory image quality on 81% of the examinations, despite the fact that in 28% of cases, bowel air and abdominal fat impaired acoustic penetration. Average scanning time was 7 +/- 3 minutes. In 83% of cases, mobile scanning adequately solved the clinical problem. Diagnostic work-up or treatment was changed because of scanning in 39% of the patients. In 64% of cases, standard-proc...
Studies in health technology and informatics
This paper describes a method for the acquisition and integrative processing of laparoscopic and ... more This paper describes a method for the acquisition and integrative processing of laparoscopic and endoluminal ultrasound images. We used a stepping motor attached to a stabilizing rig, interfaced to the laparoscope, or the ultrasound probe. 360 degrees laparoscopic scenes were constructed during minimally invasive surgery, and three-dimensional reconstructions were made of related ultrasound data. Integration of 360 degrees panoramas with geometric ultrasound models could be displayed as interactive scenes. This resulted in a better demonstration of the surgical field and topographic anatomy. In conclusion, this type of visualizations may be used in virtual reality simulations for documentation, education and in operative planning.
Tidsskrift for Den norske legeforening
If an ultrasound probe comes close to the area of interest, high ultrasound frequencies can be ap... more If an ultrasound probe comes close to the area of interest, high ultrasound frequencies can be applied. Endoscopic ultrasonography is performed by means of echoendoscopes or miniature probes using ultrasound frequencies between 7 and 30 MHz. A high frequency ultrasound image of the normal gastrointestinal wall usually shows five layers corresponding closely to the histological layers of the wall. Corrections have to be made, however, for interface echoes between layers with different acoustic impedances. We describe studies performed with the aim of correlating ultrasound images of the normal and diseased gastrointestinal wall with the histology. Ultrasound images of the normal gastrointestinal wall and pathological changes like ischemia, ulcers, tumours and inflammation are presented.
Ultraschall in der Medizin
Endosonography is an imaging method whereby a high frequency ultrasound probe is inserted into a ... more 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 pr...
Scandinavian Journal of Gastroenterology
Dieulafoy's vascular malformation may cause severe, potentially life-threatening gastrointest... more Dieulafoy's vascular malformation may cause severe, potentially life-threatening gastrointestinal bleeding. Endoscopic diagnosis may be difficult because of minute mucosal lesions, and additional intramural abnormalities are usually not encountered. Endoluminal high-frequency ultrasonography is a new modality for imaging intramural and perivisceral structures. We report two cases of recurrent severe gastric bleeding in which different endosonographic modalities were used in the diagnosis of Dieulafoy's malformation, and the impact of endosonography on therapeutic strategy is discussed. In the first case a radial-scanning 7.5/12-MHz echoendoscope and a linear 20-MHz miniature probe were applied for B-mode imaging in a stable-state patient who had undergone previous endoscopic sclerotherapy, and arterial flow signals from the small intramural lesion were recorded using a 10-MHz transendoscopic pulsed Doppler probe. In the other case urgent endosonography was performed shortly ...
Ultraschall in der Medizin - European Journal of Ultrasound, 2012
Ultrasound in Medicine & Biology, 2011
European journal of ultrasound : official journal of the European Federation of Societies for Ultrasound in Medicine and Biology, 2002
To diagnose and characterize subepithelial lesions of the gastrointestinal (GI) tract using endos... more To diagnose and characterize subepithelial lesions of the gastrointestinal (GI) tract using endoscopic ultrasonography (EUS) and search for markers of malignancy in stromal cell tumors. Fifty-four patients with suspected subepithelial lesions at endoscopy were examined using miniature ultrasound probes, integrated ultrasound endoscopes, or both. Surgical treatment was considered if a solid lesion had a maximum diameter of at least 3 cm, mixed echogenicity, or an ill-defined or irregular border. EUS disclosed 37 solid lesions and ten fluid-filled structures. In seven patients, including two with protrusion from a normal spleen, no pathology could be demonstrated. Thirteen patients were operated and 41 were observed clinically with (n = 9) or without EUS (n = 32) for a median follow-up period of 36 months. Twenty-three patients had an intramural stromal cell tumor. None of these were malignant, but increased mitotic activity was found in two medium-sized resected tumors with mixed ech...
European journal of ultrasound : official journal of the European Federation of Societies for Ultrasound in Medicine and Biology, 2002
Objective assessment of adverse reactions to food is a long-felt want. We report our preliminary ... more Objective assessment of adverse reactions to food is a long-felt want. We report our preliminary experience with a new endosonographic allergen provocation test. Twenty patients were examined, seven patients having food allergy and 13 having food intolerance. The duodenal mucosa was challenged with allergen extracts via a nasoduodenal tube. The responses were recorded using a miniprobe for endosonography through the tube. Thereafter, intestinal lavage was performed by giving 2 l PEG solution containing micro Ci (51)CrEDTA. The gut lavage fluid and urine for 5 h were collected. Increased mucosal thickness in response to provocation was recorded in 11 patients, but not more often or pronounced in the allergic than in the intolerance group. Interestingly, increased mucosal thickness associated with a new echogenic layer was seen in two patients and a sustained duodenal contraction, lasting 15-20 min associated with pain, in another two. Intestinal permeability and inflammatory mediator...
Scandinavian Journal of Gastroenterology, 2015
Ultrasonography (US) is a safe and available real-time, high-resolution imaging method, which dur... more 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.
Digestive diseases and sciences, 1997
Following cholecystectomy for uncomplicated gallstone disease (GS) some patients experience persi... more Following cholecystectomy for uncomplicated gallstone disease (GS) some patients experience persistent symptoms suggesting an underlying functional disorder. To study this phenomenon, we have compared symptomatic GS with functional dyspepsia (FD) patients and healthy individuals (C) with respect to putative pathogenetic mechanisms. Gallbladder and gastric antrum volumes were estimated with three-dimensional (3D) ultrasonography before and 10 min after ingestion of 500 ml meat soup in 18 patients with GS. Volume estimation was performed digitally after interactive manual tracing and organ reconstruction in three dimensions. Respiratory sinus arrhythmia (RSA) was calculated to index vagal tone. Abdominal symptoms were assessed by interview. The results were compared to previously published data in patients with FD and C investigated with the exact same methods. No significant differences were found between groups with respect to fasting gallbladder or gallbladder emptying. Antral volu...
Ultrasound in Medicine and Biology, 2006
Strain rate imaging (SRI) enables study of deformation in soft tissues. The aim of this study was... more Strain rate imaging (SRI) enables study of deformation in soft tissues. The aim of this study was to evaluate the accuracy of SRI in measuring strain in the porcine antral wall in vitro. An experimental set-up enabled controlled distension of a porcine stomach in a saline reservoir. Radial strain obtained by SRI was compared with radial strain calculated from B-mode
European Journal of Ultrasound, 1995
Objective: Severe arterial bleeding from the gastrointestinal (GI) wall usually arises from submu... more Objective: Severe arterial bleeding from the gastrointestinal (GI) wall usually arises from submucosal or subserosal arteries. Endosonography (EUS) is a method which can image small structures like GI wall vessels and, thus, has potential for improving the diagnosis and directing the therapy of vascular disorders of the β tract. Furthermore, ultrasonography is increasingly used in open and laparoscopic surgery to
Doppler strain rate imaging (SRI) was evaluated in vitro using a silicone strip phantom mimicking... more Doppler strain rate imaging (SRI) was evaluated in vitro using a silicone strip phantom mimicking slowly moving tissue. A test apparatus was developed that enabled controlled strain experiments with variable strain and strain rate to be performed. SRI strain was measured at eight different calculated strains (range 5.7 to 63.4 %) at three different pump speeds with tissue velocity 0.1, 0.5 and 1.0 mm/s. The effect of varying tissue velocity and strain sample size on the measured SRI strain was elaborated. SRI strains agreed well with calculated values for strain when SRI strain was measured as the average over the whole strip cross-section and the strain sample size was 1.9 mm (mean difference ؍ 2.78%, limits of agreement ؎ 9.97% for tissue velocity 1.0 mm/s, n ؍ 8). The variance was substantial if single central samples were used, especially for strain sample size of 0.8 mm (mean difference ؍ ؊7.47%, limits of agreement ؎ 20.90 for tissue velocity 0.5 mm/s, n ؍ 24). Increasing the strain sample size to 1.9 mm removed some of the underestimation (giving mean difference of ؊4.46%, n ؍ 24). We found low intra-and interobserver variation. This study indicates that, for the SRI method to give accurate estimates of strain, strain sample size should be in the region of 2 mm. Averaging over several ultrasound (US) beams increased the accuracy further.(E-mail: Knut.Matre@med.uib.no)
In the last two decades, there has been substantial development in the diagnostic possibilities f... more 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 methods have 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.
Scandinavian Journal of Gastroenterology, 1998
Dieulafoy's vascular malformation may cause severe, potentially life-thre... more Dieulafoy's vascular malformation may cause severe, potentially life-threatening gastrointestinal bleeding. Endoscopic diagnosis may be difficult because of minute mucosal lesions, and additional intramural abnormalities are usually not encountered. Endoluminal high-frequency ultrasonography is a new modality for imaging intramural and perivisceral structures. We report two cases of recurrent severe gastric bleeding in which different endosonographic modalities were used in the diagnosis of Dieulafoy's malformation, and the impact of endosonography on therapeutic strategy is discussed. In the first case a radial-scanning 7.5/12-MHz echoendoscope and a linear 20-MHz miniature probe were applied for B-mode imaging in a stable-state patient who had undergone previous endoscopic sclerotherapy, and arterial flow signals from the small intramural lesion were recorded using a 10-MHz transendoscopic pulsed Doppler probe. In the other case urgent endosonography was performed shortly after a bleeding episode, disclosing an aberrant large-calibre artery entering the gastric wall with a long submucosal branch. Both patients were successfully operated on with a transabdominal approach. Endosonography is a quick and safe diagnostic method and should be considered when vascular malformations are suspected as the cause of gastric bleeding.
Ultraschall in der Medizin - European Journal of Ultrasound, 2012
Subject headings gastric emptying; stomach/ ultrasonography; stomach/pathophysiology A number of ... more Subject headings gastric emptying; stomach/ ultrasonography; stomach/pathophysiology A number of different methods have been used to estimate gastric emptying in humans, and all have their advantages and disadvantages. The method of choice will depend on whether solid or liquid meals are studied, the level of precision required, the degree of invasiveness that the subject or patient will tolerate, ethical considerations, and not at least the facilities available. Scintigraphy, with appropriate labelling of the test meal components and appropriate corrections applied, is considered so far the gold standard for measurement of gastric empty ing. However, its application is limited by the need to restrict exposure to ion ising radiation. Other methods are gastric aspiration techniques, radiography, ultrasonography, magnetic resonance imaging, epigastric impedance measurements, applied potential tomography, tracer methods (e.g. paracetamol), and breath tests. Regardless of the method used, the investigator must be aware of the limitations of the method in use, the large inter-individual variability and of the facto rs known to influence gastric emptying.
European Journal of Ultrasound, 1998
Tidsskrift for den Norske laegeforening
We examined the usefulness and image quality of a mobile miniaturised ultrasound scanner in a med... more We examined the usefulness and image quality of a mobile miniaturised ultrasound scanner in a medical ward. The instrument (SonoSite 180), weighing 2.4 kg, is a hand-carried system powered by batteries. In 25 days we recruited consecutively 36 patients aged 23-92. Four different operators evaluated the use of the scanner. We examined one group of patients with relatively simple diagnostic challenges (e.g. gallbladder stone) and one group of patients demanding more advanced visualisation (e.g. peptic ulcer, colitis). The scanner was easy to carry around and scanning was initiated in 10 seconds. We found satisfactory image quality on 81% of the examinations, despite the fact that in 28% of cases, bowel air and abdominal fat impaired acoustic penetration. Average scanning time was 7 +/- 3 minutes. In 83% of cases, mobile scanning adequately solved the clinical problem. Diagnostic work-up or treatment was changed because of scanning in 39% of the patients. In 64% of cases, standard-proc...
Studies in health technology and informatics
This paper describes a method for the acquisition and integrative processing of laparoscopic and ... more This paper describes a method for the acquisition and integrative processing of laparoscopic and endoluminal ultrasound images. We used a stepping motor attached to a stabilizing rig, interfaced to the laparoscope, or the ultrasound probe. 360 degrees laparoscopic scenes were constructed during minimally invasive surgery, and three-dimensional reconstructions were made of related ultrasound data. Integration of 360 degrees panoramas with geometric ultrasound models could be displayed as interactive scenes. This resulted in a better demonstration of the surgical field and topographic anatomy. In conclusion, this type of visualizations may be used in virtual reality simulations for documentation, education and in operative planning.
Tidsskrift for Den norske legeforening
If an ultrasound probe comes close to the area of interest, high ultrasound frequencies can be ap... more If an ultrasound probe comes close to the area of interest, high ultrasound frequencies can be applied. Endoscopic ultrasonography is performed by means of echoendoscopes or miniature probes using ultrasound frequencies between 7 and 30 MHz. A high frequency ultrasound image of the normal gastrointestinal wall usually shows five layers corresponding closely to the histological layers of the wall. Corrections have to be made, however, for interface echoes between layers with different acoustic impedances. We describe studies performed with the aim of correlating ultrasound images of the normal and diseased gastrointestinal wall with the histology. Ultrasound images of the normal gastrointestinal wall and pathological changes like ischemia, ulcers, tumours and inflammation are presented.
Ultraschall in der Medizin
Endosonography is an imaging method whereby a high frequency ultrasound probe is inserted into a ... more 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 pr...
Scandinavian Journal of Gastroenterology
Dieulafoy's vascular malformation may cause severe, potentially life-threatening gastrointest... more Dieulafoy's vascular malformation may cause severe, potentially life-threatening gastrointestinal bleeding. Endoscopic diagnosis may be difficult because of minute mucosal lesions, and additional intramural abnormalities are usually not encountered. Endoluminal high-frequency ultrasonography is a new modality for imaging intramural and perivisceral structures. We report two cases of recurrent severe gastric bleeding in which different endosonographic modalities were used in the diagnosis of Dieulafoy's malformation, and the impact of endosonography on therapeutic strategy is discussed. In the first case a radial-scanning 7.5/12-MHz echoendoscope and a linear 20-MHz miniature probe were applied for B-mode imaging in a stable-state patient who had undergone previous endoscopic sclerotherapy, and arterial flow signals from the small intramural lesion were recorded using a 10-MHz transendoscopic pulsed Doppler probe. In the other case urgent endosonography was performed shortly ...
Ultraschall in der Medizin - European Journal of Ultrasound, 2012
Ultrasound in Medicine & Biology, 2011
European journal of ultrasound : official journal of the European Federation of Societies for Ultrasound in Medicine and Biology, 2002
To diagnose and characterize subepithelial lesions of the gastrointestinal (GI) tract using endos... more To diagnose and characterize subepithelial lesions of the gastrointestinal (GI) tract using endoscopic ultrasonography (EUS) and search for markers of malignancy in stromal cell tumors. Fifty-four patients with suspected subepithelial lesions at endoscopy were examined using miniature ultrasound probes, integrated ultrasound endoscopes, or both. Surgical treatment was considered if a solid lesion had a maximum diameter of at least 3 cm, mixed echogenicity, or an ill-defined or irregular border. EUS disclosed 37 solid lesions and ten fluid-filled structures. In seven patients, including two with protrusion from a normal spleen, no pathology could be demonstrated. Thirteen patients were operated and 41 were observed clinically with (n = 9) or without EUS (n = 32) for a median follow-up period of 36 months. Twenty-three patients had an intramural stromal cell tumor. None of these were malignant, but increased mitotic activity was found in two medium-sized resected tumors with mixed ech...
European journal of ultrasound : official journal of the European Federation of Societies for Ultrasound in Medicine and Biology, 2002
Objective assessment of adverse reactions to food is a long-felt want. We report our preliminary ... more Objective assessment of adverse reactions to food is a long-felt want. We report our preliminary experience with a new endosonographic allergen provocation test. Twenty patients were examined, seven patients having food allergy and 13 having food intolerance. The duodenal mucosa was challenged with allergen extracts via a nasoduodenal tube. The responses were recorded using a miniprobe for endosonography through the tube. Thereafter, intestinal lavage was performed by giving 2 l PEG solution containing micro Ci (51)CrEDTA. The gut lavage fluid and urine for 5 h were collected. Increased mucosal thickness in response to provocation was recorded in 11 patients, but not more often or pronounced in the allergic than in the intolerance group. Interestingly, increased mucosal thickness associated with a new echogenic layer was seen in two patients and a sustained duodenal contraction, lasting 15-20 min associated with pain, in another two. Intestinal permeability and inflammatory mediator...
Scandinavian Journal of Gastroenterology, 2015
Ultrasonography (US) is a safe and available real-time, high-resolution imaging method, which dur... more 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.
Digestive diseases and sciences, 1997
Following cholecystectomy for uncomplicated gallstone disease (GS) some patients experience persi... more Following cholecystectomy for uncomplicated gallstone disease (GS) some patients experience persistent symptoms suggesting an underlying functional disorder. To study this phenomenon, we have compared symptomatic GS with functional dyspepsia (FD) patients and healthy individuals (C) with respect to putative pathogenetic mechanisms. Gallbladder and gastric antrum volumes were estimated with three-dimensional (3D) ultrasonography before and 10 min after ingestion of 500 ml meat soup in 18 patients with GS. Volume estimation was performed digitally after interactive manual tracing and organ reconstruction in three dimensions. Respiratory sinus arrhythmia (RSA) was calculated to index vagal tone. Abdominal symptoms were assessed by interview. The results were compared to previously published data in patients with FD and C investigated with the exact same methods. No significant differences were found between groups with respect to fasting gallbladder or gallbladder emptying. Antral volu...
Ultrasound in Medicine and Biology, 2006
Strain rate imaging (SRI) enables study of deformation in soft tissues. The aim of this study was... more Strain rate imaging (SRI) enables study of deformation in soft tissues. The aim of this study was to evaluate the accuracy of SRI in measuring strain in the porcine antral wall in vitro. An experimental set-up enabled controlled distension of a porcine stomach in a saline reservoir. Radial strain obtained by SRI was compared with radial strain calculated from B-mode
European Journal of Ultrasound, 1995
Objective: Severe arterial bleeding from the gastrointestinal (GI) wall usually arises from submu... more Objective: Severe arterial bleeding from the gastrointestinal (GI) wall usually arises from submucosal or subserosal arteries. Endosonography (EUS) is a method which can image small structures like GI wall vessels and, thus, has potential for improving the diagnosis and directing the therapy of vascular disorders of the β tract. Furthermore, ultrasonography is increasingly used in open and laparoscopic surgery to
Doppler strain rate imaging (SRI) was evaluated in vitro using a silicone strip phantom mimicking... more Doppler strain rate imaging (SRI) was evaluated in vitro using a silicone strip phantom mimicking slowly moving tissue. A test apparatus was developed that enabled controlled strain experiments with variable strain and strain rate to be performed. SRI strain was measured at eight different calculated strains (range 5.7 to 63.4 %) at three different pump speeds with tissue velocity 0.1, 0.5 and 1.0 mm/s. The effect of varying tissue velocity and strain sample size on the measured SRI strain was elaborated. SRI strains agreed well with calculated values for strain when SRI strain was measured as the average over the whole strip cross-section and the strain sample size was 1.9 mm (mean difference ؍ 2.78%, limits of agreement ؎ 9.97% for tissue velocity 1.0 mm/s, n ؍ 8). The variance was substantial if single central samples were used, especially for strain sample size of 0.8 mm (mean difference ؍ ؊7.47%, limits of agreement ؎ 20.90 for tissue velocity 0.5 mm/s, n ؍ 24). Increasing the strain sample size to 1.9 mm removed some of the underestimation (giving mean difference of ؊4.46%, n ؍ 24). We found low intra-and interobserver variation. This study indicates that, for the SRI method to give accurate estimates of strain, strain sample size should be in the region of 2 mm. Averaging over several ultrasound (US) beams increased the accuracy further.(E-mail: Knut.Matre@med.uib.no)
In the last two decades, there has been substantial development in the diagnostic possibilities f... more 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 methods have 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.