https://www.gastrojournal.org/article/S0016-5085(01)00796-X/pdf

Chronic pancreatitis: Diagnosis, classification, and new genetic developments

The technical part of these Guidelines and Recommendations, produced under the auspices of EFSUMB, provides an introduction to the physical principles and technology on which all forms of current commercially available ultrasound elastography are based. A difference in shear modulus is the common underlying physical mechanism that provides tissue contrast in all elastograms. The relationship between the alternative technologies is considered in terms of the method used to take advantage of this. The practical advantages and disadvantages associated with each of the techniques are described, and guidance is provided on optimisation of scanning technique, image display, image interpretation and some of the known image artefacts.

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EFSUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography. Part 1: Basic Principles and Technology

The clinical part of these Guidelines and Recommendations produced under the auspices of the European Federation of Societies for Ultrasound in Medicine and Biology EFSUMB assesses the clinically used applications of all forms of elastography, stressing the evidence from meta-analyses and giving practical advice for their uses and interpretation. Diffuse liver disease forms the largest section, reflecting the wide experience with transient and shear wave elastography . Then follow the breast, thyroid, gastro-intestinal tract, endoscopic elastography, the prostate and the musculo-skeletal system using strain and shear wave elastography as appropriate. The document is intended to form a reference and to guide clinical users in a practical way.

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EFSUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography.Part 2: Clinical Applications

Christian Maaser,a Andreas Sturm,b Stephan R. Vavricka,c Torsten Kucharzik,d Gionata Fiorino,e Vito Annese,f Emma Calabrese,g Daniel C. Baumgart,h Dominik Bettenworth,i Paula Borralho Nunes,j, Johan Burisch,k, Fabiana Castiglione,l Rami Eliakim,m Pierre Ellul,n Yago González-Lama,o Hannah Gordon,p Steve Halligan,q Konstantinos Katsanos,r Uri Kopylov,m Paulo G. Kotze,s Eduards Krustiņš,t Andrea Laghi,u Jimmy K. Limdi,v Florian Rieder,w Jordi Rimola,x Stuart A. Taylor,y Damian Tolan,z Patrick van Rheenen,aa Bram Verstockt,bb, Jaap Stokercc; on behalf of the European Crohn’s and Colitis Organisation [ECCO] and the European Society of Gastrointestinal and Abdominal Radiology [ESGAR]

https://www.zora.uzh.ch/id/eprint/181209/9/2018_05_02_Manuscript1_ECCO_ESGAR-DiagnosticsGL_c1-3.pdf

ECCO-ESGAR Guideline for Diagnostic Assessment in IBD Part 1: Initial diagnosis, monitoring of known IBD, detection of complications

Ultrasound is an inexpensive and widely used imaging modality for the diagnosis and staging of a number of diseases. In the past two decades, it has benefited from major advances in technology and has become an indispensable imaging modality, due to its flexibility and non-invasive character. In the last decade, research investigators and commercial companies have further advanced ultrasound imaging with the development of 3D ultrasound. This new imaging approach is rapidly achieving widespread use with numerous applications. The major reason for the increase in the use of 3D ultrasound is related to the limitations of 2D viewing of 3D anatomy, using conventional ultrasound. This occurs because: (a) Conventional ultrasound images are 2D, yet the anatomy is 3D, hence the diagnostician must integrate multiple images in his mind. This practice is inefficient, and may lead to variability and incorrect diagnoses. (b) The 2D ultrasound image represents a thin plane at some arbitrary angle in the body. It is difficult to localize the image plane and reproduce it at a later time for follow-up studies. In this review article we describe how 3D ultrasound imaging overcomes these limitations. Specifically, we describe the developments of a number of 3D ultrasound imaging systems using mechanical, free-hand and 2D array scanning techniques. Reconstruction and viewing methods of the 3D images are described with specific examples. Since 3D ultrasound is used to quantify the volume of organs and pathology, the sources of errors in the reconstruction techniques as well as formulae relating design specification to geometric errors are provided. Finally, methods to measure organ volume from the 3D ultrasound images and sources of errors are described.

https://iopscience.iop.org/article/10.1088/0031-9155/46/5/201/pdf

Three-Dimensional Ultrasound Imaging

https://www.gastrojournal.org/article/0016-5085(92)91717-I/pdf

Antroduodenal motility and movements of luminal contents studied by duplex sonography.

The purpose of this study was to evaluate the accuracy and precision of a three-dimensional (3D) ultrasound system in volume estimation of abdominal organs in vitro. A mechanical sector scanner coupled to a stepping motor recorded images of porcine stomach and kidneys. The transducer was tilted through 88° yielding 81 frames, and volume estimation was performed digitally after interactive manual contour indication and organ reconstruction in 3 dimensions. This 3D system showed good correlation (r = 0.998) between estimated and true volumes. Volume estimation of stomach and kidneys using 3.25 MHz probe demonstrated limits of agreement of 0.877 to 1.146 and 1.007 to 1.125, respectively, depicting estimated volumes as a proportion of true volumes in 95% of the examinations. Intra- and interobserver variation of the tracing procedure revealed low values. We conclude that this 3D ultrasound system performs high accuracy and precision in volume estimation.

In vitro evaluation of three-dimensional ultrasonography in volume estimation of abdominal organs.

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.

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

The objective of this study was to evaluate the accuracy of a three-dimensional ultrasound system (3D-US) compared with Magnetic Resonance Imaging (MRI) in volume estimation of human kidneys in vivo. Twenty healthy volunteers were scanned fasting in supine position with MRI and with a 3D-US. An ultrasound sector scanner with a mechanical transducer coupled to a tilting motor provided images of multiple sections of kidneys. A 3.25-MHz transducer was tilted through 88 degrees yielding 81 frames, and volume estimation was performed on a Unix workstation after manual contour indication. Data acquisition with MRI was performed by using a 1-T magnet. Eighteen included kidneys [mean +/- standard deviation (SD)] measured 155.7 +/- 26.4 mL (range 110.0-205.0 mL) by 3D ultrasound and 171.8 +/- 24.6 mL (range 127.5-211.0 mL) by MRI, yielding a good correlation (r = 0.82, p < 0.001) between the two methods. The mean difference was -16.1 +/- 15.6 mL (SD) and the limits of agreement were -49.0 mL. We conclude that this 3D-US is accurate in volume estimation of human kidneys in vivo.

In vivo comparison of 3D ultrasonography and magnetic resonance imaging in volume estimation of human kidneys.

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.

Svein Ødegaard

Papers

Antroduodenal motility and movements of luminal contents studied by duplex sonography.

In vitro evaluation of three-dimensional ultrasonography in volume estimation of abdominal organs.

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

In vivo comparison of 3D ultrasonography and magnetic resonance imaging in volume estimation of human kidneys.

Sonography of the small intestine.